Measurements Obtained During the First Landing of the North American X-15 Research Airplane

NASA TM X-207

O !

#

<

<

z

MEMORANDUM

TECHNICAL

X-207

MEASUREMENTS OBTAINED DURING THE FIRST LANDING OF THE NORTH AMERICAN X-15 1KESEARCH AIRPLANE By James M. McKay High-Speed Flight Station Edwards, Calif.

AND SPACE ADMINISTRATION NATIONAL AERONAUTICS October 1959 WASHINGTON Declassified April 12, 1961 NATIONALAERONAUTICS AND SPACE ADMINISTRATION TECHNICAL MEMORAND[_4 X-207 MEASUREMENTS OBTAINED DURING THE FIRST LANDING OF THE NORTH AMERICAN X-19 RESEARCH AIRPLANE* By James M. McKay SUMMARY The first landing of the X-15 airplane was made at 8:43 a.m., June 8, 1959, on the hard surface of Rogers Dry Lake. One purpose of the first glide flight was to evaluate the effectiveness of the landing-gear system.

Some results are presented of the landing-approach characteristics, the impact period, and the runout phase of the landing maneuver.

The results indicate that the touchdown was accomplished at a verti- cal velocity of 2.0 feet per second for the main gear and 13.5 feet per second for the nose gear. These vertical velocities were within the values of sinking speeds established by structural design limitations.

However, permanent structural deformation occurred in the main-landing- gear system as a result of the landing, and a reevaluation of the gear is being made by the manufacturer.

The landing occurred at a true ground speed of 158 knots for main- gear touchdown at an angle of attack of 8.5 °. The incremental acceler- ation at the main gear was 2.7g and 7.3g at the nose gear as a result of the landing. The incremental acceleration at the center of gravity of the airplane was 0.6g for the main-gear impact and 2.4g for the nose-gear impact. The incremental acceleration at the main gear as a result of the nose-gear impact was 4.8g.

The extreme rearward location of the main-gear skids appears to offer satisfactory directional stability characteristics during the run- out phase of the landing. No evidence of nosewheel shimmy was indicated during the impact and runout phase of the landing despite the absence of a shimmy damper on the nose gear.

The maximum amount of skid wear as a result of the landing was on the order of 0.00} inch. No appreciable amount of tire wear was indi- cated for the dual, corotating nosewheels.

*Title, Unclassified.

INTRODUCTION

The approach and landing operation of unpoweredrocket airplanes

has always required considerable pilot con]entration, but has usually

been accomplished with a relatively conventional procedure. The X-15

airplane lands in a range of lift-drag ratio markedly lower than previous

airplanes have used. Because of the high sinking speeds associated with

the low lift-drag ratio of the X-15 airplane in the landing configuration, and because of other performance and operational requirements of the X-15,

a landing-gear system was incorporated which would meet these requirements

and would expend a minimumof airplane spa]e and weight.

This paper presents preliminary data from the first landing and com-

pares these data with somerequirements of the landlng-gear system.

SYMBOLS

center-of-gravity longitudinal acceleration, g units

a_

center-of-gravity normal acceleration, g units _n av main- and nose-gear incremental vertical acceleration, g units airplane lift coefficient CL acceleration due to gravity, ft/se_ 2 g h geometric altitude, ft

r./D lift-drag ratio

pitching velocity, radians/sec q t time, sec V true ground velocity, knots indicated airspeed, knots V i vertical velocity, ft/sec

Vv

angle of attack, deg angle of sideslip, deg horizontal-tail deflection, deg 8h 8s longitudinal slde-located-stick position AIRPLANE The X-15 airplane (figs. i and 2) is an experimental research air- craft designed to explore the flight regime at hypersonic speeds up to 6,600 feet per second and altitudes up to 250,000 feet and above. The airplane was designed by North American Aviation, Inc., through the coop- erative effort of the U. S. Air Force, the U. S. Navy, and the National Aeronautics and Space Administration. Physical characteristics of the airplane are given in table I and reference i.

