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FULL-SCALE DYNAMIC LANDING-IMPACT
INVESTIGATION OF A PROTOTYPE
LUNAR MODULE LANDING GEAR
by Ulysse J , Blunchurd
Lung-[ey Reseurch Center
Langley Stdtion, Hampton, Vu, N A T I O N A L A E R O N A U T I C S A N D S P A C E A D M I N I S T R A T I O N W A S H I N G T O N , D. C. M A R C H 1 9 6 9 TECH LIBRARY KAFB, NM
1 l l l l l l l l l l l l l l l l l l l l l l l l l l 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
FULL -SCALE DYNAMIC LANDING-IMPACT INVESTIGATION
O F A P R O T O T Y P E LUNARMODULELANDINGGEAR
By Ulysse J. Blanchard
Langley R e s e a r c h Center
Langley Station, Hampton, Va.
Technical Film Supplement L-1011 available on request.
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For s o l e by the Clearinghouse for Federol Scientific and Technical Information Springfield, Virginia 22151 - CFSTI price $3.00 FULL-SCALE DYNAMIC LANDING-IMPACT INVESTIGATION OF A PROTOTYPE LUNAR MODULE LANDING GEAR By Ulysse J. Blanchard Langley Research Center SUMMARY In order to subject prototype components of a lunar-module (LM) landing gear to some of the dynamic loads of lunar-landing impact, full- scale tests were conducted at simulated lunar gravity. The full-scale tests were conducted with a planar (three degrees of freedom) lunar-gravity simulator and a full- scale test vehicle. Structural integrity of a prototype landing-gear system (struts and deployment trusses) was substantiated.
Dynamic performance of the landing-gear struts was good for all landing conditions tested including those which produced near maximum strokes and loads. Theoretical results were in agreement with experimental results obtained for landing accelerations, gear forces and strokes, and vehicle pitch motions.
INTRODUCTION The LM lunar landing operation is one of the critical phases of the Apollo mission of placing a manned spacecraft on the lunar surface and returning the crew to earth. Landing impact is of particular concern because the landing-gear system must provide required shock attenuation and must maintain structural integrity in order to assure stability against overturning and prevent damage which would jeopardize postlanding launch opera- tions. Prior to an actual landing mission, dynamic proof tests of prototype landing-gear components a r e desirable. This paper presents results of a full- scale dynamic landing- impact investigation of an LM prototype landing-gear system.
The experimental investigation was conducted at Langley Research Center (LRC) with an existing lunar-gravity impact simulator and a full-scale test vehicle which had been previously used for technique evaluation tests described in reference 1. The lunar- gravity simulator made it possible to proof test the complete landing-gear system under dynamic impact loads and motions similar to those which may occur in a lunar landing.
The cable- supported vehicle and the inclined landing surface were suitable for conducting landing tests which involved planar (three degrees of freedom) motions.
Landings were made at selected initial conditions to investigate maximum loading and stroking of the landing-gear struts and to induce post-touchdown motions which provided some stability data.
In the present paper, experimental results from 21 landings with the prototype landing gear are shown. Vehicle motions, accelerations, and landing-gear forces and strokes are presented. Comparisons a r e also presented between these experimental results and theoretical results obtained by the NASA Manned Spacecraft Center (MSC).
An unpublished theoretical analysis entitled "MSC Lunar Module Landing Program" was used by the Landing and Docking Mechanics Branch of Manned Spacecraft Center to obtain the theoretical results.
SYMBOLS The units used for the physical quantities defined in this paper a r e given both in U.S. Customary Units and in the International System of Units (SI). (See ref. 2.) Appen- dix A presents factors relating these two systems.
acceleration due to earth gravity, 32.2 ft/sec2 (9.81 m/s2) g
C compression stroke
compression stroke, first stage c1 compression stroke, second stage c2 T tension stroke tension stroke, first stage T1 tension stroke, second stage T2 horizontal velocity, ft/sec (m/s) vh vertical velocity, ft/sec (m/s) V V body axes
x, y, z
DESCRIPTION OF TEST VEHICLE The full-scale test vehicle of reference 1 which was modified f o r the present landing investigation is shown in figure 1. Pertinent characteristics are given in table I. The outrigger trusses were modified in order to permit installation of four prototype landing- gear structures. Ballast mass was redistributed in order to duplicate updated m a s s and inertial properties of the LM. The test-vehicle body did not duplicate the elastic charac- teristics of the prototype LM body. Since all mass was used f o r ballast and structure, the test vehicle body was both stronger and l e s s flexible than the prototype. Duplicating prototype body structural characteristics was not considered necessary for the main pur- pose of the present investigation.
Landing Gear The prototype landing-gear components tested and shown in figure 2 included pri- mary and secondary shock-absorbing struts and deployment trusses. The arrangement shown is referred to as the "cantilever" gear. Strut and t r u s s details a r e shown in fig- u r e s 3 and 4, respectively. Pertinent landing-gear characteristics a r e also given in The landing gear w a s designed and constructed by the contractor and provided by table I.
Manned Spacecraft Center for these tests. The landing gear is a typical prototype struc- ture since subsequent and continuing refinements a r e being made in order to reduce weight.
Each of the four landing-gear assemblies (fig. 2) consists of a primary strut (with a footpad at its lower end), two secondary struts, and a deployment truss. The landing gear was constructed of high-strength aluminum alloys (2024, 7075, and 7079) and tita- nium alloys. All aluminum parts were anodized. In addition, sliding surfaces were plated with a dry lubricant. The sliding coefficient of friction of the primary-strut bearings, as determined from static bench tests, w a s approximately 0.3 for the present landing tests. The footpad used for the present test w a s not a prototype article but a spe- cial "boilerplate" pad used to vary landing surface-pad interface conditions.
The primary strut (fig. 3(a)) consists of a telescoping inner cylinder, an outer cylin- der connected through a universal joint at its upper end to the outrigger truss, and a crush- able aluminum honeycomb cartridge to absorb impact energy.
