Linearized Theory of Wind-tunnel Jet-boundary Corrections and Ground Effect for VTOL-STOL Aircraft

14 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION appendix A. The results are then as follows: encountered if this condition is not met. A subsequent section of this l)aper will indicate a (31) method of extending this analysis to include cases AWL=--I (3 COS' x+l) A"

2 wo

in which tim height above the ground may be small.

xcos3x+sinxeosx

The case of an open tloor does not have a practi- cal significance such as ground effect, but it will (32) be used in discussing the results obtained for open

+3 ta, We

wind tunnels. Tile equations for tim correspond- ing interference factors are derived in closed form Aw.=_(2si,lXcos3X--sinax,'osX--4cos'_X for tile center of lift in appendix B. These inter- ference factors are shown in figure 5(b).

(33)

' 2)Am

--2 tall _ Uo APPLICATION OP RESULTS Finding Uo, We, and x.--It will be observed from equations (5), (6), (ll), (12), and (22) that _u.---l(4sinxcos'X--3si,?x,'os'X it is necessary to know Uo, We, and x for any given 1 cos X \ Am (34) operating condition in the wind tunnel ill order to solve for the interference velocities. Reference 15 presents a simple nomographic solution for These interference factors are shown in figure 5(a) these quantities. The pertinent ch,trts are pre- for ground effect.

sented herein as figures 6 and 7. In order to use Since the model was assumed to be vanishingly these charts it is only necessary to know tim small in the analysis, it is necessary that the height above the ground be reasonably large with respect On,deg to the model dimensions. Reference 14, which 60 50 40 50 20 I0 0 treats a similar case for lifting rotors, indicates that severe changes in the interference velocities may be On, deg 90 80 70 60 50 40 50 20 IO o .6

I

.4 .Z _/_,,D ............

_, 2"-_- -,4

J

I

/

-.S

// I

-I.0 -I.0-- -I.2 (a) {b) -1.2 ,/-'/'] -1'40 tO 20 30 40 50 60 70 80 90 "I'40 I0 20 30 40 5O 6O 7O 80 90 X, deg x,deg (a) Closed boundary (ground effect).

(b) Open boundary.

FmuaE 5.--Boundary interference factors for only lower wind-tumwl boundary. F[ouR_ 5.--Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 15

5op "u 8 _0 ooo o o o o o III I I I I I I I I 7\ _ ,1,-t O, O. O. O, O, O. 0 0 I (.o !

e,J

o

I o 4-) \ O I c; to I

"9

All o,J rd !

>1#

o o0 Atl c_ _ o V @ I oJ I co I @ .,,.-t I @ 0 0_ !

_D I I I I I I Li i A___i 0 0 0 0 o o o O_ .,,-4 Bap 'X 16 TECHNICAL REPORT R--124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION O >l, O O O O !

O tM !

G0 0 0 o 0 o O !

o oO " Q ..f !

(.0 !

I !

o A, o

>I;: _I_

o>I;: i All A II I _0 I "T

%

u v !

I !

\

,o1,=

!

0 _ 0 u_ N _ - - o ,o1,: JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 17 O ,,-4 4; ,,-4 I Sap 'X 18 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION forward (or wind-tunnel) velocity, tile induced where M, is the vertical mass flow required to drag-lift ratio, and a reference velocity wn obtain the given lift, .M_ is the longitudinal nmss defined as flow required to obtain the given drag, and Mr is tile mass flow through the wind tunnel. Tile

w,=--/ i (_s)

advantage of using equations (40) to (43) is that V npAm it is only necessary to deal with simple and easily where n is the ratio of the final imlu('cd velocities found ratios rather than tl,e actual physical ill the far wake to tile initial induced velocities quantities; for example, uo and We at tlle model. If tile corrections are M,_ A,,/AT applied by machine data-reduction processes, Mr V/we (44) these charts amount to the simultaneous iterative solution of the equations and, with tile use of equation (38), Woy= 1 (36) M. M_ D, (45) 1 '/V+ D_\2

• -/_=i-7 L

and If the forward velocity is actually zero, it will, V V We of course, be necessary to use the more basic .... (37) Wh 'U)o Wh forms given earlier.

Interference at model.--Having found the four Then, tile mean value of the longitudinal induced interference velocity ratios defined in equations velocity is obtained as (40) to (43), it is evident that tile total interference at tile model is given by D_ Uo=-£ We (38) ,Sw Aw_, l_/twa -V=-V----W (4_) and the wake skew angle is obtained as and

Ixl=eos-' (w__o'_' {39)

kwh/ AU AUL I_hU D (47) V =--W- ---V-- V . D_ where x is positive if _----_o_>-_- and negative if The solution to the problem could now be stated V D, in terms of a siufilarity viewpoint; that is, the

-%0<Z

performance of the model in the wind tunnel is equivalent to the performance in free air with an Alternate form for interference velocities.--lf increased rate of sink given by _w and an increased the forward velocity is not actually zero, the velocity given by 5u.

equations for the interference velocities may be Corrections to data.--Unfortunately, the data rewritten in a form more convenient for compu- from a usual wind-tunnel test are generally re- tational ptn'poses. Note, for example, that equa- quired for a level flight condition and not for a tions (22) may be rewritten as rate of sink whictl cannot be predetermined. From figure 8, it may be seen that, with respect to the aWL _ pAmwo x A¢_ (40) _ w,L --_uw L effective relative velocity in the wind tunnel, the pArV 'Mr model is now operating at an angle of attack given by AuL _ pA,,wo x ]lI_ (41) -V -=_''_ _ .... "M_ at----a-}-Aa (48a) Z_WD , pA,,uo . AI= where V =°_'_' o-2Wv=_"_Vi-_ (42) AW ----tan-' Aw/V Aa----- tall- t __ (48b) _u AUD - pA._uo x 5I= V+Au 1 + V

-W=_,_,_ _ .... ,,M-;_ (43)

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 19 tion employed for the free boundaries in this analysis depends upon the induced velocities be- ing small in comparison with the wind-tunnel velocity; that is, the shape of the free edges of the jet is unaltered by the presence of the model.

For very low speeds, which correspond to low skew angles, this condition is severely violated iesulfon_ force since the induced effects may be large even when the model is very small. This is particularly true when the free boundary is the floor of the wind tunnel. (See fig. 9.)

In the limiting case of hovering, the wind- Model tunnel jet does not even exist and the open bound- V Au aries will have no effect whatever. (Note that the presence of the test-chamber walls exterior to FIOVRE 8.--Sketch illustrating correction of forces, the jet is ignored.) Under such llovering condi- velocities, and angles at model.

tions there will be no correction whatever to the and at a new forward velocity given by data obtained in a completely open wind tunnel.

Provided that the floor of a wind tunnel closed on Vc= 4 (V + _xu)_ + (aw)_ (49a) the bottom only can be assumed infinite in breadth, the corrections at zero skew angle will correspond or in terms of.dynamic pressure to those obtained herein for the closed floor only (with none of the free bomldaries considered).

_----(1 ' hu\2' /Aw\2 At low forward speeds other than hovering, it q \ ÷V) -I-(-_) (49b) is assumed herein that the interference velocities for the open wind tunnel will lie somewhere Since lift and drag are always defined as being between zero and those calculated for the com- perpendicular and parallel, respectively, to the relative wind, it will tiler] be necessary to resolve pletely open wind tunnel. Similarly, at low these components with respect to the new effective forward speeds, it is assumed that the interference velocities for the wind tunnel closed on the bottom velocity; that is, only will lie between those calculated for the Lc-----L cos Aa--D Sill _Xa (50a) complete wind tunnel (closed bottom and three open boundaries) and tllose calculated for only D_=L Sill ha+D cos aa (50b) tile closed floor of the wind tu|lnel (without COtl- Finally, the lift and drag coclIicicnts may be sideration of the three open boundaries). Tile formed from the corrected lift and drag forces by consequences of these assumptious are discussed using the dynamic pressure given by equation more completely in a subsequent section of tiffs (49b). Notice that any other coefficients based paper.

on dynamic pressure must also be foruled using It shouhl also be noted that the present analysis the corrected dynamic pressure. For example, treats all wind tunnels on the assumption that the wind-tunnel boundaries extend to infinity both Cr in front of and be]find the model. Reference 6 CT._=q/_ (51a) treats the case of wiled tunnels of finite test-section and length and shows that large effects may exist when the test section is at least partly open. Such c_ _--(_ (5_b) ' qdq effects exist in the present case as well; however, inclusion of these effects is substantially beyond A sample case of application of corrections to test the scope of the p|'esent study.

data is worked out, step by step, ill appendix C.

NUMERICAL CALCULATIONS OPEN BOUNDAR|ES AT LOW SPEEDS NuJacrical values of tim correction factors were it will be observed that the boundary eondi-

20 TECHNICAL REPORT R-124-NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

FIGURE 9.-Photograpb of flow through bottom of an open wind tunnel caused by a rotor at low forward speed.

obtained by evaluating equation (23) on the

The entire numerical results are presented in

digital computers at the Langley Reaserch Center

tabular form in references 9 to 12. (A major

(IBM 704 and IBM 7090 electronic data proces- portion of these results is presented graphically sing systems). With each computer, the capacity in subsequent sections of this paper in order that was such that it was possible to compute all four the general trends may be discussed.) The wind- correction factors for all seven cases treated by Lunnel configurations treated in these tables are equation (23) (28 answers in all) simultaneously. completely closed, closed on the bottom only, and In all cases, it was assumed that all images having completely open. The closed-floor-only (ground both nand m greater than 3 provided negligible effect) and open-floor-only cases are also treated.

contributions. On the IBM 704 computer ap- For those wind tunnels which are completely

proximately 45 seconds were required for each closed and those which are closed on the bottom case, and on the IBM 7090 computer approxi- only, corrections to ground effect are given. In mately 6 seconds were required for each case. The all cases, wind-tunnel width-height ratios 'Y of IBM 7090 computer, as installed at the Langley 0.5, l.0, l.5, and 2.0 are considered. For laterally Research Center, is somewhat less complete than centered models (11=1.0), the longitudinal, lateral, many commercial installations. It is estimated and vertical distributions of the interference that additional time savings on the order of 20 factors are given for ratios of semiheight to height

percent could be obtained with the complete

of model above floor r of 0.6,0.7,0.8, 1.0, 1.5,2.0, computer.

4.0, and 10 . 0. The lateral distribution of the

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 21 at x=90 °. The corroction from classical thoory is interference factors is given for models laterally offset so that _ is 0.25, 0.50,and 0.75 and simul- S taneously _" is 0.7, 1.0, 2.0, and 4.0. When a,_=_ _ c_ (57) interferencefactors for other locations are re- quired,they may be computed from the equations ]t is evident from the comparison of equations (56) derived earlier in thisreport.

aml (57) that, under these conditions, _,.,. when divided by -4 coincides exactly with the eht.qsical RESULTS AND DISCUSSION wind-tulmel correction factor. (Seeref. 8.) Thus, for these cases, ttle present theory contains INTERFERENCE AT THE MODEL exactly the older theory as a limiting case.

The interference factors at tile model for use ill When the model is not mounted in tile center correcting (!ate to free-air comlitions are presented of the tunnel (f#1.O) or when the tunnel bouml- in figures 10 to 21. The correction factors for aries are tier completely s.yl|it,mtrica.l (for example, correcting directly to a ground-effect comlition the wind ttumel which is closed on the bottom are presented in figures 22 to 29.

only), equations (52) to (57) still hold aml --_,_.L/4 Correctionsat x=90%--Exami_w limt the (.om- still correspom[s to & On the other hat,l, the pletely symmetrical cases Ire,ted herein; that is, other three correction factors are no longer always those cases where the model is centered (i'= 1.0, zero at a skew angle of 90 ° . ltowcver, if the n=l.0) in a completely symmetrical (either com- speed is high enough, and if tile lift coefficient is pletely open or completely closed) wind tmmel.

low enough, to achieve skew angles near 90 ° , then For these cases, at x=90 °, symmetry can be used Uo and We will both be small. Under such con- to show that _f=.L, $_..m aml 5,,.,, must all be ditions, the contributions of _._,, _.L, and _.o idellticldly zero. (Actually, the tables of refs. 9 to the total iatcrference at the model will be small to 12 show small values which are indicative of for the usual model nmunting heights. Thus, in the accuracy of tile calculation.)

general, tile previously available correction factors Now examine the remaining factor 5,_.L. The may be considered as nearly, although not correction resulting fi'om this factor is (from eq.

exactly, representing a limiting case of the present (40)) analysis.

Effect of x and _'._Figures 10 to 21 illustrate AWL, t_ AmW° -_ = W.L Ar y (52) tile large dependence of tile correction factors upon skew angle. In general, for model locations at or For a simple wing, of se,,|ispan s, the momentum below the center of the wiml tunnel, the correction area is factors approach those calculated for only the A,,=_rs 2 (5:9 wind-tmmel tloor as the skew angle apl)roaches zero. (This result mtly be noted directly in figs.

Furthermore, from momentum considerations, the 14 to .17 for the wind tu,me] closed on the bottom lift is only; in figs. 18 to 21 for the open wind tunnel; L= prs2V(--2Wo) (54) and in figs. 22 to 25, where the differences between so that the factors for the complete tutmel and those for the tunnel floor only are shown for the closed wind --L - CLSV (55) Wo=_= 4_rs 2 tunnel.) This trend is not as marked if the model is mounted above the center of the tunnel since Substitute equations (53) and (55) into equa- the upper boundary, because of its closer prox- tion (52), and then assume that 5w,_ is small in imity, then has an increased effect.

comparison with V, to obtain The effect of the height at which the model is mounted is extremely pronounced. Figures 10 to A(x_tan Ao_-----AWL= -5t_'L S V 4 Ar (2 (56) 21, in particular, show large differences in the correction factors even when the vertical model Equntion (56) may be compared with the classical height is changed by as little as _6 of the total wind-tunnel corrections where tile wake is always height of the wind tunnel. (Compare i'=0.8 with 22 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ?=1.0.) Thus the choice of model location offers effect are probably more accurate than the a powerful means of controlling the magnitude of corrections to free air.

the corrections required ill any specific test. This If corrections to ground cffcct are only employed point is discussed in a subsequent section of this at, the lowest speeds, which correspond to tran- paper.

sition from hovering to forward flight, correction Effect of %--It is evident from figures 10 to 29 to the ground-effect condition becomes less that the correction factors become smaller as % objectionahle since i,l practice such flight con- the ratio of wind-tunnel width to height, becomes ditions will usually be encountered near the smaller. At very low wake skew angles, where the ground.

corrections are ahnost the same as those for tile Selection of vertical height in tunnel.--The floor only, the correction factors vary almost in large effect of vertical height on the correction direct proportion to _,. it is generally physically factors affords an additional control over the possible to mount a larger model in the wider wind nmgnitude of tile correction factors. This is tunnels; however, some consideration must be illustrated in figure 30 for the case of a closed given to the magnitude of the corrections that may wind tunnel with "x----2.0. The difference in be encountered if this is done.

vertical height in figure 30 is only ]_ of the total Classical jet-boundary correction theory (for wind-tunnel height, which illustrates the powerful example, ref. l) has pointed out several combina- nature of this means of control. For maximum tions of wind-tunnel configuration and proportion effectiveness, the range of skew angles under which lead to zero corrections for a small model.

which the tests will be conducted should be known It is notable that no combination of configuration in advance so that the model height can be and proportions ti'eated herein leads to a zero- chosen so as to minimize tile corrections in this correction tunnel for the entire range of skew angles. range of skew angles.

MINIMIZING CORRECTIONS CHOICE OF WIND-TUNNEL CONFIGURATION In selecfing a model size and a wind tunnel for It has been noted previously that as the skew any test, it shouht be borne in mi,ld that there is angle approaches zero, the correction factors, for no real substitute for a very small model in a very models at or below the wind-tunnel centerline, large wind tunnel. This procedure is, of course, approach those for only the floor of tile wind not always possible, particularly when the choice tmmel. As a consequence, there is little difference is restricted to models which may already be on between the calculated correction factors for the hand, or to wind tumlels in which testing time is closed and for the closed-on-the-bottom-only con- available" When model size and wind tunnel are figurations. Both approach nearly the same fixed by such considerations, at least two alterna- corrections, ,lamely, those of the physically realiz- tive means of reducing the correct.ions are still able grouml-effect condition, as the forward speed available. These are discussed in the following and skew angle approach zero.

paragraphs.

In contrast, the correction iactors for an open Correction to ground effect.--The tirst means of wind tunnel apllroach those for an open floor at reducing the magmitudo of the boundary correc- low skew angles. Unfortunately, an open floor tions is to correct the data to the equivalent has no physical counterpart in practice. Further- ground-effect condition rather than to the free-air more, the correction factors for the open floor ara, condition. A comparison between figures 10 to in general, substantially diffe,'ent from those for 17 and figures 22 to 29 indicates that this procedure ground effect. Cons(_queutly, correction to a leads to substantially smaller corrections at low ground-effect condition leads to impossibly large skew angles. This procedure is objectionable, correction factors.

however, in at least one regard--namely, that Correction to ground effect is not in itself a ground-effect data may ,lot be desirable. On tile vital matter; however, the effect of the free other hand, these corrections are obtained by boundaries at low speed is vital. As discussed o,nitting the closest and therefore least accurate previously, the effect of the free "boundaries image of the reflection system. Thus, when the vanishes as the forward speed vanishes. Thus, corrections are large, the corrections to ground at low speeds, the actual corrections for a wind JET-BOUNDARY CORRECTIONS AND (]ROUND EFFECT FOR VTOL-STOL AIRCRAFT in which this is true is that of te_ts in which tunnel closed on the bottom only are probably between those for the complete wind tunnel and pitching moments are measured. Hero there will be a correction to the moments which will, those for ground effect. Since the differences between these two sets of correction factors are in general, depend upon the difference in tile interference at tile center of lift and the interfer- small, there will only be a small uncertainty ence at the tail location. Evaluating this cor- (figs. 14 to 17) in the proper values to use. For rection requires a knowledge of the longitudinal it completely open wind tunnel at low speeds and distribution of the interference behind the model.

high lift coeflicients, the proper correction factors This information is given in the tables of references probably lie between zero and those computed 9 to 12. For certain cases, the interferences are for the complete wind tunnel. Figures 18 and 21 show these differences to be very large, and, displayed graphically herein in order to assist the discussion of the nature of these effects.

consequently, there will be a large uncertainty Corrections to free air.--The interference factol_ in tile proper values of the correction factors.

for correcting to free air from a closed tunnel are As pointed out previously, reference 6 indicates presented in figures 32 to 35 for a model centered large effects of jet length on the corrections, even at x=90 °. For other skew angles these in wind tunnels having width-height ratios of 2.0, 1.5, 1.0, and 0.5. The corresponding interference jet-length effects may be even greater since they factors for wind tunnels closed on the bottom wouhl probably exhibit a dependence upon whether the assumed wake intersects the free only are presented in figures 36 to 39.

It will be observed that the corrections for both lower.boundary or whether it intersects the closed lower boundary of the exit cone. In view of tile wind tunnels are roughly similar in trend. This is particularly true at low skew angles. This result foregoing considerations, low-speed tests of VTOL- STOL models in open wind tunnels are not nfight be expected since it has already been recolmnended.

remarked that at low skew angles the corrections are ahnost entirely due to the floor which is iden- If only an open wind tunnel is available, it should be preferable to install a ground board or tical for either configuration. For wind tunnels with 3"__ 1.0, the main effect of decreasing 3' is to retlection plane along the lower edge of the jet in order to simulate a tunnel with a closed floor.

decrease the magnitude of the correction factors.

This solution has proved feasible even in wind This does not hold, in general, for the narrow, tunnels as large as the Langley full-scale tunnel deep wind tunnels (3,=0.5) where tile side boundaries, because of their relatively closer prox- which has a test section 30 feet high and 60 feet imity, can have pronounced effects upon the wide (fig. 31). In this case, an available rellectiou distribution of the interference factors.

plane designed for semisl)an wing tests was modified to accept the normal tunnel mounting The effect of skew angle upon the longitudinal struts. Calibrations of the tunnel jot with the distribution is very pronounced. Notice that the retleclion plane in place were thus already awfil- interference factors giving AW behave in roughly the same manner. For x=0 °, the maximum able. Many open wind tunnels already have value of these correction factors is found at the such semispan reiloction planes and can be simply model location and they decrease both in front of, modified to accept a complete model. Even in those cases where a retlection plane does not and behind, this point. As the skew angle in- already exist, construction and calibration of a creases, the point of maximum interference shifts rearward an(t i_ usually found nearly directly reflection t)lano may be i)referal)le to testing in the above the point at which the assumed wake inter- uneven flow often found in the return passages.

sects the floor. For x=90 °, of course, the final LONGITUDINAL DISTRIBUTION OF INTERFERENCE value of _._, well downstream will be twice that at the model. This is in accordance with previous While a klmwledge of the interference at tile model itself will of tell he adequate if the model is work on wings. ,, sufIicienlly small, there are many cases in which The factors givinlg the horizoutal interference it. is necessary to know much more about the velocities all vary in the same manner, but the trends are rather diffel'cut from those discussed distribution of the interference over the regioz, occupied by the mod(,l. The most obvious case previously. It will be seel_ that, in gcaeral, the 24 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION horizontal interference velocities reverse sign at corrections are small by comparison with correc- tions to tile free-air condition. The factor some point at or behind the model location. Thus, if the walls induce a horizontal velocity opposing _.o, however, displays a somewhat different behavior. In this case, the reduction in magnitude the forward velocity in froiJt of tile model, then, for the same condition, but well behind the model, as the model is lowered is much slower, and a substantial correction factor exists even at _-= 10.0 the walls will induce a horizontal velocity which where tile nlodel is virtually buried in the Iloor.

adds to the forward velocity. Notice too that, even for cases in which the corrections are zero at It will be noted that in this case the effect of skew the model, there may be substantial corrections angle diminishes markedly as the model is lowered.

Thus, at these low nlodel heights, a correction to required at points ahead of or betfind the model (fig. 35, for example). the horizontal velocity at the tail may still be Ground effect.--The longitudinal distribution of required; however, it may be possible to apply this correction without actually having to find interference in ground effect (for only the closed floor of a wind tunnel) is shown in figure 40. The the skew angle first.

trends with skew angh; will not be discussed in Measurement of forward voloeity.--Thc dis- detail since they are essentially as given in the tribution of horizontal interference through the preceding section. Note that figure 40 is presented test chamber has important consequences with in terms of x/h, which is more appropriate here.

regard to the measurement of the wind-tunnel The quantity x/h is given by velocity itself. Notice that if the forward velocity x x is measured within the test section by means of a _= __ (58) pilot tube or similar device, the walls, because of the presence of tile model, will induce a horizolital Corrections to ground effect.--The loltgitudinal velocity in the prescl_ce of the measuring device.

distributions of interference factors for correcting The proper correctioll factor t,o apply in such a directly to ground effect from a closed wind case will be equal to the difference between the tunnel with 3,=1.0 are given in tlgures 41 to 44.

correction factor at the tuodel and the corrcctiol_ The correst)ondillg interference factors for a wind factor at the measuring device. Tile measure- tunnel which is closed on the bottom only are merit can become even more difficult if tile velocity given in figures 45 to 48.

measuring device is sensitive to small changes in The corrections to ground effect, of course, do I)itch angle, since it will then be found necessary not inchJ(le the effect, of the it_tagc system directly to correct the measurillg device for tile w,rti_'ei below the wil_d-tutHlel lloor. Consequently, the interference velocity as well. Systetns which etrccts of the upper boundary and the sides of the measure forward velocity by sensing static • , / test. chamber assume a relatively greater im- pressure m the sotthng chatuber should lie much portance in deten,fining the interference. These less sensitive to such efrects.

three walls are all completely closed for the closed tunnel and completely open for the wind LATERAL DISTRIBUTION OF INTERFERENCE tunnel which is closed on the bottom only. Con- A knowledge of tile lateral distribution of sequently, it is fouled that the correspondillg interference is of importance in assessing the de- factors for tile two willd tunnels are generally of gree of nonuniforlnity of the inLerfercnce over the opposite sign and that they are usually of the same span of a model. As will be shown in subsequent order of magtlitude in absolute wtlue.

sections of this paper, tl,e lateral distributio_ of It will be seen thai 6w.n, 6,,.L, and 5¢._, all interference is also of i_@orta,_ce ill estimatittg the approach zero rather rapidly as the model is interference effects on models having elements brought closet" to the lloor, hi the case of 5,.t. and arranged in side-by-side configurations as well as 5,_.z, this decrease is so rapid t_hlit these correction in extending the analysis to l,_odels of finite span.

factors at'c usu,lly coJ@h'tely Jlegligiblc for models Closed wind tunnels.--The lateral distribution mounted t_t, or below, the wind-tunl_el centerlinc.

of tile interference fact_ors for closed wind tunnels The saz_lc result is found for low skew angles in the case of 5_.L; however, tile reduction is some- is shown in figures 49 to 52. The interfcrellce what less rapid at_ higtl skew angles. Evell so, the factors are plot_tcd against y/B which may be

JET-BOUNDARY CORRECTIONS ANDGROUND EFFECT FOR VTOL-STOL AIRCRAFT 25

obtained by noting that

which is dosed on the bottom only are shown in figures 62 to 65. It will be observed, in general, ?_/_ 1 ,Jff_] that these factors are much smaller and much less (r,:t) B--_ H variable across the tunnel width than the corre- sponding factors for corrections to tim free-air It will be seen that the interference factors condition. (Note the change in scale.)

which determine tile vertical interferene_ velocity Laterally offset models.--Tlm lateral distribution are substantially less near the sides of the wind of interference when the model is laterally offset tunnel when tile width-height ratio 3' is large and is shown in figures 66 to 69 for a closed wiud tile skew anglo x is small. Tl,is effect is much tunnel with 3"=2.0. The correspondi,ig factors less markc'd for small values of 3" aml large values for a wind tunnel witch is closed on tile bottom of X. indeed, for 3"=0.5 (fig. 49(d)) the I reild is only are slmwn in figures 70 to 73. These factors actually re.versed througholit the entire range of ilre plotted against tile lateral locatioil as Ineasured skew angles. The lateral variation in the inter- froin the center of tile wind tiliiliel rather tiiaii tile ference factors a,,L ,nd _i_.z, is not as great as tile location as llleastlred frolll tiio nlodel; that is, tiie variation in the factors a:.,. and _:.D. In general, factors tu'e plotted against y'lB which is defined the longitudinal interference factors are found to as follows: be most positive at, the lnodel and least positive ' y near the walls.

