Document
NASA Technical Memorandum 4521
Techniques To Improve Maneuver Stability
Characteristics of a Nonlinear Wide-Body
Transport Airplane in Cruise Flight
William D. Grantham and Lee H. Person, Jr.
Langley Research Center • Hampton, Virginia Melvin L. Bailey Lockheed Engineering & Sciences Company ,, Hampton, Virginia Stephen A. Tingas Lockheed Aeronautical Systems Company • Marietta, Georgia National Aeronautics and Space Administration Langley Research Center • Hampton, Virginia 23681-0001
March 1994
lot. ratings were acquired for F(:/nz variations with a Summary single break at nz = 1.3339 or 1.6679 and with an NASA, the Federal Aviation Administration, and initial slope of 50 lbf/g. As expected, pilots preferred the Lockheed Corporation perfornwd a cooperative an increase, not a reduction, in the slope of high load flight simulation experiment in tile six-degree-of- factors when the break occurred at nz = 1.3339.
freedom, ground-based, Langley Visual/Motion Sim- Slope reduction was more noticeable to the pilots ulator (VMS). An ot)jective of the study was to pro- than slope increase. A comparison of tim two meth- vide engineering guidance for acceptable nonlinear ods used to control the maneuver stability character- maneuver stability characteristics for transport air- istics shows little difference in the 1)rcak at. 1.3339.
craft.. The baseline mathematical model of the air- However, with the break at 1.6679, pilots preferred plane represented a wide-body jet transport with a a fixed fH/fc, with variable Fc/#c, particularly for pitch active control system (PACS). The PACS is higher Fc/nz slopes. This comparison provides in- a simulation of an experimental pitch-rate damper sight into a possible means of linearizing the maneu- that is installed on a single Lockheed L-1011 air- ver stability characteristics of a control system with craft, used for in-flight research. The PACS provided inherent nonlinearities.
acceptable flying qualities for negative static mar- gins to 5 percent. As the aircraft center of gravity Introduction moved aft and the static margin changed from posi- The hmgitudinal maneuver control fl)rce gradi- tive to negative, the maneuver stability characteris- ent in an aircraft is a critical parameter of fly- tics were lnodified through systematic variations of ing qualities that ensures structural protection as PACS, pitch-rate (tamper gain, control loading (eol- well as adequate prediction of load-factor control umn for(:(' per column deflection (f_./_,.)), and control for the pilot. Currently, maneuver st.alfility flight gearing (horizontal-tail deflection per control force characteristics are not Ulfiqucly addressed in Federal (_H/_(.)). The evahmtion tasks consisted of perform- Aviation IRegulations (FAIR) Part 25 for transport ing (1) small pitch-attitude changes, (2) standard op- aircraft. (ref. 1). In previous transport category cer- erational turns, and (3) wind-up turns at an altitude tification programs, the Federal Aviation Adminis- of 33 000 ft at a Mach nunlber of 0.83, aim in cahn at- tration (FAA) used a comlfination of requirements mospheric conditions. Nonlinear maneuver stability (longitudinal control, vibration and buffeting, high- is defined as a nonincrelnental change in stick force speed characteristics, and out-of-t.rim characleris- required to ef%ct an incremental change ill normal tics) to ensure safe and controllable maneuver sta- acceleration.
bility characteristics over a range of flight conditions Tile results of this experiment verify current mil- and aircraft, configurations. These regulations are itary specification boundaries for linear inaneuw_r controversial and require a consideral)le amount of stability characteristics. Also for linear maneuver time for design studies and tests (ref. 2). Addi- stability cases, a degradation in pilot ratings at ex- tional engineering guidance is needed to identify ac- treme values of column force per normal accelera- cept.abh_ nonlinear maneuver st.ability characteristics.
tion (Fc/nz) was evident tor all tasks per%rmed with particularly for relaxed stability, highly augnmnted the statically unstable configurations. However, stat- transport configurations. The current trend in large ically stable configurations appeared to be degraded aircraft design, such as the Airbus A320 (ref. 3). is only in high-load-factor tasks (i.e., wind-up turns).
toward relaxed, or even negative, static margins for Ttle inaneuver stability was made linear by either improved fltel efficiency. Advanced flight control sys- adjusting F(,/6c or (_ft/(_c. The results indicate that tems developed ['or these aircraft, in many instances, variations in bH/bc, as opposed to Fc/dc, to nmintain have rendered current maneuver stability criteria linear Fc/nz provide improved flying qualities in the either too stringent or of little practical use.
upper F,./nz range, but provide no advantage in the Swept-wing high-subsonic aircraft are prone to lower range. However, these two parameters arc def- exhibiting nonlinear maneuver stability character- initely coupled; that is, an acceptable range of _tl/(_c istics at higher h)ad factors. Figure 1 shows the at a fxed value of Fc/bc may not be acceptable at amount of cohnnn force (/:_.) required by the sim- another value of Fc/b,,.
ulated aircraft to command increases in normal ac- Tile results indicate that for tile nonlinear ma- celeration (nz). The upper limit of linear nlaneu- neuver stability cases evaluated, substantial levels of ver stability military st)ecification (80 lt)f/_z) is also nonlinearity are acceptable to lhe t)ilots as h)ng as shown in tile figure.
actual cohlinn force at. selected load factors remains The research proceeded as follows. First., tile wit.hin the current nfilitary specifications for level 1 nonlinear Fc/_tz was made linear by two methods.
(satisfactory) extremes (23.3 lbf/g and 80 lbf/g). Pi-
Second. pilot opinionsfor eachof the two meth-
(_c,1 I'illi cohmm (telh_ctiotL (luc to pilot trim
odswererecorded andcompared with tile military
beeper input, in.
standard.Third, a breakin the slopeof tile linear
_¥ol software stick position, in.
F(./nz characteristics was introduced and the opinion of tile pilot of several initial and final slope pairs were _('ol.trim cohmm deflection due to total trim recorded. Finally, a %w eases with two slope breaks and pilot force, in.
in the linear Fc/n: characteristics were evaluated by (511 the pilots. horizontal-tail (teflection, deg 7- tillt(' cottstant, set2 An objective of this study was to evahmte a broad spect.rmn of linear and nonlinear longitudinal stabil- pitch daml)er lag, so(: rlag ity characteristics to generate data for defining sat- isfactory and unaeceptatde nlall(_llver characteristics bank angle, deg as dctined by the opinions of tim pilots. This study Abbreviations: was a joint venture of NASA, the Federal Aviation Administration, and Lockheed Corporation with four AACS aileron active control system pilots participating: one fl'om NASA, ()tie from the CHIi COOl)er-ttarper ratings FAA, and two from Lockheed.
FAA Federal Aviation A(hninistration Symbols FAR Federal Aviation Regulations Measurements and calculations were made in U.S.
IMC iitstrument meteoroh)gy conditions Customary Units, and all calculations are based on airplane body axes.
PA(!S pitch active control system (_ mean aerodynamic chord, ft PIe t)ilot-in(hwed oscillation C._. airplane center of gravity, fl SAS s(at)ility augnmntatioIl sys(.(ml £. eohmm force, ibf VMS Visual/Motion Simulator maximum column force, lbf Description of Simulated Airplane minimum column force, lbf Fc,min The Lockheed L-lOll airplane with ('xtende(l acceleration due to grasqty, x, Villg span is 3 Cllrren( generation, sllbsottic, conlnler- lg = 32.17 ft/see 2 cial transport airplane (fig. 2). The airplane is l)OW- er('(t by three Rolls-I{oyee 211-225 high-byi)ass-ratio KF F feedfl)rward gain turbofan engines an(t has a flying stat)ilizcr with a geared elevator. I)uring these sinlulations the aileron I)itch-rate damper gain Kq active contr()[ system (AACS) was inoperative. Air- M Math number plane geometry and weight data are t)resented in tal)le I.
11 z normal ac(:(d(,ration, g units The sinmlated L-1011 airplane uses a flying s(.a- q pitch rate, (teg/se(: bilizer for hmgitu(tinal control, inboar(t and out- SM slati(' margin, percent l)oard ailerons and sl)oilers for lateral contr()l, and a rudder for (tirectional control. Th(_ basic lon- S Laplace transfOl'ln operator gitudinal control system includes a servoactuator, _c column defleetion, in.
cable stretch, an(t I)osilion- an(t rate-linfiter mo(tel- ing. The lateral control syst.em also inehMes a servo- eolunm defleeti(m due to Maeh trim /)c.MTC actuator and position-limiter mo(leling. Only spoiler ('olnI)ensatioll. ill.
panels 2 and 4 to 6 were modeled for lateral con- trol (fig. 2(t))). Sp()ih'r panel 1 is for ground use and bc, l'A(:S eolunm (teflection (software only) spoiler panel 3 is ot)erated only with AACS, which due to pitch active control system, ill.
wa,s not use(i for this study. The directional (:(mlr()l systc'm determines manual and stability augmenta- (_c,]J cohmm deflectkm due to pilot force tion system (SAS) c(mtributions to rudder position.
inpul, in.
The directional SAS consists of a yaw damt)er and a Tests and Procedures
wheel-driven aileronattdrudderint.erconnection for
improved tllrll coordination.