Each secondary strut (fig. 3(b)) consists of an outer cylinder connected by a ball-socket joint to the outer cylin- der of the primary strut, a sliding inner cylinder connected by a universal joint to the deployment truss, and an arrangement of crushable honeycomb cartridges that can absorb energy while the double-acting secondary strut is lengthening or shortening. The mechan- ical design of the secondary strut provides for compression crushing of different honey- comb cartridges during the tension (lengthening) and compression (shortening) strokes of the double-acting strut. All struts were vented to minimize air entrapment.
The gear deployment t r u s s (fig. 4) was tested in the gear-down position as part of
the total landing-gear structure. The gear-down lock of the t r u s s was engaged and pinned in this position, Actuator springs and mechanisms were not included as part of these tests.
Shock Absorbers The energy-absorbing cartridges contained within the landing-gear struts are shown in figure 5 before and after impact crush. The cartridge assemblies comprise crushable-aluminum-honeycomb cylinders, stage-separator plates, and strut -assembly end plates. When a design compression load is applied to the honeycomb cylinders, a progressive local-buckling failure (crush) occurs. This condition produces a constant crush-force level during the strut stroke which serves to absorb the vehicle-impact energy and limit loads imposed on the vehicle and landing-gear structure. Shock- absorber force staging was accomplished by stacking honeycomb elements of different crush strengths in a single cartridge.
The honeycomb cylinders were fabricated, precrushed, and certified by the vendor for static-crush-force levels specified in table I. More stringent honeycomb crush- force tolerances than the *5 percent specified in table I can be achieved with associated increase in unit cost. However, for the purpose of the present investigation, the subject material was considered to be adequate. The honeycomb w a s intentionally procured at static crush-force levels about 10 percent lower than the design dynamic crush force desired (table I) in order to compensate for a strain-rate effect which causes an increase in the crush-force level of aluminum honeycomb. The cartridge elements were assem- bled and bonded into units at LRC.
APPARATUS AND PROCEDURE The full-scale t e s t s were conducted on a planar (three degrees of freedom) lunar-
at the Langley lunar landing research facility. The
gravity impact simulator located lunar-gravity simulator, described in reference 1 and shown in figure 6, consisted of an inclined-plane landing surface, an overhead trolley and track, and a fixed-length cable which supported the test vehicle from the overhead trolley in a near-horizontal position on the landing surface. Lunar gravity was obtained by displacing the vehicle (fig. 6(b)) from directly beneath the overhead trolley so that the force exerted statically by the vehicle on the landing surface w a s equal to its lunar weight. Another system of cables and winches, described in detail in reference 1, was used to position and release the vehicle as a deflected pendulum, gravity imparting the desired landing speeds at impact upon the landing surface.
Test Conditions A sketch identifying vehicle axes, accelerations, attitudes, velocity vectors, and landing-gear orientation during landing is presented in figure 7. The initial landing con- ditions for each of the 21 landings a r e listed in table II. The touchdown pitch attitudes and speeds were obtained from motion-picture film. The cartridge static crush forces listed in table 1 1 a r e the average values of all like elements randomly installed in all gears prior to each landing. Two symmetric landing-gear orientations were used for the present tests: two gear legs leading with two legs trailing (2-2 orientation), and one gear leg leading with one leg trailing (1-2-1 orientation). The test vehicle was landed with positive and negative pitch attitude and at some speeds higher than that specified for LM guidance and control capability in order t o attain desired gear stroke, load, and vehicle motions. This type of landing w a s necessary since the range of possible vehicle orientations and landing-surface conditions w a s limited by the planar constraints of the
simulator. Landing-surface-pad interface conditions were varied by allowing the foot -
pads to slide at different values of sliding coefficient of friction or by constraining the pads (coefficient of friction, 00) at impact with sharp spikes installed on the bottom of the pads. Landing-surface depressions or slopes were simulated by placing elevated platforms 2 feet (0.61 m) high at the impact location for selected pads. In general, the landing conditions were selected to induce loading conditions which would involve high bearing-friction loads on the primary struts and near full stroking for various stroking phases of all the struts. Five consecutive landings were made at a single set of launch conditions (landings 11 to 15) in order to determine repeatability with regard to initial impact conditions, landing dynamics, and performance of a single gear during repeated near maximum loading and stroking. A few landings were made at conditions which pro- duced pronounced rocking motions in order to provide some stability data.
All tests w e r e conducted outdoors at ambient conditions from mid-summer to mid-
winter. The landing gears were exposed to normal atmospheric contamination, temper -
ature, and ground-level winds. The shock-absorbing struts were checked during t e s t s f o r visible signs of contamination and were kept indoors as much as possible between landings; however, some exposure w a s unavoidable.
Instruments and Measurements
Landing-impact accelerations were measured at the vehicle center of gravity with
50g linear servo accelerometers rigidly mounted on a platform attached t o the lower face of the large lead-filled counterweight. The accelerometers were d i n e d so that the accelerations were measured in the plane of the horizontal velocity vector v h for both 2-2 and 1-2-1 landing orientation. The accelerometers which had natural frequencies of approximately 650 cycles per second (650 Hz) were used t o measure normal, longitudinal, and angular accelerations. They were damped to about 65 percent of critical damping.
Angular acceleration was measured by coupling a pair of the linear accelerometers which had been adjusted so that their response and phase characteristics were matched.
The response of the recording oscillograph galvanometers w a s flat to 24 cycles per sec-
ond (24 Hz) for the angular and longitudinal accelerometers. Signals of the normal
were fed through two recording galvanometers, one having a flat response accelerometer to 24 cycles per second (24 Hz) and the other to 120 cycles per second (120 H z ) .
Axial forces generated during stroking of the landing-gear struts were measured with resistance-wire strain gages. The gages were installed at the lower end of the inner cylinders of the four primary struts and on the deployment-truss connection f i t - tings of the eight secondary struts. The stroking force measured by the strain gages was the sum of the force reacted by the honeycomb cartridge and the force reacted by bearing friction. Primary-strut axial forces resulting from secondary strut vector com- ponents acting on the outer cylinder were not measured. Response of the recording
oscillograph galvanometers was 240 to 360 cycles per second (240 t o 360 H z ) . Total
strut strokes were obtained by measuring the honeycomb-cartridge lengths before and after each landing.