The landing-gear configuration is basically an arrangement consisting of a conventional dual-wheel nose gear located well forward and amain gear equipped with steel skids located under the tail. A schematic drawing of the maln-landing-gear system is shown in figure 3(a), and a side view of the left main skid in the extended position is shown in figure 3(b). The nose gear is shown in figure 4 with the shock strut in the fully extended position. This particular nosewheel configuration was chosen to provide roll stability on the ground. The extreme rear- ward location of the main gear proved, from dynamic model tests, to pro- vide more stability than with the main gear mounted close to the center of gravity of the airplane.

The cantilevered, Inconel strut legs and the drag braces of the main gear are attached to the fuselage by means of trunnion fittings, and the struts are attached to oleopneumatic-type shock absorbers which are installed within the fuselage. Each shock absorber has a total deflection of 2.577 inches and is serviced to an inflation pressure of 750 psi with the struts in an extended position. The two 6-inch-wide, 3-foot-long skids, fabricated from 4130 steel, are normalized and are universally mounted in two planes to allow for pitching and rolling motion, but are restrained from yawing to provide the necessary parallel alinement of the two skids. The drag braces are attached to the skid ahead of the main pivot Joint to allow the nose of the skid to lift and improve the planing action.

Corotating, dual wheels were installed on the nose gear to prevent shimmy. The Vll-type nose-gear tires are 18 × 4.4 in size with a rating of 8 ply. The tires are inflated to a pressure of 185 psi and have a rolling radius of 8 inches at this inflation pressure. The nosewheel shock strut is of the oleopneumatic type and has a total travel of 18 inches. The nose-gear shock strut is inflated to a pressure of 184 psi in the fully extended position.

INSTR[_TATION The following information pertinent to the landing investigation was recorded on NASA airborne recording instruments synchronized by a common timer: Airspeed Normal and longitudinal acceleration at airplane center of gravity Vertical acceleration at nose of airplane close to nose-gear trunnion fitting Vertical acceleration at tail of sirplane directly above right main gear Angle of attack Angle of sideslip Horizontal-tall position Pitching velocity Flap deflection Airspeed was measuredwlth an NASA pitc t-statlc tube mounted on the end of the nose boom. Free-floating vanes _Iso mounted on the nose boom were used to measure angles of attack and s_deslip.

Askanla Cine-Theodolite cameras and an Air Force Missile Test Center Model II tracking radar furnished photo coverage of the X-19 airplane from launch from the B-92 mother airplane tc touchdown on the lakebed.

Akeley phototheodollte cameras tracked the E_Irplane from a height of approximately 80 feet above the runway through touchdown and final landing runout. From this photo coverage such infolmatlon as landing coordinates, airplane altitude, fllght-path velocity, vertical velocity at landing, and distance covered by the airplane along the runway was obtained.

TESTS The first landing of the X-19 airplane was made at 8:43 a.m., June 8, 1959, on a designated strip 6.8 miles long on the hard lakebed of Rogers Dry Lake at Edwards Air Force Base, Calif. The landing was made in clear weather to the north with little or no wind over the lakebed. The out- side air temperature at the time of the landing was 70.4 ° F. The touch- down weight of the airplane was 15,234 pounds, and the center of gravity in the landing configuration was 17.4 percent of the mean aerodynamic chord.

The airplane was flown by a North American Aviation experimental test pilot who had "flown" the first glide flight many times previously on an analog simulator and in flight-test programs using modified opera- tional aircraft. The airplane was flown from launch to touchdown on the lakebed by using only the slde-located-stlck control. Escort air- planes accompanied the X-15 through the landing approach, touchdown, and runout phase of the landing on the lakebed and informed the pilot of air- speed and altitude during the approach and landing.

RESULTS AND DISCUSSION A comprehensive discussion of the launch, low-speed, and landing- approach characteristics during the first glide flight of the X-15 air- plane is presented in reference i. To provide background information, however, some of the pertinent details of the approach to the actual landing are included herein.