To generate data for acceptal)le maneuver char- For this study, servoact.uator an(1rate- and acterisli(:s, this study evaluated a broad spectrum of position-limiter modeling werealsoused.The pitch linear and nonlinear longitudinal control characteris- tics that are unique to nonlinear, swept-wing, high-
activecontrolsystem(PACS)providedacceptable
subsonic, jet transport aircraft. The objective was
flyingqualitiesfor negative sta.ticmargins to 5 per-
to develop a database for acceptable maneuver st,a-
cent. The maneuver stability characteristics of the
1)ility (dlaraet(Mslies for FAR Part 25 (regulations on
simulated aircraft werenonlinear(fig. 1). For this
study,the eohmm forcepernormalacceleration was engineering guidance). Various maneuver stability eharact(Msties were (tefined bv a mathenmtical model
madelinearby oneof twodifferentmctho(ls: a non-
of an I_-1011 a.ircraft for t.h(' t)ilot(xl tests (ref. 5).
linearcontrolloading with constant stickto tail gear-
Only a nominal, cruise flighl condition wa.s consi(1-
ing or a nonlineartail gearingwith constantstick
cred (Weight = 3(i0000 lift, Altitude = 31000 ft, forceperinchcontrolh)ading.
51 - 0.83). The basic maneuv(_r stability (F_,/n:)
Description of Simulation Equipment
charact.eristies were systematically varied by (1) mov- ing the aircraft c(,ntcr of gravity (e.g.) location,
Thisstu(tywasmade in thegeneral-purl)OS(_ cock-
(2) changing the pitch-rate feedback multiplier gain pit of the LangleyVisual/MotioilSimulator (VMS), (Kq) ()t" I.hc ncar-ternl PACS (fig. 4 and ref. 2),
a ground-based six-degree-of-freedom motionsimula-
(3) (:hanging the Fc/_,. and (.1) changing the 5ft/bc.
tor. Forthis study,the VMShada transt)ort-tyt)('
The basic longitudinal ('(mlr()l syslem is des(:ril)ed
cockpitequit)I)ed with c(mventi(mal flightandengine-
in reference 2. \Vh(_n F,./(% was varied, bll/(_,, was
thrustcontrols anda flight-instrumenl (tisplay repre-
set t.o a constant -1.0°/in. (?onverscly. wh('n (_lt/(_c
sentative of th('(x)ntr()] panelfoundin (2lrretltIi'atls-
was varied, f_./5,, was set t() a ('onslant 15.77 lbf/in.
port airplanes. (See tig.3.) hlstlunnents thal in(ticat(_
These eon(titi(ms allowed F,./J_: to t)(' varied as shown
angleof altack,sideslip angle, tlapangle, h()riz(mt.al-
in tigure 5 instead of following lhe bast'lint _ nonlinear stabilizer angle, andcohmm f()r(:( _ wereills()i)rovide(t.
sdmdule sh()wn in figure 1. A digilal normal a('celer-
A digital normalaceelcratioI_ imlicatorwasl()cat(xt
ation in(ticator was h)cate(t on the illstrument I)anel
on th(' instrumentt)anela(tjac(ml to thecontrolcol-
a(tja(:('nl t,()a (:(mtr()l cohmm force meter to verify the
umnforcemeter,anda (tigitalMa('hmeterwaspro-
linearity ()f F,/7_:.
videdon an extended instrum(ml1)an(q abovethe
conventional panel. Seven aircraft e.g. locations v,,er(_ simulale(t.
which rel)r('s(mt(_d static margins from at)t)roxinmlcly
Thecontroltortesonlhe wheel, cohmm, andrud-
33 t)ere(mt (e.g. - 0.12c) to -5 percent (e.g. =
tier t)e(tals weret)rovi(ted t)ya hydraulic systenlcou-
0.50c). Fa(%ors that were eonsid('red in th(' s('le('-
pledwith an analog (x)inputer.The systenlallow('(1
tion of maneuver stability chara(:t(uislics ark in(li- for the usualchara(:teristi(:s of stiffness,damping, care(1 in figm'e 5. The configurations evaluated are
couloml)friction, breakoutforces,detent.s, and in-
indicated in t.able l I. Although 176 configurations are
ertia. No visualcues[romoutside wererequired for
indicated in the table, eonfigm'ations 22 through 27
thisstudy;therefore, evaluations were con(tucted un-
and 46 through 51 were not evaluated. All configu- derinstrument meteorology conditions (IMC).
rations were not ewduated by a.ll pilots. Table IlI
The average motiondelayof the VMS, includ-
summarizes the configurations evaluated by each
ing comt)utational time, is lessthan 70 reset. The
t)ilol.
was}lOllt s}_sl(:lll llS(_([ l,() t)r(?s(?ll(, lllOtiOll-CllO ('o111- For ea.eh configuration, the pih)t comt)hqe(t the man(is to the motion base is nonsta.n(tard and was comment card (fig. 6) |)y assigning a Cool)('r-tlarper conceiv(xt and (l(weh)t)(_d at Langley (ref. 1). The rating (CHI:I) t.o each maneuver (ref. 6 anti fig. 7) and washollt systetIl colltillllOllslv a(tal)is to paFa, Hl(_tcF by conmlenting (m the t('n(h'twy toward I)ilot-induced changes to (1) minimize a cost functional through oscillation (PtO). Th(! pilot was asked to t)er[orm and contimlous st.e(_pest (h_s(:ent metho([ and (2) product' evaluate the following four primary tasks: InotioIt Cll("s for translatiolial a('eelcrations and rota.- tional rates within the motion enveloi)e o[ the syner- 1. Trimmability: Evaluate the ease or (tifliculty to initially trim the airerafl and to recapture gistic base.
trim from a disturbed condition.
Aural cues inclu(ted engine noise and a t,one that 2. Small pitch-altitude changes: Evaluate atti- t)eet)e(t intermit1(_ntly at 1.Sg and increased to a solid tude stability when pitch attit, u(te is changed tone at. 2.09. This tone signale(t g milts in win(t-up tlli'HS. and held with cohmm force only.
3. Operational turns: Evaluateturn entry and
tasks are presented subsequently in the discussion.)
exit characteristics when30° to 40 ° banked
Figure 12 indicates overall pilot ratings for linear turnsareperformed at,constant airspeed with Fc/nz obtained by varying _SH/b_., with Fc/_Sc con-
cohmmforceusedto controlattitude andal-
stant. For both the variable Fc/(Sc and bH/hc con-
titude. Airspeed shouldbemaintained within
ditions, Kq, was set. at 2.0 (highest tested value)
5 knots,altitudeshouldbemaintaine(l within
for improved phugoid damping. The short-period 100ft, anda 30 ° banked turn shouldproduce frequency and damping characteristics were within the level 1 boun(taries of reference 7. The trend 1.15g.
curves indicated in figures 11 and 12 were visually
4. \Vind-upturns: Evahlate inaneuver for(:e and
fitted through the available data points. Because stabilitycharacteristics duringwind-upturns.
data for the highly stable configurations (c.g. forward
This emergency maneuver is performed at
of 0.40c) were limited, the analysis concentrated on
maximum powerby rolling to a 60° t)anked
configurations with low static margins ranging frolll
tm'nwith a mininmm of 2gandwith()utlosing
5 percent (e.g. - 0.4()_) to -5 percent (e.g. = 0.50g').
altitudeor stallingthe airplane.
The PIe tendencies were evident primarily at low
Results and Discussion
nmneuver stability levels. Typical of these was con- figuration 34 with c.g. = 0.40g" and 15 lbf/g. This con-
Center of Gravity and Pitch-Rate
figuration evoked comments about PIe such as "Os-
Damping
cillations tend to develop when pilot initiates abrupt
The first 21configurations wereevaluated to de-
maneuvers or attemt)ts tight control."
terminethe effects ofe.g.andpitch-ratedamping on
The overall pilot ratings shown in figures 11
the maneuver stability characteristics of the Inath-
and 12 are replotte(t in figure 13 for comparison of ematical modelof the basicairplane.As expected, techniques used to maintain linear maneuver stabil-
increasing t)itch-ratedamping increased Fc/nz, and
ity. The level 1 maneuver stability boundaries of ref- moving the e.g. aft decreased Fc/_:. (See fig. 8.)
erence 7 are also indicated in figure 13. The two Th(, evaluation of these 21 configurations for pilot 1 methods used for varying Fc/nz and maintaining a is also indicated in tigure 8. The average ratings of linear slope show little difference in the lower F,./nz all pilots who ttew the c(mfigurations are given in ta- range for e.g. locations of 0.40c and 0.45a. (No coil- bh, II. These results indicate that when t)it, eh-ratc clusions were drawn for tile statically unstable con- damping was high, pilot 1 rated Fc/t_z as accept- figuration, e.g. = 0.50c, t)eeause all available data able (CHR < 6.5), although the maneuver stability for the variable F,./5,. method were within level 1 was ntmlinear. Also, with Kq = 2. the F,/_z was boundaries of ref. 7.) However, the pilots seemed ratett within the satisfactory (CItR < 3.5) linear lim- to t)e more sensitive to variations in Fc/(5_: than to its of references 7 and 8. However, to maintain level 1 variations in _H/b,c in the upper Fc/nz range. The short-t)eriod damt)ing ratio, Kq should be less than implication is that a (lesign with inadequate maneu- 2 for e.g. locations forwar(t of approxinmtely 0A0g' ver stability characteristics can be improved more (fig. 9). Also, maintaining h'q as high as t)ossit)le is readily through variations in Fc/(Sc than in 5H/bc.
advantageous for l)hugoid stability (fig. 10). There- Howew_r, these two parameters are defnitely cou- fore. for configurations 28 through 176 (table II), pled. That is. an acceptable range of 6H/5c at a all tests were performed at the highest possible Kq specific value of Fc/_c may not be acceptable at a for l)hugoid suppression while retaining level 1 short- different value of g./6,.
period characteristi('s.