Landing impacts were observed and were also recorded by motion-picture cameras located at the overhead track. Motion pictures (taken at 24, 64, and 200 frames per
second) and a background grid were used to determine vehicle landing speeds, pitch atti-
tude, and pitch-motion time histories during landing impact.
RESULTS AND DISCUSSION Experimental landing-gear force and stroke, vehicle acceleration, and pitch-motion data a r e presented. Accelerations are expre’ssed in units of earth gravity. These exper- imental data are also compared with theoretical results obtained from computer- simulated landings. The geometry and mass-inertia properties of table I; initial landing- impact conditions and average honeycomb static crush forces of table II; and modifying effects such as honeycomb strain rate, strut-bearing friction, and viscous damping were used in the theoretical model of the full-scale test vehicle.
A motion-picture supplement (L-1011) showing the tests discussed in this paper has been prepared and is available on loan. A request card form and a description of the film are included at the back of this paper.
Landing -Gear Forces The axial stroking forces measured during honeycomb crush on each of the sec- ondary and primary struts of the four landing gears for all landings are presented in table 1 1 1 and plotted in figures 8 and 9, respectively. The data points are the faired value of the force time histories obtained during dynamic crushing of each honeycomb-cartridge stage and includes strut-bearing friction and possibly some pumping due to entrapped air.
The dashed-line curves of figures 8 and 9 indicate the predetermined static crush-force range (nominal lt5 percent) of the corresponding honeycomb cartridge stages.
In the case of the secondary struts (fig. 8 ) , the average of the strut forces mea- sured for all the landings was very near the nominal honeycomb design dynamic crush force (solid line), 4500 lbf (20 kN) for the compression stroke and 500 and 5000 lbf (2 and 22 kN) for the first and second stages of the tension stroke, respectively. The secondary struts a r e only loaded axially and the friction forces a r e small; therefore, the increase in measured force over the honeycomb static force is primarily due to dynamic (strain-rate) effects. The data indicate that the honeycomb shock absorbers and the struts w e r e performing according to design.
The axial stroking forces measured on the primary struts during landings are shown in figure 9. Unlike the secondary struts, the primary struts can be loaded trans- versely (by the secondary struts) as well as axially. Because of the cantilever design of the primary-strut inner cylinder, these transverse loads can result in significant bearing-friction forces in addition to the honeycomb crush force during the strut stroke.
The magnitude of the bearing-friction forces is dependent upon landing orientation and atti- tude, strut-stroke sequence and phasing, and landing-surface conditions. In most cases the measured stroking forces shown in figure 9 a r e higher than the honeycomb design dynamic crush values (solid lines) of 4500 and 9500 lbf (20 and 42 kN). For landings at positive pitch attitude (unflagged symbols), this increase is more pronounced during crushing of the first-stage elements of the honeycomb cartridges. One of the contrib- uting factors is that during the first-stage portion of the stroke, the longer cantilevered length of the strut inner cylinder results in larger bending moments and associated higher bearing-friction forces. During first-stage stroking in the case of 1-2-1 landings (fig. 9(b)), forces measured on landing gear 1 w e r e approximately 50 percent greater than those for the honeycomb-design dynamic crush level. Forces were not obtained for landing gear 3 because of instrument failure; however, they should have been about the same as those for landing gear 1. In this landing configuration, the primary struts ,
of gears 1 and 3 (side gears) stroked very little and were at the maximum cantilevered
condition with large transverse loads acting. The flagged data (fig. 9(a)) are for landings
at negative pitch attitude and they exhibit similar characteristics with even greater
bearing friction force evident than for landings at positive pitch attitudes.
Landing number 16 (fig. 9@)) was made to obtain large secondary-strut tension strokes and to impose large bending moments on the primary struts. The landing was
made with vertical speed only and with g e a r s 2 and 4 impacting on raised platforms. In
addition, the gear footpads were allowed to slide outward. The coefficient of surface- pad friction for this landing was about 0 . 4 . The landing energy was absorbed by sub-
stantial stroking of both the primary and secondary struts of gears 2 and 4 . The maxi-
mum primary-strut stroking force measured during all the t e s t s (12,500 lbf (56 kN)) w a s obtained during this landing. For the next landing (number 17), the coefficient of friction was reduced further to about 0.15 in order to allow the pads to slide more freely. As a result, practically all the impact energy w a s absorbed by near-maximum tension stroking of the secondary struts of g e a r s 2 and 4 . The primary struts did not stroke o r develop significant axial loads; however, it was evident from motion pictures that high bending
loads occurred in primary struts 2 and 4. No failures occurred and the struts subse-
quently functioned normally.
During the varied and repeated loadings of the present tests, the four prototype
landing gears performed as designed and no structural deficiencies were noted. The
variable bearing-friction force in the primary struts w a s not a problem during these
tests and, in general, the force pulses generated were similar to the constant-force
characteristics of crushable aluminum honeycomb. Strut-force characteristics were repeatable. The structural integrity of the landing gear, designed for a single landing cycle on the lunar surface, w a s substantiated.
Comparisons of theoretical strut stroking forces with the experimental values of the present investigation a r e shown in figures 10 and 11. Typical stroking-force time histories are compared in figure 10. Figure lO(a) shows a typical 2-2 landing at positive pitch attitude, figure lo@) shows a 2-2 landing at negative pitch attitude, and figure 1O(c)
shows a 1-2-1 landing, There is good agreement between experimental and theoretical
time histories. The stroking forces experienced during each landing by each of the cor- responding struts of the full-scale vehicle and the theoretical model a r e plotted as abscissa and ordinate, respectively, in figure 11. The first-stage tension-stroke force data for the secondary struts are not shown since their magnitudes were small. The solid line (1:l slope) represents exact agreement. Close agreement was found between
experimental and theoretical results. The stroking forces (applied forces) are an impor-
tant factor in the landing dynamics, and the correlation between measured and predicted forces is a strong indication of the validity of the theoretical analysis.
a
Landing -Gear Stroke The maximum strokes experienced by each landing-gear strut for the test vehicle
landings are presented in table IV. The comparison of primary and secondary strut
strokes between the test vehicle and the theoretical model a r e shown in figure 12. The stroke during each landing for each of the corresponding primary and secondary struts of the test vehicle and the theoretical model are plotted as abscissa and ordinate, respec
tively. The test data of table IV show that strut strokes were not as symmetric as they
should be with symmetric 2'2 and 1-2-1 landings. This condition was particularly true for the secondary struts. Yaw oscillations experienced during launch of the test vehicle on the simulator combined with variations in pitch attitude, pitch motions, and surface conditions contributed to asymmetric stroking of the struts during the landing impact.