The flight plan representing the geographical path of the X-15 air- plane from launch to touchdown on the lakebed is shown in figure 7. The landing pattern of the first glide flight is shown in figure 6 in terms of distances away from the touchdown point, which is designated as 0 sec.

The turn into the final segment of the approach was completed at an alti- tude of approximately 1,500 feet where the initial flare was started about 30 seconds before touchdown. The flap cycle was initiated at an altitude of approximately 700 feet, and the flaps were fully down at an altitude of about 200 feet. The landing gear was then lowered and was down and locked at an altitude of about 80 feet. The oscillations indi- cated in figure 7 at 18 seconds prior to touchdown became so severe and were of such magnltude that increased pilot concentration was required in performing the landing maneuver.

Figure 8 presents some values of lift-drag ratio obtained from the first landing. The values shown are for the landing configuration and are only for conditions in which the longitudinal pitching velocity resulting from the pitching oscillations encountered is a minimum. A plot of some values obtained from wind-tunnel tests is also shown for compari- son. There appears to be a reasonable correlation between the flight and wind-tunnel values.

Some of the quantities measured durizg the landing are presented in figures 9 to ll as a variation with time _rom impact. The data in fig- ures 9 and lO are presented for a period cf several seconds prior to initial main-gear touchdown, the impact period, and for a small interval of time after nose-gear touchdown. The ncse- and main-gear upper-mass accelerations at touchdown and during a short period of the ground run are shown in figure ll. It can be seen from these time histories that Just prior to touchdown the airplane experienced an increase in angle of attack to approximately 12 ° (fig. 9(b)) as a result of the associated pitching oscillations. As a consequencej the forward speed reduced to approximately 158 knots true ground speed at touchdown (fig. lO). The angle of attack of the airplane was approximately 8.5 ° (fig. 9(c)) at the time of initial touchdown. Just prior to ground contact the center- of-gravity vertical acceleration was of the order of 1.4g and the verti- cal velocity at main-gear touchdown was approximately 2 feet per second.

An analysis of the accelerometer records (fig. ll) indicates an incremental acceleration of 2.7g for the main-gear touchdown measured in the airplane upper mass directly above the right main gear. The incre- mental acceleration as a result of the nose-gear touchdown measured at a position in the airplane upper mass next to the nose-gear trunnion fitting was 7.3g. The incremental acceleration at the main-gear- accelerometer position as a result of the nose-gear impact was 4.8g.

The response at the center of gravity of the airplane due to main-gear impact (fig. 9(c)) was an incremental acceleration of 0.6g and 2.4g as a result of the nose-gear touchdown.

The airplane first contacted the lake0ed on the left main skid as shown in figure 12 and table II. The second and final touchdown of the left main skid was made 15 feet down the r_nway from the initial skid mark. The right main skid first contacted the lakebed 24.6 feet down the runway from the initial left main-skld touchdown point. The right main skid then contacted and remained on the lakebed 37 feet down the runway from the initial left maln-skid mar_. The nose-gear touchdown occurred 0.52 second later at a vertical velocity of approximately 13.5 feet per second at a point 187 feet d>wn the runway from the left main-gear initial skid mark. A closeup view of the nose-gear touchdown marks is shown in figure 13(a), and a diagcam of the skid marks is shown in figure l_(b).

An inspection of the airplane after the landing indicated that dam- age had occurred in the main-landing-gear system to the bell-crank arm connecting the main-gear strut leg to the )leopneumatic shock strut.

The damageoccurred in both the left and right main gears, with the

greatest damageincurred by the right gear. The bell-crank arms experi-

enced permanent deformation in bending, thus allowing the gear to spread

beyond the maximum designed tread as indicated from measurementsof the

landing skid marks (fig. 12). As a result of the damage, a reevaluation

of the main-landing-gear system is being madeby the manufacturer.

Photographs of the main-gear skids and nosewheel marks on the lake-

bed are shown in figure 14(a) for a distance of approximately 300 feet

from touchdown and in figure 14(b) toward the end of the landing run.