The trend curves of figure 13 also indicate an opti- Linear Maneuver Stability mmn linear maneuver stability level of approximately 50 to 60 tt)f/g for the subject configuration. In addi- Before determining acceptal)le levels of nonlinear tion, a degradation of pilot ratings at extreme vahms maneuver stability, the validity of current military of F(./n: ix in(licated and is most severe as cohlnin level 1 boun(laries for linear Fc/n: must first be forces t)(,come lighter (i.e., reduction in F,,/,_: from tested (relM. 7 and 8). (Boundaries for Fc/*_z at'(!
optimunl of 50 to 60 lbf/g).
the sanle in ret_. 7 and 8). For an L-1011 airplane with a limit load factor of 2.5, these t)oundaries are For each configuration, the pilots rated individ- 23.3 lt)f/g and 80.0 lbf/g. Figure 11 presents overall ual tasks such as ot)erational turns (g < 1.5) and pilot ratings an(t associated trend curves for linear win(t-up turns (9 > 1.5) (fig. 6). Pilot ratings F,./n: obtained t)y varying F,./5, with 5tt/5,, con- for operational turns and wind-up turns are pre- stant. ;fhese overall ratings inchute all tasks per- sented in figure 11 for variable/';.//5c arid in figure 15 f()rme(I by each pilot. (Pilot ratings of individual for bH/b,, configurations. Trend curves were fitted visuallythroughtile data. Again,it. appears that and presented in tigure 22 h)r comparing the effects degradation in pilot ratingsis moresevere in lower of Fc/#,. with h[t/h c. These trend curves indicate F,./I_: regions part.ieularly when the variable _ll/(Sc thai the pilots preferred a linear F,./I_: variation for low-lea(t-factor tasks (oi)t.itlmnt pilot ralings at method is used (fig. 15). The pilot comments also in- dieated a PlO tendency for low F,/_z configurations. approxiinately 5() lift/g, which implies no break), but they l)reh'rr('d a slight redu('tion in slope above For the small pitch-attitude chang('s and oper- 'r*z - 1.667q. K)r the configuration with e.g. - 0.50c ational turns using the variabh' (F,/b,) melhod, and SM = -5 percent with variable hll/b c, the pilots the pilot ratings were eonsistently good for stat- preferred a reduction in Fc/t_z slope from 50 lbf/g ieally stat)le (e.g. = 0.,10c) and neutrally stable to 30 lbf/g at ltz -- 1.667g. Also, with the break at (e.g. = 0.45_) configurations (fig. 14). Tiles(' con- z_z = 1.333g, tile pilots strongly preferred an increase figurations were degraded by extreme Fc/nz levels in slope over a retluetion ill slope, as indicated l)y only for high-load-factor pilot tasks (i.e., for wind-up a more rapid increase in pilot ratings with reduced turns). However, statically unsta.bh, configurations slope after the break. Tile effect of slope reduction (e.g. = 0.50c) appeared to be degraded at the ex- was much more noticeable to the pilots than the effect treme maneuver stability levels for all pilot tasks, of slope increase, especially when the slope was near including the small pitch-attitude changes and op- zero or n_,gative (fig. 5). However. with the break erational turns _}l("ll the (5tf/6 c method was used at. nz = 1.667g, the pilot rating curves were faMy (fig. 15). The pilot ratings for small pitch-attitude sylnlnetrical about an ol)timum second slope value changes were the same as the ratings for operational (fig. 28).
turns for the configurations in figures 11 and 15.
A comparison of the txv() methods used to me(l- Based on a maximum level 1 Coopvr-ttarper i5' the maneuver st.at)lilly characteristics (fig. 22) rating of 3.5. the level 1 boundaries suggested by shows little difference at low P)./rt: values with the the results of the linear maneuver stability por- break ,it 7)z -- 1.33'39 for all e.g. locations ewdu- tion of this study arc summarized in tal)le IV.
ated. \Vh(m the break occm'red at _*: 1.6679 These results are based on both overall and in- (fig. 22), the pilots had a slight preferenc(' for the dividual pilot task ratings indicated in tigm'es 13 t;;./h,, method for stat:ically stable (e.g. = 0.10c) to 15. Although the limited results of this study pre- and neutrally st.at)h- (e.g. - 0.45c) configurations.
clude determination of suggested maneuver stability However, for the statically unstable contigurati(m boundaries, for this particular aircraft, a shift of ap- (e.g. -- 0.50c), th(! pilots had a strong l)refcrenco for proximately 10 lbf/g higher for values {}f f)./_: for tilt, htt/be, method.
tttinimmn and maximum level 1 maneuver stal)ility These results probably depend on the value se- boundaries forum in references 7 and 8 apt)ears to bc lected for the fixed parameter (either (511/(Sc or f)./_5,) appropriate.
and only provide a single test point in what should be a more detailed analysis. |towevcr, this conq)arison Nonlinear Maneuver Stability provides insight into the t)roper means of lineariz- Although pilots prefer linear f_./r?z, providing ing the maneuver stability elmracteristics of a control such charaeteristics is sometimes difficult because of system with inherent nonlinear illall(!llV(!r stability.
relaxed static stability in t.ransports with advanced However, this study did not provide sutticient data control systenls. The degree of nonlinearity in lll_l- to conelu(te which method is better.
neuw_r stability characteristics accepta|)le to the pi- In addition to the overall Coop('r-Itarper ratings lots was evaluated during this study by parametric for each configuration, set)arate ratings were obtained variations of F./_z slope and are presented in fig- for each tank. Figures 221through 26 present pilot rat- ures 16 and 17. Fc/_z variations with a single break ings fl)r configurations with static margins of 5 per- at 7_z = 1.3339 or 1.667/9 with an initial slope of cent and -5 percent and a single break in the F,./,_: 50 Ibf/.q. This initial part of the slope falls in the curve for the operational tm'n (tic < 1.4.(/) and wind- midrange of acceptable values as st)ecitied in refer- up turn (_: _< 2.09) tasks. These are the same con- encc 7 for level 1 flying qualities. The slopes of I@/lt z figm'ations for which overall pilot ratings were pre- were controlled through either E./bc or (51f/(5c.
sented in figures 18 through 21. Pilot ratings ()f the Figures 18 through 21 present pilot ratings for small pitch-attitude changes were consistmltly good configurations with a single break in the F,/ne curves and, therefore, are not presented. This task did not at either nz = 1.6679 or 7_z = 1.aa3g with the static explore maneuver stability regions at[eeted by the breaks evaluated in this study. The data of figures 23 margins ranging Dora 5 percent to -5 percent. The through 26 are replotted in tigure 27 fl)r comparison.
tren(l curves fitted through these (tata are ret)h)tted Figure 27 indicatesby favorablepilot ratings improvements over single-break configurations and for the operationalturns task with the breakat for the sake of brevity were limited to at least one pilot flying each configuration.
,_: = 1,6679 that whenthe pilot evaluation task
occursin tile linearportionof the maneuver stabil-
Near the conclusion of this study, the primary
ity curve,no degradation in flying qualitiesis de-
project pilot was asked to design what he believed
tected.However, whenthetaskcalledformaneuver-
would be the optimum maneuver stability curve for
ingbeyond thebreakpoint(ill eitherdirection), large
this particular airplane. The result is presented in
changes in maneuver stabilityresulted in poorpilot
figure 29, but because of insufficient evaluations no
ratings. Evenlargeincreases in maneuver stability
analysis was made of the F,:/nz characteristic. This
from nz = 1.3339 had little effect on pilot ratings
pilot opted for three distinct values for Fc/nz instead for the operational turns with the statically unsta- of a constant value. He chose a nolninal value of ble configuration (e.g. = 0.50c). (The only augmen- 45 lbf/9, then a reduction of 40 percent to 27 lbf/g tation for this sinmlated aircraft was an electronic between nz = 1.15g (¢ _ 30 ° ) and 1.6g (¢ _ 50°), pitch-rate danlper.) With the task performed at a and finally an increase in Fc/nz to 65 lbf/g beyond maximmn load factor of 1.49, column forces had not nz = 1.69.
yet become unreasonably high; thus, maneuver sta- bility (F_,/nz) increases were still undetected. The Concluding Remarks pilots were not seriously affected by large increases in maneuvering stability at ,tz - 1.3339 for any tasks NASA, Federal Aviation Administration, and pert'ornmd with the unstable (e.g. = 0.50_) configu- Lockheed Corporation performed a cooperative flight ration. However, severe degradations in pilot ratings simulation experiment in the six-degree-of-freedom, are indicated with the statically stable (c.g. = 0.40_) ground-based Langley Visual/Motion Simulator configuration. Likewise, reductions ill Fc/nz slopes (VMS). All objective of the study was to provide at t_z = 1.3339 1)I'ought about large degradations in engineering guidance for acceptable nonlinear ma- pilot ratings tbr both the stable and the unstable neuver stability characteristics for transport aircraft.