These asymmetric results are considered to be realistic and representative of an actual landing; however, the theoretical approach assumes perfectly symmetric and planar landings and this assumption accounts for some of the scatter of the data in figure 12.
In general, the agreement between experimental and theoretical results is good, and theoretical results are conservative in the case of large strokes.
Vehicle Center -of -Gravity Acceleration The maximum center -of -gravity normal, longitudinal, and angular accelerations measured during the test-vehicle landings are presented in table V. The normal and angular accelerations experienced for the four general types of landings conducted are also shown in figure 13. The maximum normal acceleration experienced during landings of the test vehicle w a s approximately 2.2g, and the maximum angular acceleration was about 7.5 rad/s2. The agreement of maximum normal and angular acceleration during each landing between the test vehicle and the theoretical model is shown in figure 14.
Experimental and theoretical values for maximum normal acceleration (fig. 14(a)) a r e in good agreement whereas the data for angular acceleration (fig. 14(b)) show a larger amount of scatter. The greater difficulty in measuring angular accelerations together with the nonsymmetric landings contributed to greater scatter in the angular acceleration data than f o r the linear accelerations.
Vehicle Motions The pitch-motion time histories obtained from motion pictures of five consecutive 1-2-1 landings are shown in figure 15 for vehicle launches which were intended t o give the same touchdown pitch attitude and speed. Although the curves and table 1 1 indicate a sub- stantial variation in these initial impact conditions, the pitch-motion trends of the vehicle were very similar during the 1-2-1 landing impacts, and the displacement along the time scale of individual time-history curves reflected the variation of initial impact conditions.
II I I I 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 . 1 1 I I I I 1111111II 1 1 1 . . 1 1 1 1 1 111 I I1111111111111.1 ..11.11.1 1111111.1- .. -I --.-. -__ Landings at or near the same attitudes resulted in almost identical pitch time histories.
The deviations in initial impact conditions were primarily caused by vehicle oscillations and inherent launch- and support-cable dynamics during launch and prior to initial impact.
The pitch-motion time histories for three 2-2 landings resulting in rocking motions are shown in figure 16. After initial impact on the rear legs, the vehicle rotates (pitches) downward to second impact on the front legs; then the rear legs lift off the surface ("rock up") and return t o a third (final) impact. This sequence of events is illustrated by the
sketches in figure 16. The solid lines are for the experimental landings, and the dashed
lines are for theoretical landing simulations using the same touchdown conditions as for the experiment. Touchdown pitch attitude and vertical speed w e r e to be held constant while horizontal speed was increased for each successive experimental landing. Verti- cal speed w a s almost constant for all three landings (see table 11), and pitch attitude was
essentially constant for landings 7 and 20; however, initial pitch attitude w a s low for
landing 21. In addition, landing 7 was almost short (rear pads contacted partially on inclined ramp of elevated surface), and a negative pitch rate of about 0.031 rad/s w a s measured at initial contact for landing 21. Therefore, landing 20 w a s considered the best of the three landings since speed and attitude were stabilized.
During the three experimental landings (7, 20, and 21), the maximum rock-up atti- tude increased with increase in horizontal speed. The theoretical results do not show the same trend. The theoretical model appears relatively insensitive to the initial impact conditions at this point in the time history ( 1 . 0 to 2.0 seconds). However, landing 20 shows very good correlation between theory and experiment for pitch attitude trends, magnitude, and time. This agreement supports the ability of the theoretical analysis to predict vehicle motions and stability boundaries. More extensive correlation can be obtained with small and more controllable free-body dynamic models where uncertainties in initial impact conditions and support-cable dynamics can be minimized.
CONCLUDING REMARKS Structural integrity of a prototype LM landing-gear system (struts and deployment trusses) w a s substantiated during 21 landings of a full-scale test vehicle at simulated lunar gravity and at earth ambient atmospheric conditions. Dynamic performance of the landing-gear struts w a s good for all landing conditions tested including those which pro- duced near maximum shock-absorber strut strokes and loads. Theoretical results were in agreement with experimental results obtained for landing accelerations, gear forces and strokes, and vehicle pitch motions.
Langley Research Center, National Aeronautics and Space Administration, Langley Station, Hampton, Va., January 9, 1969, 124-08-04-09-23.
, ., , APPENDIX A CONVERSION O F U.S. CUSTOMARY UNITS TO SI UNITS The International System of Units (SI) was adopted by the Eleventh General Confer- ence on Weights and Measures held in Paris in 1960. (See ref. 2 . ) Conversion factors for the units used are given in the following table: Conversion SI Unit U.S. Customary factor Physical quantity
unit
(**)
(* 1
1 hertz (Hz)
Frequency . . . . . . . . Cycles per second
meters 0.0254 Length ..........
{ 2 meters
0.3048 14.594 kilograms (kg)
M a s s . . . . . . . . . . . slug
Ibf 4.4482 newtons (N) Force . . . . . . . . . . .
slug-ft 2
1.3558 kilogram -meter s2 (kg-mz) Moment of inertia . . .
Velocity . . . . . . . . . ft/sec 0.3048 meters/second (m/s)
*Multiply value given in U.S. Customary Unit by conversion factor to obtain equivalent value in SI Units.
**Prefixes to indicate multiples of units are as follows: Multiple centi (c) kilo (k) REFERENCES 1. Blanchard, Ulysse J.: Evaluation of a Full-Scale Lunar-Gravity Simulator by Compar- ison of Landing-Impact Tests of a Full-scale and a 1/6-Scale Model. NASA TN D-4474, 1968.
ASTM Metric Practice Guide. NBS Handbook 102, U.S.