Wind tunnels closed on the bottom only.--The lateral distribution of the interference factors for The location of the model for each curve is wind tunnels closed on the bottom only is shown indicated by the symbol on eaeh curve.

in figures 53 to 56. These figures are also pre- As expected, the distribution of interference is sented i,l terms of y/B.

no longer symnlctrical about the model location It is observe(I in figures 53 and 55 that the when the model is not ntounted in the center of interference factors giving the vertical interference the wind tunnel. Tile differences in interference velocities are uniformly most negative at the at a given distance fi'om the model are small when model nnd become less negative toward the walls.

the model is still near the center of the wind The opposite trend is shown in figures 54 and 56 tunnel (r/=0.75) but become increasingly larger for tile interference factors yielding the horizontal as the model is mounted nearer the wind-tunnel interference velocities when the width-lieight ratio wall (,7= 0.25).

is large. For small width-lleight ratio, however, hlterference factors have only been calculated there is a tendency for this trend to reverse, for niodel loclttions approilehhig one widl of tile yiehling the most negative factors at the model.

wind tunnel. There is all obvious syulluetry with Ground effect.--The lateral distribution of respect to model location. This symmetry may interference factors in groulld ell'oct is shown ill be stated by specifying that the correction factors figure 57. ]lere the interference factors are for a position given by y/H and ,_ are the same as presented plotted against the approl)riate nell- those for --y/H and (2--r/).

dimensional length y/h where VERTICAL DISTRIBUTION OF iNTERFERENCE Y = ¢ H (60) A knowledge of tim distribution of interference above and below a model becomes of importance when assessing tile interference for nlodels which In till cases, in ground effect, the maximttnl inter- ference is found at the model, and as wouhl be consist of lifting elenlents ari'anged in a vertical array. Tile simplest such case is l)robably that of expected, tile interference factors decrease rapidly with distance from tile model.

tile unloaded rotor or "Roiodyne" coiifiguratiorI.

Closed wind tunnels.--The vertical distrit)ution Corrections to ground effect.--The lateral (if the inlerference factol's for li closed wind distril)ution of interference for correctitlg from a t,uiine[ with a width-height ratit) of 2.0 is shown closed wind tunnel to ground efl'ecl is shown in ill figlll'es 74 I.o 77. These Jllterfel'elice factors figures 58 1o 61 for it square wind tunnel (,=1.0).

are Iflotted agaiilst the hl('ation hi 1he wilid tullneJ The correspondi,g factors for a wind tunnel 26 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION as given by maximum increase is noted for skew angles near 30 ° .

z' z . 1 MORE COMPLEX MODELS _=_+_--i (62) The foregoing considerations apply to models The location of the model corresponding to each consisting either of a single lifting element or of curve is shown by tile symbol on tile curve.

several elements which are very closely spaced Ill general, tile mininnun rate of change of tile with respect to the wind-tunnel dinmnsions. When interference factors with vertical position is found these conditions are met, the interference factors presented previously may be used directly. When to correspond with model locations at or slightly above the center of the wind tunnel. Tile actual the model consists of several lifting elements which are widely spaced in comparison with tile wind- model location for |ninin|unl rate of change is, however, a function of skew angle. tumml 'dimensions, such a simple treatment is not, For a closed wind tunnel, $_.,. is a mi||imum at in general, adequate. In such cases, it is necessary to consider the various elements of tile model approximately the same model location as that for mininmnl rate of change (fig. 74). For models independently and to consider additional inter- mounted above this point, _f_._ is greater above ference at each lifting element caused by tile the model than below the model. For models presence of the other elements within tile wind tunnel as well as the interference at each elemeut mounted below the point for minimunt interference, _._ is always larger below the model than above due to its own presence in the wind tunnel. These it.

considerations are illustrated herein by examining The remaining three correction factors, _I_.L, three cases of equally loaded two-element lifting $,,.D, and $_.D, display an entirely different systems with tim elements.arranged in tandem, behavior. Figures 75 to 77 show that _,,.L and side by side, and vertically. In all cases, the $,.D always increase in the positive direction and discussion as well as the figures presented refer that _,_.D increases in the negative direction as the to a closed wind tunnel with a width-height ratio model is lowered. of 2.0.

Wind tunnels closed on the bottom only.--The Tandem system.--Consider a lifting system of corresponding correction factors for a wind tunnel two individual equally loaded elements arranged closed on the bottom only (with _=2) are shown one behind the other, separated by a distance H in figures 78 to 81. It may be seen in figure 78 equal to the senfiheight of the wind tunnel, and centered ill the wind tmmel. Since effects of that, for this tunnel, _,o.n is always greater in the positive sense above the model for all vertical finite test-section length are neglected in this locations of the model. The other three correc- analysis, the longitudinal distribution of inter- tion factors, in general, display minimum values ference factors shown in part (a) of figures 32 to for model locations near the center of the wind 35 applies to either element, provided that the origin is always assumed to be at the location of tunnel. The opposing character of the trends between this and the preceding case may be the appropriate element.

explained by the fact that in the previous case Each element of the lifting system, because of the model was positioned between two similar its own presence in the wind tmmel, experiences interferences at its own location which are found boundaries whereas in the present case the model was positioned between two dissimilar boundaries. at x/H=0 in figures 32 to 35 (or alternatively, as Ground effect.--The vertical distribution of the given in ligs. 10(a), ll(a), 12(a), and 13(a) for interference factors above and below a model in _'=1.0). This interference is shown in figure 83 as the curves labeled "Isolated element." In ground effect is shown in figure 82. It may be seen that all four interference factors always addition, because of the presence of the rear ele- increase below the model and near the ground. men{,, there is an additional interference at the front element. This interference may be found The increase toward the ground is always greatest at low skew angles for those factors which give (in figs. 32 to 35) at the position of the front ele- the vertical interference velocities. For the factors ment (x/H=--l.0) with respect to the rear ele- ment. The total interference at the front element giving the horizontal interference velocities, the JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT is the sum of the interference caused by its own the presence of the other rotor. This ensues from presence and tile interference caused by tile pres- the fact that these two effects are caused by differ- ence of the real" element. This sum is shown in ent systems which may have different lifts, drags, figure 83 as the curves labeled "Front element of and nmmentum areas. In such cases, it is neces- pair." Similarly, tim rear element of the pair sary to maintain the identity of the source of experiences an additional interference due solely interference by finding four, rather than two, sets to tile presence of tile froat element in tile wind of interference factom. These are as follows: tmmel. Thus, the total interference at the rear The interference at the front element due to its element is the sum of the interference caused by own presence, the interference at the rear element its own presence and the interference caused by due to tile presence of the front element, the inter- the presence of the front rotor (found at x/H= 1.0 ference at the rear elelnent due to its own presence, and the interference at the front element due to in figs. 32 to 35). This sum is shown in figure 83 by the curves labeled "Rear element of pair."

the presence of the rear element. Then the in- It will be seen in figure 83 that the interfere|ice terference velocities at both elements may be factors are quite differcut fi)r tile front and rear determined by using Am, Uo, and We of the front elements of tile system. Thus, if tile model is clc,nent to tirol tile first two interferences, and large, or if the lift is great, each element of the A:, Uo, aml We of the rear element to fiml the system will operate at substantially different second two interferences. Finally, the appropri- effective rates of sink and effective forward veloci- ate interference velocities at each element may be added to obtain the total interference velocities.

ties. Under such conditions, the actual test data It is implied, of course, that the il_dividual lift and may be of dubious value. It is imperative, there- drag of each element must be known in order to fore, that models incorporating tandem lifting carry out this procedure.

systems be kept quite small in order to minimize Side-by-side model.--Consider now a side-by- such effects.

side nmdel consisting of two lifting elements The interference factors obtained in the pre- separated by a distance H equal to the semi- ceding manner are based upon only the momen- height of tile wiml tunnel. Assume, further, that tum area of a single element. If it is desired to the entire system is centered in the wind tunnel correct only the overall lift and drag of the tandem such that the two elements assume the positions system, it is preferable to base the coefficient UllOn described by ,/=0.75 and ,7--1.25. Because of the total ntomentun_ area of the entire system.

the symmetry of tile system it is necessary to Since this momentum area is twice that of a single consider only one element, say the element at mitt, the correction factors in this system will be _----0.75.

one-half of those computed by the foregoing pro- Because of its own presence in the wind tunnel, cedure. Such interferem'e factors, giving tile cach clement of tile pair i_mum interference ve- average hlterference of both elements, are pre- locities correspomling to the interference factors sented as the curves labeled "Overall correction" for 7/----0.75 at x/H=y/H=z/H=O. These factors in tigure 83. The correction factors obtained iu are shown as a function of skew angle in figure 84, this manner are markedly less at low skew angles whc|'c it may be seen that they differ only slightly than the isolated element corrections. As will from those for _----1.00.

be she,ll in a subsequent portion of this paper, Because of the presence of the second element similar effects are ol)taiRwd as a result of finite in the wiml tlmnel there is an additional inter- size of a single element.

ference which may be fouml (from the symmetry The l)reeedillg example is I'elativcly simple in considerations previously discussed) as the inter- that the lifts of tile two elements have l)een con- ference for n--0.75 at x/H=z/H=O, y/H=--l.O.

The total interference is the sum of these two sidered to be in a fixed relation to each other; that is, the lifts were assumed to be always equal.

terms and this sum is shown in figure 84 as the When the lifts of the two elements are assumed to curves labeled "Either element of pair."

vary according to the el)crating condition, it is no It may be seen in figure 84 that the total longer permissible to add together the effects of interference at either element is substantially the lifting system on itself and tile effect due to increased over that of a single isolated element.

28 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ltowever, if as before, an overall correction based wind tunnel of width-height ratio _,----2.0, this on the total momeutunl area within the wind system of partial wakes would appear as showx, tunnel is used, tile net result is tL decrease in the sehemaLically in figure 86. At any point on ill,.

interference factors. Tile decrease is greatest at wing sl)an, the interference faelol_ will be given a a smmnation of the form low skew angles and again is similar to the trends with tinite size that will be discussed subsequently.

Vertically arranged model.--Fimllly, consider a y_, _iA? ,Xs model consisting of two equally loaded elements (6:_) AT arranged one above the other and separated by a /x8 distance equal to 0.2H, where H is the semiheight of the wind tumml. Assume that the upper A sample case is worked in tabular form in eh, ment is centered (_'---1.00) ill tim wind tmmel; appendix D.

the' lower element is then situated at _-=1.25.

Rotors and propellers.--Equation (63) should The interference for isolated elements in these 1)e adequate for systems where the wake is planar positions is shown in tiguro 85. In a,hlition t,o as a result of originating essentially along a lin.

this interfere,we, each element experiences an representing the trailing edge. For a rotor or a interference due to the presence of the other propeller, however, the wake originates from ap element. The total interference for each element area, and thus describes a solid cylinder rathe: is as shown in figure 85. The overall correction, than a plane. In such cases, the following alter- however, when based on total nlonientum area, nate form nlay be used to obtain the effect (_ is at)proximately that for a single isolated element finite size: located nfidway between the two elements of the pair.

EXTENSION TO FINITE-SIZE MODELS The theory developed herein expressly al)plies _---- AL AA (64 only to models which are wmishingly small with respect to tile wind-tmmel dimcnsious. Ill EFFECT OF FINITE SIZE FOR WINGS general, most wiml-tumml tests are conducted Interference at center of span.--Calculafious with nlodels of a comparatively large size. It is well kuown that classic wiml-tmmel interference according to equation (63) have been made for theory (for example, ref. 2) predicts substantial wings of varyh_g spau-to-tuuncl-width ratio a in a eifects of model size on the wiud-tmmel inter- closed wind tunnel havhlg a width-height ratio of ferenee. Similar work for rotors fief. 8) predicts 2.0. The coml)utcd interfcreuce factom at the similar effects. center of the centrally located whig are shown as a function of skew angle in figure 87. It may be Actually, it is possible to :lse the present results, together with superpositions thereof, to seen that, in this case, au increase in span always obtain equivalent results for finite-size models. results in a significant decrease in the magmitude of all four interference factors. This does lint In essence, the procedure is to consider the wake originating from tile model as broken into seg- necessarily mean, however, that the interference ments, each repl'eselltiug the wake of only a velocities themselveg decrease, because the mo- portion of the model. The effect of each partial mentum area of the wing increases rapidly with wake as well as tile hlterferences of all the other the spau of the wing. Note that, in general, for partial wakes in the wiml tumml can then be wings, added at each point on the model in order to A_ _s 2 _ 2 (65) obtain an overall correction for the finite-size _-;=_= _ • model.

Thus, as a increases, the interference velocities in- Wings.--For a wing, the system of partial wakes crease although not as rapidly as the monmntum just described would superlicially resemble the area increases.

wakes of several vanishingly small models flying Distribution of interference over span,--Tlm side by side. For a wing with a ratio of span to distribution of the interference velocities over the whld-tulmel width a=0.625 centered in a closed

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 29

The interference factors, computed as outlined span of a series of finite-size wings is shown in figures 88 to 91 for tim same cases treated above. above, for a=0.333 are shown in figure 93. In In general, although not without exception (fig. each case, the equivalent factors for a=0 are also 91(a)), an increase in span-width ratio leads to shown. In addition, for $_.L, the interference reduced interference factors ill the central portion factors for a=0.3 and 0.4, as obtained by direct of the wind tumml and increased interference fac- integration of the cylindrical vortex wake in tors near the walls of the wind tumwl. These reference 8, are shown for comparison. It may interference distributions are of most importance be seen, first, that the results obtained by the in determining the distortion of flow over the present method are entirely equivalent to those model as a result of wind-tulmel interference. The obtained by the method of reference 8. Second, it may be seen that, in this case, as well as for the significant item to be obtained for any indi- vidual case is the Inaxhnuln difference iu the wings treated previously, the effect of finite size interference velocities between any two points is to decrease the correction factors. Although the trends are the same, however, a closer com- on the span. Thus, not only is it necessary to • ccount for the increase in momentum area parison of figures 87 and 93 will show differences which are ascribable to the differences in model _ith span, but it is also necessary to account configuration.

for the varying span itself in determining the pertinent difference. Note, for example, that Effect of finite size on _, at rotor center.-- )ecause of its zero span, a wing having a=0 has More complete calculations for a rotor could b_ no distortion whatever, despite the fact that such carried out according to the approximate method wing produces the most nonlinear distribution outlined above. On the other hand, if the dis- of the interference factors on the lateral axis of cussiou is restricted to _,,. only, the equations of the tunnel. This point will be discussed nmre reference 8 provide a more rapid means of obtain- fully with respect to rotors in another section of ing this factor entirely on the digital computer.

this paper.

It will be noted that the equations of reference EFFECTOF FINITESIZEFORROTORS 8 are essentially equivalent to equation (23) in the present report with the sole exception that Wake of rotor.--For rot,ors (or, equally well, tim K functions are replaced by expressions more for propellers near a----90°), the wake may be appropriate to the basic cylindrical wake and represented as a continuous distribution of vortex image system shown in figure 94.

rings, parallel to the rotor disk and carried away, Figure 95 presents $_.L as a function of wake under the mutual inlluence of the downwash and skew angle for several size rotors ia a closed wind forward velocity, along an axis inclined to the tunnel and in a wind tunnel closed on the bot- rotor axis by the skew angle x (ref. 16). For the tom only. Also shown in figure 95(b) is the inter- case of uniform disk-load distribution, this wake fcrelJce for only the closed Iloor of either tumml.

resolves itself into a single skewed cylimler, the In all cases, the rotor is centered in the wind tun- surface of which consists of continuous, nniforlnly nel and _, is 2.0. It may be seen that, regardless distributed, vorticity.

of wind-tunnel configuration, an increase of rotor Approximate calculation" of wind-tunnel inter- size generally decreases the interference factor.

ference.--For the approxhnate calculation of Furthermore, the magnitude of the decrease is wind-tunnel interference, that is, by using the essentially the same in all cases. In particular, present results to obtain interference factors for a figure 95(b) indicates that even when finite size rotor, the disk area of the rotor is broken into five is considered, the interference at low skew angles equal portions as indicated schematically in flgnre is still primarily due to only the floor of the 92. The wake of each portion of the rotor is wind tunnel.

then represented by a doublet wake, as shown, and furthermore, under the assumption of uniform Effect of finite size on distribution of _.L.-- disk-load distribution, the strengths of the five The longitudinal distribution of _._ for various doublet wakes are all equal. Then the interfer- values of _ is presented in figures 96 to 98 for ence factors at the center of the rotor for ¢--0.333 the three cases treated in the preceding section.

in a closed tunnel with _.=2.0 are computed by The equivalent lateral distributions are presented the use of equation (64).

in figures 99 to 101. It may be seen that, in _32643 o--B2--3 30 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION as general, an increase in a does not alter the gen- eral trends indicated by calculations for a=O.

Aw . TR _ 7r However, all increase in rotor size does distinctly _o=6_.,.4-_./=_ _._ (66) affect the maximum values of the interference factors found along tile axes. In general, tile In consequence of equation (66), the vertical maximum interference factor decreases with an interference velocity is now expressed explicitly in increase in rotor size. As before, however, this tel',ns of the mean vertical induced velocity of the decrease in the factor is not sulIicient to overcome rotor itself, lf, now, the niaximuni difference in the effect of increased momentum area so that vertical interference velocity along the axes of the the actual interference velocities still increase with rotor is obtained from figures 96, 97, 99, and 100, rotor size.

it is possible, after some cross plotting, to obtain charts such as those given in figure 102. This MAXIMUM ALLOWABLE SIZE OF MODEL figure shows the size of rotor which incurs a given maximum difference in interference velocity along In any test, there is a maximum size of model its principal axes. This maximuni difference is which can be satisfactorily employed without the stated as a fraction of the mean induced velocity necessity for excessively detailed correction proce- of the rotor itself.

dures. For normal tests of conventional models, Figure 102 may be used as a guide in selecting this size is sometimes stated in terms of a maxi- a rotor size for a given test. It would appear munl allowable correction. For example, reference that for tests in which only crude qualitative 17 states that the model size should be chosen so data are expected, interference nonuaiformities that the maximum angle-of-attack correction due of as much as 50 percent of the rotor induced to wall interference shall be less than 2 ° . Such velocity might be tolerated with a niaximum limitations as those of reference 17 actually con- nonuniformity of 25 percent of the rotor induced tain within themselves two features. The first is velocity being desirable. For general-purpose that the theoretical corrections are only approxi- mations and a limit to the maximum size of correc- quantitative test work, the corresponding per- centages would be nearer 25 percent and 10 per- tion also limits the approximation errors in the cent. If, however, it is desired to do very detailed theory. The second feature is that if the overall work, such as measuring the pressure distribution correction is small, then the accompanying dis- on the blades for loads work, it may be necessary tortion of interference over the model will also be to restrict the maximum nonuniformity of inter- small. Thus it will not be necessary to provide ference velocity to the order of 5 percent or even corrections for such etrects as induced camber due 2 percent. Thus, once the purpose of a planned to nonmfiform interference.

test is firmly in lnind, and once the range of wake As pointed out in reference 13, the aforemen- skew angles ia which the test will be conducted tioned criterion for maximum correction angle is known, it is possible to use figure 102 to obtain should be relaxed to some degree when the results the luaxinmm allowable rotor size that is of the present analysis are used to correct data.

The basis for this statement is the faeL that tlle 2 ° permissible.

Figure 102, of course, only applies to centrally limitation is set on the basis of a theory which ab- located rotors in wind tumlels having width- sorbs all effects of wake skew angle as an approxi- height ratios of 2.0. For other mounting posi- mating error. In the present case, this problem is tions, wind-tulmel proportions, and model con- taken into account.

Tile actual size limitation for models will be set, figurations, similar charts can be prepared by using the considerations discussed in the earlier in general, by tile degree of nonuniforlnity of the sections of this paper.

interference over the region occupied by the model.

Reference 13, by using the distributions of inter- EXPERIMENTAL VERIFICATION ference sinfilar to those given in figures 96 to 101, The utility of the computed corrections, of develops a criterion for rotors on this basis. Note course, depends upon tile degree to which they that for rotors, where the nmmentunl area is _rR_, the vertical interference due to lift can be written can be verified by experhnent. Unfortunately, JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT the existence of more tha_J one correction factor, the data appear as in figure 105(e). it may be seen that the data from the two test sections now as well as the dependelme of the correction factol_ upon skew allgle, makes direct experimental agree within the probable experimental accuracy of the tests.

determination of the correction factors extremely difficult. Thus, in the present ease, the alterna- Jet flap in ground effect.--A similar comparisoll tive approach of attemptilJg to correct eOml)ara- may be obtained from the ground-effect tests rust tive data from differellt wimld-tutmel test sectiolm on the saane model in the 17-foot test section.

will be used.

Neglecting the finite extent of the ground board, One source of such comparative data is reference these tests would be roughly equivalent to operat- 7 which presents the results of tests of a number of ing the model in a position lower than the center- different VTOL configurations in both a 7- by line in a tumlel of width-height ratio greater than 10-foot test section (fig. 103) a,_d a 17-foot-square 2.0. The correction factors for such tunnels test sectiofi (fig. 104). The data of refereuce 7 have not been computed; however, as pointed have all been partially corrected by the use of out elsewhere in this paper, the correction factors standard wing correctioiis al)plicd to ol_ly that h)r such cases should be almost identical to those portion of lift not provided by direct thrust, that for simple ground effect. Consequently, an is, the so-called "circulation" lift. Such correc- attempt has been made to correct these data to tions provide no correlation at low speeds and they the free-air condition by applying the correction have been removed from the data before pre- factors for ground effect. The uncorrected data sentation herein as uncorrected data.

are shown in figure i06(a). After correction, the In all cases, the interference factors for a data appear as in figure 106(b) where the peak vanishingly small model have been used in values of C_.¢ and z_a are shown in each ease.

correcting the data.

Finally, after correction to a common value of C,, Jet flap.--As the fil_st example, consider the the data appear as in figure 106(c).

swept wing with a jet. flap deflected 60 °. The data It will be observed in figure 106(e) that reason-.

for this configuration are presented in figure 105(a) able agreement is obtained between the data for (obtained from fig. 9(a) of ref. 7). The uncor- the two highest heights; but that the agreement rected data for the 7- by 10-foot and 17-foot sec- becomes substantially poorer at the two lower tions are shown to be quite similar except for the ground heights. There are several reasons for angle of stall which is substautially less in the 7- by this disagreement. Note, in particular, that there is a variation of the wind-tunnel-wall induced 10-foot test section. The corrections presented in this paper alter the two sets of data so that they interference along the chord of the model. This appear as shown in figure 105(b). The disparity variation is relatively moderate with the model in stall angle has now essentially disappeared; but, in the two highest positions but becomes increas- at first glance, it would appear that the agreement ingly severe as the model is progressively lowered.

between the two sets of data has been worsened This gradient of interference is, in fact, aerody- in all other respects by the corrections. It should namically equivalent to camber. The percentage be noted, however, that the alteration in dynmnic of camber, computed by assuming a circular-arc pressure has altered C, as well as both CL and camber line between the one-quarter-chord and C_. Thus each point on each curve represents the three-quarter-chord points of the mean aero- the performance at a different value of C, as well dynamic chord of the airfoil, is noted in figure as a different value of a. The peak values of both 106(c). (lt should be noted that the effective C,., and 5a are noted for each case. It will be camber i_nd dihedral will also vary along the span observed that the peak values are substantially because of sweepback as well as because of lateral different for the data from the two test sections.

gradients of interference. These features are In order to obtain a more graphic picture of neglected herein.) The differences between t.he the validity of the theory, the data have also been fully corrected curves are of the nature and magni- corrected to a common value of C, by the use of tude that might be expected as a result of the large induced inverse camber. The main point the experimental data for jet flaps as presented in reference 18. After this additional correction, of figure 106(c) is that the model size and tuamel 32 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION size should be chosen so as to avoid pronomlced require correction by an amount approximately equal to one-third of the difference between the variations in interference along the chord. This, rather than the absolute size of the correction two sets of data. In general, this is the magaitude of the correction predicted by the present theory.

factor, probably determines the maximum size The impact of corrections upon the conclusions of model that can be tested successfully ill a to be drawn from the data is illustrated by the given wind tmmel. In this regard, there is no data from the deflected-slipstream model tests real substitute for a very small model in a very presented in figure 109. Here the extent to which large wind tunnel.

the aircraft may decelerate in unstalled flight is Several other reasons exist for poor agreement indicated by the portion of the drag polar on the ill this case. These include: Tile fact that the right (positive drag) side of tim ordinate. On system used to correct the data to a common this basis, the uncorrected 17-foot tmmel data value of C, is only valid before stall; tile finite would indicate that this aircraft would have to extent of the ground board; the small differences accelerate to avoid stall at Cr=14, and the 7- by between the corrections for ground effect and 10-foot tunnel data would indicate that level those for the appropriate wide wind tunnel; and, ffigh t without stall could just barely be main tained linally, tim representation of the nmdel as a point at Cr=14. On the other hand, the corrected source of lift, a representation that becomes 17-foot tunnel data indicate that the aircraft difficult to justify when applied to a model of could nmintain steady unaccelerated level flight over 7-foot full span operating only 1N feet above at a Cr of 15.1, and the corrected 7- by 10-foot the ground.

tunnel data indicate an ability to maintain de- Propeller-driven conflgurations.--Reference 7 celerations of 0.2g in level flight without stall also presents data for a series of propeller-driven VTOL models in both test sections. Since no at a Cr of 17.0. The effect of the corrections is, therefore, of extreme importance in determining systematic means exist for correcting the operating the limiting conditions of flight for this variable Cr to a common basis, it is not possible to use these data to obtain a clear-cut indication configuration.