The skid marks shown in figure 14(b) indicate that toward the end

of the runout phase of the landing the airplane veered to the right. It

is believed that the nature of the damageto the main-landing-gear system

allowed the airplane to assumethis particular path. However, in spite

of the damageto the main gear, the skid marks on the lakebed after the

impact period indicated satisfactory directional stability characteristics.

No evidence of nosewheel shimmywas indicated during the impact and run-

out phase of the landing (figs. 13(a) and 14(a)) despite the absence of

a shimmydamper on the nose gear. Tests madepreviously by the NASAon

the landing track at Langley Research Center during somehigh-speed

ground runs with the X-15 nose gear without a shinm_y damper had indicated

the absence of shimmy. As a result, the shimmydamperwas removed from

the nose gear of the X-15 airplane prior to the first glide flight. The

depth of the main- and nose-gear marks on the lakebed resulting from the

impact and runout phase of the landing were too small in magnitude to be

measured. A closeup view of a typical main-gear skid mark is shown in

figure 14(c).

The maximum amountof skid wear as indicated from measurementstaken

before and after flight (table III) was on the order of 0.005 inch for

both main-gear skids. This occurred in the vicinity of the trunnion

fitting connecting the skid to the cantilevered strut leg. No appreci-

able amount of tire wear was indicated on the dual, corotating nosewheels

after the landing (fig. 15(a)). Tire slippage resulting from the landing

was 9/16 of an inch with respect to the wheel rim on the left nosewheel

(fig. 15(b)). No apparent slippage of the tire was indicated for the

right nosewheel.

Figure 16, prepared from unpublished data, presents the variation

of vertical velocity with time for the X-15 nose gear as dictated by

structural design limitations. The design limits are based on a minimum

approach speed of 164 knots indicated at an airplane attitude angle of

6° and an overall airplane vertical velocity of 9 feet per second. At

main-gear touchdown, the nose-gear vertical velocity increases to a value

of 18 feet per second, at which time nose-gear touchdown occurs. The

vertical velocity of the nose gear then reaches a value of zero in the

time indicated on the design-limited envelope. If the overall airplane

vertical velocity is less than the limit design value of 9 feet per sec- ond, the nose gear would also touch down at a vertical velocity less than its design limit of 18 feet per second, and, consequently, the time for the nose gear to touch down after main-gear impact would be greater.

As can be seen from figure 16, the actual landing occurred at a vertical velocity of about 2 feet per second for the main gear. The nose-gear touchdown Occurred 0.52 second later at a vertical velocity of about 13.5 feet per second.

CONCLUSIONS The principal conclusions resulting from this preliminary evaluation of data obtained during the first landing of the X-15 airplane are: i. The touchdown was accomplished at • vertical velocity of 2.0 feet per second for the main gear and 13.5 feet per second for the nose gear.

These vertical velocities were within the _alues of sinking speeds estab- lished by structural design limitations. However, permanent structural deformation occurred in the main-landing-gear system as a result of the landing, and a reevaluation of the gear is being made by the manufacturer.

2. The landing occurred at a true gr_ind speed of 158 knots for main- gear touchdown at an angle of attack of 8.5 ° . The incremental accelera- tion at the main gear was 2.7g and 7.3g at the nose gear as a result of the landing. The incremental acceleration at the center of gravity of the airplane was 0.6g for the main-gear impact and 2.4g for the nose-gear impact. The incremental acceleration at tlue main gear as a result of the nose-gear impact was 4.8g.

3. The extreme rearward location of the main-gear skids appears to offer satisfactory directional stability c_racteristics during the run- out phase of the landing. No evidence of nosewheel shin_ywas indicated during the impact and runout phase of the Landing despite the absence of a shimmy damper on the nose gear.

4. The maximum amount of skid wear as a result of the landing was on the order of 0.005 inch. No appreciable amount of tire wear was indi- cated for the dual, corotating nosewheels.

High-Speed Flight Station3 National Aeronautics and Space Admini_tration, Edwards, Calif., September 18, 1959.