configuration. The baseline mathematical model of the airplane represented a wide-body jet transport with a pitch- The question arises as to whether the pilot rat- active control system (PACS). Tile PACS provided ing degradations due to abrupt changes in maneu- acceptable flying qualities for negative static margins ver stalfility (F,./I_: slope) were actually caused by to 5 percent. The maneuver stability characteristics the change ill stability or by the fact that colunm were modified through systematic variations of PACS forces nmy be approaching unacceptable values, as pitch-rate damper gain, aircraft center of gravity, indicated in figures 16 and 17. Comments indicated control loading (cohmm force per column deflection that the pilots frequently (lid not detect a change in (F,,/b_.)), and control gearing (horizontal-tail deflec- control characteristics at the actual break point, but tion per control force (_H/_c))- The evaluation tasks rather as the cohunn force approached established consisted of performing (1) pitch-attitude changes, level 1 maneuver stability boundaries. For example, (2) standard operational turns, and (3) wind-up when the slope of Fc/Ttz at 7_z = 1.6679 changed turns, at a representative flight condition in calm at- fl'om 50 lbf/g to -4(1 lbf/9, degradation in flying qual- mospheric conditions.
ities was detected as the coluinn force approached the lower level 1 boundary (1.99), instead of where the The current military specifications dictate mini- actual break occurred. (See fig. 16.) Pilot colnments mum and maxinmm levels of maneuver stability (col- fl'equently suggested that the break occurred near umn force per normal acceleration, Fc/nz) for level 1 level 1 boundaries, not where the actual break oc- (satisfactory) flying qualities. These boundaries are era'red. Configurations that actually did have a break 23.3 lbf/9 and 80.0 lbf/9, respectively, for tile base- in the Fc/nz curve, but did not (:ross level 1 bound- line airframe used in this study. The results of this aries were typically rated as satisfactory. When the experiment verify tile specification boundaries, with slope was -10 lbf/9 after tile break at nz = 1.6679 only a slight possible shift toward higher (by approx- is one example (fig. 16). A second example, with a imately 10 lbf/9 ) column forces recommended for this slope of 80 lbf/9 after the break produced comments type of aircraft. However, the present specification such as "a little heavy but very flyable." level 1 boundaries appear to t)e reasonable.
Pilot ratings for double-break maneuver stability A degradation in pilot ratings at extrelne values variations (fig. 28 and configurations 152 through 170 of Fc/nz was evident for all pilot tasks for statically of table II) were acquired but were insufficient for unstable configurations evaluated. However, the detailed analysis. Initial pilot ratings indicated no statically stable configurations appear to be degraded J. J.; Davis, W. J.; \Villey, C. S.; Weaver. W. A.; only, in high-load-factor pilot tasks (e.g., wind-up and Cokeley, I/.: Handling Qualities of a Wide-Body turns).
Transport Airplane? Utilizing Pitch Active Control Systt ms The maneuver stability was made linear by either (PACE) for RelaJ:cd Static Stability Application. NASA adjusting Fc/_Sc or 6H/gS_.. The results indicated that TP-2182, 1985.
variations in <SH/(_c rather than Fc/_c, to maintain 3.
.Jagger, Dougb_s H.: New Technology in the A320. AIAA- linear F(:/nz provided improved longitudinal flying 84-2444, Oct. Nov. 1984.
qualities in the upper F,./nz range but provided no advantage in tile lower range. However, these ,:1.
Martin, D..I., ,lr.: A Digital Program for Motzon Wa,s'hout two parameters are coupled; that is, an acceptable on Langlcy's Siz-Degree-of-Freedom Motion Simulator.
range of 6H/6c at a fixed value of Fc/<Sc may not be NASA CR-145219, 1977.
acceptable at another value of F_/<Sc.
5.
Grantham, William I).; Smith, Paul M.; Person, While this research was comprehensive, some Lee H., Jr.; Meyer. Robert T.; aim Tingas, Steph(m A.: configurations were tested by only one or two pi- Pilot_'d Simulator Study of Allowabl_ Time De:lays in.
lots and these configurations may deserve further Larqe-Airplane Response. NASA TP-2652, 1987.
investigation.
6.
Cooper, George E.; anet ttarper, Robert P., .lr.: Th_ _ (,qse NASA Langley Research Center of Pilot lMling in tlu! Evaluatio,_ of Aircraft Handlin 9 Hampton, VA 23681-0001 Q'aalitics. NASA TN D-5153, 1969.
December 15, 1993 7.
Military Spccificatkm Flying Qualities of Piloted Air- References planes. MIL-F-8785C, Nov. 5, 198(I. (Supersedes MIL-F- 8785B, Aug. 7, 1969.)
1. Airworthiness Standards: Transport Category Mrplanes.
FAR, Pt. 25, Federal Aviation Adm., .hme 1974.
S.
Military Standard Flying Qualiti(!s of Pilote(l Aircraft.
2. Grantham. William D.; Person, Lee H., .Jr.; Brown, MIL-STD-1797A, ,lan. 30, 1990. (Supersedes MIL-STD- Philip W.; Becker, Lawrence E.; thmt, George E.; Rising, 1797(USAF), Mar. 31, 1987.)
Tabh_ I. Airplane Geometry and \Veight Data Wing: Reference mean aerodynamic chord, ft 2 .......................... 24.46 Span, ft ........................................ 164.33 Aspect ratio ...................................... 7.817 Horizontal tail: Span, ft ......................................... 71.58 Aspect ratio ....................................... 4.{) Vertical tail: Span, f'I......................................... 29.67 Aspect ratio ....................................... 1.6 Weight: Max|reran ramp, lbf .................................. 424 000 Maximmn takeoff, lbf ................................. 422 000 Maximum landing, lbf ................................. 358 000 Zero fuel, lbf ..................................... 312 460 Operating empty, lbf ................................. 261 000
TableII. Average Evaluations of Configurations
First SecondSecond Third
slope, Average No. of break, slope, break,
Configuration
CHR
ntlnlber
e.g. SM Kq Y_,/6c _iH/_c Yc/nz breaks nz Yc/_z nz
3.5 0.12 33 0 Fixed Fixed Basic 0 3.0 0.12 33 1 Fixed Fixed Basic 0 3.5 0.12 33 2 Fixed Fixed Basic 0 5.0 0.25 20 0 Fixed Fixed Basic 0 3.5 0.25 20 1 Fixed Fixed Basic 0 3.5 0.25 20 2 Fixed Fixed Basic 0 6.0 0.35 10 0 Fixed Fixed Basic 0 5.5 0.35 10 1 Fixed Fixed Basic 0 3.5 0.35 10 2 Fixed Fixed Basic 0 9.0
10 0.40 5 0 Fixed Fixed Basic 0
6.0 0.40 5 1 Fixed Fixed Ba.sic 0 3.5 0.40 5 2 Fixed Fixed Basic 0 10.0
13 0.45 0 0 Fixed Fixed Basic 0
6.5
14 0.45 0 1 Fixed Fixed Basic 0
3.5
15 0.45 0 2 Fixed Fixed Basic 0
10.0
16 0.47 -2 0 Fixed Fixed Bask: 0
7.0 0.47 -2 1 Fixed Fixed Basic 0 4.0 0.47 -2 2 Fixed Fixed Basic 0 10.0
19 0.50 -5 0 Fixed Fixed Basic 0
10.0
20 0.50 -5 1 Fixed Fixed Basic 0
5.5
21 0.50 -5 2 Fixed Fixed Basic 0
22 0.12 33 0 Fixed Variable
i 30
i
6.0 15 0
28 0.25 20 1 Fixed Variable
i 3.5 3.0 3.0 4.0 6.0 Table II. Continued First Second Second Third i Configuration No. of break, slopc, break, slope, Average IlllIllbeI' e.g.
SM Nq breaks llz F,./n_ nz /;_./nz CHR 0.40 5 2 Fixed 0 6.0 4.5 3.0 I 3.0 3.5 I ,1.0 4O 0.45 0 '2 Fixed Variable 5.0 3.0 I -12 2.5 I 2.0 3.O 4.0 46 0.47 -2 '2 Fixed Variabh' 5.0 5O 5 , '2 0.50 Fixed Variable 15 6.5 5.0 3.5 6O 3.0 4.0 5.0 33 0 Variable Fixed 30 9.0 0.12 7.0 I 7.0
I
1 .