2. Comm. on Metric Pract.: Dep. Com., M a r . 10, 1967.
TABLE I . . PERTINENT CHARACTERISTICS O F FULL-SCALE TEST VEHICLE
AND PROTOTYPE LANDING GEAR Vehicle mass. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 (6440) Moment of inertia. slug-ft2 (kg-m2) Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12000 (16300) Yaw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Constrained Roll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Constrained Height of center of gravity above ground line. in . (m) . . . . . . . . . . . . . . . . . . . . 141 (3.58) Landing-gear radius. in . (m) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167.5 (4.25) Landing-gear mass. total. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.92 (232.3) Primary-strut mass. each. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.72 (39.7) Padmass. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.75 (11.0) Inner slide mass. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.93 (13.6) Honeycomb cartridge mass. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.23 (3.4) Primary-strut moment of inertia. each. slug-ft2 (kg-m2): About axis normal to long strut axis: Inner slide extended . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.4 (38.5) Inner slide stroked . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6 (22.5)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 (0.8)
About long strut axis Inner slide only with pad: About axis normal to long axis 6.3 (8.5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Secondary-strut mass. each. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.31 (4.5) Honeycomb cartridge mass: Tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.027 (0.39) Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.016 (0.23) Deployment t r u s s mass. each. slugs (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.64 (9.3) Landing-gear strut stroke. in . (m): Primary. first stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 (0.254) Primary. second stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.0 (0.584) Secondary. compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.8 (0.249) Secondary tension. first stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 (0.102) Secondary tension. second stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.0 (0.330) Honeycomb-cartridge static crush force (i5%). lbf (kN): Primary. first stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4090 (18.2) Primary. second stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8640 (38.4) Secondary compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4090 (18.2)
first stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 460 (2.0)
Secondary tension.
Secondary tension. second stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4550 (20.2) Honeycomb-cartridge design dynamic crush force. lbf (kN): Primary. first stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4500 (20.0) Primary. second stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9500 (42.3) Secondary compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4500 (20.0)
first stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 (2.2)
Secondary tension.
Secondary tension. second stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5000 (22.2) TABLE I I . - INITIAL CONDITIONS FOR LANDMG-IMPACT TESTS O F FULL-SCALE VEHICLE Zartridge average static crush force. lbl k N ) VV’ Pitch Pad-surlaci Landing Gear allitude, ft/sec P r i m a r y struts Secondary ,uts friction Surface characteristic number orientation ~ coefficient (m/s) deg C C1 c 2 T 1 T 2 1 2-2 0 10.0 4095 8815 4135 445 4545 0.4 Flat (18.2) (39.2) (18.4) (1.98) (20.2) (3.0) 2 2-2 8 2 10.0 4260 8795 4135 455 4545 0.4 Flat (18.9) (39.1) (18.4) (2.02) (20.2) (3.0) 10.0 4245 4560 Flat 3 2 -2 8 4115 8750 455 0.4 (3.0) (18.3) (38.9) (18.9) (2.02) (20.3) 4 10.0 4135 4585 m 2-2 71 4115 8815 445 Flat (18.3) (39.2) (18.4) (1.98) (20.4) (3.0) 5 2-2 9 10.0 4140 4090 4545 (0 Flat 8855 450 (20.2) (3.0) (18.4) (39.4) (18.2) (2.00) 6 2-2 10.0 4195 8775 4110 445 4465 m Elevation at g e a r s 1 and 4 9 3 (18.7) (18.3) (1.98) (19.9) (3.0) (39.0) 7 2-2 8 10.0 4080 8780 4100 450 4500 m Elevation at g e a r s 1 and 4 (18.1) (39.1) (18.2) (2.00) (20.0) (3.0) m 8 1-2-1 8 1 7.5 4205 8895 4080 445 4565 Elevation a t gear 4 (18.7) (39.6) (18.1) (1.98) (20.3) (2.3) ~ ~~ 1-2-1 8.0 m 9 61- 4255 8605 4040 450 4525 Flat (2.4) (16.9) (38.3) (18.0) (2.00) (20.1) 10 1-2-1 7 8.5 4255 8780 4065 455 4575 m Elevation a t gear 4 (18.1) (2.6) (18.9) (39.1) (2.02) (20.3) ~ m 11 1-2-1 72 7.5 4225 4070 4575 Elevation at gear 4 8605 450 (18.1) (2.3) (18.8) (38.3) (2.00) (20.3) m 12 1-2-1 8 7 . 0 4230 8670 4085 455 4555 Elevation at gear 4 (18.8) (38.6) (18.2) (2.02) (20.3) (2.1) m 13 1-2-1 9 1 7.0 4205 8725 4115 445 4545 Elevation a t gear 4 (18.7) (38.8) (18.3) (1.98) (2.1) (20.2) m 14 1-2-1 9 3 7.0 4180 8745 4085 450 4515 Elevation at gear 4 (18.6) (38.9) (18.2) (2.00) (20.1) (2.1) ~ _ _ m 15 1-2-1 9 1 7.0 4120 8640 4080 445 4545 Elevation at gear 4 (18.3) (38.4) (18.1) (1.98) (20.2) (2.1) - 16 1-2-1 14.0 4170 8815 4040 450 4630 0.4 Elevation at g e a r s 2 and 4 (18.5) (39.2) (18.0) (2.00) (20.6) (4.3) - _ _ 17 1-2-1 9.0 at g e a r s 2 and 4 4185 8650 4040 450 4590 0.15 Elevation (18.0) (2.7) (18.6) (38.5) (2.00) (20.4) - 5 1 m 18 2-2 9.5 4155 8140 4040 455 4550 Flat (18.5) (38.9) (18.0) (2.02) (20.2) (2.9) m 19 2-2 -4 10.0 4170 6690 4050 450 4610 Flat (18.5) (38.7) (18.0) (2.00) (20.5) (3.0) m 20 2-2 71 9.5 4185 8650 4095 445 4630 Elevation at g e a r s 1 and 4 (18.6) (38.5) (18.2) (1.98) (20.6) (2.9) m 21 2-2 52 10.0 4095 8830 4035 450 4460 Elevation at g e a r s 1 and 4 (3.0) (18.2) (39.3) (17.9) (2.00) (19.8)
I
.