Ducted fan.--The ducted-fan data of reference of the validity of the theory. The data of refer- 7 are of particular interest since comparative ence 7 have, however, been corrected by the tests in the 7- by 10-foot and 17-foot test sections present theory in order to provide an indication indicated that a wall correction exists even though of the magnitude of the corrections and their tlm fan area was less than 2 percent of the 7- effect upon the data. Tim data, uncorrected and by 10-foot tunnel area. The corrected and corrected, are presented for the same model tested uncorrected data are shown in figure 110. For as a tilt-wing VTOL aircraft, a tilt-wing-with-flap this case, the correction to Cr is small percentage- VTOL aircrafL, and a deflected-slipstream VTOL wise, and, as a consequence, the corrected curves aircraft in figures 107, 108, and 109, respectively.

nearly coincide.

The degree of agreement or disagreement Rotors.--Reference 19 gives data for rotor between the data for the two wind tunnels is not tests ill an 8- by 12-foot tunnel and in 3- by 4.5- the main item to be gained fi'om these figures foot and 2.4- by 3.6-foot inserts within the wind because the degree of improved agreement will be tunnel. For high speeds and reasonably small dependent upon the sensitivity of the model lift coefficients, it is shown that the use of standard performance to changes of velocity in the velocity wing corrections brings the data from the various range through which it is tested. The magnitude test sections into satisfactory agreement. This of the corrections is, however, important. The is as shown by the work presented herein. At main difference (neglecting small changes ill skew the lowest speed and at lift coefficients greater angle and wind-tunnel width-height ratio) between than unity, the @ing corrections failed to bring the data obtained in the 7- by 10-foot and 17-foot test sections is a reduction of area ratio by a the data into satisfactory agreement. Unfor- factor of 4. The effect of the walls should there- tunately, the complete report (ref. 20), of which reference 19 is a summary, indicates that the fore be reduced by approximately the same factor presence of a 2-foot leaditlg-edge extension on of 4; that is, the 17-foot tunnel data should still JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT the wind-tunnel inserts caused a change in the with the results of classical jet-boundary-correc- data at the lowest speed which was of the same tion theory. When the wake is directed sub- magnitude as that observed by placing the rotor stantially downward, the correction factors are within the insert. In view of this result, it much increased in size. Furthermore, with sub- appears that the test inserts of references 19 and stantial wake deflections, the longitudinal as well 20 were too short to simulate completely the as the vertical interference velocities must be accounted for.

smaller tunnel at this speed. Therefore, no attempt is made herein to correct these data.

2. When the wake is deilected to nearly vertical Extent of veriflcation.--The foregoing material angles, the wind-tunnel interference is primarily indicates that there is at least partial experi- determined by the wind-tunnel floor. Therefore, mental verification of the theory available. A under these conditions, tests ill a wind tunnel more complete verification would require tests with a closed floor closely correspond to tests in in different wind tunnels at very closely spaced simple ground effect. Under similar conditions increments of velocity in order that a uniform in a wind tunnel with an open floor, large dis- value of the operating conditions could be obtained tortions of the lower boundary will occur so that, by interpolation between the corrected data. in practice, the corrections will be indeterminate.

Such complete comt)arative wind-tumml tests For this reason, the use of completely open wind are not presently available.

tunnels for low-speed and high-lift-coefficient testing is not recommended.

CONCLUSIONS 3. The theoretical results, as presented herein, A linearized theory of wind-tunnel jet-boundary strictly apply to single-element, vanishingly small corrections and ground effect for VTOL-STOL nmdels. However, methods of extending the aircraft is presented. Numerical values of the present results to multielement systems and to interference factors for a wide variety of rec- finite-span models are indicated, and sample tangular wind-tunnel configurations are pre- results are presented for a number of cases.

sented in tabular form in NASA Technical Notes 4. The tlleory is at least partially verified by D-933, D-934, D-935, and D-936. A study of available wind-tunnel test data. Complete veri- these nLunerical values indicates the following fication, however, would entail substantially more conclusions: meticulous tests than those for which data are 1. Wind-tunnel interference and ground effect presently available.

are functions of the degree to which the wake is LANGLEY RESF.ARCH CENTER_ deflected fi'om the horizontal. When undeflected, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION_ the present results correspond ahnost exactly LANOL_Y AIR FORCZ BASE, VA., July 18, 1961.

APPENDIX A DERIVATION OF CLOSED-FORM EXPRESSIONS FOR THE INTERFERENCE VELOCITIES AT THE MODEL IN GROUND EFFECT VERTICAL INTERFERENCE DUE TO LIFT Tim vertical interference velocity due to lift (w_ke of vertica2 doublets) is given by equation (26) as A {_ L\ Am where, from equation (23) (with the double summation set equal to zero), \ l \ l u z \-I .x z xy z x 2_ K _---;[ ( _,_,_, _--ta,, • I)--K _,_, _-t,--_--2)-l-K _,,_-- tan x, _, _+ 1)j (Alb) where, in turn, from equation (5b), ix\2 /y\2 x -] I-/x\_ /y\2 /z\2-1 s/_

[_/(_) +(_) +(_) +_oo_ ___ s_,, _JL,,Z +,,Z *_._ J

_; _*oo___'_.v'(_) *(____) +(,____)

X2 y2 Z 2 Z X . X2 y2 Z" l[-,/(_) +(x) .(_) .,,,_o_ x_,,,,. _],,/(,_) .(,,).(,,) (..,.,.c, Since it is the interference velocity at the model itself which is of interest herein, z=y=z=0 in equations (A1). Then, substituting equation (Alc) into equation (Alb) yields 6w r_ 2{ --tali2X [ l+eosX_/l+tall2X ]_ _-__=--; (_/i_+cosx+tanxsinx)(l+tan2x)S_2 F (_x+cosx+tanxsiax)41+tan2x +F --2+2 cos X_ "]_-I tan'x x) s/_ 1(2--2 cos x)(2)/ (_/[--+tan _ X--cos x+tan x sin x) (l+tan 2 -- (41+tan _ x--cos x+tan x sin x)41 +tan' (A2) [ -- 1-4-cos X-_/l +tan' X :_3_} Equation (A2) may be considerably shnplified and yields 8_,_ 2

_=-;(-__,,. _co_. _,_o_. _,_,_ co_._) (_

or _z 2 JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT Finally, substituting equation (A4) into equation (Ala) yields z_w_=--I (3 cos_ xq-1) Am (AS) -xo wo LONGITUDINAL INTERFERENCE DUE TO LIFT The lottgitudinal interference velocity due to lift (wake of vertical doublets) is given by equation (27): Wo (A6a) where, from equation (23) (with the double summation set equal to zero), (A6b) yz (__tan y z where, in turn, from equation (6b), xz #) +(#) +(#) +# cos X--# sin x [(_) +(_) +(_)_ Z • X2 y2 Z 2 X . X 2 y_ Z _ X2 y2 Z 2 Z X . ]2 X2 y_ Z Substitutittg equation (A6c) into equation (A6b), with x=y----z=O, yields 6_.L=_2 [" --tan x t"_T r [.(_/1 +tmff XTcos x+tan x si. x) (1 +tan 2 x) a/2 Jc(l+cosx_)(--tan x--sin X_) (_/1 + tan' X+cos X+ tan x sin x)'(1 + tan _ X) (--2+2 cos X)(--2 sit| X) tan X (2--2 cos X)2(4) ({i-'+ tan 2 X--cos X+tan Xsin X)(1 +tatx' X) a,2

(--l+cos X_/l +tan _ X)(--tat, x--sin l

(A7)

.I

which, after simplification, reduces to (A8) '_,z l( 2) _=_r 3 sin x cos 3 x+sin x cos x+ 1 tan Substituting equation (A8) into equatiou (A6a) yields (Ag) Z_uL= 3 sin x cos 3 x+sin X cos X+_ tan -_]_-oWo VERTICAL INTERFERENCE DUE TODRAG The vertical it|terferet|ce velocity due to drag (wake of loagitudinal doublets) is given by TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION equation (28) as Uo (h 10a) where, from equation (23) (with the double summatioa set equal to zero), $_Df._=__.2[_K(h_ta nx,_,_*l)_K(_,_,___2)+K(__tanx,_,___,)z x y z x y z .\ where, in turn, from equation (llb), XZ K -'"-'- : 7V/x\_ /y\2 /zX_-la/2 h h h r //x\ 2 /y\2 /zV _ z x

L_/t_) +_) +_,J +_¢o, _-_,i,, xjL[,_) +[,_) +_,T,) J

Z X 2 y 2 Z 2 X . X _ y 2 Z 2 (Aloe) x ' y 2 z ' Zcos x x ' y _ z z and from equation (llc) (A 10d)

_]=Ff ,y +pJy +f ,yT'

L\_,] \_] \fi,]/ Substituting equations (A10c) and (A10d) into equation (A10b), with z=y= z---0, yields _.D=_2[" --tat, X (I +cos X41 +tan' x)(tan \+sin X41 +tan' X)

_ _LG/_ \+cos x+tan x sin X)(1 +tan' x) 3/' (_/l+tan' x+cos x+tan x sin x)2(1Wtan ' X)

tall x (--2+2 cos X) (2 sin x) x) */_ (All) (2--2 cos X)2 (4) (_/l +tan2 X--COS X+tan X sin X) (1 +tan' X)3/' t (l+tan2 which, after simplification, reduces to

6o.o=1_(2 x) f_ 7r\ sin x cos 3 x--sin 3 x cos x--4 cos 3 x--_ tan _ (A12)

Finally, substituting equation (A12) into equation (A10a) yields &wb¼ 2 sin x cos* x--sin 3 x cos x--4 cos s x--_ tan _]_-_auo (A13) LONGITUDINAL INTERFERENCE DUE TO DRAG The longitudinal interference due to drag (wake of longitudinal doublets) is given by equation (29) as _-_uo (A14a) JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT where, from equation (23) (with the double summation set equal to zero), x z zy z

,.°

-pT=-_.

(A14b) where, ill turn, from equation (12b), lyX' IzX 2 x x2 ys zl t _f _--sin x _/(_) +(_) -t-(_) (Al4c) Z_ y2 Z 2 z _. Xl ya g_ and, from equation (12c), (A14d)

[(0,(0,(07

Substituting equations (A14c) and (A14d) into equation (A14b), with z=y----z=O, yields 6, D 2 f --1 +[" --tan x--sin x_/1 + tan' x ------_r _. (_/T+ tan 2 x+ cos x + tan x sin x) (1 + tan _x)S/_ L (_/1 + tan' x+cos x+ tan x sin x) _/1 + tan' xJ' (-2) _ --2 sinx "]_ 1 "_ (2-2 cos x) (4) s/2 (2----2-c-_-x-)__] ' (_/l+tan' X--cos x+tan X sin x)(I-t-tan' X) '/' (A15) +E --tan x--sin x4i--Wtan' x -]' 2 tan X (Vi-+ta,,_ _--_o_ _--_i_ x---_-_ xJ -(_ +tan' x)"'} which becomes, after simplification, (A16) $,,.o==1( , 1 cosX ) -_ _ 4 sin X cos_x--3 sin _ x cos X+_ l+cos x Finally, substitution of equation (A16) into equation (A14a) yields (AIT) 1( cosx "_A. hue= 4 sin x cos' x--3 sin _ x cos 2 x+ 1 1 +--_s X] Aoo Uo

APPENDIX B DERIVATION OF CLOSED-FORM EXPRESSIONS FOR THE INTERFERENCE VELOCITIES AT THE MODEL FOR ONLY AN OPEN LOWER BOUNDARY VERTICAL INTERFERENCE DUE TO LIFT The vertical interference velocity due to lift (wake of vertical doublets) is given by equation (26) as AWL_(_ ) "Ao w°A= (Bla) where, from equation (23) (with the double sunnnation set equal to zero), where, in turn. fronl equation (Sb), _ ly\2

_)+_)

( _x y z =_ X /z\2-p/2 K\h' /t' h/ X 2+ y _+ Z 2@Z COS s!nXlr/x\2 Z X_ y2 Z _ 2 -- x_ yB z 2 z x • x2 y2 z z

_[,/(0 +G) +(0 +_ co. ___.,,,_],/(0 +(_) +(_) J

and, from equation (5c), /z\ 2 /y\_

_ _) +_)

,_,_-_.(_,-_,0 = _, _., _ _..__,,._ ..,-_,,

[,/(_) +(0+G) -_] Lw +W +_ J

-- x _ y _ z _ x z 2 y _ z 2 (Bld)

[,/(_) +(_) +(_) -_l,/(O +(0 +(0

Since it is tile interference velocity at tile model itself which is or interest herein, x=y=z=O in JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOIr.STOL AIRCRAFT 39 equations (B1). Then substituting equations (Blc) and (Bld) into equation (Blb) yields ___. _ 2 f -- tan' X =--_" ),. (_/1 +tan' X+cos xWtan x sin X) (1 +tan' x) a/' +F 1 +cos x_/1 + tan _x m(ql + tan' x-t- cos x+ tan x sin x) _/1 + tan 2 x]' [" --2__2 cos x m tan' x --[.(2--2 cos X)(2).J (_/1+tan'x--cosxWtanx sin x) (1W tan' x) 3/_ 2 tan' x 2 (41.t_tan, x+tan X)4i+tan' X (B2) "_ (_/1 + tan' X+ tall X) (1 + tail' X) 'n Equation (B2) may be considerably simplified, to yield 7 sin s x-- 3 sin _ x) (B3) 5.,L 1 (_--8 sin x+4 sin2x+4 Finally, substitute equation (B3) into equation (Bla) to obtain the vertical interference velocity at the model for an open lower boundary: Aw_=l(__8 sin x+4 sin, x+4 sins x_3 sin, X)A"--a w°A- (]34) LONGITUDINAL INTERFERENCE DUE TO LIFT The longitudinal interference velocity due to lift (wake of vertical doublets) is given by equation (27) ma AU_=(_) _4--o woA'_ (B5a) where, from equation (23) (with the double summation set equal to zero), xy z z y z _f.___ =__r [_K (__tan x ,2 x _, _+ 1)--K (_, _,--_--2)+K (_-- tan x, _,--_-- 1) where, in turn, from equation (6b), xz Z z s y' Z' X • X,' y' Z' (B5c) X X _ y' Z z' y' z' __ZcosX__ sinx]'[(_)+(_)+(#)_ TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMIN'ISTRATION and, from equation (6c), Since it is tile interference velocity at the model itself which is of interest herein, x=u=z=O ia equation (B5b). Theu substituting equations (B5c) aud (B5d) into equation (BSb) yields _.L 2 [" --tan x _-_ =--_" m(_/1 +tan _ x+cos x_----_an x sin x) (1 +tan 2 x) s/2 (1+cos x_/_)(--tanx--sinx_/l+tan _ x) (--2+2 cos x)(--2 sin x) (_/1 +tan_ X+cos x+tan x sin X)2 (1 +tan_ x) _" (2_2 cos x)_(4) -- tan x 2 1 -F (_/l+tan _ X--cos X+tan X sin X)(l+tan _ X) u2"_ (l+tan 2 x) *tl (B6) which may be simplified to yield = 3 sin x cos a x -1 tan _-sm x cos x--4 cos 3 x (B7) Finally, substitute equation (BT) into equation (B5a) to obtain We (B8) 1( 1 _--smX. "cos cos3 \A"x) hut----- 3 sin X cos' X-- 2 tan X X--4 VERTICAL INTERFERENCE DUE TO DRAG The vertical interference velocity due to drag (wake of longitudinal doublets) is given by equation (28) as

(Bga)

where, from equation (23) (with the double summation set equal to zero), • x z zy z x y z '_'_-=--_2[--K (_--tan x, _, _+I)+K (_, _,--_--2)--g (_--tan x, _,--_-- I)] (B9b) where, in turn, from equation (llb), zz

+ + cos si,, Lt ) +W ]

Z X 2 y J Z 2 X . X 2 y 2 Z _ Z X 2 :r 2 y _ Z 2 JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 41 Substitution of equation (Bgc) into equation (Bgb), with z--y----z=0, yields #_.D 2[- --tan x (l+cosx_)(--tanx--sinx_/1-t-_) _-_'---_-rL(_/l+tan=x+cosx+tanxsinx) (l+tan_X) a'' _ (_/_X+cos X+tanX sin X)'(l +tan= X) _(--2+2 cos X)(--2 sin X) __ tan X (2--2 cos X)2(4) (_/l+tan = X--cos X+tan X sin X) (1 +tan =X) sn

(--1+cos x41_) (--tan x--sin x_)7

__-:_o_t--_.x;_--_-l+-_,;_ j (Bmo)

Simplification of equation (B10) yields _.D 1(3 cos X-{-_tan_) (Bll) ----_r\ sin x cos 3 X+sin X l X Finally, substitute equation (B11) into equation (B9a) to obtain X'X A., AWD=---1 (3 sin X cos' X+sin X cos X+_ tan _) _-_o u o (B12) LONGITUDINAL INTERFERENCE DUE TO DRAG The longitudinal interference due to drag (wake of longitudinal doublets)is given by equation (29) as _aa uo (Bl3a) where, from equation (23) (with the double summation equal to zero), _=,D 2 x x y z x y z -_=--_r[--K(_--tanx,_,h+l)--K(_,_,--_--2)+K(_--tanx,_,-_--l)] (B13b) where, in turn, fi'om equation (12b), /y\= /z\ =

[_/(_) +(_)+(_)+_ cos x-_sin xjL_ ) +_,_) +_,_) j

X . X= yS Z = = X = y _ Z _ Z X • x = y = Z = 42 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Substitution of equation (B13c) into equation (B13G), with x=y=z=O, yields 6_ 2 f --1 Ff --ta"x--si"X'_l+tat'_X ]2 _------_rl (_/_ x+cos x+tan x sin x) (1 +ta,12 x) 3/2 L(_/1-+ tal_ x_ x-+-t_-mn x sin x) _/1 +tall' x 4 V --2 sin x j"12_l_(___{_tan 2 X--cos X+ tlt (2--2 cos X)(s)+L(2:_-i:;; k_(2) x si. x) (1+ta. _x)_/, (BI4) --[(_/1 --tan x--sin x_/i +tan' x T_ +ta_ 2x-cos x+ta,_ x si,_x) _/t +t_,,' xJ / Simplification of equation (B14) yields 1 cos x "_ $. D 1{2 2 1_"_ X/ (B15) =_\ co¢ x-sin _ x cos' x Finally, substitute equation (B15) into equation (B13a) to obtain (B16) 5u'----l(2 e°s' x--sin' x c°s' x--_ 1 +cose°Sx x]'_ A"U°A.

APPENDIX C SAMPLE CASE OF APPLICATION OF CORRECTIONS TO TEST DATA Assume the following characteristics of the small V V/wn --0.487 o ._._._ (5) ....

model and the closed wind tunnel: (6) From figure 7 S----8 sq it Am----10 sq ft X=39.7 ° _l----2 • Am 10 sq ft (7) From figure 10(b) At= 100 sq ft; _hereforc, _--_----_----0.100 -r=l:5 _.,_= --0.87 _'=1.0 _=1.0 (8) From figure ll(b) The test is conducted under standard atmos- _ ,.=0.72 pheric conditions with the following conditions and results: (9) From figure 12(b) Cr=10 $,.D=--0.66 V=25 ft/see; therefore, q=0.743 lb/sq ft a=30.0 ° (10) From figure 13(b) L= 125.0 lb D=--30.0 lb for which all estimated vtdue _,D=0.28 of D_=--35.0 lb is obtained (11) From equation (44) The following steps are then followed in the 111,o Am At 0.100 o 1_o computation of this sample case: v-- o - ....

D_ --35.0 lb (12) From equation (45) (1) T=_ =-o.28o 11I_ M_D_ (2) From equation (35) Mrr ----M-r -L-= (- 0.180) (-- 0.280) = 0.0504 (13) From equation (40) AwL M_ V =_"" _-_= (-0.87)(-0.180) =0.157 __/ 125.0 lb 2(0.002378 slug/cu ft) (10 sq ft) (14) From equation (41) =-51.3 ft/sec V 25.0. ft/sec 0 487 (3)

=- ---V-_$,.,. ----(0.72)(--0.180)=--0.130

(4) From figure 6 (15) From equation (,42) 5wD__ MM__= (_ 0.66) (0.0504) = _0.0333 • . . . .

SPACE ADMINISTRATION AND TECH-NICAL REPORT R--124_NATIONAL AERONAUTICS From equation (43) --q_ q=0.797 (0.743 lb/sq ft) =0.592 lb/sq ft (22) (16) q'-- q Au_ _ D--_r_( 0 28)(0'0504)=0 0141 V 2_, [ 2(0.592 lb/sq ft) _ =22.3 ft/sec -- "' " (23)

,=¥-7=¥o.oo2378 slug/__t

From equation (46) (17) From equation (51a) (24)

_=_y,_ +_y,'-- o.157 + (-6.0333)=0.124

Cr 10 -_ -r.

v e From equation (47) (18) From equation (50a) (25) __ffi__+____=-0.13o+o.o141=- o.116 L,=L cos Aa--D sin Aa = (125.0 lb) (cos 8.0 °)- (--30.0 lb) From equation (48b) (19) (sin 8,0 °) = 128.0 [b z_a=Lan -1 Aw/V tan_t 0.124 =8.0 ° From equation (50b) 1 q---_ 1 --0.116 (26) D_=L sin AaA-D cos Aa From equation (48a) = (125.0 lb) (sin 8.0 °) + (--30.0 lb) (20) (cos 8.0 °) =- 12.3 lb at= ¢x_- ha=30.O ° -_-8.0 ° =38.0 ° (21) From equation (49b) (27) , L, 128.0 lb f_)_27.03 'L.t=q--_=(0.592 lb/sq ft) (8 sq qc f Auk2. {Aw\2 C D, -- 12.3 lb ..... 2.60

_=LI+_) %9-) (28)

v.,= _-_----- (0.592 lb/sq ft) (8 sq ft) = 1--0.116)2+(0.124)2-----0.797

APPENDIX D SAMPLE CALCULATION OF INTERFERENCE FACTOR FOR A FINITE WING Ill this appendix, _.L will be computed at distribution, with a total lift of 2.50. For the y'/II=0.5 for a wing having a span-to-tunnel- purposes of this calculation tile wing wake is width ratio ¢ of 0.625 and operating at ×=60 ° in represented by five doublet wakes as indicated a closed wind tmmel with a width-height ratio ill figure 86. The calculation is carried out in tabular form as follows: -y of 2.0. The wing is assumed to be centered in the wind tunnel and to have a uniform span-load (obtained by symmetry con- _w,L Relative strength Doublet wake It siderations from ref. 9) for-- for doublet of doublet wake, for y]l//_ = 0.5 wake _L at ,7 _ -- As As ylH 0. 50 --0.5 0. 50 -0. 50 --0.546 O. 50 -- 0. 273 • 75 0 .75 0 --.638 • 50 --. 319 1.00 .5 1.00 .50 --. 482 ,50 --. 241 1.25 1.0 • 75 -1. 00 --.224 . 50 --. 112 1.50 1.5 • 50 -1. 50 --.051 . 50 --. 026 Summation ............................................................ 2. 50 -0. 971 Then, with the use of equation (63), In order to carry out the calculation for a loading AL other than uniform, it is only necessary to adjust 6w,,. _-_ AS --0.971 the column for the relative strength of doublet 2.50 AL _w'L= AL As .... 0.388 wake_ As to correspond to the desired loading• 632643 0--62--------4 46 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION REFERENCES 1. Theodorsen, Theodore: The Theory of Wind.Tunnel Tunnels Having Width-Height Ratio of 1.0. NASA Wall Interference. NACA Rep. 410, 1931. TN D--935, 1961.

9. Glauert, H.: The Interference on the Characteristics 19. Heyson, Harry H.: Tables of InterferenceFactors for of an Aerofoilin a Wind Tunnel of Rectangular Use in Wind-Tunnel and Ground-Effect Calcula- Section. It.& M. No. 1459, BritishA.It.C., 1932. tions for VTOL-STOL Aircraft. Part IV--Wind 3. Rosenhead, L.: Interference Due to Walls of a Wind- Tunnels Having Width-IIeight Ratio of 0.5. NASA Tunnel. Proc. Roy. Soc. (London), ser. A, vol. TN D--936, 1961.

142, Oct. 2, 1933,pp. 308-320. 13. Ileyson, Harry H.: Wind-TunneL Wall Interference 4. Theodorsen, Theodore, and Silverstein, Abe: Experi- and Ground Effect ior VTOL--STOL Alreraft. Jour.

mental Verification of the Theory of Wind-Tunnel Am. Helicopter See., vol. 6, no. I, Jan. 1961_ pp. I-9.

Boundary Interference. NACA Rep. 478, 1934. 14. Heyson, Harry H.: Ground Effect for Lifting Rotors 5. Silverstein, Abe, and White, James A.: Wind-Tunnel in Forward Flight. NASA TN 1)-234, 1960.

'Interference With Particular Reference to Off- 15. Heyson, Harry H.: Nomographic Solution of the Center Positions of the Wing and to the Downwash Mordentum Equation for VTOL-STOL Aircraft.

at the Tail. NACA Rep. 547, 1936. NASA TN D-814, 1961.