7.O O.25 2O Variable Fixed 30 i 3.O (i3 ,15 3.,5 I 3.5 i 9O 4.0 7.O Variable Fixed 5_ 2 45 3.0 3.O J ,1.;5 ()'i t°
l
il
7O 5.0
TableII. Continued
S(,(:()I 1(1_ SoC()lld Third _F_:s_ Configurat ion No. of i break, 1)roak, slop(', slope, Average IlllllI|)('T })teaks _z CHR F(,/II 2 /+/,: lie 71 0 2 Variable Fixed 3O 0 3.5 45 2.5 6O 3.0
l
74 4- 90 4.0 75 Varialfle Fixed 3O 3.5 76 45 3.0 77 60 3.0 90 3.O 79 0.50 Variabh? Fixed 3O 3.0 80 0.5O Variable Fixed 45 3.0 81 0.50 Variable Fixed 6O 0 4.5 Fixed Variabh' VariabhJ 1.667 -70 10. 0 -,10 9.0 -10 6.5 20 3.0 8382 ().[() 86 80 3.0 87 170 8.0 Fixed Variable Variable 1.(i67 - 70 10.0 -40 8.5 10 7.0 91 2O 3.0 88 0.15 9'2 80 3.5 93 170 8.0 Fixed Variabl(_ Variable 1.667 -70 10.0 95 .... 10 8.5 96 10 4.0 97 21) 3.0 91 0.i() I S() 98 3.O J_ 171) 99 6.5 100 Fixed Variable 1 8.0 1.667 i -10 4.0 102 -20 3.0 0.ill 103 80 3.0 r - 10 10i 170 5.0 F tlnitial sh)pe 50 lbf/y.
TableII. Continued
First Second Second Third L No. of break, slope, break, slope, Average
Configurat ion
lllllllber Fc/nz breaks _= Fc/nz nz F(:/nz CHR : e.g. SM h'q Fc/_c -40 8.0 105 0.45 0 2 Variable Fixed Variable 1 1.667 --10 5.0 -20 2.5 i 80 4.0 i 170 5.0 1.667 -70 9.5 0.50 -5 '2 Variable Fixed Variable 1 i -40 7.0 -10 4.5 I 2O 3.0 80 8.0 0 40 5 2 Fixed Variable Variable 1 1.333 -10 10.0 116 5 7.0 20 5.0 35 3.5 I 65 3.5 110 4.5 J i 155 7.0 i 1.333 -10 10.0 122 Variable Variable 1 0.45 0 2 Fixed 5 7.0 123 !
i 20 5.0 , I 35 3.5 65 3.5 110 6.0 155 6.0 1,333 -10 10.0 129 0.50 5 2 Fixed Variable Variable 1 5 7.0 20 6.0 35 3.0 65 3.0 110 4.0 155 5.0 i Fixed Variable 1 1.333 1 7.O 136 0.40 5 2 Variable 20 4.0 137 I I 35 3.0 !
65 4.5 110 5.0 J 155 6.0 i •
TableII. Conclud<_d
First Seeon(t Second Thir( Configuration No. of break, slot)c, break, slope, Average Illllll[)er CHR e.g. SM Kq F,/6, 712 F,/,< ,,: E./._ 1,12 0.45 0 2 Variable Fixed Variable 5 6.0 1.333 20 5.0 35 3.5 65 3.5 146 :: [10 3.5 F i 147 0.50 -5 2 Variable Fixed Variable 1.333 --lO 8.5 I 7.0 i 20 6.5 35 5.0 J 65 5.5 0.25 20 1 Fixed Variable Variabh_ 1.333 0 1.667 -20 8.5 0.25 20 1 Fixed Variable Variat)le 1.333 20 1.667 20 7.0 154 0.25 20 1 Fixed Variable Variat)le 1.333 50 1.667 5O 7.0 155 0.25 20 1 Fixed \Su'iat)le \7arial)le 1.333 -20 1.667 0 10.0 I l ! 20 10.0 i 40 9.0 : q 70 9.0 159 0.50 -5 2 Fixed Variable Variat)le 1.333 0 1.667 -2O 10.0 160 0.50 -5 2 Fixed Variable Variable 1.333 0 1.667 20 6.0 161 0.5O -5 2 Fixed Varial)le Variat)h, i l.333 0 1.667 50 6.0 i 0.50 -5 2 Fixed Variat)l(, 1.333 -20 1.667 0 10.0 20 10.0 4O 7.5 70 9.0 0.25 20 1 Variat)le Fixed Variable 1.333 0 1.667 20 8.0 167 0.25 20 1 Variable Fixed Variable 1.3331 50 1.667 50 7.0 168 0.50 -5 2 Fixed Variable Variable 1.333 0 1.667 -20 5.0 0.50 -5 2 Fixed Varial)le Variabh, 1.333 20 1.667 -20 6.0 170 0.50 -5 2 Fixe(t Variable Variable 1.333 50 1.667 -20 6.0 171 0.40 5 2 Fixe(l Variable Varial)le 2 1.155 27 1.600 65 3.0 0.45 0 2 Fixed Varial)h_ Varia})le 2 1.155 27 1.600 65 3.0 0.50 -5 2 Fixed Variable Variable 2 1.155 27 1.600 65 3.5 174 0.40 5 2 Variable Fixed Variable 1.155 27 1.600 65 5.5 175 0.45 0 2 Variable Fixed \;ariat)lc 1.155 27 1.600 65 3.5 176 0.50 -5 2 Variable Fixed Variabh, 1.155 27 1.600 65 5.0
TableIII. Configurations Evaluated by EachPilot
Pilot 4 Pilot 1 Pilot 2 Pilot 3 Pilot 4
Pilot, 1 Pilot 2 Pilot 3
Configuration
Configuration
55 X X X X
1 X X
X
X 56 X X X
2 X
X X X
X 57 X
3 X
X
X X X 58
4 X
X
X X X X 59
60 X
X X X X
X 61 X
7 X
X 62 X
8 X
X 63 X
9 X
X
X X X X 64
X
X X X X 65
X 66 X
12 X X X
X X 67 X X X X
13 X X
X X
X X X X 68 X X
X X X X
15 X X X X 69
X X X X
16 X X X X 70
X
X 71 X X X
17 X X X
X X
X X 72 X X
18 X X
X X X X
X X 73
19 X
X X X X
X X X 74
X 75 X X
21 X X X
X 76 X X
28 X
X X
X 77
29 X
X X
X X 78
79 X X X X
X X
X
X 80 X X
32 X
X X X
X 81
33 X
X X X
X X X X 82
X X X X
X X X X 83
X 84 X X X X
36 X X X
X X
X X 85 X X
37 X X
X X X X
X X X 86
38 X
X X X X
X X X X 87
X 88 X X
40 X X X
X
X X X 89 X
41 X
X
X X X X 90 X
X X
X X X X 91
X X
44 X X X X 92
X 93 X X
45 X X X
X X 94 X X X X
52 X X
X X
X X X X 95 X X
X X
X X X X 96 X
TableIII. Concluded
1 Pilot 2 Configuration Pilot, Pilot, 3 Pilot 4 Configuration Pilot 1 Pilot 2 Pilot 3 Pilot 4 97 X X X X X X 139 98 X X X 140 X 99 X X X X 141 X 100 X X X X 142 X X X 101 X X X X 143 X X X 102 X X X X 144 X X
! x
103 X X X X 145 X 104 X X 146 X 105 X X X 147 X X X 106 X X X 148 X X X X X X X 149 X X X X X X 150 X X X X 1(19 X X 151 X 110 X X 152 X X 111 X X X X X 153 X X 112 X X X X 154 X X X 113 X X X X 155 X X X X 156 X 115 X X 157 X X 116 X X X 158 X X 117 X X X 159 X X 118 X X X 160 X X X X 119 X X 161 X X X 120 X X X 162 X 121 X X 163 X 122 X X 164 X X 123 X X X X 165 X !
124 X X 166 X X X 125 X X X 167 X X X 126 X X 168 X 127 X X X 169 X X 128 X X 170 X X 129 X X X 171 X X 130 X X X 172 X X 131 X X 173 X 132 X X X X 174 X X 133 X X X 175 X X 134 X X X X 176 X X 135 X X X 136 X X X 137 X X X 138 X X X
TableIV. LinearManeuver Stability Level 1 Boundaries of This
Study and Military Specifications Force per acceleration, F,,/nz, lbf/g-unit Static margin, Technique used to Maximum Sollrce Minimum lincarizc Fc/nz percent 5 41 107 Variable _H /Sc Present study 0 29 Variable (S H / _ic 31 82 -5 Variable (SU /bc 5 39 85 Variable F,./G 0 27 74 Variable F,:/b,.
-5 Variable F_,/G Military Specifications (_33.4 _'9().2 (ret_. 7 and 8) 23.3 80.0 "Average 80 -- Linear upper limit F c, Ibf 0 P'- , I , I , I , I , I 1.0 1.2 1,4 1,6 1,8 2.0 n z,,_units Figure l. Maneuver stability charactcrist, ic,s,
t
55.33 164.33 l -- ° -- "178.62 / Outboard aileron jj Rudder _j.J .... (ARCS off) _ // /_J- Sp°ilerslt°6 _2_ _ @ "_"4-_. __/./_-_ _E,evator _5_j ,,,9_-__ Flying stabilizer /_ j/-:-_ ,,,,,,_'_ __ Inboard aileron ORIGINAL PAGE B!..AC_ AND WHITE PHOTOGRAP_ L-75-7570 (;t) l,;lll_.{l(' 5" \_is_l_ll,/[kl()li_li ."4iiii_ll;tl()r.
l_'i<_lii-c , _J. l,_.il_](Lx' 1,_li;i] i L'X,l()ii_lli _]liill];tt<li ;lil(l ili_t i'ilill('lil ]);ill('l <]i_l/l_-ly.