TABLE IU.- LANDING GEAR EXPERIMENTAL FORCE DATA [NR denotes no data recorded; blank spaces indicate no honeycomb crush1 (a) U.S. Customary Units -- Strut stroking force, Ibf Landing gear 2 Landing gear 1 __ .and Secondary strut Secondary strut P r i m a r y Primary r u b ~ strut strut Left Right Left Right ~ C C C C c2 T1 C 1 T1 T1 T 2 T2 C1 c 2 T1 T2 - __ 9 384 1 646 4866 540 66: 4830 9 66 NR 2 729 5213 506 705 NR 6030 NR 3 NR NR 604 473 5309 9 4 1 7 0 7 611 4 601 4657 574 511 5309 9 89 7 0 7 4880 611 5 684 4267 4726 595 5 1 1 5335 9 04 4240 NR 65s 10 320 6 684 4191 4657 NR 6064 4494 7 1 C 520 7 684 4500 620 495 5469 9 27 4794 694 a 659 6287 687 5469 9 98 650 NR 9 NR NR NR NR NR NR NR NR NR 4000 10 660 430 6340 NR 5588 9 39 482 4558 11 6403 620 5960 9 301 482 12 556 6940 566 5232 9 51: 482 4532 13 7 03 6740 715 5404 9 96' 520 4300 599 14 747 6916 674 5120 9 981 569 4257 15 791 7150 NR 5113 9 871 477 1960 16 391 $890 5288 $531 2 45! 558 5166 17 179 4975 i564 600 506E 18 592 644 5769 627 $411 1 00' 1438 715 6195 615 19 348 i290 1 121 1608 600 20 637 5117 135 579 I O l i i564 9 91: L566 729 2 1 680 392 5168 675 192: i201 0 16( 1523 a58 Landing gear 3 Landing gear 4 . . ..
44 1 7 00 9 655 9 484 522 505 40( 1 4802 47 1 100 10 30C 56E 66E 444 2 5677 557 NR 60s 585 444 5381 3 5349 10 22: 470 NR 565 58€ 444 5101 498( 4 i230 9 39( 47 3 4900 NR 620 582 448 9 65E 495( 425( 5 i432 448 60!
473 NR NR 555 541 4371 6 i397 474 TR 733 582 7 4a2t 476( 9 16E I140 624 448 523 2 2 1 647 NR 47 1i VR NR NR M NR NR NR YR 523 767 5 10 666 493 442t 10 NR 479 560 604 672 $98 459t 11 NR B80 $887 NR 707 498 NR 479 12 NR 523 767 NR 524 198 NR 13 NR 566 381 NR 566 543 NR 14 NR 479 540 431 566 198 4378 15 NR 445 J R NR i199 528 171 543 5400 16 090 480 278 i103 475 57 582 5168 490 173 573 546 497 4888 .O 908 18 i a 1 475 383 470 i88 492 4711 .1 040 19 120 480 395 604 i46 5480 4845 .O 060 20 696 490 3 8 1 7 04 j30 $916 4412 .O 059 2 1 696 - . ~.
- - . . . . .. . . .
TABLE m.- LANDING GEAR EXPERIMENTAL FORCE DATA - Concluded (b) SI Units Strut stroking force, Newtons (kN) Landing gear 1 Landing gear 2 _ _ .anding Secondary s t r u t Secondary s t r u t lumber P r i m a r y P r i m a r y ____ strut strut Left Left Right Right ~ C C C T 1 c 2 C1 C1 T 1 T 1 c 2 T2 T 1 T2 T2 T2 __ 1 11.7 21.6 2.87 2.40 43.0 21.5 NR 2.95 2 3.24 2.25 23.2 26.8 NR NR 3.14 3 NR 2.69 41.9 NR 21.1 23.6 2.72 3.14 4 2.67 2.55 44.0 20.1 22.8 23.6 21.7 2.72 3.14 5 3.04 40.2 21.0 19.0 23.1 18.9 2.65 22.9 NR 2.93 6 3.04 NR 15.9 20.1 18.6 27.0 20.0 2.31 3.16 7 20.0 3.04 2.76 41.2 22.0 24.3 21.3 3.09 2.93 8 19.1 28.0 3.06 44.4 24.3 2.89 2.93 9 NR NR NR NR NR NR NR NR NR NR 10 1.91 28.2 17.8 NR 41.8 24.9 2.14 2.94 11 20.3 2.76 28.5 26.5 41.4 2.14 2.96 12 18.6 2.47 2.52 42.3 30.9 23.3 2.14 3.13 13 20.2 3.18 44.3 30.0 24.0 2.31 3.13 14 19.1 30.8 2.66 3.00 44.4 22.8 2.53 3.32 15 18.9 NR 31.8 22.7 2.12 43.9 3.52 16 2.56 j5.4 23.5 29.0 2.48 11.7 13.0 3.96 24.7 2.67 12.5 12.1 3.46 18 2.86 25.7 19.1 2.79 49.0 28.5 3.08 19 3.18 2.74 L9.5 27.6 28.0 20.5 2.61 2.88 20 2.83 2.58 44.1 22.8 22.3 24.7 20.3 3.24 3.21 21 23.0 20.1 3.03 3.00 45.2 21.9 23.1 3.82 3.08 Landing g e a mding gea 3 1 2.32 12.2 43.0 21.4 20.9 1.96 2.25 1.78 2 2.51 45.8 25.2 22.7 2.09 2.98 1.97 3 2.71 15.5 23.8 NR 23.9 2.48 2.60 1.97 4 2.51 11.8 23.3 22.1 NR 22.7 2.09 2.61 1.97 5 2.76 13.0 24.2 18.9 21.8 NR 22.0 2.10 2.59 1.99 NR 20.5 2.41 6 2.47 24.0 19.5 NR 2.10 1.99 7 3.26 $0.7 22.9 21.2 NR 21.5 2.11 2.59 1.99 8 2.88 NR 21.0 23.2 2.33 2.78 1.99 9 NR NR NR NR NR NR NR NR 10 2.27 NR 19.7 21.2 2.33 2.96 2.19 11 2.69 NR 20.4 24.7 2.13 2.99 2.21 12 NR NR NR 21.7 2.13 3.14 2.21 21.7 13 NR NR NR 21.2 2.33 2.78 2.21 20.7 14 NR NR NR 21.1 2.52 2.96 2.41 22.1 15 1.92 NR 19.5 20.2 21.6 2.13 2.96 2.21 16 2.35 NR 22.6 NR 24.0 1.98 3.43 2.41 23.1 17 2.11 21.9 23.0 2.13 2.99 2.59 22.1 18 2.55 18.5 27.5 21.1 21.2 2.18 2.43 2.21 19 2.09 19.1 21.2 21.0 26.2 2.11 2.62 2.19 14.7 22.2 20 2.69 25.3 21.6 24.4 2.13 2.43 1.99 21 3.13 14.7 25.3 19.6 22.2 21.9 2.18 2.80 2.19 ~~
I
TABLE N.- LANDING GEAR EXPERIMENTAL STROKE DATA (a) U.S. Customary Units ~ Strut maximum stroke, in.