6. Katzoff, S., Gardner, CliffordS., Diesendruck, Leo, 16. IIeyson, Harry H., and Katzoff, S.: Induced Velocities and Eisenstadt, Bertram J.: Linear Theory of Near a Lifting Rotor With Nonuniform Disk Load- Boundary Effects in Open Wind Tunnels With ing. NACA Rep. 1319, 1957. (Supersedes NACA Finite Jet Lengths. NACA Rep. 976, 1950. (Su- TN 3690 by Heyson and Katzoff and TN 3691 by persedes NACA TN 1826.)

Heyson.)

7. Kuhn, Richard E., and Naeseth, Rodger L.: Tunnel- 17. Anscombe, A., and Williams, J.: Some Comments on Wall EffectsAssociated with VTOL-STOL Model High-Lift Testing in Wind Tunnels With Partic- Testing. Presented to Wind Tunnel and Model ular Reference to Jet-Blowing Models. Rep. 63, Testing Panel of AGARD (Brussels, Belgium), AGARD, North Atlantlc Treaty Organization(Paris), Mar. 9-5, 1959.

Aug. 1956.

8. Heyson, Harry H.: Jet-Boundary Corrections for 18. Lockwood, Vernard E., Turner, Thomas R., and Lifting Rotors Centered in Rectangular Wind Tun- Riebe, John M.: Wind-Tunnel Investigation of nels. NASA TR R-71, 1960.

Jet-Augmented Flaps on a Rectangular Wing to 9. Heyson, Harry H.: Tables of Interference Factors for High Momentum Coefficients.NACA TN 3805, Use in Wind-Tunnel and Ground-Effect Calcula- 1956.

tions for VTOL-STOL Aircraft. Part I--Wind 19. Ganzer, Victor M., and Rae, WilLiam If., Jr.: An Tunnels Having Width-Height Ratio of 2.0. NASA Experimental Investigation of the Effect of Wind TN 1)-933, 1961.

Tunnel Walls on the Aerodynamic Performance of a I0. Heyson, Harry H.: Tables of Interference Factors for Use in Whld-Tunnel and Ground-Effect Calcu- Helicopter Rotor. NASA TN D-415, 1960.

lations for VTOL-STOL Aircraft. Part II--Wind 20. Rae, William II.,Jr., and Ganzer, Victor M.: An Tunnels IIaving Width-Height Ratio of 1.5. NASA Experimental Investigation of the Effect of Wind TN I)-934, 1961. Tunnel Walls on a LiftingRotor in a Closed Rec- II. Heyson, Harry H.: Tables of Interference Factors tangular Test Section. Rep. 470, Univ. of Wash- for Use in Wind-Tunnel and Ground-Effect Calcu- ington Aero. Lab. (Contract NAw-6442), Apr. 15, lations for VTOL-STOL Aircraft. Part III--Wind 1958.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT en, deg 90 80 70 60 50 40 30 20 IO 0

o I

!

f_.o.8 _w,L 70 80 90 X, deg (a) 7 = 2.0.

Figure i0.- Interference factors for vertical interference velocity due to lift for a small model mounted in a closed wind tunnel. _ - 1.0.

48 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION en, deg 90 OO 70 60 50 40 30 20 I0 0

o I I

_,o.e-, C-Lo_ I I _k_/_, -_'- / I--- /

//_ %1-37"

-I /" /' /" / /

/ / (_'15-

/ \ / /

/

/ (;.o6-

/

\ -2

/ \ /

/__.......- ----- I J

t /

/

/

/

/

-3 8w, L /

/

/

/

/

/ J C.2,o-\/ -4

/

/

-5

/

/

i -6 o I0 20 30 40 50 60 70 8O 9O x, deg (_));, = z.9.

Figure i0.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 49 en, deg 90 80 70 60 50 40 30 20 I0 0

o I I

i !

_.?.e_ _-,,.o_ _.o.7_ ...w__ \ J_ -I I f

_.,_ / /

(;.0.6-,

Z_- /

_--_7 /

t / / -2

" /

/

/ /

,/' _w,L

j.-'l

_'2.0- \ / -3

/

/

/

/

-4

/

-5 0 I0 20 30 40 50 60 70 80 90 X, deo (c) _ . z.o.

l_gare lO,- Continued.

TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0 0 0 "" C,o7-_ C,o.8--_ (;,l.O.-_ I r /" _-""---- ,_ .._..... _ __ .._..__" J / .------ / _w_L // C.o.6-, ,--{;.a.5 // -Z - _, ,2,0

/

/ f

E

-3 0 I0 20 30 40 50 60 70 80 90 X, deg (_) ;_ - 0.5.

Figure i0.- Conolucl.ecl..

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 51 On, deg 90 80 70 60 50 40 30 20 I 0 0

/ \

/ ', / \,

2 / \ \ _.2o

/ / ,<

/ \ _/-(:-1.5 \ \ \

/ / _,, \

/ / \\

' /

// / _ _'-------- _ _ _ \ ,+,.o

I/ /_ -"

8u,L 0 _ _ / _,o.s.j _ -_ _ ,,.,= \ .% ",,,,.

\

-I % \ \ \ C,0.6.,f \ \

\

\

-2

\

\

\ \ \ -3 O I0 20 30 40 50 60 70 80 90 X, dlo (a) _, - 2.0.

Figure Ii.- Interference factors for longitudinal interference velocity due to lift for a small model mounted in a closed wind tunnel. _ = 1,0.

52 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 0 80 70 60 50 40 30 20 I0 0 ,/ \\.

/ \,

\

/

kJ

\

/ \

I

\ r_.zo \

- \

I /

\ \

I /" \k

\ /-¢:-_.s \/ \

/ //

\ \

' I/

-_,I,0 I 8u,L f

// //

° __ _.08 - _,O.TJ

\

\

-I _.o.6./ \ \ \ \ \ \ -2 0 I0 20 30 40 50 60 7O 8O 90 X, deg

(b) 7.1.5

Figure 11.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT

8n. deg 290 80 70 60 50 40 :50 20 I0 0

,/ \\

/ "\

/ \ -_-zo / / / / /-_., o _u,/ --_._ _.08-/"_ -'_ "-._ "7" _;.o.7- J -2 9O 0 I0 20 30 40 50 60 70 80 X, deg (=) _ - z.o.

I'_.&,ure 11.- Co-tlmuecl.

54 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, =leg 90 80 70 60 50 40 30 EO I0 0 80 90 (d.) 7 • 0.5.

Fi_u__e 11,. Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOI._STOL AIRCRAFT 55 On, deg 90 80 70 60 50 40 30 20 I0 0 / / / / / /

/

/

/

_w,D /

/

20 50 40 50 60 70 80 90 X, deg (a) ?' - 2.0.

Figure 12.- Interference factors for vertical interference velocity due to drag for a small model mounted in a closed _ind tunnel. _ = 1.O.

50 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 290 80 70 60 50 40 50' 20 I0 0 / / / / ,/ _. 0.6--, / \ / / / / / _;,o.7-.-, I / E'0.8-,, / / / / / / f / / ./ / / / / I / ./ / i / / / / / / / .,/ / / ._.2 o-,,,/ ./ /

/

/ /

/ /

/

/ / / /

/

/ /

/ /

/ /

/ /

-3

/ /

/

/

/

/

-4 0 I0 20 30 40 .50 60 70 80 90 X, deg (b) 7--1.5.

Figure 12.- Continued.

JET-BOUNDARY COIIRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT en. deg 90 80 70 60 50 40 30 20 I0 0 / / / J / / _= 06--, f f / j_ .f ,I J / (;'07, Q08 \ / f / .° I / f /f o I / / 4 J f / / / / / / J f / jf \ J -_ol.O / / t jl / / / I /,f / / / / E f 8w, D - I f / /

/

/ d / jl

/

/

/

/

/

/

/

-2 / /

/

_;'27

/

/

/

/I

-5

/

/

/

-4 30 40 50 60 70 80 90 0 I0 2O X, deg (c) 7 = 1.0.

Figure 12.- Continued.

58 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 50 20 I0 0 I / / 8w, D -I / / / / / / / -3 0 I0 2o 30 40 50 60 70 80 90 X, dig (_) _ . o._.

Figure 12.- Concluded, + JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 59 Bn, deg 90 80 70 60 50 40 30 20 I0

/

/

\

J ,---C;,I.5

/

fz_ \

/

/

!

\

/ \

\

\

///

\

\

\

,-_.1.0

\

//

_'ujD

\

\

,f /-_,O,B % n ///,i _

/

f_

_-;,0,7 /

/ d / /" J f I _" 0.6- \ _/ -I f f d f

J

/ -2 0 I0 20 30 40 50 60 70 80 90 X, deg (a))' = 2.0.

Figure 13.- Xnterference factors for longitudinal interference velocity due to _rag for a small model mounted in a closed wi=d tumael. _ = i. 0.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 6O 8n, deg 90 80 70 60 50 40 30 20 I0 0 f _ - _.2.o

/ \

'\

/

\

\

/f

I /

\

',\

/,/

\

8u, D ljJ .

,-_-o8 l f _,.._....I J / _ ......_ ----_ / / ,.--_,0.7 / / /' / / /

./

/ J J _,. 0.6-'_ _f -I /f f / -2 0 I0 20 30 40 5O 60 70 80 90 X, deg (b) 7 = z.5.

Figure 13.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 61 8n, deg 90 80 70 60 50 40 30 20 I0 =7 / /"

/

-2 80 9O I0 20 :30 40 50 60 70 X, deg (_) _,. 1.o.

632643 0--62--5 Figure 13.- Continued, 62 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n° deg 90 80 70 60 50 40 :50 20 I0 0

' I

_,2,o--,_

I "

\ /v I / (:.Ls-, _ _.Lo- f \ f -20 I0 20 30 40 50 60 70 80 90 X, deg (a) ;,. o._.

Figure 13.- Conclua_.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR _rI'OL-STOL AIRCRAFT 63 en, deg 90 80 70 60 50 40 30 20 I0 0 / / J f / 2 / -_-0,6 I I / Complete wind tunnel-_ 8w, L A

/

!

/

/

-3 60 70 80 go 40 50 0 I0 20 30 X, deg (a) 7 = 2.0.

Figure I#.- Ya_terference factors for vertical interference velocity due to lift for a _ model mounted in a wind tunnel closed on the bottom only. _ - 1.0.

TECtiNICAL REPORT H--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 290 80 70 60 50 40 30 20 I0 0 / / ..t J I / _,07--, /'f / Complete wind tunnel- ....- / / ¢,_)e- ,/ / (>0.6-, ......

O /I- _ / --_ / / Closed floor only-

S -

/ / / _ "_,-r.., 5 /

///'" _ /_ ____--_ =

--I / 8w, L z _ _-_-2.o

t //"

t /

//" '1' --2

,/ /

/ /

/

-3

/ /

" /

//"

/

-4 0 I0 20 50 40 50 60 70 BO 90 X, deQ (b) _ - 1.7.

Figure 14.- Continued.

JET-BOUNDARY COIH_ECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT Bn, deg 90 80 70 60 50 40 50 20 I0 0 ........

t jf _- 0.6- / \ f \ / J J f I I __ ....,.- I Complete wind tunnel--,, ------ _...-.

J/ I """ _; ,0,7- _I _" I =.....

/'_'" (;,08-, _'" f / .-.-_ _ _ _-_ _. ,.__ r f =......

i" I ..I -Closed floor only "/ /" k-C'O.8 ,/S / _ / L-I;.i.O //_/ A/_ / (/' -_;-2o

,// Z

//,-_.,_ ,_'

-2 q

/

!

-3 ¢

/

//

/

// -4 30 40 50 60 70 80 90 0 I0 20 X, deg (c) 7 = z.o.

Figure 14.- Continue&.

TECHNICAL REPORT R--124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 6G 8n, deg I0 0 90 80 70 60 50 40 50 20 f ,.o,_, T.L; i _I r J _ _:.-- 8w, L < / i/ / _--Complete wind tunnel __.... i I. I / -I _"--- " =(;'1.5 / / '-Closed floor oni_

//

-2 - L{;,2. 0 -3 8O 90 0 I0 20 30 40 50 60 70 X, deg (_) _ - o._.

Figure i_.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 67 8n, deg 90 80 70 60 50 40 30 20 I0 4 /

/ \

\

/

_k_ _:, 0.6-_

\ /

/ "

8u,L

• / _, ,--_.2.o

I ,/ "\ ." , / Com:)lete wind ,unn.el--._,_x7

/ / \\ %

i

// - , / ,--Closed floor only TM %_ J

/

/ /

/ /, .,,..._

_'.c.(;, o.6 C (;,o.8--' --

i 0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 - 2.0.

Figure 15.- Interference factors for longitudinal interference velocity due to lift for a small model mounted in a wind tunnel closed on the bottom only.

_ = 1.0.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICSAND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 SO 20 I 0 3 f1_.

/ \

/ \

\

Bu,L

/ - \

/ \ .>\

I Closed floor on_.T_ / "_

_:':_.6J _.o.7, J ¢.o,sJ - ---_ _ =-_-=--=

0 I0 20 SO 40 50 60 70 80 90 X, deg (b) _, . l._.

FiEure 15.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 69 8n, deg 90 80 70 60 50 40 30 20 I0 _ Complete wind tunnel-

"\\\ /

/ /

_u,L l /" " _ /_ "_ _" 0.6 , _ :.21o _ _.

// .._ ,..4...

Z

_. o.o- / _;.o.7. _;.o.oJ _-C_o,e_ ,,oo, on,y

-I 80 90 0 I0 20 30 40 50 60 70 X, deg (c) _ - l.o.

Fi&'u_e 15.- Contl,,ued.

70 TECHNICAL REPORT R-124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0

_-_;,zo

I /_ / "_ Com )lete wind tunnel-_

C.o.6_ _.o.8-/ _.,.o -_/ o

Closed floor only--'- -I 0 I0 20 30 40 50 60 70 80 X, deg (d) _ - 0.5.

Fibre 1_.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STO]b AIRCRAFT 8n, deg 9O 50 40 30 20 I0 0

° I

_. 0.6_ X, deg (a) _ = 2.0.

Figure 16.- Interference factors for vertical interference velocity due to drag for a small model mounted in a wind tunnel closed on the bottom only. _ = 1.0.

72 TECIINICAL IIEPOI{T I{-124--NA'rlONAL AERONAUTICS AND SPACE ADMINISTI{ATION 8n, deg 090 80 70 60 :50 40 30 20 I0 0 1 I I %" I r,'0.7 -/ -I

L/"

j/ /" J

j_

- /

.d_/_Closed floor only / f

\

_--_,ko /_/_/,_ I

/ \

A \ -2

\

-r,,2.0 Complete wind tunnel/

/

_w, D

//

/

-3 /

/

/

/

/

-4 /

/

i

-5 40 50 60 70 80 90 3O 0 I0 20 X, deg (b) _ = z.5.

Figure 16.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 8n, deg 90 80 70 60 50 40 30 20 I0 O i i I

:.o.6-, <:,o.,. \ ¢.o+.8_

.-...-+-,,.---- _ ,---- _,. _<.:.. _+ ...

d / / /

-'_- _ // _

_,-_.,.o /,/ /_i" c.o._-'\

// /,"

-2 _ //_ /

/, .-_.,_ /--

_w, D

,"5"- / (/ 7/

/ / /+ _-_.2.o -3 x-Complete wind tunnel -4 '--Closed floor only /

/

0 I0 20 30 40 50 60 70 80 90 X, deg (c) 7 - z.o.

Figure 16.- Continued.

74 'TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE A.D,%IINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0 0 I i (>0.6 I;-o.7-,_ , (;.o.7._ C;.o.8_, X (;.o.8-, \ r I / _,0.6 -j ,./ / ., Bw,D -I

./ _/ /

._/L_.,.5 / \x"'

F / //_ -Complete .ind tunnel

/ / I

/ / -Closed floor only -2

/

/

-\

/ ,-_.2o

/

-3 60 70 80 90 0 I0 20 30 40 50 X, deg (d) 7 - 0.7.

Figure 16.- Concluded.

f

I ?5 JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-BTOL AIRCRAFT 8n, deg 490 80 70 60 50 40 30 20 I0 0 _ =.,.=_.

r \

/ \ /-co=,,..,._ ,o..,, _' Clo,ed f,oor o.l_ "_

, \

8u, D ::' rC'f.5 • _ _. _ ,\.

0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 = 2.0.

Figure 17.- Interference factors for longitudinal interference velocity due to drag for a small model mountel in a wimi tunnel closed on the bottom only.

_ = 1.0.

70 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, dig 39 80 70 60 50 40 30 20 I0 0 / Closed floor only---_ --Complete wind funnel k 8u, D / , -3, \ -_'_ _.0.7-_

_'_ -7.o, J _.o,- _-_ _ _= ___ ___

0 I0 20 30 40 50 60 70 80 90 X, deg (b) 7 = 1._ Figure 17.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 8n, deg I0 0 290 80 70 60 50 40 30 20

ill

r !_,._/-C°mplete wind tunnel

A_'°"d i,,oor on,y-_

/, __ -_.2o

'

.__- _ ,-C,l 5 8u, O o _ -_-_ _ _" _- / _,o.6 - _;.o-t J _=oeJ -I 8O 0 I0 20 30 40 50 60 70 X, deg (c) _ = l.o.

8n, deg 190 80 70 60 50 40 30 20 I 0 __ ___ --_/-Closed floor only "i0.6- C'0.7- " • 8u, D 0 I _,LO- _-_,,I.0 -I 30 40 50 0 IO 20 60 70 80 X, deg (a) _ = 0.9.

632643 0----62_6 Figure 17.- Concluded.

7s TECHNICAL REPORT R-I24--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 0 80 70 60 50 40 30 20 I0 0 "-Complete wind funnel

\\ \ /

4 \\ '-_.zo (;" 5A / 8w.L 3

\

\\\

\ k , \\ \

\ _ -"_ _-o.,-

_. _ {;,o8-_ \ _" ------I------- L

,\_\. \ \

",_ t_, 1.0 -/ _, \ . ,<t,.o6 _ --4 .....

F-..:_"X\_ +o, -_.o8 ._.,o

-.__._ __----/-_--I ......

0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 = 2.0.

Figure 18.- Interference factors for vertical interference velocity due to llft for a small model in an open wind tunnel. _ = 1.O.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 79 8n, deg 70 60 50 40 30 20 I0 0 690 80 _-(;,2o wind tunnel \ ,, I_ _ C°mp 'ere floor only

_ "'t / \'-°*°

\\

1\

8.,L \ \\,,, \ \

\

\ _,0.7- \ \ _-_,o6 "', / \ \ {,o.8 J \,\/"\ r_.o., _.." ...

-Z;,o.e ,-{;.1.0 9O IO 20 30 40 50 60 70 80 X, deg (b) 7 = z._.

Figure 18.- Continued.

TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8O 8n, deg 90 80 70 60 50 40 30 20 I0 0 _,2.o -Complete wind tunnel 8w,L -Open floor only 3 _ ;.1!

\ \

\\

,\\

_....- _;" 0.6--,

._\\ _

\

\\ \\\

\

\

\

\ \

_'0.7_ I \ \-_ \ /-- C.t.o j _-OS- ,.. ",,_ r_.o.7 _t_,O,S --T ---=-_ I0 20 30 40 50 60 70 80 9O X, deg (c) _ = z.o.

Figure 18.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT en. deg 90 80 70 60 50 40 30 20 I0 0

\

,2.0

V

_-C°mplete wind tunnel I

\\

8%L v'X _Open floor only I I \ \/ , t', 0.6-_ .,.

\

J

\

(;'0.7-_ _ ________.__ _'- ,.- r,, o.6 J / _;.o 8-_ / _,o.7J _,_.o j -I 9O 0 I0 20 30 40 50 60 70 80 X, deg (d) _ = 0.7.

Figure 18.- Concluded.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0 0

/

/

/ / /

/

/ (;° 0,64

/

/

Corn _lete wind tunnel

y-

,/ / J //

/ J

f ,// ¢-0.7- _ / / J i / // 8u,L f= .4 / " _.o.6_ i/, _ /.." _ -.

.,KL_-h- .- _, --

1_._ i i//i/, f .--

d f .- / / _/.

/ //_ / t" _-t.,0.8 / / /

" / /,, d"

1 I 1 i

/,/ //' /_"

/ / Open floor onlyX 9 <,

//" "_+',.o / //

/ /k( , 9

_, // I,

o ,o _o _o ,o _o _o ,o _o ,o

X, deg (a) _, = 2.0.

Figure 19.- Interference factors for longitudinal interference velocity due to lift for a small model in an open wind tunnel. _ = 1.O.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT On, deg 90 80 70 60 50 40 30 20 I0 0 2 / / f

/

/ jJ

,/

/_'0.6 ' '- I 11 jJ f_ I I / j jj i J - j/ /" // / 8u,L -I .I _

//- /> -

/" - %_:o.8 / .,// / ..< ..

'i, //_-_.2o

/ -2

//

/,/ //\

;! t / \_O)en floor only

/ -3 \_Complete wind tunnel /;

;/

i//'

-4 //_/

40 50 60 70 80 90 3O o IO 2O X, deg (b) _,. z._.

Figure 19.- Continued.

84 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION en, de9 290 80 70 60 50 40 30 20 I0 0 / J f J I , f J" _'0.6-\ _ I" I _.o.8- _.o.7-. _--'-" "" .........

0 / / / _ ._ /_'oB // //. , 8u,L ...--"k.__.,, o / / //" / •

// /,"

// ,,/z"

//'_-_.15 //_ _Open floo, only '7 / / / / -2 // / _, Complete wind tunnel // // /_/'< _--_.2o

/

-4 0 I0 20 30 40 50 60 70 80 90 X, deg (c) _ = z.o.

Figure 19.- Continued.

JET-BOUNDARY CORR_)CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 85 8n, deg 90 80 70 60 50 40 30 20 I0 0

' I 1 _ r

C.a6-_ C.o8- c.o._- C-o.6-

c.o:,-_'-\ c.,o- _ \, \

/

/

J -3 0 I0 20 30 40 50 60 70 BO 9O X, deg (a) 7 = o._.

Figure 19.- Ooneluded.

_6 TECHNICAL REPORT R--124--NATIONAL AEI{ONAUTZCS AND SPACE ADMINIST|{ATIO.N 8n, deg 90 80 70 60 50 40 30 20 I0 0 / \, \ \ \\ _-_,.2 o X

//

..// ..

I ,_ ___ .j.o8 _._ .<

o " _. _.G'_ "_ ...

_w, D -----. _.._ '_ _,. r,oe_k"_ -, /\, N Complete v,ind tunnel _' X\ \ \ ¢.oo_,x,, -2 \

\

\

\

-3 0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 = 2.o.

Figure 20.- Interference factors for vertical interference velocity lue to &rag for a small mo&el in an open wind tunnel. _ - 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 87 _n. deg 90 80 70 60 50 40 30 20 I0 0 3 /--

/ \

/ / N / \ X _ .____..._ \ / \ \ _ e-C,20 / // \\ r_..,._"_\.

' i // oo.° ,,oo. o.,, 7 \% <

/ ¢_ --=_>_---:>."-

0 _ .........._... _. _ _ -"-- _ "_ b.,._;,o8, ;:'- ,,,, )'-..

_,'0.7J '\ N -i / \\ Complefe wind tunnet-J \ h\

i "\

-2 0 I0 20 30 40 ,50 60 70 80 90 X, deg (,b) 7 = 1.5.

Figure 20.- Continued.

88 TECt-INICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 0 80 60 50 40 30 20 IO 0

\

/

",,, / ',,, • .4 ;'20 _ Open floor only / ¢.o_ - LZ. _- _-"=-- _'_ _,'0 7- Complete wind tiunnel --_ -I _,o6- _ \ -20 I0 20 30 40 50 60 70 80 90 X, deg (c) 7 = 1.o.

en, deg 40 30 20 I0 0 90 80 70 60 50 I / /-Complete wind tunnel _L= ' ' ' ' ' / -¢.., 5 "< ,,= i] _;.2o 8._ o __----:_ Open floor _.o7_/ _ _,osJ l;,o 8- _.o6 J -I 50 60 70 80 90 0 IO 20 30 40 X, deg (d) 7 = o.5.

Figure 20.- Concluded.

1 !

JET-BOUNDARY CORRECTIONS AND GROUND EFFI_CT FOR V'IX)L-STOL AIRCRAFT Sn, deg 590 80 70 60 50 40 30 20 I0 0

\

4 \r-C'zo

\

\

\

\

8u, D wind tunnel r Complete /--l;-o.6 -% \ "7 '_ ,_. _ r'_'0.7

_'_' J I _ ..... _ _ _"

Open floor on'rJ _'C_._ _'_j/ -I 0 I0 20 30 40 50 60 70 80 90 Xo deg.

(a) 7 = 2.0.

Figure 21.- Interference factors for longitudinal interference velocity due to drag for a small model in an open vlnd tunnel. _ = 1.O.

90 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION en, de_ 90 80 70 60 50 40 30 20 I0 0 \ _u,D /-Complete wind tunnel / -I 0 I0 20 30 40 50 60 70 80 90 X, deg (b) 7 = 1.5.

Figure 21.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 91 On, deg 90 80 70 60 50 40 30 20 I0 0

2 \

k ,-_;-zo \ 8% D -- _ -- _. _ /-- Complete wind tunnel

_ \.\ _ _ _-_.o_

Open floor only --/ _-"_ "'_P'_"- -I 9O 0 I0 20 30 40 50 60 70 80 X, deg (c) 7 : z.o.

Figure 2!.- Continued.

92 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION On, deg 90 80 70 60 50 40 30 20 I0 0 _-_'2.0 /,--Complete wind tunnel I ,_ / /--Open floor only ----- _ /

, ._.,_.._< /

Bu,D ---- _=_ _ _ /--_,0.7

_ - -_____ _o8 r_.,o

_. o.6J C-o8- -- --_---_- - • I _.0,7 J _'I.0 -- --I 80 90 0 I0 20 30 40 50 60 70 X, deg Ca) 7 = 0.7.