L-78-7794 Pitch damper Lag gain Prefilter
I' Fq
_lagS + 1 0.0as + 1 Feedback lagged_ q, deg/sec pitch damper Ioop_._ Servo Series servo command limit, in. Column, in.
Basic 1 i 0.67 5c, PACS longitudinal control S ,___. Cable_in] 0.000625s 2 + 0.05s +1 -0.78 1.25 _-- system ) L--"]I Washout Feedforward lagged--_ col, trim = column minus trim Ioop,_ 5 c,p - (Sc,trim + 5c, MTC) Feedforward Cable, in.
Lag gain Prefilter Column, in.
oo s+ 11
Figure 4. Amdytical diagram of near-term PACS.
Vary initial gradient and gradient after break Vary initial gradient F c, Ibf F c, Ibf
\
n Z n z Vary gradient after first break, Vary initial gradient, location of second break and location of break and gradient after second break gradient after break Fc, Ibf F c, tbf n z n Z Figure 5. Possible maneuver stability characteristics for pilotod flight simulation evahmtion.
DATE: CONFIGURATION: PILOT: 1. TRIMMABILITY:- 2. SMALL PITCH CHANGES: Initial response:- Damping:- Predictability/Precision :- PIO:- Cooper-Harper Major Reason:- 3. OPERATIONAL TURNS (.q < 1.5): Entry/exit characteristics:- Ability to hold altitude (+100'):- Tendency to PIO:- Stick Force Characteristics:- Special techniques:- Cooper-Harper Major reason:- 4. WIND-UP TURNS (g >1.5): Ability to attain/stabilize desired load factor:- Tendency to PIO:- Maneuver Force Characteristics; Predictability:- Forces:- Disp:- Sens:- Linearity:- Special Techniques:- Cooper-Harper Major reason:- SUMMARY: Good Features:- Major Problems:- Overall Cooper-Harper Task Overall PIO: Rating Phugoid:- Figurc 6. Pilot comment card.
DEMAND ON THE PILOT ADEQUACY FOR SELECTED TASK OR AIRCRAFT IN SELECTED TASK CHR REQUIRED OPERATION" CHARACTERISTICS RATING OR REQUIRED OPERATION* Excellent Pilot compensation not a factor for Highly desirable desired performance Good Pilot compensation not a factor for Negligible deficiencies desired performance Fair--Some mildly Minimal pilot compensation required for unpleasant deficiencies desired performance Yes Minor but annoying Desired performance requires moderate deficiencies pilot compensation Is it Moderately objectionable Adequate performance requires y without Deficiencies deficiencies considerable pilot compensation improvement?
require improvement Very objectionable Adequate performance requires but tolerable deficiencies extensive pilot compensation Major deficiencies Adequate performance not attainable with _(es maximum tolerable pilot compensation.
Controllability not in question.
adequate performance Deficiencies Major deficiencies Considerable pilot compensation is required _ttainable with a tolerable require for control )itot work load?
improvement Major deficiencies Intense pilot compensation is required to retain control Yes Is Major deficiencies Control will be lost during some portion of it controllable? Improvement required operation mandatory *Definition of required operation involves designation of flight phase and/or subphases with accompanying conditions.
I Pilot decisions I Figure 7. Pilot rating system (from rcf. 6).
8O [] Kq=0 ._ • Kq=l o Kq=2 6O o Fc,mi n J CHR " Fc'max _ J3.5 4O Fc, Ibf 3.0 3.5 2O 0 I 1.0 2.2 1.2 1.4 1.6 1.8 2.0 nz, ,_, units (a) Configurations 1, 2, and 3; c.g = 0.12_; SM = 33 percent.
8O - n Kq = 0 /_ • Kq = 1 '_ Kq = 2 _CHR 6O . o Fc,min J [] 3.5 y 3.0 Fc, Ibf 40 6.5 2O 0 I I J I I 1.0 1.2 1.4 1.6 1.8 2.0 2.2 nz, ,_,units (b) Configurations 4, 5, and 6; c.g. = 0.25_.; SM = 20 percent.
8O - [] Kq=0 ./fie • Kq=l [] Kq=2 6O o Fc,mi n _CHR • Fc, max _ 3.5 Fc, Ibf 40 2O 4.0 5.0 0 J I I I i 1.0 1.2 1.4 1.6 1.8 2.0 2.2 nz, ,_units (c) Configurations 7, 8, and 9; c.g. = 0.35_; SM = 10 percent.
Figure 8. Effect of e.g. and Kq on Fc/nz and on pilot rating.
- n Kq=0 ./,m '1' Kq=l o Kq=2 - o Fc,mi n _CHR • Fc max ' 4.5 F c, Ibf 40 6.0 9.0 0 i i 1.0 1.2 1.4 1.6 1.8 2.0 2.2 n z, ,q units (d) Contigurations 10, It. and 12; e.g. = O..lOc: SM 5 p(wc(!nl..
60 - [] Kq = 0 j . * K_=I / 40 c,min /u-" F c, tbf 20 0t_ 6.5 I -20 i i i i i 1.0 1.2 1.4 1.6 1.8 2.0 2.2 n z, z units (e) Configurations 13. 1.1, and 15; e.g. 0.45<:; SM O.
Figm'c _. Contimted.
[] Kq=0 / * Kq=l [] Kq = 2 /_.._ CHR o Fc,min /.1_- _ 3.5 Fc, Ibf 20 /___.,,i,_/_ _ 7.O 10.0 -20 1.0 1.6 2.2 1.2 1.4 1.8 2.0 n z, .k,units ([') (%nfiguration,_ 16. 17, and 18; e.g. 0.,17('; SM = -'2 [)('rc('nt.
- [] Kq = 0 / * Kq = 1 / a Kq = 2 _ o Fc,min //__.
CHR 4.0 F c, Ibf 20 Ot 10.0 -20 I t I t'_ 10.0 L ) 1.0 1.2 1.4 1.6 1.8 2.0 2.2 n z, ,_ units (g) (%niigurati(ms 19, 20, and 21: e.g. = 0.50c; SXI = 5 tmrcunt.
Figure 8. Con(:hM('d.
Kq .8 [] 0 • 1 /13 I / [] 1.5 / _Satisfactory , 0 " ' I , I , 'I , I , I •1 .2 .3 .4 .5 .6 c.g., percent Figure 9. Effect of c.g. and Kq on short-period damping.
.2 Satisfactory Unsatisfactory Unacceptable -.2 Kq Kq [] 0 -.4 • 1 -.6 I _ I , I , I _ I -.8 .1 .2 .3 .4 .5 .6 c.g., percent _.
Figure 10. Effect of c.g. and Kq oil phugoid damping.
Pilot
O 1
[] 2
o 3
A A 4 A
CHR5
I i i , I , I , I , l 0 20 40 60 80 100 120 Fc/n z, Ibf/g unit (a) Configurations 67 through 70; c.g. = 0.40c; SM = 5 pcrcent.
Pilot O 1 [] 2 o 3 A 4 [] CHR 5 [] O , I _ I , I _ I J I , I 0 20 40 60 80 100 120 Fc/n z, Ibf/_ unit (b) Configurations 71 through 74 c.g. = 0.45c; SM = O.
tO Pilot O 1 A [] 2 o 3 CHR 5 A 4 O I-1 O A I , I , I , I , I _ I 0 20 40 60 80 100 "120 Fc/n z, Ibf/z unit (c) Configurations 79 through 81 c.g. = 0.50_ SM = -5 percent.
Figure 11. Pilot ratings for various levels of maneuver stability. Variable F,:/_c; _g/_c = -1.0°/in.
Pilot 0 1 [] 2 7 O O CHR 2 & A I _ I , I _ I , I , I 20 40 60 80 1 O0 120 Fc/n z, Ibf/_ unit (_) Configurations 34 through 39; e.g. = 0.40c; SM = 5 percent.
Pilot Ot D 2 o 3 CHR 5 _ZX 1 [] , I _ I , I , I I , I 20 40 60 80 100 120 Fc/n z, Ibf/_ unit (b) Configurations 40 through 45; e.g. = 0.45c; SM = O.
Figimo 12. Pilot ratings fl_r various levels of linear maneuver stability. Variable 61t/6,.; Yc/dc = 15.77 lift/in.
3O Pilot 0 1 [] 2 ¢, Z& 7 O 0 CHR 0 3 0 I , I , I , I , I _ I 0 20 40 60 80 100 120 Fc/nz, lbf/_ unit (c) Configurations 52 through 57; c.g. = 0.50_; SM = -5 percent.
Figure 12. Concluded.
5H/8 c Fc/5 c Level 1 region (ref. 7)
\
CHR I
\
f / 4 \ 1 lj / I I , I t _ I 0 2O 40 60 80 1O0 120 Fc/n z, Ibf/,_ unit (a) c.g. = 0.40?'; SM = 5 percent.
5H/6 c Fc/5 c 8 Level 1 region (ref. 7) CHR 5 \ J .--I" /
" / /
I
, II _ I , i , , i , I 0 20 40 60 80 100 120 Fc/n z, Ibf/_ unit (b) c.g. = 0.45_'; SM = O.