Landing gear 1 Landing gear 2 ~ Landing Secondary strut number Seconc ‘y strut P r i m a r y P r i m a r y Left R It Left Right strut strut __ T C T C T C C T 2 . 8 11.7 2 . 2 3 . 3 11.2 3.1 4 . 8 2 9.9 4.0 3 . 9 9 . 1 2 . 6 3 9 . 2 2.8 14.5 3 . 7 4 . 8 3 . 9 3 . 9 9 . 6 .7 4 . 8 13.9 3 . 9 4.0 9 . 5 . 3 0 . 2 5 . 5 12.0 1 . 6 3.2 6 11.9 . 4 2 . 7 5.5 . 8 7 . 5 1 . 2 2 . 4 2 . 6 9 . 6 .6 4.9 15.4 2.8 3 . 9 2 . 5 2 . 1 1 . 2 4.0 2 1 . 8 1.6 9 9.9 1 . 6 1.0 3 . 9 .8 5 . 3 18.7 1 . 7 10 4 . 9 1 . 9 3 . 9 . 4 3 . 9 28.2 3 . 9 11 3 . 3 21.8 3 . 9 . 8 4.0 3 . 6 12 2.2 1.1 3 . 9 2 3 . 8 2 . 9 . 8 1 . 5 13 3 . 0 3 . 9 23.4 1 . 3 2 . 7 . 5 14 2.9 .1 2 . 3 .6 2 . 7 23.9 1 . 2 15 2 . 1 2 . 6 21.0 1 . 1 1 . 7 1.5 1.8 9 . 8 3 . 2 1 . 1 18.0 9 . 2 1 3 . 2 . 2 12.6 18 .5 . 8 1 . 7 12.9 9.0 4.0 4.0 1 . 0 1 . 5 4.0 1 4 . 0 7 . 9 4 . 0 2 . 2 8 . 9 . 2 4 . 9 1 4 . 9 4 . 5 3.9 2 . 4 6 . 8 . 4 5 . 9 16.4 3 . 0 4.0 - gear 3 Landing gear 4 Landi .- ~ - 11.2 3 . 1 11.3 1 . 7 3.5 3 . 5 9 . 4 3 . 9 10.3 4 . 0 3 . 8 4.0 3 14.9 4.0 4.0 9 . 9 4 . 8 3.9 16.7 3 . 9 0 . 3 3 . 9 7 . 4 5 . 7 3 . 9 14.3 4.0 2 . 3 4 . 1 9 . 4 7 . 4 4 . 0 9.0 2 . 2 . 9 1 . 2 11.8 2 . 4 1 . 2 3 . 9 7 15.8 3 . 9 4 . 1 3 . 2 8 . 3 4 . 1 3 . 9 8 2 . 2 4.0 1 . 7 1 . 8 5 . 0 3 . 9 4 . 0 9.8 5 . 1 . 8 3 . 9 3 . 6 3 . 9 4.0 10 4.4 3 . 9 2 . 9 2 . 1 4 . 6 3 . 9 3 . 9 11 1 . 2 4 . 0 2 . 3 . 3 4 . 7 4 . 0 4 . 0 2 . 6 4 . 0 1 . 5 1 . 8 4 . 1 3 . 7 4 . 3 13 1 . 7 3 . 9 1 . 2 1 . 0 4 . 9 3 . 2 3 . 6 14 1 . 3 2 . 4 1 . 2 1 . 1 4 . 6 2 . 8 3 . 2 15 2.5 1 . 5 .6 .6 5 . 7 2 . 7 3 . 3 16 4 . 5 . 4 1 8 . 0 1 . 2 7 . 7 7 . 7 17 .6 1 . 4 13.3 15.4 18 14.3 4 . 0 5 . 4 1 . 5 .2 4 . 0 4 . 0 19 14.4 4.0 4.0 4 . 0 4 . 0 . 4 4 . 0 20 15.8 3 . 9 4 . 7 2 . 3 7 . 0 4.2 3.7 21 1 7 . 9 4 . 0 3 . 0 2 . 2 7 . 2 5 . 6 3 . 1 -
I
TABLE W.- LANDING GEAR EXPERIMENTAL STROKE DATA - Concluded (b) SI units Strut maximum stroke, m e t e r s Landing gear 2 Landing gear 1 1 strut Secondary strut Secon& Primary P r i m a r y Left Right Left Right strut strut C T C C T T C T 0.079 0.297 0.084 0.056 0.284 0.071 .066 .231 .122 .251 .099 .lo2 .122 .099 .368 .094 .234 .071 .099 2 4 4 .122 .018 .353 .099 .081 .lo2 0.041 2 4 1 0.005 .140 .008 .305 .020 .061 .191 .010 .030 .302 .140 .069 .124 .099 .015 .391 .066 . 0 7 1 .244 .041 .053 0.030 .lo2 .554 .064 .043 .099 ,025 .251 .020 .135 .041 .475 .124 .010 .099 .099 .048 .716 .099 .084 .020 .lo2 .091 .554 .099 .038 .074 .056 .020 .099 .028 .605 .099 .033 .594 .069 .076 .013 .074 .015 .069 .033 .003 .607 .058 .053 .038 .066 .028 .533 .043 0.046 .234 .457 2 4 9 .081 .028 .320 .005 .335 .102 .229 .013 .043 .020 .328 .lo2 .102 .038 .356 .lo2 .201 .025 .114 .226 .124 .099 .005 .378 .056 .102 .061 .076 .173 .150 .010 .417 Lan ng gear 0.281 0.089 0.089 0.284 0.043 0.078 .239 .lo2 .099 .262 .097 .102 .122 .099 .378 .lo2 .lo2 2 5 1 .099 .188 .145 .099 .424 0.008 .099 .058 .lo4 .lo2 .239 .188 .102 .363 .030 .099 0.061 .229 .023 .030 .056 .300 .lo4 .099 .401 .lo2 .081 .099 .211 .046 .127 .099 .102 .056 .043 .lo2 .249 .020 .099 .130 .091 .099 .102 .117 .099 ,099 .112 .074 .053 .099 .058 .008 .lo2 .119 .lo2 .102 .030 .038 .046 .lo2 .lo4 .094 .109 .066 .081 .091 .043 .030 .025 .099 .124 .030 .028 .117 .071 .081 .033 .061 .015 .038 .015 .064 .145 .069 .084 .196 .196 .114 .030 .010 .457 ,036 .338 .391 .015 .363 .137 .038 ~ 102 .005 .lo2 .102 .lo2 .102 .366 .127 .lo2 .lo2 .010 .058 .178 .lo7 .094 .401 .119 .099 .079 .455 .076 .056 .lo2 .183 .142 ~ TABLE V.- TEST VEHICLE EXPERIMENTAL ACCELERATION DATA ~ Maximum acceleration Landing Longitudinal, g units number Nor mal, g units Positive Negative Positive Negative - .