Figure pl.- Concluded.

/ JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAgq' en, d|g 90 80 70 60 50 40 30 20 iO 0

I 1 i/ i /

c_,__" o J__ _'I5-J _.io. _.iol _'0.8 "-J --- __ C;,0.7- -I BW, I.

-2 -3 30 40 50 60 70 80 90 0 I0 20 X, deg (a) 7 = 2.0.

Yn, Oeg 50 40 30 20 I0 7O 6O 0 9 80 I 7 , _.-_5 "----_'_°-j • ¢:.oaJ

i

_,07--' -I 8w, L _ .-...-..._.....__ -2 / _.o6-J -30 I0 20 30 40 50 60 70 80 90 X, deg (b) _, = l._.

Figure 22.- Interference factors for vertical interference velocity due to lift for correcting from a closed wlnd tunnel to ground effect. _ - 1.O.

632643 0--62--7 TECIINICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 80 70 60 50 40 30 20 I0 0

/ 7-/ / -

¢ _L _V- ? -- ':--

,;.o7-' _,.oe..... t..zo t _;.4o. r..=oo- I 8w, L -I / (;,o6-/ -2 I0 20 30 40 50 SO 70 80 X, de9 (c) 7 = 1.0.

@n, deg 50 40 30 2O I0 90 80 70 60 I _,15 \ t;.20 \ ._.40 ,, t.,lO0_

\_, \ _ '---L._ _'--

_w,L _. -- --- _..

-I -2 10 20 30 40 50 60 70 80 90 X, deg (d) 7 = o..5.

Figure 22.- Concluded.

JET-BOUNDARY C0RRE, CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 95 en, deg 90 80 70 60 50 40 SO 20 I0 0 I _,10.0 _ I _.4.o-_'_

_.2o--. \_

' _4 / _.08 _ _ _ (;.Lo--, _'_ -I 8u,L

\

\

\ \ \ \ \ -2

\

\

(;'06-'% -3 0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 = 2.0.

Figure 23.- Interference factors for longitudinal interference velocity due to lift for correcting from a closed vlnd tunnel to ground effect. _ = 1.0.

TECHNICAL IIEPOI_T H-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, (leg 80 70 60 50 40 30 20 I0 0

"_ _. _.,o/C.lsJ -_'9_. /

-I (_, 0.6 _ \ \ ,,,,, 8%L

\

\

-2

,\

-3 0 I0 20 30 40 50 60 7O 8O 9O X, deg (b) _ = 1.5.

Figure 23.- Continued.

I JET-BOUNDA}IY COI_RE, CTIONS AND G_OUND EFFECT FOR VTOL-S'}'OL AIRCRAF'P 8n, deg 190 80 70 60 50 40 30 ZO I0 0

I

[;'0.8 J

--j_

8u,L (;-_,0 - -I -2 60 70 80 90 30 40 50 o I0 20 X, de9 (cl _ = z.o.

8n, deg 3O 20 I0 0 6O 5O 40 90 80 70 I

I

_'4.0_

_..2.o- _.,o':o-., \

_,0.8_ _,i,O-\

\ \

8u,L ---..,..,.

_ _,o._- / _.o.6.J _

1 -"

-I 70 80 90 0 I0 20 30 40 50 60 X, deg (d) _. o..5.

Figure 23.- Concluded.

' I TECIiNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Un, deg 90 80 70 60 50 40 30 ';'0 I0 0 /

/

/

/

# ./ 8w, D / / / f {.40- ..,_J J _"08' \ {;,t.O-, i//' _"017_ __.._,--

,C

\ IO 20 30 40 50 60 70 80 90 X, deg (a) 7 = 2.0.

90 8O 7O 60 3O zo 1o o

/

/

/ J / 8w, D / / _f / / / _._o o_, /

.---_ = ] ] , , ,\ \-

I0 20 30 40 50 60 70 80 90 X, deg (b) _ = z._.

Figure 24.- Interference factors for vertical interference velocity due to drag for correcting from a closed wind tunnel to ground effect. _ = i.O.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 99 #n, deg 290 80 70 60 50 40 30 20 I0 0 J f J J jf ¢.o6_ I 8w, O I

¢,ll.5--/ //

._oJ

/

i r,, 40 J -I 20 30 40 50 60 70 90 X, deg (c) 7 = 1.0.

8n, deg 90 80 70 60 50 40 30 20 I0 0 I t- I _.06_ ........ _ _ _'0.7- \ _ _ llw, D 0 __._.4._.._.= _ =._="

/

(-20 y (;.410 J _.100 .j

L I

-I 40 50 60 70 80 90 0 I0 20 X, deg (cl.) _ I 0._.

F'J.gu.z'e 24.- Concluded.

° 100 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 090 80 70 60 50 40 30 20 I0 0

.--- _ 11 _o._ /

_4o _{2o _ .5 /_o6 / / _,_o.o / Bu,D -I f4 / J f f i -2 0 I0 20 30 40 50 60 70 80 90 X, deg (_) _ = 2.0.

en, deg 80 70 60 50 40 30 20 I0 0 j /i _ '-_.40 _'2"0.100 /" J'/ " 8u, D - i i -2 0 I0 20 30 40 50 60 70 80 90 X, deg (b) 7 - 1.5.

Figure 25.- Interference factors for longitudinal interference velocity due to drag for correcting from a closed rind tunnel to ground effect. _ = 1.0.

I01 JET-BOUNDARY CORRECTIONS AND GROUND EFF]DCT FOR V'I_0L-STOL AIRCRAFT 8n, deg 80 70 60 50 40 30 20 I0 0 9o _ / _ [ _ _ 2 _ 0 _ _ ' I l 5 / / / _-_'10,O \_14.0 / / / / / / / -2 0 I0 20 30 40 50 60 70 80 90 X. deg (c) 7 = z.o.

8n, deg 90 80 70 60 50 40 30 20 I0 0 !

8u, D i_ _ _ .._ 5_/ _/"_-:.,5_/%¢.,.0 \ -:.o.8 • / J I -2 0 I0 20 30 40 50 60 70 80 9O X, deg (a) 7 =o.5.

Figure 29.- Concluded.

1¢)2 TECHNICAL REPORT I{-124--NA'rlONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 3O 2O I0 0 _ t,. 06 8w, L r"" 07- _ I;.,.o- \ C',_,,_.zo- \ _ _ I _ I \ I \ ----I---_ 30 40 50 60 70 O0 90 0 IO 20 X, de9 (a) _' = 2.0.

In, dig 60 50 40 30 20 I0 0 390 BO 70 I ....... I j _ ..,_......-----" _w,L _.07-_ ,,....... _ .......

._._.,_.._._ ...._.- -"" {.40- c.i_.., ' _.,._. . "\_ ,\i__

i ,t -

60 70 BO 90 0 I0 20 30 40 50 X, deg Cb) _, - z.5.

Figure 26.- Interference factors for vertical interference velocltydue to lift for correcting from a wind tunnel closed on the bottom only to ground effect. _ = 1,0.

JET-BOUNDARY CORR_ONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 103 8n, de_) 20 IO o 90 BO 70 60 50 40 30

I

.,...... ---" I _.0.6 _ ,,.,.- ---" "" ..,.,...._..._i_..._. _ _ awwL /

_.!o-,I c.,o- / I;._o.o j

_.l 5 -j _.4,o- -I IO 20 30 40 SO 60 70 80 90 o X, de9 (=) _ = z.o.

Yn_ oeg f 9O 80 70 60 50 40 30 20 I0 0 I f jl I _. _ I Bw, L

--_--'-- _ _ c.o.-_ _.,o-,__---_

• _ ,..-----" _--- _ _ --_-- _ ..-.-- -"r (;.i0 0 j , - _ _ r,,,40,_ , __ 0 io 20 30 40 50 60 70 80 90 X, deg (a) _ = o._.

Figure 26.- Concluded.

104 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg ZO I0 0 90 80 70 60 50 40 30

/

/

/ / / / / / / / / / / _'06"-_,. /

2"

8u, L I

/

_'0.7 TM / t-

J

/ / (;,0.8-_ J i f i I I .....-- 0 "/_

/ /

/

_;.,.o J _.,_J r,-2o--/ C-4,o-' -I 0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 = 2.o.

Figure 27.- Interference factors for longitudinal interference velocity due to lift for correcting from a wind tunnel closed on the bottom only to ground effect. _ = 1.0.

JET-BOUNDARY CORRF-_FIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT #n, deg 90 80 70 60 50 40 30 20 I0 0 / / _;'0.6- \ /' / 8u, L I / f,,.'

J fJ I J ¢,0,8- J / ......

(;.0.7_ ......

J f J __.-..

0 i "'_ / (;,i.o J _,-I.5-

/

(;,2.0- -I 60 70 80 90 30 40 50 0 I0 20 Xo deg (b) _ .z._.

Figure 2_.- Continued.

i TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION @n, deg 90 80 70 60 50 40 30 20 I0 0 / / r..o.6- -I 0 I0 20 30 40 50 60 70 80 90 X, deg (c) _. z.o.

8n, deg 90 80 70 60 50 40 30 ZO I0 0 I

I

_. o.6A _'1.0_ _'0.8_ _'0.7 "k, _u,L 0 _ _ I _'2_-- ¢'I0.0- , / _,.4.o-_ -I 0 I0 20 30 40 50 60 70 80 90 X, deg (_) _ - o._.

FI.Suz'e 27.- Concluded.

JET-BOUNDARY CORR_ON8 AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 8n, deg 190 80 70 60 50 40 30 20 I0 0 (;" 0.0.\ C.Ls-_ ¢-2.o- _'4.0- \ \ __ "" "-" "-- ---- --..._.. _:-o8, r"'--------.

(:.j.O J -_ _;,0.7-' ""_ _ -I 8w,O \ \ /, -2 • 0.6 J \ \ \\

\

-30 I0 20 30 40 50 60 70 80 90 X, deg (,,) 7 = 2.0.

Figure 28.- Interference factors for vertical interference velocitM due to drag for correcting from a wlnd tunnel closed on the bottom only to ground effect. _ - 1.0.

108 TECIINICAL I{EPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 50 40 30 20 I0 0 190 80 70 60

I

_.zo- I °i "" "--- _ (;'0,8 r'_ % 8w, D -I (:.o6__',_ \.

\, -2 -5 0 I0 20 30 40 50 60 70 80 90 X, deg (b) _ = z.5.

Figure 28.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 8r,, deg 190 80 70 60 50 40 30 20 I0 0 I (;.tO.O_ (;-t 5--, t;.4o-, (;.ko--, C;.ZO--,

'\ \

• _-08 -/ -" _..

8.,o _ _;.o._J ,% _.d.6> \ -I \ I0 20 30 40 50 60 70 80 90 X, deg (c) 7 = z.o.

8n, deg 70 60 50 40 30 20 I0 0 9O 80

t L L

_,I.o, _,z.o_

_.o,_ \_.', ___

8.,D 0

_.,'oJ

-" > _.0.7- _;'I0,0- _, _.o.6J -I0 I0 20 30 40 50 60 70 80 90 X, deg (a) 7 = o. 5.

Figure 28.- Concluded.

632643 0--62--_ TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, fleg 90 80 70 60 50 40 30 20 I0 0 ,-- _:,o.6 40 50 60 70 80 90 0 I0 20 30 X, deg

(a)

7 = 2.0.

en, deg 90 80 70 60 50 40 30 20 I0 0 Bu, D I 0 I0 20 30 40 50 60 70 80 90 X, deg (b) 7 = l...5.

Figure 29.- Interference factors for longitudinal interference velocity due to drag for correcting from a wind tunnel closed on the bottom only to ground effect, q = 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 8n, deg 90 80 70 60 50 40 30 20 I0 0 _u, D I0 20 30 40 50 60 70 80 90 X, deg (c) 7 = i.o.

8n, deg 20 I0 0 90 80 70 60 50 40 30

_____. c =lo.o

___-...J "---.._ r_',s ,,-C-J.o ,--_.o.a Bu,D -I 70 80 90 0 I0 20 30 40 50 60 X, deg (a) _ = 0.5.

Figure 29.- Concluded.

112 TECIIN]CAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 80 70 60 50 40 30 20 I0 0 I

/// _-.... _%.L

/

/

/i / ,,,t / /

y,<"

-I / \_'- _w,L / /

/ /

/

/

//

/

-2

/

-3 9O 0 I0 20 30 40 50 60 70 80 X, deg (a) ; = i.o.

Figure 30.- Illustration of reduction of wlnd-tunnel interference at low speeds by above-center model mounting in closed wind tunnel.

7 = 2.0; T I = 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 113 8n, deg 9O 80 70 60 50 40 30 20 I0 0 I I I I I I

J J

/- _u,L _u,D- ./ "\ f ._ _ =--.=-_.

/

/

/ // f

/

,/

/

/ --.------- /j -I

/

,¢ ,/

/

//

,/ / / d / -2 60 70 80 90 30 40 50 I0 2O X, deg (b) _ - 0.8.

Fi&,_.re 30.-Con_u_d.

,

J

- >-3 t<l () ~ ..... () > t"' :::0 t<l "d 0 :::0 >-3 ~ ...... .., "" ~ > >-3 ..... 0 2: > t"' > t<l :::0 2: > >-3 ..... ~ "d > t<l >-3 i-' i-' ~ 0 0 () en t1 en () 1; ~ ..... ~ en :::0 > >-3 H 0 2:

is

L-96046

section

Test

tunnel.

full-scale

wide.

Langley

feet

in

and

high

installation

feet

ground-board

of

Photograph

31.-

Figure

JET-BOUNDARY CORRECTIONS AND GROUND EFFF__T FOR VTOL-STOL AIRCRAFT 115 h--" r /-" ._X-90 ° -I "._._ _ _ _./_ ....

8w, L ,, ,"X'75° / j / \ / -2 /# I -%. , # • / X "45" _j\

"-'_'-x "6o °

I -3-2 -I 0 I 2 3 4 5 xlH (a) 7 = 2.0, /

/ E_x-9o° _//"

# 8w, L - I /s-"

x°15 L' \ /x

i / \_, X --30_ :_ __ , .p'--_ _ -2

x'45oJ

X "75_ X "60°J I -3 I 2 -2 -I 0 3 4 5 x/H (b) _' = 1._.

Figure 32.- Effect of wind-tunnel width-height ratio on longitudinal distribution of vertical interference due to lift in a closed wind tunnel. _ = 1.0; _ = 1.0.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION :'_ / f "°" / • _]w,L /-X :90' -I . __ j A.._:.. "// X:I5_-J

7_. _ -

X "75°"-/

x-3O'-/ x-6O "--/

I 4 5 I 2 3 -I 0 x/H (c) 7 = 1.0.

xl,s\ _

x:SO\ \

-I 8w, L x-6OtY'x -2 x,Kd:, .....

i -I 0 I 2 3 4 5 xlH (d) _ = o._.

Figure 52.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOH VTOL-STOL AIRCRAFT X'45_ --60" _u,L 0 X" "_-:--° I

x.jSO_/ _ ,_..:-,-"_..--

-I I / X-30°-/ I -2 -2 -I 0 I 2 3 4 5 x/H (a) _ = 2.o.

-X "60° X • 45_-.,, _X"75° % 8u,L -I X "30 _ I -2 -2 0 I 2 3 4 5 x/H (b) _, = 1.5.

Figure 33.- Effect of wind-tunnel width-height ratio on the longitudinal distribution of longitudinal interference due to lift in a closed wind tunnel. _ = 1.03 _ = 1.0.

118 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION X-45% _X-75 X'30:_ % r-X'60 °

/ /-x.9o"

8u,L X" 0°-- _ \\ 3 4 5 -I 0 I 2 x/H (c) ;, = z.o.

I

I

X,45%

.75°

-X "900 X "30_ 8u,L ,_,_. ,----.

-X "60" . r m !

/

X,I5o-..

!

-I 0 I 2 3 4 5 x/H (e) _, - o..5.

Figure 33.- Concluded, JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT I ,-X" 4 5o ,-X "9 0 ° m

o

x" oC ,,, -,, L

\ \ Bw,D '-X "60" "-X'75° X "SO_ Z-"" -2 \ / -3 -2 -I 0 I 2 S 4 5 x/H [a) 7= 2.0.

-x =90'

,_.X=45 ° / ___" .::--_-_. - _,_ __ :__ .

Bw, D

X = 0°--" '_ _. :_-_'- _X.75 °

-I x- x "60" I I

,\

X =30_ I -2-2 -I 0 I 2 3 4 5 x/H (b) 7 - z.5.

Figure 34.- Effect of wind-tunnel width-height ratio on the longitudinal distribution of vertical interference due to drag in a closed wind tunnel. _ = 1.0; _ = 1.0.

120 'TECHNICAL REPORT R--124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION _X--90 ° _w,D k_X :75 ° x--O _ -I I' i X'-50 _-- I -2 -2 -I 0 2 3 4 5 x/H (c) 7 -- 1.o.

_X"90_ EL __

:×.6o o

_-X=75" X " OS _'_/ -I / ,

x--15"-/

X_X-- 45 °

x4od

I -2 -2 -I 0 I 2 4 3 5 x/H (d) Z.o._.

Figure 3_.- Concluded.

JET-BOUNDAI{Y COIU{ECTIONS AND GROUND EFFECT FOR VTOL-STOL AII{CLtAFT 121 / -X'45 ° / -X"60° _ _L-_"_ _ /-X "75° r_.X- 90 ° ,. , X--15°J/_ -I X =30o-'

F

-2 -2 I 2 3 4 5 -I 0 x/H (a) 7 = 2.0.

_)(=45 ° --X =75" Bu, D ,--X "90° -2 -2 -I 0 I 2 :3 4 5 x/H (b) ?,= i.5.

Figure 35.- Effect of wind-tunnel width-height ratio on the longitudinal interference due to drag in a closed wind tunnel. _ = 1.O; _ = 1.O.

122 TECHNICAL REPORT I{--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ..X-45° I /-X-60

4'

,--X'75°

/

_--X'90° -I -2 -2 -I 0 I 2 3 4 5 x/H (c) 7 = i.o.

_X=45° __ /-X "60°

x-- o__ .x-gu

, -I X=30 • -2 -2 -I 0 I 2 :3 4 5 x/H (a) 7 = o.5.

Figure 39.- Concluded.

JET-BOUNDARY CORRF_TIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 123

,-x :9O°

f

ff

I f s

\i " "%

,,,,//

/

-I 8%L i i _ #f • N X

/ x/

/ /-, ,y

, \ )_,/Z,\, X "75° -2 / × =30 °-' J'-J,_',

X_ x =60 °

X=45°--/ I -3 4 5 I 2 3 -I -2 x/H (a) 7 = 2.0.

I

,--X-'90°

___2

\/ _w,L -I

rX =75

X = O_

/

_J /

x457-/ "7"

-2

-- \,.._

X =30°- I X.45._., I -3 -I 0 -2 I 2 3 4 5 x/H (b) _' ,: 1.5.

Figure 36.- Effect of wind-tunnel width-height ratio on the longitudinal distribution of vertical interference due to lift in wind tunnel closed on bottom only. _ = 1.0; _ = 1.0.

I 124 TECHNICAL REPORT R-124--NAT10NAL AERONAUTICS AND SPACE ADMINISTRATION I I _X-90 o _× =75 ° / I' _ _---_ _ - _w,L X .

J J -I J ×.15°-_

, / \

X = 50°-" \ -X'45 ° _-X "60°

t*

, I I -I 0 I 2 5 4 5 x/H (c) 7 = 1.0.

I x=9OL_ x=T5L \ I X =60°-\ _w,L -I x/H (d) 7 - o._.

Figure 36.- Concluded.

,/I,Tr-I]OUNI)AIIY C(}III{ECTIONS AND GROUND EFFECT FOR VTOL-STOI, AIRCIIAFT 125 _-X"90° /-X "600 %, _-X'75° /, 8U, L 0 x'-OL/ '_ _>_ X,15°J _.X,45° x'3OL/ -2 -2 -I 0 3 4 5 x/H (a) 7 = 2.0.

,-X "90°

.60 i-x' 5 °

-J-,-,. _,_ .. ___ 8u, L 0 2 5 4 5 x/H (b) 7 = 1.5.

Figure 37.- Effect of wlnd-tunnel width-height ratio on the longitudinal distribution of longitudinal interference due to lift in wind tunnel closed on bottom only. _ = 1.O; _ = 1.O.

632643 0--62--9 126 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION I I -X'90" / / _u,L Xffil5 _-./ / I X "75°'-/ -I X "307-/X "4_°j X'60°J -2 -2 -I 0 I 2 3 4 5 xlH (c) 7 = 1.0.

I I Bu,L -X"60° X: 15oJl_/ : -I X.30 °- -I 0 I 2 3 4 5 x/H (d) _ - o.5.

Figure 37.- Concluded.

JET-BOUNDARY CORI1E, CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCItAFT I rX'90* f -, i.

-I S.<,

B%D

'--X -60" _X"45" -2 -3 -2 -I 0 I 2 3 4 5 x/H (a) 7 = 2.0.

I ,-X -90"

_ /-x-75" .... /

_ _ _,.__. :._ __-------_ -- _. _j ;--:--_ _.-

Bw, D -I -X -60" -2

x=_5._/,/_(.)z,, \_x.45o

X =30"- -3-2 -I 0 I 2 5 4 5 x/H (b) 7 = Z.5.

Figure 38.- Effect of wind-tunnel width-height ratio on the longitudinal distribution of Vertical interference due to drag in wind tunnel closed on bottom only. _ = 1.O; q = 1.O.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION I fx'9o°., -'-X"75° / / 8w,D "_ LX -60 o -X,45 I 2 3 4 5 x/H (e) 7 = 1.o.

I i I

I

-X "90o m m 8w, O Io -'_

o

X.,5__/ ./_>_ -×-45" -I X..30,._ J -2 3 4 5 -2 -I 0 I 2 x/H (d) ;, = 0.5.

Figure ,'38.- Concluded.

JET-BOUNDAI{Y CORI{I'_C'I'IONS AND GROUND EFFECT FOR V'IX)L-STOL AIRCRAFT 129

/-..... /-X-75"

._" _'_'_ _ J f

/-2=

8u,D 0 _ -- -.

. x. o_ _:_

X...IS_J - -I X__30o_/ X--45 _- -2 I -2 -I 0 I 2 3 4 5 x/H (a) 7 : 2.0.

I X =30° _X--45 °

I r-x °6o°

._ ._ -X'75° _m !

k--X - 90"

x-i,_L/

[ I -I -I 0 3 -2 I 2 4 5 x/H (b) 7 = z._.

Figure 39.- Effect of wind-tunnel width-height ratio on the longitudinal distribution of longitudinal interference due to drag in wind tunnel closed on bottom only. _ = 1.O; _ = 1.O.

130 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

2 Fx:_o o

I __X:90

- .. v-___-._:__

X:I5 ° - I -I 2 5 4 5 -2 -I 0 I x/H (c) 7 = 1.0.

2 !

X-- 0_-\

=45 X :60° I

x:,5:_

roll

L x.9o °

I -I 4 5 -2 -I 0 I 2 :3 x/H (a) : . 0.5.

Figure 39.- Concluded.

I JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 131 X =0 °--/\ -I X _15_.-, X-30°-J X.60 °- X,75 oj I I I -2 0 I 2 3 4 5 -2 -I xlh (a) Vertical interference due to lift.

_X.45°

/-×:Ts-

/

X " 0°-

/

\

-I X =30°-J -X -60" -2 -2 -I 0 I 2 3 4 5 x/h (b) Longitudinal interference _ue to lift.

Figure 40.- Distribution of interference factors along longitudinal axis for only the closed floor of a wind tunnel (grouud effect).

.

132 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION _X=45 O rXlgO ° _-X-75° X_-OS/ "_ -I X_-15o--/ __ _-X --60° /J X =30_ I -I 0 I 2 5 4 5 x/h (c) Vertical interference due to drag.

X--15_-k x=OL, -- r _-X'90 ° __/" -X "60° /-X _ 75 °

x

X-45 _

i--"

I 0 I 2 3 4 5 x/h (d) Longitudinal interference due to drag.

Figure 40.- Concluded.

JET-BOUNDARY CORRE'CTIONS AND GROUND EFFECT FOR YTOL-STOL AIRCRAFT 133 I I

I

_.,s\

X= 50_

Ix-o\

f I j° i 8w, L _..X,75 o -I X145=--/

_-i _----. ..... _-X'90"

I -2 3 4 5 -2 -I 0 I 2 xlH (a) t_ = 0.7.

I x!'s I

_w,L / -I

' x-;o'-/

X "75°j X 19 0°-_

I

-2 0 I 2 3 4 -2 -I xlH (b) ; = z.o.

I

X = 0_-,_ i x -60 "-_/---- X "75_

x-9O =j

I I -I -I 0 I -2 4 5 2 3 x/H (c) ; = 2.0.

Figure 41.- Effect of vertical location of model on the longitudinal distribution of vertical interference due to lift for correcting from a closed wind tunnel to ground effect. 7 = 1.0; S = 1.0.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION -- 0% _

- L x.9o _

_u,L

x-so_'/ \_-x-6o o

-I X-45 _ _.--X=75 ° -2-2 -I 0 I 2 3 4 5 x/H (a) r_ : o.7.

X : 0%, 8u,L __.X:90 ° I I -I -2 -I 0 I 2 S 4 5 x/H (b) _ - 1.o.

Figure h2.- Effect of vertical location of model on the longltud£nal distribution of longitudinal interference due to lift for cor- recting from a closed wind tunnel to ground effect. 7 " 1.0; = i.'0.