Figure 13. Pilot ratings for techniques used to maintain linear maneuver stability.
8H/5 c Fc/5 c Level 1 region (ref. 7)
\
\
CHR \ J
i
, I 0 2O 4O 6O 8O 100 120 Fc/n z, Ibf/_, unit (c) c.g. = 0.50¢:; Slkl = 5 percent.
Figure 13. Concluded.
Pilot
Ot
[] 2 o 3 A 4
O
O
CHR
o o [] I _ I a I , I _ I I 40 60 80 100 120 2O Fc/n z, bf& unit Operational turns Pilot z_ Gt [] 2 6 A o 3 A 4 [] [] CHR 4 O O I _ I , I _ [ _ I _ I 0 20 40 60 80 100 120 Fc/n z, Ibf/_ unit Wind-up turns (a) Configurations 67 through 70; e.g. = 0.40& = 5 percent.
Figure 14. Effect of magnitude of linear maneuver stability on t)ilot rating for operational and wind-up turns.
Variabh, F,./bc: htl be = - 1.O°/in.
Pilot O1 [] 2 o 3 z_ 4 CHR [] O _ 0 [] i I I J I _ I _ I i I 2O 0 40 60 80 100 120 Fc/n z, Ibf/_, unit Operational turns Pilot O1 [] 2 o 3 [] z_ 4 CHR 4 2 O O I _ I _ I _ I _ I _ I 0 20 40 60 80 100 120 Fc/n z, Ibf& unit Wind-up turns (b) Configurations 71 through 74; c.g. = 0.45c; SNI = O.
Figure 14. Continued.
Pilot O1 [] 2 o 3 z_ 4 CHR ¢, r-I [] Q Z_ I , I I I , I , I 40 60 80 100 120 0 2O Fc/n z, Ibf/x unit Operational turns 8_ Pilot O1 [] 2 o 3 CHR 4 I , I , I _ I , I , I i 0 20 40 60 80 100 120 Fc/n z, Ibf/_ unit Wind-up turns (c) Configurations 79 through 81; c.g. = 0.50_; SM = -5 percent.
Figurc 14. Concluded.
Pilot 7 0 0 01 D2 A 4 CHR 4 A A I , I , I , I , I _ I i 0 20 40 60 80 100 120 Fc/n z, Ibf/g unit Operational turns Pilot [] 2 o 3 6 [] z_ 4 O CHR 4 O A A I , I J I _ I , I , I i 0 20 40 60 80 100 120 Fc/n z, Ibf/g unit Wind-up turns (a) Configurations 34 through 39; c.g. = 0.40c; SM = 5 percent.
Figure 15. Effect of magnitude of linear maneuver stability on pilot opinion for operational and wind-up turns.
Variable (5H/5c; Fc/Sc = 15.77 lbf/in.
Pilot O1 [] 2 o 3 /k 4 CHR __O O [] I a I , I J I _ I _ I 20 40 60 80 100 120 Fc/n z, Ibf/_ unit Operational turns Pilot O1 [] 2 o 3 A 4 Z& CHR 4 O [] 1 [] I _ I , I _ I , I _ I 20 40 60 80 100 120 Fc/n z, bf&, unit Wind-up turns (b) Configurations 40 through -15; e.g. = 0.45c; SIX[ = 0.
Figuw 15. Continued.
7 O Pilot O1 [] 2 o 3 A 4 CHR 4 2 /k [] [] I , I , I _ I , I , I 20 40 60 80 IO0 120 Fc/n z, IN/k, unit Operational turns 8 _ [] 'O Pilot Ot [] 2 O '_ 3 Z& 4 CHR 4 [] _@ [] 2 A A , I _ I , I , I , I _ I 0 20 40 60 80 IO0 120 Fclnz, Ibfl_ unit Wind-up turns (c) Configurations 52 through 57; c.g. = 0.50c; SM = -5 percent.
Figure 15. Concluded.
..... Level 1 boundaries (ref. 7) 1O0 Second slope Maneuver stability 170 80 ,/I-" 8O Fc, Ibf 60 ,,'I_// 40 ..,, ,- """ "" "________________ 20 -, -, , , , , 01.t 1.2 1.4 1.6 1.8 2.0 nz, # units Figure 16. Maneuver stability characteristics with single break at 1.6679.
Second slope 12O ..... Level 1 boundaries / (ref. 7) 10080 --Maneuverstabilt 'ty / /,.110 Fc, Ibf 60 65 40 35 2O 2O 5 "" -10 ,-21" 0 _---I , I , I _ I i I 1.0 1.2 1.4 1.6 1.8 2.0 nz, g units Figure 17. Maneuver stability characteristics with single break at 1.3339.
4O Pilot O1 [] 2 o 3 A 4
CHR 5
3 o
2 o o 0 .... I .... J • , , , I , , , , I .... I , , , , I - 100 -50 0 50 t 00 150 200 Fc/n z, after break, Ibf/g unit (a) Configurations 100 through 104; c.g. = 0.40_.; SM = 5 percent.
Pilot O1 _O', [] _3 o 3 [] 4 CHR -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit (b) Configurations 105 through 109; e.g. = 0.45_; SM = O.
Figure 18. Effect of single break in maneuver stability on pilot opinion. Break at 7t z = 1.6679 variable Fc/bc; _5H/_5c = -- 1.0°/in.
9 Pilot 8 0 1 7 X O i [] 2
&, ! °_ 6 [] A 4
, o _
3 o I I I I !
I t_l I I I I | I I , i I .... I .... | I I , , I .... I u -1 O0 -50 0 50 1O0 150 200 Fc/n z, after break, Ibf/_ unit (c) Configurations 110 through 114; e.g. = 0.50< SM = -5 percent.
Figure 18. Concluded.
® Pilot 8 O1 [] 2 o 3 /k 4 CHR 2 o 0 .... I .... I .... I _,,, I,, , , I .... I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_, unit (a) Configurations 82 through 87; e.g. = 0.,i0_; SM = 5 percent.
10 0 9 FIfO 0 Pilot 7 1 O1 D2 CHR 5 4 [] 0 .... I .... I .... I .... I .... I , , _ , I -100 -50 0 50 100 150 200 Fc/nz, after break, Ibf&, unit (b) Configurations 88 through 93; e.g. = 0.45(:; SM = 0.
Figure 19. Effect. of single break in maneuver stability oil pilot opinion. Break at n z = 1.6679; variable _5H/5c; Fc/_c = 15.77 lbf/in.
Pilot O1 _2 @ 6 A4
CHR 5 [] °i
¢ i I I i O I i I i -50 0 50 1O0 150 200 -100 Fc/n z, after break, bf/_ unit (c) Configurations 94 through 99; e.g. = 0.50_:; SM = -,5 percent.
Figure 19. Concluded.
Pilot
b
I I O1 I I [] 2 <> 3 A 4 CHR O
i
A , , , I , , , , ] , , , , I , , . , I , , , , I j i i i | 0 j, -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/g unit (a) Configurations 136 through 141; c.g. = 0.40c; SM = 5 percent.
Pilot O1 O [] 2 o 3 CHR
4 i
3 _1-1_ I 2 _ <> <> I I 1 i I fl .... I .... • .... I .... I .... t .... I v -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit (b) Configurations 142 through 146; e.g. = 0.45_; SM = 0.
Figure 20. Effect of single break in maneuver stability on pilot opinion. Break at rtz = 1.333g; variable Fc/_c; btf/6c = -1.0°/in.
" Ot [] 2 o 3 Pilot A A 4 CHR 5
°i \[]
i°\°
I I O I I I I m O0 -50 0 50 1O0 150 200 -1 Fc/n z, after break, lbf/_, unit (c) Configurations 147 through 151; c.g. = 0.5(}('; SM = 5 p_r(:cnt.
Figure 20. Conclu(h_d.
Pilot O1 I [] 2 8- A 4 CHR 5 I I I I I I I , , , , I , , , , [ , , , , I , _ _ , I , , , , I , , , , I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf&, unit (a) Configurations 115 through 121; c.g. = 0.40('; SM = 5 t)ercent.
lo i
Pilot 8 [] O1 7 [] [] 2 6 A A 4 CHR 5 4 O_ O O 2 A 0 .... I .... , , , , I .... 1 .... I , , , , I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf&, unit (h) Configm'ations 122 through 128; c.g. = 0.45c; SM = 0.
Figure 21. Effect of single break in ntaneuver stability on pilot ()pinion. Break at 7lz = 1.3339; variable _tt/_(.; F_./_,. = 15.77 lI)f/in.
Pilot 9 O 1 8 [] 2 7 o 3 6 i O A 4 CHR 54 _ _O O AO_ 2 A I 0 i i l , i , , J , . * , i t , . , , i , , i , I , . , . i - 100 -50 0 50 100 150 200 Fc/nz, after break, Ibf/g unit (c) Configurations 129 through 135; c.g. = 0.50_; SM = -5 percent.
Figure 21. Concluded.
Variable 6H/6 c Variable Fc/5 c
,/
CHR 5
\ .7
.... I , , , , I , , , , I , , , , I , , , , I .... I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/<_ unit Break at n z = 1.333<_, Variable 5H/5 c Variable Fc/5 c
\
\\
//
\\ /, \\ / i i CHR i , , , I , , , , i , , , , I .... I , , _ , I , , , , I 0'' -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_, unit Break at n z = 1.667_ (a) c.g. = 0.40c; SM = 5 percent.