REFERENCE

1. Finch_ ThomasW., and Matranga, GeneJ. : Launch, Lo_-Speed, and

Landing Characteristics Determined From the First Flight of the

North American X-15 Research Airplane. NASA TMX-195, 19_9.

lO

TABLE I.- PHYSICAL CHARACTERISTICS (iF THE AIRPLANE Wing: Airfoil section ....................... NACA 66005 (Modified) Span, ft .................................. 22.56 Mean aerodynamic chord, ft ......................... 10.27 Root chord, ft ............................... 14.91 Tip chord, ft .... . .......................... 2.98 Taper ratio ................................ 0.20 Aspect ratio ............................... 2.50 Sweep at 25-percent-chord line, deg ..................... 25.64 Flap - Type .................................... Plain Area (each), sq ft ............................ 8.50 Span (each), _t .............................. 4.50 Inboard chord, ft ............................. 2.61 Outboard chord, ft ............................ 1.08 Ratio flap chord to wing chord ...................... 0.22 Ratio total flap area to wing area .................... 0.08 Ratio flap span to wing semispan ..................... 0.40 Trailing-edge angle, deg ......................... 5.67 Horizontal tail : Airfoil section ....................... NACA 66005 (Modified) Total area (includes 63.29 sq ft covered by fuselage], sq ft ........ 115.34 Span, ft .................................. 18.08 Mean aerodynamic chord, ft ......................... 7.05 Root chord, ft ............................... 10.22 Tip chord, ft ................................ 2.11 Taper ratio ................................. 0.21 Aspect ratio ................................ 2.83 Dihedral, deg ................................ -15 Ratio horlzontal-tail area to wing area ................... 0.58 Movable surface area, sq ft ......................... 51.77 Deflectlon - Lateral differential (pilot authority), deg +15 Lateral differential (autopilot authority), deg .............. +50 Control system ......... Irreversible hydraulic boost with artificial feel Upper vertical .tail: Airfoil section .......................... i0 ° single wedge Total area, sq ft .............................. 40.91 Span, ft .................................. 4.58 Mean aerodynamic chord, ft ......................... 8.99 Root chord, ft ............................... 10.21 Tip chord, ft ................................ 7.56 Taper ratio ................................. 0.74 Aspect ratio ................................ 0.51 Sweep at 25-percent-chord line, deg ............... , ..... 23.41 Ratio vertical-tall area to wing area .................... 0.20 Movable surface area, sq ft ......................... 26.49 Deflection, deg ............................... +7.90 Control system ......... Irreversible hydrsJlic boost with artificial feel ll TABLE I.- PHYSICAL CHARACTERISTICS OF THE AIRPLANE - Concluded Lower vertical tail: Airfoil section .......................... i0 ° single wedge Total area, sq ft .............................. 32.41 Span, ft .................................. 3.83 Mean aerodynamic chord, ft ......................... 9.17 Root chord, ft ............................... 10.21 Taper ratio ................................. 0.78 Aspect ratio ................................ 0.43 Sweep at 25-percent-chord line, deg ..................... 23.21 Ratio vertical-tail area to wing area .................... 0.17 Movable surface area, sq ft ......................... 19.95 Deflection, deg ............................... +7.50 Control system ......... Irreversible hydraulic boost with artificial feel Fuselage: Length, ft ................................. 50.75 MaxLmumwidth, ft .............................. 7.33 Maximum depth, ft .............................. 4.67 Maximum depth over canopy, ft ........................ 4.97 Side area (total), sq ft .......................... 215.66 Fineness ratio ............................... lO.91 Main landing gear: Type ...................... Two (6 in. wide, 3 ft long) skids Shock strut .................... Oleopneumatic (inside fuselage) Strut-inflation pressure, psi ................. 750 (fully extended) Shock-strut stroke, in ............................ 2.577 Tread distance, ft ............................. 8.83 Nose landii_ gear: Tire type .................................. VII Tire size ................................. 18 × h.4 Wheels ............................. Dual, corotatlng Shock strut ............................. 01eopneumatlc Strut-inflation pressure, psi ................. 182 (fully extended) Airplane attitude: 0leo static ................................. -2 ° 21' 0leo extended ............................... -i ° 20' Speed brake: Area (each), sq ft ............................. 5-57 Span (each), ft ............................... 1.67 Chord (each), ft .............................. 3.33 Launch Landing Weight, ib ............................. 13,452 13,232 Center-of-gravity location, percent mean aerodynamic chord ..... 18.1 17.2 Moments of inertia_ slug-ft 2 Ix ................................ 3,4oo 3,40o Iy ................................ 79,000 77,900 IZ ................................ 80,800 79,600 TABLE II.- _ SKID AND NOSE_IEEL MAREB