JET-BOUNDAItY COR_tF_CTI(JNS AND GROUND EFFECT FOR VTOL-STOL AIRCflAI_I" 135 X =60 O v, I L

Ix. o o

-I 0 2 5 4 .5 xlH (a) _ = 0.7.

X'90\ X =75__ I,-- X " 0 °-/ -I -2 -I 0 I 2 3 4 5 x/H (b) r_ = l.O.

Figure _3.- Effect of vertical location of model on the longitudinal distribution of vertical interference due to drag for correcting from a closed wind tunnel to ground effect. 7 - 1.O; _ - 1.0.

136 TECIINICAL REPORT R-124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION I

/__x=9o o

I /-X=75 °

LFx,6o"

BU,D _J

X.30°-/

-I 0 I 2 3 4 5 x/H (a) _ = 0.7.

i ,-X "90° I

/ /-x "6o°

X = 0 °J

x-_5 °J

--I I X"30_ -2 0 I 2 3 4 5 -2 -I xlH (b) _ : l.O.

Figure 4J4.- Effect of vertical location of model on the longitudinal distribution of longitudinal interference due to drag for corr_.cting from a closed wlnd tunnel to ground effect. 7 = 1.O; _ = 1.O.

,IET-BOUNDAIiY CORRF_CTIONS AND GROUNI) EFFECT FOR VTOL-STOL AIRCRAFT 137

l

• V'-'-'%_ -×-_o °

8u,D X'30°-/ / -I X"60°-/ -I 0 I 2 4 5 x/H (e) _ - 2.0.

"I- /-X "90° Bu,D X • 0 _--/ I

-L z

-I 0 I 2 4 xlH (d) _ - ZO.O.

YiEure 4-4.- Concluded.

TECHNICAL REPORT R-124--NATIONAL AERONAIfTICS AND SPACE ADMINISTRATION I x-45_ \ -x'9O"

'

[ 8w,L "'- _ _"_ "-_ ,--X'75 ° 0 x. OL / --I J -2 -I 0 I 2 3 4 5 x/H (a) _ ." o. 7.

I x'SO__ 8w, L ..... . ......

X " 0 °- I X.15°-/ t -I 0 -2 -I I 2 3 4 5 x/H (b) t .,1.o.

x.6Ot, x:75_ x-9_

Bw,L 0

/

x,O _ --I --2 -I 0 I 2 3 4 5 x/H (c) _ = 2.0.

Figure _.- Effect of vertical location of model on the longitudinal distribution of vertical interference due to lift for correcting from a wind tunnel closed on bottom only to ground effect. 7 = l.Oj _ = 1.0.

JET-BOUNDARY CORRE_CTIONS AND GROUND EFFEC_I ' FOR VTOL-ST£)L AIRCRAFT i - 0 @

/-×i

=15" / ;3o.

I to i X.75'-/ -I -2 -2 -I 0 I 2 5 4 5 xlH Figure 46.- Effect of vertical location of model on the longitudinal distribu- tion of longitudinal interference due to lift for correcting from a wind tunnel closed on the bottom only to ground effect. 7 = 1.0; _ = 0.7; = 1.0. (Plots for other values of _ are omitted since 5ui L for > 1.0 is negligible when plotted to this scale.)

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION I I X " 0°-_ -X'50 ° 0 l__ ____ , LX "90° I _-X"60° --I -2 -I 0 I 2 5 4 x/H (a) ¢ - 0.7.

I l /-X " 0 ° Bw, D \ _-X "90° I -I-2 -I 0 I 2 :3 4 5 x/H (_) ¢ - 1.o.

Figure 47.- Effect of vertical location of model on the longitudinal distri- bution of vertical interference due to drag for correcting from a wind tunnel closed on bottom only to ground effect. 7 = 1.0; B -- 1.0.

JET-BOUNDARY CORRE_'IONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT

I

X • 30"-.

,\

x-iS\

×.oo--, _,m_ m_..,. /

_mmm 8u, D X "4 5='- _-X=9Cf' [ -I X =60_ 2 3 4 5 xlH (a) _ - o. 7.

X = O_ , \ X "30°- \_, m 8u, D 0 -I X "90°- -Z -Z -I 0 I Z 3 4 5 xlH (b) {. z.o.

Figure _.- Effect of vertical location of model on the longitudinal distri- bution of longitudinal interference due to drag for correcting from a vlnd tunnel closed on bottom onlM to ground e_fect. 7 = 1.0_ _ = 1.0.

032643 0--62--10 142 TECHNICAL REPOItT R. 124--NATIONAL AEItONAIYrlC8 AND SPACE ADMINISTRATION × - 0_-.,, \ Bu, D 0 .--- ._.._ _ \ '-X "90°

I

-I 3 4 I 2 -2 -I 0 x/H (c) {_ -2.0.

X " OL \"_....._ .._- 8% D \ _--X'90° I -I -2 -I 0 I 2 3 4 5 x/H (d) _ - ZO.O.

Fibre 48.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 143 I 0 I I X "9(7 X -60"- 11 .,,::= = _.-.=: -I ,' ..I I" '--X • 50" <2 ,; /i/ ./ I ×" A, / /_ 8,,,L I/'/_ -×.m" 8w, L / "15" t / -x.o" -2 j./ -2

J \-x-o"

-3 -3 1.0 ,5 1.0 0 .5 4" y/B -I- y/B (a) 7 - 2.0.

(b) 7 = 1.5.

_X,60 ° r-X,75 ° X'90* -X,30 ° _X-45 °

____. ---- -:_ _x._5"

_w,L -I B%L -I

x.)s'J x'o:J -'"

-X'30" I - 0 ° -x'IS" -2 o .5 tO -gO .5 LO 4-ylB 4-ylB (c) 7 - Z.O. (d) 7 = 0._.

Figure 4 9. - Effect of wind-tunnel width-height ratio on the lateral distribution of vertical interference due to lift in a closed wln4 tunnel. _ = 1.0; _ = 1.0.

144 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION FX "30° -X.30 ° / ,-X'45 ° 8u,L 8u, L I / ' -%, t-X "60° _ f _X"60" ×.!5 -_"_-._ _..._ ,.,,.. _. X'75" "%.. EX-75° __-...=_ --. _ I ._ _- __..___ ::_

_x,9,o% =" io'-

x:O'-_ X 5 \ X" 90'''-,, o .5 1.0 0 .5 1.0 +y/B +y/B (a) ;,= 2.0. (_) _,= l._.

'i

J

-X-30 ° _X,45 ° X'I5 ° /-x'3O" .... /_ __ _X"4S ° X_" 0"- <" o 8u, L 0 -_'X'60" "'_ -'_ _-×,90" _u,L X_I5. y \ _X.75.

_X "7 5° X • 0°- _-'X" 90° -I -I lO ,5 I.O o .5 ±y/B :t..y/B (o) _,-z.o. (d.)_,-o._.

Figure 50.- Effect of wind-tunnel wldth-hel_ht ratio on the lateral distribution of longitudinal interference lue to llft in a closel wind tunnel. _ - 1.01 _ - 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 0 , 0 I

_-.'4.-- _...__ _.,o- __ -- _.,o-

' ' .--_- / . .X.75 = £-X-75"

- / _ _ ,,_ "-X "60" ' / / -J .,/i / \ _ -I " / \-x'so" ,, /_-x'SO ° _ /

/ t

BwpD / _x't5 ° 8w, O ---'- / \-x's5 °

" K

/ z-(

\ J'" /'_-X " O" _X " O" -2 / -2

J

-3 -3 1.0 0 .5 1.0 0 5 ±Y/B ±y/B (a) 7 =2.o. (b) 7 =l._.

, -x,9O" x.9o'-I/ -x-Ts"

' -" ..... X,75 ...... Z "60" I __ i -X'45" ...... "'- .-..Z -X'30" ..... _ ....-.--I -X'60"i _ _ ..... "_ r-X'45"I / -X'30* 8w, D -I --k'- "_-- Bw, D -I _--'"- _'X"lS* \-X"15* \ "--" "_" _X " 0 ° \ -X " 0 ° -2 -2 0 .5 1.0 0 .5 1.0 ± y/S -,I- y/e (c) _ =1.o. (d) _ =o.5.

Figure 51.- Effect of wind-tunnel width-height ratio on the lateral distribution of vertical interference due to drag In a closed wlnd tunnel. _ = 1.0; _ = 1.0.

146 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION I

I ' I

-X.15 ° __-X "15° -._-x-3O o ..._ _/-X "50 ° ___-X'45" _X'60" 0 " 8u, D 0 8u, D _x'75" \ r - _ .-:.

x-is"- x'9O _'-- "'_-_ .... -X'90* ""_ _ X " 0°-/ -I -I 0 .5 1.0 .5 LO _+y/B -I- y/B (a) _, ,- 2.0.

(b) 7=1.5, ;:.75 ,.-X.60" _9;_ -X" 75" .... - X "60° X'15*J x'5Ot/"" ""-._

--4

-- -X:30' I 8u, O _X,I5* , F "--" """ _, _ _ 8U, D X " 0_-/ -X " O" -I -I -...< -2 "2 0 5 1.0 0 5 LO +y/B !'y/B (c) >.l.o. (a) _.o.5.

Figure _2.- Effect of wind-tunnel width-height ratio on the lateral distribution of longitudinal interference due to dra_ in a closed rind tunnel. _ - 1,0_ _ - 1.0.

JET-BOUNDAHY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 147 ! I × .?5°-` x.9O'- \ : _ _ _5 ....

_X "60" x,TS'- __.__ _..-.-- _._ i_ ....

o .... .---_.,_ ,f _ o I i

-X.45 °

_.I -I

• f /-' / ,_/ \ _X'30" / _.,_ -. / / _ -- _..L -' ,/, _..X, 15" .i- / !// / ,_/ _X'30* _ • / _ _X" O" .,// \-x.s" -2 -z j \.×.o.

-3 -3 .5 LO 0 5 I.O o 4-y/B +_y/B (b) _ = l._.

(a) 7 = 2.0.

I

x.9O'-,, __.; __ ... _ _ .X.75 • X'60" x.4'5" /, -x ,60 Bw, L 0 --- J_w,L 0 _'" ..... .--t -'_'" _ -",- , .X.45' X "0: ....

_ \-x.O" -I -I 0 .5 LO 0 .5 LO ±y/B -]'v/B (c) _ = z.o. (d) _ =o.:_.

Figure 53.- Effect of wind-tunnel width-height ratio on the lateral distribution of vertical interference due to lift in a wind tunnel closed on the bottom only. _ = 1.O} _ = 1.O.

148 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 2 2 -Z,45* -X'30° /-X'45° ' "_//-X "15° --X "60° /i -X'50° _u,L I _:_ -_'_. /--X "75° 8u, L I -X'I5 ° -X "60°

- _

_'- _ "_'_ _ _...l f/ [ _ X , 9 0 * 0 °- X " 0"-\ X I" "_ 0 .5 1.0 0 .5 LO _+y/B +. y/B (b) _ ,, l.._.

(_) _ = 2.0.

I X" 45"_

!

i \ • I °

x-,o"

8u,L [--- -, -..__. _fX "90° ......... X " 0* / rX" O" I 0 .5 0 .5 1.0 LO _+y/B ._+ y/B (c) _ =z.o. (a) _ =o._.

Figure ._4.- Effect of wind-tunnel width-height ratio on the lateral distribution of longitudinal interference due to lift in a wind tunnel closed on the bottom only. _ = l.O; _ = 1.O.

JET-BOUNDARY CORRF-,CTIONS AND GROUND EFFECT FOR VTOL-S'IY)L AIHCRAFT 0 X'igO"- \ .i,,

/,-p

X'[t5"- \ \ -X ,60" / /? _-x :6o'

\./,,, "2

j._ , r

,,/

'/" / _/i

-'-" / / _-x.45" \ ,'(,_

/'_// ,"i ,"tl

'-.° J X/ '-,°

_X °30" /1\ k--X'. 15" ,/,, / \.x-3O" -2 '.o- / \-_,,_.

/\

\ "X " _)" -3 1 -3 0 .5 LO 0 .5 tO +_),/e ±y/e (a) _ =2.o. (b) Z =!.9.

I I X'! '0"- -X'?5" X'60"-_ _ X'90"- __. _

..... /< /J_\_'_"

/ _._ / x'3o ° _.._/ _..x:rS, -a _-x O' -20 .5 LO -20 ,II, LO + y/O :1: y/B (c) _.l.o. (_) _-o,5.

Figure 55.- Effect of wind-tunnel wiath-height ratio on the lateral distribution of vertical interference due to drag in a wind tunnel closed on the bottom only. _ = 1.0; _ = 1.0.

150 TECHNICAL REPORT II-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 2 2 -X ":_0° -X "30" -X 15" 8u, O I 8u_O I

4"

_-X =60° .._ FX " O° _X "60° -X " O* _X.'45.

!

_-X'75" r_X.75" _ i x'9Cf' 0 5 1.0 0 LO -fy/B (a) : =2.o. %) : =l.._.

_- X "30 ° _-X'45" 8u, D 0 _X "60" _-X "75= M-X" 75* -I -I 0 .5 I.O 0 .5 IO :_y/B -I.y/B (c) : =l.o. (d) _.=0._.

Figure 56.- Effe6t of'wind-tunnel width-height ratio on the lateral distribution of longitudinal interference due to dra_ in a wind tunnel closed on the bottom only. _ - l.Oj _ - 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 151 _X =7'5°

_. ir-x--9o °

o _ _.,,,,_ _-_ ==-

j/ / -I _/_ -X--30° \-X " O° -2 0 I 2 3 _-+y/h (a) Vertical interference due to ill%.

Figure _7._ Lateral distribution of interference factors in ground effect.

TECHNICAL IiEP011T I{-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION, 1.0 _X=45 ° 8u,L I .5 X =50° ///-_ -X =60° -X =750 " / I \ //:__._o.

----,<:7_-- _'_

"t. _'.=_ _ - _, X =1 =-"_'-__ _ 0 I 2 3 ±y/h (b) Longitudinal interference due to lift.

Figure 57.- Continued.

JET-BOUNDAI{Y COI{I{ECTIONS AND GROUND EFFECT FOR VTOL-$TOL All{CRAFT _ X "60" -I ----//_/ X'45°

_-- x.so o

--_ _-x-,s"

_-X " O"

-2 0 I 2 3 +y/h (c) Vertical interference due to drag.

.5 I : 0 °

__.../-× ,so /-×:so"

"_ . x-4s ° -×-6o"

-X'90°

-- _-_ !F_x:Tso

-- .____-_---___2 _-_- _ _

I 2 "+y/h (d) Longitudinal interference due to drag.

Figure 57.- Concluded.

TECHNICAL REPORT R-124--NATIONAL AERONAL_ICS AND SPACE ADMINISTRATION o o ,,,,_ ,,,_ ,,=. _L-X "15e _-X"30* -_ ==::_--__,_ __.,_.

x- o'--, x.3o" \

X,15".. _ X-45"-

,,\

8w, L'.-.4 == =-_ ._ :"_ _ _-_--/-x'6o" X.90 =- X,75'L -'80 .! LO

-%

tO +-.y/B (b) ; - l.o.

(a) ; = o.7.

-- 7:.-f 3, I

8w_L x.','s'J t / _, =X X,45- I ' ] • -'60 ' .5 tO "+y/B (c) ; = 2.0.

Figure _.- Effect of vertical location of mo_el on the lateral distri- bution of vertical interference due to lift for correcting from a closed wind tunnel to ground effect. 7 = 1.0; _ = 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 155 , 0 'T-" --" T/ "x "15" ......... -/ .... " -2 \ ; -.2 "_ " \ _.__X.30" X'90°" X'60 "J -X "30" \ \ ; _ _-..,-- .... _---_ -X'45" X.}5 _-.-1 X.45"-.-1 8u, L -.4 _ _ 8u, L --.4 _._.. .... -k_x.6 o.

_" \-x-75" _, --.6 _-X'90' -'80 [ .5 LO -.8(_ ,5 tO --+--y/B '+-y/B (a) ¢=o.7. (_) _ =l.O.

Figure _9.- Effect of vertical location of model on the lateral distr£- button of longitudinal interference due to lift for correcting frcxn a closed wind tunnel to ground effect. 7 = 1.Oj B = 1.0.

.8 X-9OP- r-X-75" / .4 "X "60" -X-45" 8w,D 2 ._._ -X" 90" --X'75" _w, D "X'300 1 -.---_ .__._ / -X .60" X • 0"-/ X.15"-J o___._. _ -- /_x-4s

x.o- /

--,2 -2 X,_15, -

[

-.4 --.4 0 LO .5 tO 0 .5 +-.y/B ' "l" y/B (a) _ .o.7. (t,) _; - l.O.

Fl_e 60.- Effect of vertice_ Location of model on the late_ _Lstz_- bution of verbtcal interference due to _e_ for correct_g from a close_' _md tunnel to ground effect. 7 = 1.0) q - 1.0.

156 TECHNICAL REPORT R-124--NAT10NAL AERONAUTICS AND SPACE ADMINISTRATION o I = "X 175" -.2 .... """ -X'60* ..... I i \ --. _ ..... .X,45, -x "60° -.4 m4

i

8u, D 8u_ O

-X,45" 7 _-. / "\ x.3o"

-.6 ""_ -.6 \ X " 0"-- X'15 *-/_ _,

i

I -X,30 ° -.8 -.8 _ ----- .___ _ _ X.]5 *J

, x'O*- _

- I'00 ' .5 1.0 - 1.0(_ 5 I0 -+ y/B ± y/B (a) : =o.7. (b) : =1.o.

.......... -_;-_ -_.75" _ \-_-_o"

? ?

-.2 _ , X " O°J X'30 °': 8u'O X" O_ _ _ --X "45" 8u'D X" ISa- -\ ; -.4 --X "30* .5 LO -'60 .5 LO +-v/B +y/a (c) : -2.o. (a) _-1o.o.

Figure 61.- Effect of vertical location of mo4el on the lateral distri- bution of longltu41nal interference due to dxag for correcting from a close4 win4 tunnel to groun4 effect. 7 - 1.0_ _ - 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-$TOL AIRCRAFT 1.0 I°O _ I -X'90" l .g -X'90" !'_ =_ "-._ t-X'60*

.6 /

/ -X'75" / -X "60" 8w, L

8"L _/ - : 2--.. --''-r-x'4_"

.4 ' I .... ] _- ._ -X'30"

X" ;5'-/ X'30"_ .... :_.,_

2.

2.

"-- I_ _ __Xll5 * \--X" 0 ° I LO l.O 5 +_y/B (a) _ l 0.7. ('b) _ l -]-.0!

.6 .X.45 ° 4 X"75- \_/f_ B w,L

x,o. :b..t V,/,_

_X 130t

_---I-T_-.._":- _

0 5 1.0 +_y/B (c) _ - 2.0.

Figure 62.- Effect of vertical location of model on the lateral distri- bution of vertical interference due to lift for correcting from a wind tunnel closed on the bottom only to ground effect. 7 = 1.0; Ti - 1.0.

632643 0--62--11 158 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION _X,90" .4 ' I .2 _. _ _X 75" ,-X "60" 8u,L .... "" = 8u,L X .60_ j X'30" .X.30 o _ _ __ _ .._.__ _"_-X" 0 °

°\

_-X " 0": ",--X" 15" x.9Oe-' I -2 ° .5 LO - % .5 L0 +_y/s +_y/B (a) ¢-o.z. (b) _;-l.O.

Figure 63.- Effect of vertical location of mo_el on the lateral _stri- bution of longitudinal interference due to lift for correcting from a wind tunnel closed on the bottom only to ground effect. 7 - 1.03 II " 1.0.

+_y/B (a) _ =o.7. (b) _ =Z.0.

X -60"- _._ x" o'_ \ x'9o' 0 .5 LO _ y/B (c) ¢ - 2.0.

Figure 6_.- Effect of verticel location of model on the lateral distri- bution of vertical interference due to _rag for correcting from a wind tunnel closed on the bottom only to ground effect 7 - 1.03 T] = 1.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT .6 .6 't

tx-_O'_ t

.4 ,,4, X" ,_. _J/-X -60" 8u,, D . _ -_ - - - .._ _ i Su, O ........ /, _-X'60" .2 i 2. ..., ,-X "75, 0 .5 LO 0 .5 LO -I.y/B -1- y/B (a) _ =o.7. (b) _ -1.o.

.4 .4 • - "X "45. X'30 t .2 8u, D ............... ...--, _ %.. = _.. ,a -.. • X'9OeJ / 0

\ \

I _-X.75" _X -90* t A .5 1.0 -20 .5 LO -.20 -- y/B -I- y/B (c) r. = 2.o. (d) ¢ = _.o.o.

Figure 69.- Effect of vertical location of model on the lateral distri- bution of longitudinal interference due to drag for correcting from a wind tunnel closed on the bottom only to ground effect. 7 = 1.0_ _ = 1.0.

160 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION -4 - 1.0 -.8 -.6 -.4 -.2 0 .2 ,4 .6 .8 1.0 y'/B (a) X = 0°.

Figure 66.- Lateral distribution of vertical interference due to lift for laterally offset small mo_els in a closed wind tunnel. 7 = 2.0; = 1.01 symbol denotes location of model.

JET-BOUNDARY CORRE_ONS AND GROUND EFFF_CT FOR _"IX)L-S_X)L AIRCRAFT 161 \ 1 " \ / \ \ ,

_,\ ',,i "- -\ /"

\ \ , /

\ \ , _ "

-I B%L

\ ' ""x' /

\ ,,, ,,,l _.,oo_/\I\< .X, x, ,._// , _"0.50-

,,.0._, ,/_

-3 -1.0 -.8 1.0 -.6 -.4 -.2 0 ,2 .4 .6 ,8 (b) x =3o °.

Figure 66.- Continued.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .r/-l.O0 - / -I 8w,L n,o.5o - -2 -3 .6 .8 1.0 -I.0 -.8 -.6 -.4 -.2 0 .2 .4 y'/B (c) x : 60°.

Figure 66.- Oontlnuea.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOIJ AIRCRAFT 163 _--_ ._ _ -.. "_ 8w,L '9"0.50 'r/-0.75 _ -I

\)I

_-0.25

\

-2 -.8 1.0 -I.0 -.6 -.4 -.2 0 .2 .4 .6 .8 y'/B (d) x = 900.

Figure 66.- Concluded.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION /. -,_ -0,75

/

J /_

8u,L

J " X "-" "

/ ./ / \ /'\ " -I.0 -.B -.6 -.4 --_2 0 .2 .4 .6 .B 1.0 y7 B (a) X = 30°.

-_ "0.75 8u,L 'r/.I.O0- \ / /-W'0.50 ,-, , -_7"0.25 v / --- l/ . -- k _ _,.___. _ _- o -I.0 _8 -.6 -.4 -.2 0 .2 .4 ,6 .8 1.0 y'/B (b) ×-6o o.

Figure 67.- Lateral distribution of lomgitudlnal interference due to lift for small models in a closed wind tunnel, y = 2.0_ _ = 1.O; symbol denotes location of model. (Plots for × = 0° and X = 90 ° are omitted simce 5u,L is uniformly zero.)

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 165 • -.-- _.:

\ \ /

\ , \ / ,, -| \ ' t /

\ \ ,, \/ /

\ \, /',, ,

\ \' _,/ \ /

\ _w, D ,.,.oo- \ \11 ,1_ , -2, \; \,, /, #"

,'t _, \I\ i

k " _ .o.75- J \ -3 ,to.so- J / _b _,0.25 - -4 - 1.0 -,8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 y'/B 0o .

Ca) x =

Figure 68.- Lateral distribution of vertical interference due to drag for laterally offset small models in a closed wind tunnel. 7 = 2.0i = 1.O_ symbol denotes location of model. (Plot for × = 90° is omitted since 8w,D is uniformly zero.)

166 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION •,--..,,..,.

/ \ \ "\ "\ ,, ," .,.

,,, \ ,< .

\ Y, \/

-I > -

'_-I,00- _ , _ _,,_. \ 8w, D

. ,.o.,_- / \

_,o.so -/ -2 -3 -.8 -I.0 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 y'/e (b) X=_ °.

__- -" _ _-'-:. :_. .....

,moo- ,_,0.75- _ \.. -_---,-- ,,,,,,_ -_,0.50

/

'_'0,25- -2 -I.0 _8 -.6 -.4 --.2 0 .2 .4 ,6 ,8 1.0 y'/B (c) x=6o °.

F±gu.re 68,- Concluded., JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 167 i I /-_.ioo /-_-OTS

--%- I

T/-0.50 -%

\

-I "\

8% D V'0.25 "-" -2 .4 .6 .8 1.0 -I.0 -_8 -.6 -.4 -.2 0 .2 y'/B (_) x = o °.

-W'0.50 -I - 1.0 --.8 -.6 -.4 -2 0 .2 .4 .6 .8 1.0 y'/B (b) x = _o °.

Figure 69.- Lateral distribution of longitudinal interference due to drag for laterally offset small models in a closeEwind tunnel. 7 = 2.0; _ = 1.0; symbol denotes position of model. (Plot for X = 90 ° is omitted since 6u, D is uniformly zero.)

I ) r 168 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE _DMINISTRATION -_ -0.75 ,7._.oo._,x / /-,_-0.50 ;._..- / 8%D _X'L- ' _'O.Z5 -I -I.0 -.8 -.6 -.4 -.2 0 .2 .4 ,6 .8 1.0 y'/B (c) x :6o °.

Figure 69.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOI,-STOL AIRCRAFT 169 \ \ f-_.b_s /

\ \

\ ,, /

X

X\..\,., \/, i!

• \ )', \ -I \ ",, IXI ,

\ \ \1 X i

\ \ A / "'-+--

8w, L \ \ t _,,I i /\ .,).¢ SO -Z _.,oo-1 \1 ""*",.