Figure 22. Trends for methods used (variable _SHh5 c of Fc/gsc) to adjust maneuver stability characteristics.
- \i Variable 8H/8 c
Variable Fc/8c 6'- CHR \ \ , , , , I , , , , I , , , , I , , , , I Illl[lll I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Break at nz = 1.333g Variable 8H/8c
\
9 Variable Fc/8c /
\
//
\ //
//
CHR \\\i
///
,, JJ 3- .... I , , , , 1 , , , , I , , , , I .... I .... I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Break at nz = 1.667_ (b) e.g. = 0.45_:; SM = 0.
Figure 22. Continued.
5O Variable 5H/_5c Variable Fc/8 c CHR / /
\
/ 00 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Break at n z = 1.333_, Variable 5H/8 c
\\ /
Variable Fc/8 c !
/ CHR
/
/ / / .... I .... I , , , , I , , , , I .... I .... I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Break at nz = 1.667_, (c) c.g. = 0.50_ SM = -5 percent.
Figure 22. Concludc'd.
Pilot O1 [] 2 <> 3 6 A 4 CHR I i i I I I I ] I ' _ , I , , , , I _ , , , I _ _ . , I , , , _ I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Operational turns Pilot O1 _2
- I o3
A
oi
_4
!
CHR 5
\ i
\!6
',0' 2 _ o [] [] 0 _, _ J I i _ , ..... I .... I .... I .... I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/k, unit Wind-up turns (a) Configurations 100 through 104; c.g. = 0.40c; SM = 5 percent.
Figure 23. Effect of single break in maneuver stability curve and e.g. location on individual pilot ratings. Initial slop(' = 50 lbf/g; break at nz = 1.667g; variable F_/b_:; bH/_. = --l°/in.
Pilot Ot [] 2 o 3 A 4 CHR 4 0 , 0 3 _0 0,, [] i 2 o [] ml, [] ,_ I I I I n .... i .... I .... i .... I .... i ....
-1 O0 -50 0 50 1O0 150 200 Fc/n z, after break, Ibf&, unit Operational turns O Pilot Ot [] 2 O_ODO 0 [] _> 3 A 4 CHR <> \Al l A _,
O%Jo
i
,I @ I I I I I i i . ] i i A . I , i i . I . , , . I , , , . I , , , , I 0'' -100 -50 0 50 1O0 150 200 Fc/n z, after break, Ibf/g unit Wind-up turns (b) Configurations 110 through 114; c.g. = 0.50(:; SM = -5 percent.
Figure 23. Concluded.
Pilot O1 [] 2 o 3 A 4 CHR 4 A <> ' A 2 <> 0 #. ,_ A , , , , I , , , , I , , , , I , , , , I , , , , I , , , , I -50 0 50 100 150 200 -100 Fc/n z, after break, Ibf/_, unit Operational turns Pilot ol 9 ® O1 [] 2 A 7 <> 3 Z& 4 CHR 5 4 I-1, -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf& unit Wind-up turns (a) Configurations 82 through 87; c.g. = (}.40c; SM = 5 percent.
Figure 24. Effect of single break in maneuver stability curve and c.g. location on individual pilot ratings. Initial slope 50 lbf/g; break at _: = 1.667(t; variable bH/bc: F,./b,. = 15.77 lbf/in.
Pilot ©1 D2 o 3 A 4 CHR 0 010 0 0 Q Q AI A A Q I I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/,_, unit Operational turns Pilot O1 [] 2 o 3 A 4
[] i
CHR 5
i
o \,, / & & O .... I , , , , I , , , , I , , , , I , , , , I , , , , I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/k, unit Wind-up turns (t)) Configurations 9,i through 99; c.g. = 0.50_'; SM = -5 percent.
Figure 24. Concluded.
Pilot Ot 17 2 o 3 CHR 5
t b
0 .... ' .... I .... i .... , .... , .... , - 100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/g unit Operational turns I Pilot I O1 I I [] 2 I o 3 6 Z& 4 CHR 5 I , A I I I I 0 i i i i I i i i i I i i i , I , , , , I I , , , I , , , , I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/¢ unit Wind-up turns (a) Configurations 136 through 141; c.g. = 0.40_; SM = 5 percent.
Figure 25. Effect of single break in maneuver stability curve and c.g. location on individual pilot ratings. Initial slope = 50 lbf/9; break at nz = 1.3339; variable Fc/6,:; _fH/_fc = --l°/in.
Pilot O1 [] 2 _' 3 A 4 CHR Ol I I
i
I I I I A , , _ I , , J , I , , _ , I , i m I I m m i m I m m m J J 0'' -100 -50 0 50 1O0 150 200 Fc/n z, after break, Ibf/,_ unit Operational turns I Pilot O1 [] 2 o 3 A 4 CHR 5
°i \D
-1 00 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Wind-up turns (b) Configurations 147 through 151; e.g. --0.50c; SM = -5 percent.
Figure 25. Concluded.
Pilot O1 [] 2 OO A 4 I
o
CHR 5 I I I m , , , , I J a , , ] , , J , I J , , , I , , , , I , A , , I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/g unit Operational turns I Pilot I I I Ot ,, [] 2 A 4 CHR 5 D¢_ 13- 0 i , i i I i i L , I I I I I I * ' ' ' I , , * , I , , , , I -1 00 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Wind-up turns (a) Configurations 115 through 121; c.g. = 0.40_. SM = 5 percent.
Figure 26. Effect of single break in maneuver stability curve and c.g. location oil individual pilot ratings. Initial slope = 50 lbf/9; break at nz = 1.3339; variable 6tf/8,,; F,:/Sc = 15.77 lbf/in.
Pilot O1 [] 2 o 3 7 C a 4 6 O CHR
i\ ° o o o
I , , , , I , , , , i , , , , I , , , , I , , , , I , , , , I -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/_ unit Operational turns 1o Pilot 9 O 1 8 [] 2 7 o 3 6 O A 4 CHR 54 _ 0 a__ 3 _ o o 2 a I 0 .... I .... I .... I .... I .... i .... i -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf&, unit Wind-up turns (t)) Configurations 129 through 135; c.g. = 0.50c; SM = -5 percent.
Figure 26. Conclud(_d.
0 i/I, Variable _5H/5c li Variable Fc/5 c 7 I /_Wind-up turns
,, ,//
turns \ \ // _perational CHR i i i , I .... I , . , , I , , , i ! i • • • I .... I -50 0 50 100 150 200 -100 Fc/n z, after break, Ibf/,4 unit Break at n z = 1.333,4 Variable 5H/8 c Variable Fc/5 c
8 /
i / / /I
\ \ /
\ , CHR 5 \ \', _-Wind-up turns 3 k_,, ___perational turns -50 0 50 100 150 200 -100 Fc/n z, after break, Ibf/,4 unit Break at n z = 1.6674 (a) e.g. = 0.40_; SM = 5 percent.
Figure 27. Conlparison of pilot rating trends of individual tasks with single break in inaneuvcr stability curves.
lniti_d slope = 50 lbf/g.
6O 10- //i Variable 8H/6 c \1/i Variable Fc/8 c i _I_X,\ //Wind-up turns CHR Operational turns -100 -50 0 50 100 150 200 Fc/n z, after break, Ibf/g unit Break at n z = 1.333_ Variable 8H/8 c Variable Fc/8 c Wind-up turn/_ / / CHR 5
,\
\ " "_ Operational turns , , , , I , , . , I , , , , I , , , , I , , , , I , , , , I -1 00 -50 0 50 100 150 200 Fc/n z, after break, Ibf/g unit Break at nz = 1.667,_r (b) c.g. = 0.505.; SM = -5 percent.
Figure 27. Concluded.
Level 1 boundaries fief. 7) -- Maneuver stability .t 8O /' .i J 7" 6O i" /.
f /- F c, Ibf /.
40 / Third slope / 50 /-" 20 J // _ _ _ _ _ _ s -20 £I I , I , I _ I 1.0 1.2 1.4 1.6 1.8 2.0 nz, ,_ units (a) Second slope of zero.
.... Level 1 boundaries (ref. 7) -- Maneuver stability // /, /, ./ J F c, Ibf 4O / Third slope //..-/ _ 70 //,/ 40 .-" 0 1.2 1.4 1.6 1.8 2.0 1.0 nz, ,_ units (b) Second slope of -20 lbf/.q.
Figure 28. Configurations 152 through 170 with (touble break in maneuver curves. Initial slot)e = 50 lbf/fl.
100 .... Level 1 boundaries (ref. 7) 80 -- Maneuver stability J .I I" /" 60 /// t. "/ /,1" F c, Ibf 40 //// 65 Ibf&, unit J 20 5 Ibf/,, / / 27 Ibf/_ unt • unit '_/.// ._ _._.__ _---_- 0 __i_" _,.<t __ _--I _ I _ I 1.0 1.2 1.4 1.6 1.8 2.0 n z, ,_,units Figure 29. Preferred maneuver st a}fility characteristics of tile test airplane by pilot number one.