I I

I

IY _k---Dimensions shown between r dimensions centerline of skids from centerline of left skid to center- line of tires Maximum allowable tread = 9.17 ft Distance down Nose-gear runway, ft Tread, ft dimensions, ft Remarks Initial touchdown, left skid 15.oo Final left-skid touchdown 22.5o 7.42 Right-skid first touchdown 37.00 7.92 Final right-skid touchdown 43.83 8.31 58.83 9.13 73.83 9.48 88.83 9.21 lO3.83 9.00 i18.83 8.73 8.48 133.83 148.83 8.39 163.83 8.58 178.83 9.08 187.00 Not measured 3-67 Nose-gear initial touchdown Not 193.83 9.63 measured 199.75 Not measured Not measured Final nose-gear touchdown lO.o4 208.83 4.19 lO.o4 223.83 Not measured 4. oo 238.83 9.78 253.83 9.50 3.08 268.83 9.29 3.67 283.83 9.25 3.71 298.83 9.58 3.85 313.83 9.58 4.00 328.83 9-73 4.25 343.83 9.71 4.25 358.83 9.73 4._5 373.83 9.67 4.25 388.83 9.67 4.25 403.83 9-69 4.33 418.83 4.42 9.71 433.83 _.46 9.73 448.83 9.71 4.58 463.83 9.78 4.58 478.83 9.71 4.67 493.83 9.69 4.75 TABLE III.- SKID THICKNESS BEFORE AND AFTER LANDING Maln strut Weld _/ A B C D Preflight Measurements Skid A B C D Left 0.164 0.155 0.167 0.168 Right •167 .165 .168 .16_ Postfll iht Measurements Skid A B C D MeasnU_ment Left 0.163 0.155 0.162 dependable Rlght .165 .164 .163 .163 WEB/- Skld A B C D Left 0.001 0 0.005 .........

El ght .002 .001 .005 .001 Nose-gear Tire Wear _3/3R in. before, 3/32 in. after I [__ _'-"----3/32 in. before, 3/32 in. after _,_-----3/32 in. before flight, 1/16 in. after Both tires !

g

r-I ,.r4 r-4 !

X !

.I 50.75 reference line Fuselage _ I.

39.1 18.08

L_

8.83--_ Figure 2.- Three-view drawing of the X-15 airplane. All dimensions in feet.

QJ e_ r_ r_ _J rml !

C_ !

v 1T

\

E-4689 Figure 4.- Front view of nose gear with shock strut in fully extended position.

ROGERS

DRY

LAKE

N

ROSAMOND

DRY

LAKE

LAUNCH

/ /

I,, ,, I , , ' ' I ' '

0 5 I0 15

SCALE IN NAUTICAL MILES

Figure 5.- General flight plan of the first X-15 flight.

2O

PLAN VIEW

. O_IEC 30SEC 6O $EC

I0

LATERAL

DISTANCE, FT

50xlO 3 _ l ,

PROFILE VIEW

I10 SEC ALTITUDE, - _ 0 SEC

I0

FT

60 SEC OjSEC _--_,_30 S_C I

I0 0 I0 20 50xlO 3

LONGITUDINAL DISTANCE, FT

Figure 6.- Landing pattern of first X-15 glide flight.