\ .vl = ,75 ---31.0 .-_8 -.8 -.4 -2 0 2 .4 .6 .$ 1.0 y'/B (a) X = 0 °.

-_'02S f,_" / i \ \ "',, \ "'._., / aw, L "X " >, • ,,,,, %

\ " 7, /

x /

/\ "_' _-"\

-il'O 50 _l'lO0" j _ _ ,,i,, X -,I "0,'1'5 -2 -I.0 -_8 -.6 -.4 -2 0 2 .4 .6 ,ll 1.0 y7e (_) x = 3o °.

Figure 70.- Lateral _istribution of vertical interference due to lift for laterally offset small mo_els in a win_ tunnel which is close_ on the bot- tom only. 7 = 2.0; _ - l.O; symbol _enotes location of mo_el.

TECHNICAL REPORT R-124_NATIONAL AERONAUTICS AND SPACE ADMINISTRAT10N

l

/ -_-GSO ,,/ 8w_L -I -LO "_8 ".6 --4 -2 0 2 .4 .6 .8 LO y'l B (c) X = 60 °.

_-025 -

H

_w,L

/

• _.0 SO- _/' o -LO ..=8 -.6 -,4 -2 0 .2 .4 .6 .8 LO y'/8 (a), x. 9o °.

l_.gure 70.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR v'rOL-STOL AIRCRAFT i ',,r.050- \

\ !\

Du,L I " I F /" +/ I ./" I _. ".

..... i o -I.0 mo -,6 -,4 -2 0 2 .4 .6 .8 1.0 y'/ll Ca) x - 30 °.

,_'0.25 $U,I.

,,._'_- \ _ -I.OO- ./ o -.4 -2 o 2 .4 -I.O -_o -.6 • .8 I.o y'/O (b) X=60 °.

/ !,.aso ,.;oo- -_ , r _.i --- _ _'-" Su,L o "_"_-- .....

-I.0 -'.0 -.6 -.4 -2 0 2 .4 • .8 i.O y'# 8 (c) X - 90 °.

Figure 71.- Lateral distribution of horizontal interference due to lift for laterally offset small models in a wind tunnel closed on the bottom only.

7 = 2.0; _ = 1.0; symbol denotes position of model. Note that _u,L is uniformly zero for X = 0°.

172 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION \ / \, / , \ \ ",, / \ \ " -I \ / \/ /

\ \

,, /\ % #

\ '

\ / ",/ / B.,I)

\

,\1 IX /?

\ -2 \ i \ / / _.I.00 - /i\ _,, 'Q.t, \ I _.- -_ ,0.75 -3 -LO _8 -6 -,4 -2 0 .8 1.0 ,2 ,4 ,6 y'/B (a) X = 0 °.

/ ..._,0.25 ":". 7,0 "'._.,/" /'/ _w, D % ", f_'/ I \ \, ", / / \. \ IX /\i I x_ ), ", W ,I,00"- _. x

I

-2 _8 -.6 -.4 -2 0 2 ,4 ,6 -I.O .8 1.0 y'/B (b) X = 3o0.

Figure 72.- Lateral distribution of vertical interference due to drag for laterally offset small models in a wind tunnel which is closed on the bot- tom only. 7 = 2.0; _ = 1.O; symbol denotes location of model.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 173 ;) i-,,/.0.50 \,,. " g_D 0 ,_.l.oo. J _ _ _ ,.-< .e- \ , w,,O_

i I

-!

-f.O -.8 -.6 -.4 -.2 0 2 .4 .6 1.0 yV e (c) x = 60°.

I

i

8w, D 0 "-_ L:._... --_---_-- _'100- "--- --._ 2._ ,----' I \-_-o_

I

-I -I.O -.8 -.6 -.4 -2 0 ,2 .4 ,6 1.0 y'/B (d) x = 9o °.

Figure 72.- Concluded.

632643 0--62--12 174 TECHNICAL ]{EPOItT R-124--NATIONAL AERONAUTIC, S AND SPACE ADMINISTRATION V02S- -_ \ g'u, D t _.oso- \ I

i,_.0.7"j- 2i "

• _-t.O0 _ -_ .

o -I.o -.8 -.6 -_4 --,2 0 2. .4 .6 .8 I.O y'/B (a) X = 0°.

,7-o.z5- \ \2 ,t.O.SO- .._ ,, 'q.0_- \ ,," _upD ,_.1O0 - -._ / .o_ _ -I.0 -8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 V'/8 (b) x = 3oo.

BU. D o -I.0 _8 -.6 -,4 -.2 0 .2 .4 .6 ,8 1.0 y'l B (c) × . 600.

Figure 73.- Lateral distribution of longitudinal interference due to drag for laterally offset small models in a wind tunnel which is closed on the bot- tom only. 7 = 2.0; _ = 1.0; symbol _enotes location of model. (Plot for X = 90 ° is omitted since 5ujD is uniformly zero.)

JET-BOUNDARY CORRF_TIONS AND GROUND EFFECT FOR YTOL-STOL AIRCRAFT 175

I

, /--- ..._

Do.6- /-(;-o.7 \ _b ,/, .2" zTH 0

_-_.,.o

..._ ==_ -'-_'_ "-!;'1.5 _L(;,2.0 -I ' I -6 -5 -4 -2 -I (a) x - o°.

I

"_ _, v {;.o 8

z2H 0 _'1.5 - /_" _;-J o (;.20- \ _._..<_ _._ -I -6 -S -4 -3 -2 -I 0 8w,L (b) x. 50 °.

Figure 74.- Vertical distribution of vertical interference due to lift for a .mall model in a closed wind tunnel. 7 = 2.0; _ = 1.0; symbol denotes loca- tion of molel.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ---...., ........_

I

¢._

_... /-(;,o.7

%

_.o,8-/_L z_'H 0 _,Lo-; r,.zo - \ /

/ A-_.,5

/ _-;-4.o -5 -2 -I 0 -6 -5 -4 8w, L (c) X = 60 °.

I

_, 0.6 - t;-o.8_ z2H 0 / _-2.o-_, , p

_', ',-_.,5

(;- 4.0 - \ i .====- ._ -I -4 -3 -2 -I 0 -6 -5 8w, L (a) x =9o °.

Figure 74,- Conclu4ed.

JET-BOUNDARY CORRE, C'TIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 177 -,,,.

¢;.o.6-' \/_ /- _;-o.8 [=0.7__/'

\

z/'H ., /--_,L5 (;.2.0--' C-4.o -b -I -3 -2 -I 0 I 2 3 4 8u,L (a) x = 30°.

_;- 0.6- _-C-I.O

,/

z2H 0

\

,-C-2o -I -4 -3 -2 -I 0 I 2 3 4 5 8U,L (b) X = 60 °.

Figure 75.- Vertical distribution of longitudinal interference due to lift for a small model in a closed wind tunnel. 7 = 2.0; _ = 1.0; symbol denotes location of model. (Plot for X = 0 o is omitted since 8u# L is zero for all values of _.)

178 TECHNICAL REPORT R--124_NATIONAL AERONAUTIC_ AND SPACE ADMINISTRATION _.o.6 / /_ / - t,.oB _.o,7-/ /-_.Lo z_'H O ,d/_- (::'2,o _.40"_ -I -5 -4 -3 -2 -I o I 2 3 4 5 Bu,L.

(c) x : 9o°.

Figure 75.- Coneluaea.

JET-BOUNDARY CORRF__TI_ONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 179 0.6 / z_'H s -I -S -4 -3 -2 -I 0 I 2 8w, D (a) × = 0 °.

/

//(-J ;,o.8 z_'H 0 / J / f

\L;.2o

_, I

-5 -4 -3 -2 -I 0 I 2 8w, D (b) X = 30°.

Figure 76.- Vertical distribution of vertical interference due to drag for a small model in a closed wind tunnel. 7 = 2.0; _ = 1.0; symbol denotes location of model.

TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION f /q) _-I.0-

_,,I _' _-(;.0.8

z/'H 0 /

#

f_.4.0 /

(+,.5

° / _'_ , - (_.zo

I

-I -4 -3 -2 -5 -I 0 I 2 3 4 5 Bw, D (c) X = 60 °.

I

f _"0.7_ -(;-o.6 _.=.o-, ._=o.e z_'H 0

i//

_._.o _,,,,_

-_.1.5 _.4.0 - \ i / f J .,.==. _ -I Z 3 4 5 -5 -4 -3 -2 -I 0 I 8w, O (d) x = 9o °.

Figure 76.- Concluded.

JET-BOUNDARY CORRF-_c_IONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 7_ /_, 0.6 -/ "k \_)_/-_=o.8

_-o.7 _/'/b -_-,.o

i

z/'H 0

/'- _'4.0 ",_, ",-Z \ -i I -4 -3 -2 -I 0 I 2 5 4 5 _u, O (a) X = 0°.

_,0.6 -/

_\ \% i/-;.o.8

;=o.7 j_ b \\ _,Lo z2H 0 ,--t,-z.o "_ _-_ _. _ I

_, t

-4 -3 -2 -I 0 I 2 3 4 5 Bu, D (b) x = 300.

Figure TT.- Vertical distribution of longitudinal interference due to drag for a small model in a closed wind tunnel. 7 = 2.0; _ = 1.0; symbol denotes location of model. (Plot for X = 90 ° is omitted since 5u, D is zero for all values of _.)

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ......, ,-t,,, o.6 ,/-_.o.7 \ V

I

zTH O _,o:8- / /-C-,.5 _,\ r_,z.o \I_,,, %.

-I 0 I 2 3 4 5 -2 -I 80, D (c) X = 60 °.

Figure _.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOIrSTOL AIRCRAFT 183

I

I v I f _"_ • 0. 6 ¢,o.7-, J -..,,_ /I z;'H 0 -I-6 -5 -4 -3 -2 0 5 (a) X = 0 °.

I _-o.6-,, / ./ //i _"\,...C.o.7 z?H 0 0 _{;.,.o f / ¢.2.o- ,._.... _-(; ! ..EI'I" =..I I, -I -6 -5 -4 -3 -2 -f 0 I 2 3 4 8%L ('b) X l _}O01 Figure 78.- Vertical distribution of vertical interference due to lift for a small model in a wind tunnel which Is closed on the bottom only. 7 - 2.0; = l.O; symbol denotes location of model.

184 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION I (;.o.6-_ I /,' z_'H 0 (;,I.5_ "-(;,I.0 / _'/ / .=.,I 4.0 I -Ls -5 -4 -3 -2 0 I 2 5 4 (c) x = 60 u.

I (>0.8-- z_H 0

//

/,_ ¢;-2.o- _.!/-_;-,.s _,4.0-_ J j- .'3.°- / -I -6 -5 -4 -5 -2 0 I 2 3 4 (a) x = 9oo.

Figure 78.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT I I _;-0.6--. ,- \ /'

S

k, 2-g,_.o z?H 0 "d ._,Z.O.

i C.4.o. k" I -I 0 I 2 , 5 5 6 8u,L (a) x=_ °.

g'!

_--{;-o.8 z)H 0

\ rt..2o

l;,4.0- I -I 0 I 2 5 4 5 6 8u,L (b) x = 60° Figure 79.- Vertical distribution of longitudinal interference due to lift for a small model in a win_tunnelwhich is closed on the bottom only.

is 7 = 2.0; q = 1.0; symbol denotes location of model. (Plot for X = 0° omitted since 8u3L is zero for all values of _.)

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

I

/I I -_. 0.6 _-0.7-\ .

Y 1.0 z_H 0 _,'_ ,-(;'2.0 _(;'4.0 -I I 2 4 5 6 (=) x=9o °.

Figure 79.- Conclude_.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-S_OL AIRCRAFT

¢.o._-_ _.-c-_._

,J

{_-0.8---_ f z_'H 0 _-I.0 _-1.5--%, I _ow- _o_-{;.z0 -I -6 -5 -4 -I 0 -2 (a) X = 0 °.

I -_.o.6 l I _:.o.7

\

_,,0.8"-, )

I

//

_-I.0--.

z_'H 0 f / J o ;.zo-.._ ...%. "

..-o---- .-_-" _

-I -6 -5 -4 -3 -?. -I 0 Bw, O C_) x. _o.

Figure 00.- Vertical d/stribution of vertical interference due to drag for a small model in a wind tunnel which is closed on the bottom only. 7 = 2.0; = 1.0; symbol denotes location of model.

188 TECHNICAL REPORT R--124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

I

./-C-o.z \

\

t,,O.8- {;-I.0- ITH 0 Y

/

/ _.2.0-,, / ,0 I --{_'4.0 -I i -6 -5 -4 -I 0 (c) X = 60 °.

' __j

I

{_,0.6-

/-{;-o._

• I ¢-{:,o.8

%

z_/H 0 _-2.0-)' p _'/ _'4.0"_ j-- f -I -6 -I -5 -4 -3 -2 8w.O (4) x = 9o °.

Figure 80.- Concluded.

JET-BOUNDARY COI{R_CTIONS AND GROUND EFFECT FOR VTOL-STOL AlltCRAFT

r_-¢.o.6

_'0.7 '_'-_,0.8 0 -4) .... -l- zi'H _'-_-I.0 ¢ -15 .... , \ <-_'4.0

__.2__x -_., -....._

I''-- ._ (;,_o.o- i -t 5 4 5 6 0 I 2 8u, D (a) X.0o.

L ....

"-_-0.8 Z/'H 0 -- Q / (;.20-

y

_, ]

_;.,4.o- 5 4 ,5 6 0 I 2 8u, D (b) x. 30 o.

Figure 81.- Vertical distribution of longitudinal interference due to drag for a small model in a wind tunnel which is closed on the bottom only.

is 7 = 2.0; _ = 1.0; symbol denotes location of model. (Plot for X = 90° omitted since 5u,D is zero for all values of _.)

632043 0--62--13 190 TECIIN1CAL HEPORT I(--124--NATIL)NAL AERONAUTICS AND SPACE ADMINISTRATION

fl

_ ¢.;_

/

-._'0.7 "-C;,0.8 z_'H 0 "---(;,I.O

V--_.,5

\, t_-IO.O-,_ I _-2.0 _ _.4.0-

I

-I I 4 5 0 3 6 I 2 8u, D (c) x = 60°.

Figure 81.- Concluded.

JET-BOUNDARY CX)RRE, CTION,_ AND GROUND EFFECT FOR ¥TOL-STOL AIRCRAFT 2 2 I -X"90" x-9_ t/h z/h

IL

x "_'_ //-. -X'6_ o /" x.3o_ / I!

x .o'-, ! ', ,_.,..., i

_.o."\

,,\ -..

/

-I -1..-5 -4 -3 -2 -I 0 0 I 2 3 8w.c au.L (a) Vertical interference (b) Longitudinal interference due to lift.

due to lift.

_.,¢- J/!. '

I/h X "_J I _-x'90'.

/ _ _-_._

_,o_, / ti _"

" i! o t / ;_o.

X" 0_,, J l j] (",,

,I /I \\

-I -I -5 -4 -3 -2 -I 0 0 I 2 3 8u.O (c) Vertical interference (_) Longitudlnal interference due to drag.

4ue to drag.

Figure 82.- Vertical distribution of interference factors in ground effect.

TECHNICAL REPORT R-124--NATIONAL AERONAIYI'ICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0 Isolated element-

-k

\ -I _,_ " _--Overoll correctio'n I ........I

//

-2 _w,L Front element of pair

J

/

/ j" J

/

/

/ #

/

I / /'X-.Rear element of pair ,/

/

-3 _..

# /

/

-4 0 I0 20 30 40 50 60 70 80 90 X, deg (a) Vertical interference due to lift.

Figure 83.- Correction factors for a two-element model centered in a closed wind tunnel with 7 = 2.0. Elements are separated longitudinally by a distance equal to H. (Curve labeled "Overall correction" is based on Am of entire system.)

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT I0 0

\

\

8u,L \ / _-Rear element of )air

/

/

-I 0 I0 20 30 40 50 60 70 80 90 X, deg (b) L_ngitudinal interference 4ue to lift.

Figure 83.- Continued.

TECHNICAL REPORT R-124--NATiONAIJ AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I 0 0

/

Isoloted element--_ __'-- J /

/

Overoll correction_ / -I

X,, /'

p'

>2

f J J J

// //

,/

J f ,s" ¢/¢

/

/

,///

I -2 8w, D /'/,"ron, element of poir /

/

/

/ /

/

/\

f /

/ _--Reor element of po=r / f

J

i -3

J

J -4 0 I0 20 30 40 50 60 70 8O 9O X, deg (e) Vertical. interference clue to drag.

Figure 83.- Continued.

JET-BOUNDARY CORRF_CTIONS AND GROUND EFFECT FOR VTOI.,--STOL AIRCRAFT On, deg 90 80 70 60 50 40 50 20 I0 2-- of pmr r Front element

/

if I _._ J ,I l Isolated

J

I--

/"

,f J I"\ _u tD -Overall correction

S'" \

J

...-"

J

.f J kk--Reor element of pair -I / / /

/

-2 I0 20 30 40 50 60 70 80 90 X, deg (d) Longitudinal interference due to drag.

Figure 83.- Concluded.

TECIINICAL REPORTR-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION On, deg 90 80 70 60 50 40 30 20 I0 i Overall correction-_ J" // .f s' .,iti ..,,,, I °'_ ....

," j / ",--Isolated element,_.l.O0 /" j \," I I

J /, /%

-Isolated element,_.O.75

/

i

-2 f /

Bw, L J X' I / \ '--Either element of pair

/

o /" / -3 J -4 0 I0 20 30 40 50 60 70 80 90 X, deg (a) Vertical Inter£erence due to lift.

Figure 8_.- Correction factors for a tvo-element model centered in a closed rind tunnel with 7 = 2.0. Elements are separated laterally by a distance eqtu_l to H. (Curve labeled "Overall correction" Is based on A m of entire system. ) JET-BOUNDARY CORRF_,CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 197 en, deg IO 0 90 80 70 60 50 40 50 20 Either element of pair--_ /--Isolated element, _/.0,75, _/=1.00

/ / \_

/ ._-_- _-___ 8u,L

f _ \

/

/

/ /,/.

Overall correction -/ _ _ _ /_///// O0 I0 20 50 40 50 60 70 80 90 X, deg (b) Longitudinal interference due to lift.

Figure 84.- Continued.

198 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 50 40 30 20 I0 0 90 80 70 60 Overoll / 7 d_ • /," -I /" // // _f s j,- _ Isoloted element,_'l.O0 I I 7_-- Isolated element, W'0.75 p-

/

/ /

-2 _w,D ¢" /

/

/ _Either element of poir

//

-4 0 I0 20 30 40 50 60 70 80 90 X, deg (c) Vertical interference due to drag.

Figure 8_.- Continued.

JET-BOUNDARY CORRDCTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT en, deg 250 20 I0 90 80 70 60 50 40 I i i i , i 'lsoloted element, _/"0.75-_

I1

I .Isolated element, _9"1.00 /- ' i i I 1 / ,--Either element of poir t f s J correction --/ Overoll / f _u, D • / -I 0 I0 20 30 40 50 60 70 80 90 X, deg (d) Longitudinal interference due to drag, Figure 84,- Concluded, TECIINICAL REPORT R-124uNATIONAL AERONAUTICS AND SPACE ADMINISTRATION On, deg go 80 70 60 50 40 30 20 tO 0 -80 IO 20 30 40 50 60 70 80 90 X, deg (a) Vertical interference due to llft.

Figure 85.- Correction factors for a two-element model in a closed wind tunnel with 7 - 2.0. Elements are separated vertically by a distance of 0.211 vith the upper element centered in wind tunnel. (Curve labeled "Overall correction" is based on Am of entire system.)

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOLr-STOL AIRCRAFT 201 _, dig 90 80 70 GO 50 40 30 20 I0 0 _Lower element of pelt / "\_/

/ \

/ \

\ /- Upplt element of poir |u,L

/ ....... A

\ / /J " ,'! / .. _--- __.. \ "\

/ ,///, / Ill 7"-.:"-.. ,.\

i_ / ,_o,,;,,.i.,.,:c.,.i_-,1 / _,-L_ I 1' I I t / I O0 _ , IIo,Ote..:eml,nt._..:,O0 i I--/ kk I0 20 30 40 50 GO 70 80 90 X* dig (b) _ongitudinaA interference due to lift.

Figure 89.- Continued.

202 TL2HNICAL REPORT R-124--NATlONAI.J AERONAUTICS AND SPACE ADMINISTRATION _, deQ tO 0 90 60 70 60 50 40 30 20 9O (c) Vertical interference due to _rag.

Figure 8_.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOIl VTOI.r-STOL AIRCRAFT 203 On, deg 90 80 70 60 50 40 30 20 tO 0 |u, D I -I 0 to 20 30 40 50 60 70 80 go X, deu (d) Longitudinal interference due to drag.

Figure 85.- Concluded.

204 TECHNICAL REPORT R--124--NATIONAL AERONAUTIC_ AND SPACE ADMINISTRATION

Z I i -_ ZH - Wind tunnel _0.5--*- ,,.--0.5 _ :'_i, : " " _-Wi' iI It ng ID H 1 _--Doublet wakes IP p

L

IL LIL & 'r/=1.50 'r/=125 =1.00 ? "0.75 r/=0.50 Figure 86.- Sketch illustrating calculation of interference factors at y'/H = 0.5 for a finite-span wing with _ = 0.625 in a closed rectangular wind tunnel with 7 = 2.0.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 8n, deg 90 80 70 60 50 40 30 20 I0 0 I J j-'_, / ,f_ / / j 1 f -I / _- o'-0.875 / / \/ .i v / /_ .,,.o.625 8w, L / /', / \/ i /'X _ =,, 0.575 / -2 / _-- o',0 -3 0 I0 20 30 40 50 60 70 80 90 X, deg (a) Vertical interference due to lift.

8n, deg I0 0 90 80 70 60 50 40 30 20 8u,L I _,0.875 o'-0 375_ _ -¢r-O 625 0 I0 20 30 40 50 60 70 80 90 X, deg _b) Longitudinal interference due to lift.

Figure 87.- Interference factors at the center of a series of finite-span wings centrally located in a closed wind tunnel with 7 = 2.0. Wings are assumed to be uniformly loaded.

632643 o--G2-- -_4 TECHNICAL REPORT R-124--NATIONAb AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0 0 J --| s- J .o- f J 8w, D /' '---¢. 0.375

/

J -z X' / \ -¢r.O / /

]

-3 I0 20 30 40 50 60 70 eo 90 X, deg (c) Vertical interference due to drag.

8no deg 80 70 60 50 40 19o 30 20 I0 0

I

F

o-=0 .._ • • 0.375 _ f _--cr-0.875 "'" ""---'" 8u, O 5"f _="0,625

I

-I I0 20 30 40 50 60 70 eO 90 X, deg (d) Longitudinal interference due to drag.

Figure 87.- Concluded.

JET-BOUNDAIlY CORRECTIONS AND GROUND EFFEC'I' FOR VTOL,-S'I'OL AIRCRAFT \"x // \\\ -\ -I 17,5 Y- -- i-_ _--=-.o.( 0"-0.625 8w, L -2 /'-,-0.375 I'< -_.o -5 - 1.0 -,8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 y'/B (a) X = 0 °.

//1/ I ,_,_\ ./-- =,-0.875 _x_--_/ -I _w.L ' \ '---0"-0625

\ .... -/

- o'.0 I -2 - 1.0 -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 y'/B (b) x = 3o °.

Figure _.- Lateral distribution of vertical interference due to lift for a series of finlte-span uniformly loaded wings centered in a closed wind tunnel with 7 = 2.0.

208 TECHNICAL REPORT R-124--NATIO_gAIa AERONAUTICS AND SPACE ADMINISTRATION 0 I I I _,_ /-o'-0.875 /--o"0.625 _ _ -¢r'0.375 .-" "_ _S_.v.._ " l .- 8w, L I k_ =r-O -- LO -.8 -.6 -.4 -.2 0 2 .4 .6 .8 1,0 y'/B (c) x = 60 °.

8w, L y'/B (d) X = 9O°.

Figure 88.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 209 i \---X .......

8u,L

\

-8 -.6 -.4 -.2 0 .2 .4 .6 -I,0 .8 1.0 y'/B (a) x = 3o ° 0-= O- - o',0.625 8u,L -_-0.875 I I .2 .4 .6 -I.0 -8 -.6 -.4 -.2 0 .8 1.0 y'/B (b) ×=6o °.

Figure 89.- Lateral distribution of longitudinal interference due to lift for a series of finite-span uniformly loaded wings centered in a closed wind tunnel _rlth 7 = 2.0. (Plots for X = 0° and X = 90 ° are omitted since 5u,L is uniformly zero.)

210 TECHNICAL REPORT R--124mNATIONAL AERONAUTICS AND SPACE ADMINISTRATION -I 8w0D -2 -3 -I.0 _8 -.8 -.4 -.2 0 .2 .4 .6 .8 1.0 y'/B (a) x = o°.

Figure 90.- Lateral distribution of vertical interference due to drag for a series of finite-span uniformly loaded wlngs centered in a closed wind tunnel with 7 = 2.0. (Plot for X = 90° is omitted since 8w,D is uni- formly zero.)

JET-BOUNDARY CORRFJCTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 211 -I o- 0.375 8w, 0 \ _-- o'=0 -2 .8 1.0 .4 .6 -.8 -.6 -.4 -2 0 .2 -I.0 y'/B (b) X = 30 °.

.:-o-/ / \ _-J.o.e_s

8w, D I l \ I I ¢r,0.375 -/ --o- 10B75

[

-I 1.0 .6 .8 -.2 0 .2 .4 -8 -.6 -.4 -I,0 y'/B (c) X=60 °.

Figure 90.- Concluded.

212 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION O- i 0--_ 8u,O I I _.. _- ¢r'-0.6 -a'-0.875

_, ]

-I.0 -.8 -.6 -.4 -.2 0 .2 .4 ,6 .8 1.0 y'/B (a) X = 0 °.