Vi KNOTS -IE) F'I'/_:C vv.

2000 FLAP h, FT moo0 h I_AR 0 _ On, g

_F-- on

UP 12 R'£.

=,.8, I:_

_'h BEFORET(X,IO,IO(:)V_, SEC Figure 7.- Tlme history of the flare and touchdown.

UP 16 -

O FLIGHT O WIND T_JNNEL

/

O

8-

a, DEG

O 0 fl I I I I

L/D

I

0 .2 .4 .6 .8 1.0

C/ Figure 8.- Lift-drag ratio of the X-15 Jn the landing configuration.

I a, deg -4 C q, radiansZsec I a n, Q_, g units

(a)

Figure 9.- Variation with time of angle of attack, pitching velocity, and center-of-gravity vertical and longitudinal acceleration during the first landing of the X-15 airplane.

i _ __.__---- a, deg i C q, radians/sec i -,2 I !

I o n, a_, g units o z -2 2.2 2.0 I8 i.6 1.4 1.2 1.0 .8 .6 .4 .2 Time before touchdown, sec

(b)

Figure 9.- Continued.

2_ ] i _,deg J .4 l I

I

.2--- I f--,,,,, / q, radianslsec -.4

I

i

I -.6 .......... l_ [r-- 011, 0_, g units

I

I

-2 1.8 1.4 1.6 0 .2 4 .6 .8 1.0 1.2 ,2 Time after touchdown, sec --- ,-- (c) Figure 9-- Concluded.

o b.O

c_

/

(D p, C) hi) .,--t °_

/

v--t _,--4 I

_x

/

° +-_ -o % _. o .,b.O ,--t "d

ed

0_-_ © 0 -0 _ hi?

,o %

t

4-_ .,-4

/ 0

°H 0 0 0 0 I -r--t Od 0 !

% Od I >- % °_ 4-_ .r-.t I

\ b.O

\ ._

)

i UI o 4._ t I1) t \

JI

'\ \ \

\

O_

A_

..-2 _ / 4_ I'- J © J 4_ _D CJ

_x

G) _ co t o

_°

m., / f © E

S

D _ ,-,-4 m_ © i / o _ 4_ r_ C_3 o C' G Od 4_ ._ ©

t

-M 0 4-_ _3 I .r-t I [ I Od t I CO t_ ,--4 I I © Cl .,--t O.9 rmile I 1 _--- First nose-gear , _ touchdown 7.92 _ _£_Right skid, first _-_ _ touchdown 7.42 _ I _ 37' Left skid, first touchdown Figure 12.- Diagram of the X-15 main- and zose-gear skid marks on lake- bed for the touchdown and runout phase ef the first landing. All dimensions in feet.

_D !

i

,,,.4 4._ "1--I o o e_ 4_ II) t_ I--I !

!

,--t 3o End of _3cuff Maximum width of scuff

/

40.67 26.00 2.42 i0.33 5.17

' J

l

(b) Diagram of the X-15 nose-gear initial touchdown marks.

All dimensions in feet.

Figure 13.- Concluded.

0 _1 () I o m -0 0 0 I o

_D

_o

!

r_ r-i Q_ cH o o QJ !

Q) o r_ r_ v @ I1) °,--t 0 !

G) ,-4 °_ eJ °e.-t Q) ul ,-4 rj !

•_ 4-_ 4._ I1) m +-_ •,--t _:_ o r.O !

_ ,--4 .r--I 3_ I o o

_0

o o rj !

i1) °;-I ,M r_ ,la o t'-- kid I1

o_

cO .rt 4-_ 0 r-I O ® -H _0_ M_ r--I I bO ® II r-_ I.O F_ @ h0 hO _) I ® _d

L

.r--t _d ID m -O -O re) 4o % O O', 4o UI Od _0 .M _ ._ -O % _u® b3 © _--

\ A _ '_

5_

.r-t ul O L@ - ,--I I M o 1:o '_" i OJ ,A ,--t (D h0 .r--t T-L7 L_