=t*O-\ .....-- ---_

..o375-

-/..-,-- ..... :_ _ .... I/ 8u, D o'-0.625 J / ¢r.0.875" -- 1.0 -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.0 y'/B (b) X = 30 °.

I or=O-- _ 8u, D ,_o'-0 875

\

i/ =__

[

.2 .4 - 1.0 --.8 0 .6 .8 t.0 -.6 -.4 y'/B (c) X = 60 °.

Figure 91.- Lateral distribution of longitudinal interference due to drag for a series of finlte-span uniformly loaded wings centered in a closed wind tunnel with 7 = 2.0. (Plot for X = 90 ° is omitted since _ujD is uni- formly zero.)

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-,_TOL AIRCRAFT 213

Z

¥

×

/

Figure 92.- Schematic view of ioublet-_nLke representation of the wake of a helicopter rotor.

214 TECHNICAL HEPOI_T R-124--NATIONAL AERONAUTIC_ AND SPACE ADMINISTRATION 9n. deg 80 70 60 50 40 30 20 I0 0 o9O _.__. __ ..-_ --- Direct Inte_lrotlon a reference 8 ._/ f B,. L m_.-- --_-\ j=#'/x-Infegrolton of present retultt.=r-0333 / -2 / \ t / -='.0 -50 I0 20 30 40 50 60 70 80 90 X. dig (a) Vertical interference due to lift.

9n, deo 90 80 70 60 50 40 30 20 I0 0 I °"O-" / / /

'/'/"<-.-o333

4/

0 tO 20 30 40 50 60 70 80 9O X. deg (b) Longitudinal interference due to lift.

Figure 93.- Interference factors at the center of a flnite-size rotor (_ = 0.333) for a closed vind tunnel (7 = 2.0; _ = 1.O; _ = 1.O), including a comparison_rlth the results of reference 8.

JE'r-BOUNDAIIY CORRECTIONS AND GROUND EFFECT FOR VTOI.,-STOI, AIRCRAFT 215 8no deg 90 80 70 60 50 40 30 20 I0 0 0 _ .."_

J

I o'-0333 _ / -I

\//

7 4 8wo D /___ _/_.o

/

-2 / r -3 0 I0 20 30 40 50 60 70 80 90 Z, deg (c) Vertical interference due to drag, On, deg I0 0 80 70 60 50 40 30 20 9O I cr,O--_ ./ _ _.

8u, D ¢ -I 0 t0 20 30 40 50 60 70 80 go X, deg (d) Longitudinal interference due to drag.

Figure 93.- Concluded.

216 TECHNICAL REPORT R-124mNATIONAL AERONAUTICS AND SPACE ADMINISTRATION Z Figure 94.- Basic cylindrical wake and image system used to calculate correc- tions for a uniformly loaded rotor. Sample element of vortlclty is shown.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 217 en, deg 90 80 70 60 50 40 50 20 I0 w J J _ 0,-=0.8 _I / -I ....._......... ¢ "O.E / /

,,Y

8w, L

Z

e*£) / -2 ..o..0 j -5 0 I0 20 30 40 50 60 70 80 90 X, deg (a) Closed win& tunnel.

Figure 9_.- Effect of finite rotor size on the vertical interference iue to lift at the rotor center. 7 - 2.0; _ - 1.0j _ - 1.0.

218 TECHNICAL REPORT R-124--NATIONAb AERONAUTICS AND SPACE ADMINISTRATION 8n, deg 90 80 70 60 50 40 30 20 I0 0 I I Complete wind tunnel-, o--O8--__..._ BwoL / / / / ,'/ ,0 .'Z. _' /

2"

-2 /_ a / :/ -3 0 I0 20 30 40 50 60 70 80 90 X, deg (b) Wind tunnel close_ on the bottom only.

Figure _.- Conclude_.

JE'I"-Bt)UNDAItY COItREC'rlONS AND GROUND EFFEC£ FOIl. VTOL,-,_TOL AIRCRAFT -.4 -.8 8%L -I.2 -I.6 -2.0 -3 -2 -I 0 I 2 3 4 x/H (a) X = 0 °.

Figure 96.- Effect of rotor size on the longitudinal distribution of vertical interference due to lift for close, win& tunnel. 7 - 2.0; _ = 1.0.

220 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION -.4 --.8

• _,jco-,o.6

-1.6 //_-0"0.4 -2.0

.,o \_ _'°.2

--2.4 -2 -I 0 I 2 -4 -3 3 4 x/H (_) x. 14.o_ °.

Figure 96.- Continued.

22l JET-BOUNDARY CORRE,CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT

.4

I _.4' -.8

/

"',,,_._ \ //-- _r'06

\,\ _,,/

-I.6

\ \

),,f

- 2.0 -2.4 i--O-. 0 -2.8 2 3 4 -4 0 -5 -2 -I x/H (c) x = 26._6 °.

Figure 96.- Continued.

632643 O--62--15 2_ TEC}INICAD REPORT R-124--NAT10NAL AEI_0NAUTICS AND 8PACE ADI_IINISTRATION .4 f -.4 / s ,,_--o'-Q8 ,,' --.8 8%L -I.2 -I.6 !

_rlO.2 - 2.0 -2.4 O-lO--_ / 0 I 2 3 4 -3 -2 J xlH (ct) x = _5.0oo.

Figure 96.- Continued.

JET-BOUNDARY CORR_IONS AND GROUND EFFECT FOR VTOI_STOL AIRCRAFT 223 .4 -.4 -.8

__ /--=.,Q8

",\/--o"0.6 -1.2 8w, L

\\\

-1.6 _'0- 1 -Z.O -2.4 -3 -2 -I 0 I 2 3 4 x/H (e) x = 6_._f.

Yigure 96.- Continue_.

224 TECHNICAL REPORT R--124--NATIONAb AERONAUTICS AND SPACE ADMINISTRATION .2 -.2 r_'0.8 -.4 " -o-.0.6 -.6 _w,L -.8

..o2 _,,,, \

-I.0 -o"0.4 o'=O -1.2

\

-1.4

\

-2 -I 0 2 3 x/H (_) x = 79.97 o.

Yisure 96.- Continued.

JET-BOUNDAI{Y COIIR_SC'I'IONS AND GROUND EFFECT F011 VTOL-STOL AIRCRAFT -.2 -- o'=Q8 -.4 _w,L -.6 _=0.6 i " -.8

\

,,. o-=0.4 -I.0 0-=0--/

,,.--

-1.2 -2 -I 0 I xlH (g) x. 8_.29 °.

Figure 96.- Continued.

226 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .2 -.2 , _o-,,Q8 !,h -A _',, '_ , -.6 =0.6 -.8 0"0.2--'_ -I.0 ,.,...,..=_ -2 -I 0 i 2 3 xlH (h) X = 90.00°.

Fl__-"e 96o- Concluded.

JET-BOUNDARY CY)RRF_,CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT -o'=Q8 ,," / -.4 -.8 I -"'/,/"_-o'=0.6 -1.6 "_/_--_=04 -Z.O -2.4 -4 -:5 -2 -I 0 I 2 5 4 x/H (a) x - o°.

Yigure 97.- Effect of rotor size on the longitudinal dAstribution of vertical interference due to lift for wind tunnel closed on bottom only. 7 - 2.0; . 1.0.

2_8 TI,:CIINICAL ltgP01tT I{-124--NATIONAL, AgRONAUTICS AND 8PACE ADMINISTRATION .4

/-..o8 /t _'''

-.4 -.8 Bw, L -I.2 -I.6 -2.0 -3 -2 -I 0 I 2 3 4 xlH (b) x = 1_..o_ o.

Figure 97.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT .4 -.4 -.8 8w, L -I.2 -I.6 -2.0 - 2.4 -4 xlH (:) X = 26.76 ° .

Figure 97.- Continued.

230 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .4 -.4 --.8 -¢-0.6 _w,L -I.2 -I.6 0-= -2.0 o'=O--_ -2 -I 0 I 2 5 4 x/H (d) x = _5.oo °.

Figure 97.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT .4 -.4 \<_,---o'=Q8 --.8 _'0'2--/ -1.6 0-=0--, -2.0 -2.4 2 3 - 0 -2 -3 x/H (e) x = 63._.3 °.

Figure _F.- Contlnue_, 232 TECHNICAL ]{EPOI{T R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .2 -o"Q8 -.2 \, ,/_o"0.6 -.4 a'll O- 8w, L

\

-.6

\

\

-.8 -I.0 -I.2 2 3 -4 -3 -2 xlH (f) X l P'_lgl_.

Figure 97.- Continuea.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 233 .I

_ ./-_=o8

" :o6

ml \ _N _w,L

-\

-.2 \ -0"=0.4

\

-3

\

0 2 5 4 -3 -2 x/H (g) x = 8_.29 °.

___'°.___L .....

_L_--______ _

_w,L -I -4 -3 -2 0 2 3 4 x/H (h) x. 9o.oo °.

?±8_re 9T.- Conclu4e4.

234 TECIINICAL REPORT R-124_NATIONAL AERONAUTIOS AND SPACE ADMINISTRATION 0 _

_2 ,,S

- 1.0 I/ x Bw,L - 1.2

!\ ,",t _-..o.6

-i.4 t \I \ _-=--o,4 -i.6 ....

-2.0 " -" t):o.

-__ ' ' .-!.o

I -24 ,- -5 -4 -3 -2 -I 0 I 2 :5 4 5 xlH (a) X = 0 °.

Figure 98.- Effect of rotor size on the longitudinal distribution of ver- tical interference due to lift for closed floor only (grOund effect).

7 = 2.0; _ = l.O.

JET-BOUNDARY O0111_,IbCrlON8 AND GROUND EFFECI' FOIl v'rOL-S'IYOL AIRCRAFT 23_ •2 "' -.2 _\ _" o'"O8 -.8 -1.0 8w, L -12 _ il '-'a'°0.6 -I.4 _a'-0,4 -I.6 , -I.8 / -2.0 _'_cr'0.2 -2.2 I _"'_o"O

I

-?...4 --5 2 3 4 5 --4 -3 -2 -I 0 I x/H (b) x=z_._ °.

Figure 98.- Continued.

236 TECHNICAL REPORT R-124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .2 m f -.2 -.4 --.6 '_¢r,Q8 -1.0 aw_L I "J _',-.-_o"0.6 - 1.2 -1.4 -1.6 -1.8 %L -2.0 _- o"0.2 -Z.2 _v_- -o" "0 -4 -3 -2 -I 0 I 2 =3 4 5 x/H (c) °.

Figure _.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-_0L AIRCRAFT 237 .2

f

-.2

/

-.4 -.6 -.8 -I.O 8w, L -I.Z -1.4 \ -1.6 -1.8 -2.0 -2.2 -2.4 0 I -5 -4 -3 -2 -I 2 3 4 5 x/H (_) x = _0.oo °.

Tigure 98.- Continued.

6326{3 0--62--16 238 TECHNICAL REPORT R-124_NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .2

\

-.2 \, -.4

/

\

-.6

/

_,,_o"Q6

/

-.8

\

%. /

o',0.2--_ i_, \ -1.0 -1.2 8w, L

/

o"0-, -1.4 -1.6 -1.6 -2.0 -2.2 -2.4 -2 -I 0 I 2 3 4 5 -4 -3 xlH (e) x = 6_._.3°, Figure 98.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT .2 __q -.2 --,4 --°6 0"-0.2-_ \_,'"_--°"Q8\ / \,\ ",,,,, _'lO" _ _ p..._l O. 4 " -I.0

i\

-I.2 _w,L -I.4 -I.6 -I,8 -2.0 --2'.2 -2.4 -2 -I 0 I 3 4 5 -4 -3 x/H (_) x. T3.9-r o.

Figure 98.- Continued.

TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .2 -.2 -.4 8w,L -.6 -.8 -I.0 -I.2 -5 -4 -:3 -2 -I 0 I 2 3 4 x/H Cg) x = _.Lx)o.

.2 ,--¢.Q8 -.2 ,_,_0"-0.6 8w, L o'.o.2-- -.4 -.6 =,,o- _ -5 -4 -3 -2 -I 0 I 2 3 4 5 x/H (h) x. 90.00 o.

Figure 98.- Concluded.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOIx-STOL AIRCRAFT 241 -.5 I E=0.6_._ -I.0 w, L 0.--0.4._ -I.5 _i -`/ 0"=0.2-7' / -2.0 -2.5 1.0 2.0 +y/H (a) X = 0 °.

Figure 99.- Effect of rotor size on the lateral distribution of vertical interference due to llft for closed wind tunnel. 7 = 2.0; _ = 1.0.

242 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION -.5 f s f o----Q8 --._ /

J

t 0"--0.6 -_,

J

-I.0

/

o'--0.4_," J

o.--o.zT'//!

-2.0 _'--o'--0 -2.5 1.0 0 2.0 _+y/H (b) x = 1_..o4 °.

Figure 99.- Continued.

i !

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 243 -.5 t J a'=Q8__.

_=06_.

8%L -I.0 o'=0.4--_ -I.5 __20.2 -2.0 0 1.0 2.0 ±ylH (c) X = 26._ °.

Figure 99.- Continued.

632642 0--62----17 244 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION -.2 -.4 --.8 -1.0 '_-o-:0 -1.2 0 1.0 2.0 _ty/H (d) x = 4_.oo °.

Figure 99.- Continued.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT -.2 I t -o'=Q8 _w,L -.4 --_=0.6

____.q_ - _--o.4

-.6 k--_<r =0 -.8 0 1.0 20 +ylH (e) x = 63.43 ° .

Figure 99.- Continued.

246 TECHNICAL REPORT R-124--NATIONAL AERONAUTI0$ AND SPACE ADMINISTRATION -.2 0"--0.6---.

-o---Q8 _w,L --.4 __=0.2 "_- ff =0 -.6 0 I.O 2.0 .--+ y/H (_) × = 7_.7r o.

Figure _.- Continued.

JET-BOUNDARY CORRISCTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 247 -.2 r--o'=Q8 _w, I _.=0.6 ._ --4

J/

o-=0.2 -.6 0 1.0 2.0 _.+ ylH (g) × = 8_.29o.

Figure 99.- Continued.

248 TECHNICAL REPORT R--124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION --.2 e';0.6-_ w, L -.4

/-_<,=o.4

,Y

-,6 2.0 0 1.0 ±ylH (_) x = 9o.oo °.

Figure 99-- Concluded.

JET-BOUNDARY CORRF_,CTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 249 J s s S 0-=0.8-- -.5 J -o-=0.6 s J -1.0 0.4 J .2 -2.0 -2.5 0 1.0 2.0 ---F-y/H (a) X =0 °.

Figure I00.- Effect of rotor size on the lateral distribution of vertical interference due to lift for wind tunnel closed on bottom only.

), = z.o_ _;. l.o.

250 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ..f

0"=08--,,/-"

¢.,,. =,, ,

-.5

o'-0.6-_ 8%L -I.0

.-o4.7f

-1.5

, / , i X-o'-O

-2.0

1.0 2.0

+y/H ('o) x. 1_.o_ °.

Figure i00.- Continued.

JET-BOUNDARY CORRDC_ION8 AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 251

/

J

J

o---0 8---_.

-.5

________

-o"0.6 -I.0 __--o'=__ o.=0 0.2 -1.5 2.0 1.0 • --+ ylH x = 26._ °.

(c)

_=O8 ,/-_'

/

-.z _,o __//.,/,/

-.4 .L_,// ,-- or-0.6 8w, L '0.4 --.6 _ L_,O.2 -'.8 0 1.0 2.0 +-ylH (_) x = 45.oo o.

l_l_re i00.- Contlnue_.

252 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .2 .I --0"=08 8w, L 0 --I -.Z 0 1.0 Z.O _+y/H (e) x = 63._3 °.

.3

/

.2 //

_.ofZ,<

--0" =0 _1 Z.O 0 1.0 -+y/H (_) x. 75.9? o.

Figure i00.- Continue_.

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 253 .3 o--Q8-,,,/ i t

/

/ /

_-o.6_

-.I 2.0 1.0 +-y/H (¢) x = 8_.z9 o.

.3 t' 0--0.8%/ J .2

/

1 t / /

J/

_1 1.0 2.0 -+y/H (h) x - 90.00 o.

Figure i00.- Concluded, 254 TECHNICAL REPORT R-124--NATI0_AL AERONAUTICS AND SPACE ADMINISTRATION O .,.

-.2 -.4 o'=Q8_

2///

.6;-

_w,L -I.2 _ a.=O._-7/ ' -1.4 -I.6 --I.8 --0"=0.2 -2.0 --2.2 -2.4 0 1.0 2.0 :l:ylH (a) X = 0°.

Figure i01.- Effect of rotor size on the lateral distribution of vertical interference due to lift for closed floor only (ground effect). 7 = 2.0.

JET-BOUNDARY COItltDCTION8 AND GROUND EFFECT FOR v'roL-STOL AlltCRAFT -.2 -.4 -.6 --8 -I.0 _w,L

!/J

-1.2 -1.4

i '

-1.6 -1.8 o---0.2

_"

--2.0 _-'0 --2.2 2.0 (b) X = 14.o4 °.

Figure i01.- Continued.

256 TECHNICAL REPORT R-124--NATIONAL AERONAUTI_ AND SPACE ADMINISTRATION -.2 -.4 -.6 ,_'0"6,,'_,_/ -I.0 /'x44- o---0.4 --1.2 --1.4 -1.6 2.0 1.0 _y/H (c) X = 26.56 ° .

Figure i01.- Continued.

JET-BOUNDARY CORREC-_ION$ AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 257 .2

Y

-.2 / s i -o'=O8 Bw,L -.4 _--¢=0.6 -.6 -.8 -I.O 2,0 0 1.0 -+y/H (d) x = 4_.oo°.

Figure I01.- Continued.

2_8 TECHNICAL REPORT R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTRATION .I -.I / "'/ /''"----o'--08 _w,L -.2 --0"-0.6 -,3 "_/-o'-0.4 ._o"0.2 -.4 _l_,O -.5 0 2.0 1.0 +-ylH (e) X = 63.43 °.

.I 0 f -.I -o'-'08 Bw, L

_-f

-.2 ,._//' -.3

o-,o.2

I -.4 0 2.0 1.0 _.+ylH (f) X = 77.97 ° .

Figure lOl.- Continued.

t I JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 259 .I f

/

-.I _=Q8 _)w,L --.2

_.__jy- _o'--0.4

-.3 _,0 °''0.2 --.4 0 I.0 2.0 ± ylH (g) x ='8U.29 o.

-.I -or=Q8 8w, L -.2 --.3 _0"=0.4 k--. O- z 0 I -.4 0 1.0 2.0 (h) X = 90.00 ° .

Figure i01.- Concluded.

260 TECHNICAL REPOI_T R-124--NATIONAL AERONAUTICS AND SPACE ADMINISTllATION _n, deg 90 60 30 0 .8 e2 __02W 0 I 30 60 90 X, aeg la) Closed vlnd tunnel.

#nf oeg 9O 60 30 0 .S _ J O.So WO • 0 30 60 90 X, oeg (b) Wind tunnel closed on the bottom only.

Figure 102.- Values of diameter-width ratio g for given variations in ver- tical interference due to lift along the principal axes of rotors centered in a rectangular _rlnd tunnel having a width-height ratio of 2.0.

JET-BOUNDARY CORRECTIONS AND G ROUND EFFECT FOR VTOL-STOL AIRCRAFT 261

L- 822 08 Figure l03.- Typical semispan model installation in the Langley 300-MPH 7- by lO-foot tunnel.

L- 57 -ll9 2 Figure lo4.- Typical installatio n of semi~pan model and ground board in l7 -foot test section of Langley 3OO-MPH 7- by lO-foot tunnel.

632643 0-62 - 1 TECHNICAL REPORT R-124--NATIONAL AF_,RONAUTICSAND SPACE ADMINISTRATION .... l/-ft test section -- -- --7- by lO-ft test section

I

CL ,8 -20 0 20 40 -4 0 =, deg CD (a) As teste4 at Cp = 6.20, vith no Jet-boundaa*y corrections.

"'C/A = 7.40,A0 °¢_l"

/ f-1

CL f Semispan - 3.:ft-'__ 60° Area - 3.1 sq it

I l f L__L

-20 0 20 40 -4 0 4 8 12 =, deg C D (b) With Jet-boundary corrections.

Figure lOT.- Tests of a svept-_rlng Jet flap model in iT-foot test section com- paredwith those in 7- by lO-foot test section. (Uncorrected data from fig. 9(a) of ref. 7.)

JET-BOUNDARY CORRECTIONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 263 l/-ft test section 7- by lO-ft test section J f

/

/ /

CL Semispan • 3.36 ft so" Area • 3.2 sq ft I I I I I -20 0 20 40 -4 0 4 8 12 a, deg CD (c) With additional correction to C_ = 6.79.

Figure 109.- Concluded.

264 TECHNICAL REPORT R-124_NATIONAL AERONAUTIOS AND SPACE ADMINI_/rRATION h c 82 (ground board outl 4.8 2.7 1.5 2O CL i p.

I I I 1 I - _,J05 ft -7

_ "_. _

I1

I

-20 0 20 40 60 -,¢ 0 O 12 16 a, deg CD (a) As tested for ground effect at Cg = 6.2.

_4 ,....

Fc/_.l: Ao._e4o 20 i'_/-'_c/= "'° o; = "'','"

\

/'t ! _ _ CF=S.7;&o =2,2° 16 / ..._,.._ -/ /J // CL /// Lli //I

//

i, L/_

T' i

I

-20 0 20 40 SO -4 0 4 8 12 16 =, deg C o (b) Corrected to free air.

Figure i06.- Ground-effect tests of a s_ept-wing Jet flap model using a ground board in the 17-foot test section. (Uncorrected data from fig. i0 of ref. 7.)

JET-BOUNDARY CORR_ONS AND GROUND EFFECT FOR VTOL-STOL AIRCRAFT 265 h -- 8.2 (ground board out) 4.8 _-_ 27 1.5 _CAMBER =. :).:*% u / I----o,, /-- / C L \ '%N ____._'J.05 It 7

' lllJ

-20 0 20 40 60 -4 0 4 8 12 16 o, deg c O (c) With a_lditional correction to C_ = 8.4.

Figure i06.- Concluded.

266 TECHNICAL REPORT R-124bNATIONAL AERONAUTICS AND SPACE ADMINISTRATIO/_T 17-ft test section D.2 ft -- -- -- 7- bylO-ft test section 7 • f /.

f,

i/ //

CL

' /

/

/

/

4 / 0 40 80 -12 -8 -4 0 4 0, deg CD (a) As tested at CT = 10.3, with no Jet-boundary corrections.

2O _..-C T =11.0; An=4.0 = ._- C T :12.4; .'_.O =9.0 °

,_ / I/

CL

/

' / /

./ /

0 40 80 -12 -8 -4 0 4 =, deg CD (b) With Jet-boundary corrections.

Figure i07.- Tests of a tilt-wingVTOL configuration in 17-foot test section co=paredwith those in 7- by lO-foot test section. (Uncorrected data from fis. 6(a) of ref. 7.)

JET-BOUNDARY CORRF__r_IONS AND GROUND EFFECT FOR VTOL--STOL AIRCRAFT 17-ft test section --- -- 7- bylO-ft test section 2O

jP_

/ C L

/

J

8 / /

/ !

4 / / -40 0 40 80 -12 -8 -4 0 4 ,,, deg CD (a) As tested at CT = 9.2, with no Jet-boundary corrections.

2O /- CT=9.9; A(I =3.7 ° k =11.1, AG'8,6 e 16 _ _\ / , ... J_ "_

_, //

IZ _7 CL

J /

/ /

4 !

-40 0 40 80 -12 -8 -4 0 4 <=, deg CO (b) With Jet-boundary correctionz.

Figure 108.- Tests of a tilt-wing-with-flapVTOL configuration in 17-foot test section compared with those in 7- by lO-foot test section. (Uncorrected data from fig. 6(b) of ref. 7.)

TECHNICAL REPORT R-124_NATIONAL AERONAUTIC_ AND SPACE ADMINISr£RATION -- 17-ft test section 7- by lO-ft test section .,'7 A

_o /\ ,//

- A

/! I

is /,,/ _, CL /

,2/_/ \---"

/

/

s o 80 -12 -8 -4 0 4 • .-4o 0 40 a, deg CO (a) As tested at CT = 143 with no Jet-boundary corrections.

24 , -¢;T • 15.1; Aa "3.8 i" I I Aa "13.0"

20 / ,'1 /'/_..._.:/:'"

i 7"'7"-/ t '/ I / 1/"

l, \_ /i/

°<" t/ //

,2 ( i / o -40 o 40 80 -i2 -s -4 o 4 s o, de@ Co (b) With Jet-boundary corrections.

Figure 109.-Tests of a deflected-slipstreamVTOL configuration in 17-foot test section compared with those in 7- by lO-foot section. (Uncorrected data from fig. 6(c) of ref. 7-) JET-BOUNDARY CORRF__ONS AND GROUND EFFECT FOR VTOII-$TOL AIRCRAFT 269 17-ft test section ft 7- by lO-ft test section _ ...---- ..._ 8O .---...--- - _ ,.. _

/

CL

/

/

4O

/

40 80 120 -80 -40 0 40 8O a, deg CD (a) As tested at CT = 73, with no Jet-boundary corrections.

!

J 80 v

/ \

v C L

/

C T" 76.4

/

4O

I

jt y

/

40 80 -40 0 0 40 80 120 -80 CD a, deg (b) With Jet-boo,cry corrections.

Figure ii0.- Tests of a _ucted-fan configuration in 17-foot test section com- pared with those in 7- by lO-foot test section. (Uncorrected _ata from fig. 12 of ref. 7.)

_.S. @0_MENT PW_NIING OFIrKE: IM2 O---@12g45

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