1 2.2 0.00 0.00 1.69 1.97 2 1.8 .45 .29 5.29 2.65 3 2.0 .27 .70 6.67 3.20 1.3 .21 1.12 5.85 6.27 5 1.5 .24 1.12 7.31 4.35 1.2 .83 .67 2.79 2.23 1.1 .19 1.01 5.10 6.48 8 1.6 .13 .82 4.55 2.21 9 1.6 1.03 .13 3.86 2.07 1.3 .16 .73 4.27 2.07
1 10
11 1.6 .11 .80 4.69 4.14 12 1.6 .13 .75 3.90 2.51 13 1.7 .14 .91 3.72 4.00 14 1.7 1.08 .13 4.88 4.88 1.7 .13 1.00 5.85 5.29
I l5
2.3 . 00 . 00
.oo . 00
1 .o .19 .16 1.25 1.11
1.3 . 00 .79
2.37 4.18 1.7
. 00 .85 2.67 6.86
1.3 .21 1.08 5.15 3.20 1.4 1.32 .21 5.43 3.20 -. ~ . - - . . . - 2029.1 68- - L vehicle.
test full-scale of Photograph 1.- Figure t-..') .......
-
-
L-68-2028.l Figure 2.- Photograph of prototype landing gear.
1247.1 - - L .
components strut strut. shock-absorber Primary (a) landing-gear of Photographs 3.- Figure ----- .
~ c..:l -
--
-- 68-1249.1 - L strut.
Concluded.
- 3.
Secondary re igu (b) F
t-:) "'"
1743.1 68- L- truss.
deployment landing-gear of Photograph 4.- Figure I:\:) CJ1 1250.1 - -68 L crush.
impact after and before struts landing-gear from cartridges shock-absorbing honeycomb aluminum of Photograph 5.- Figure t..:I 0') i -5995.1 -67 L simulator.
impact m))
1.8
view.
lunar-gravity x grid Overhead
(1.8
full-scale (a) of squares Photographs Photogr~hic 6.- . 6-foot x Figure
(6
------ ------
------- --~- t-:) -J -67-5997.
L view.
Concluded.
6.- Ground (b) Figure
J
".
(
Support ~ Full-scale cables Release t-.!) 00 Angular acceleration \ / \' V \ ' h 1-2-1 orientation tch attitude
Oo pitch attitude- &
Negative pitch attitude Figure 7.- Sketches identifying axes, accelerations, attitudes, velocities, and flight path.
N CD
0 First-stege crush
A Seconddtage crush
a
4 - 4 - Figure 8.- Stroking forces measured on landing-gear secondary s t r u t s d u r i n g test vehicle landings.
0 F i r s t s t a g e crush
A Second-stage crush
0 fi Negative pitch attitude
Landing-gear orientation
n2 ' h
1 2 Honeyconib-cartridge design dynamic crush force ai
E
e
! f
Y
6 R
u H o n e y c o e a r t r i d g e s t a t i c k PI crush force range I 1 I I 1 2 3 4 Landing-ear number (a) 2-2 landing-gear orientation.
Figure 9.- Stroking forces measured on landing-gear primary struts during test vehicle landings.
0 First-stage crush
A Second-stage crush
Landing-gear orientat ion Honeyco@-xrtridge design
/- dynamic crush force
e /
No data available
I r
I
1 2 3 4
Landing-gear number (b) 1-2-1 landing gear orientation.
Figure 9.- Concluded.
R
e
- 2 5 i?
IM
E
G
i 2
-P Firsbetage crush
B
t
Second impact '0 (a) 2-2 orientation; positive pitch attitude.
Figure 10.- Comparison of typical s t r u t stroking-force time histories d u r i n g landings of test vehicle and theoretical model.
Experimentd (average) Theoretical Secondary s t r u t (compression stroke) , c u * u
' Landing-ear number
k
- 2 5 8
- 0 0.2 0.4 0 0 0.2 0.4 sec Time, (b) 2-2 orientation; negative pitch attitude.
Figure 10.- Continued.
Landing-gesr number
r4
. 8 1 . 0
.4 . 6
‘0 .2 Time, sec (c) 1-2-1 orientation; positive pitch attitude.
Figure 10.- Concluded.
W UI w Q, 0 Flrst-stage crush A Second-stage crush 6 12
a
25 20 1 -
Compression stroke 20 c.
25 '
I I I I 4 v 1 I I I I I I I 4 6 4 6 8 10 12 Dqerimental stroking force, kips 1 I I 1 J I I I I I I 10 15 20 25 20 30 40 5 0 Bperimental stroking force, kilonewtons (a) Secondary struts.
(b) Primary struts.
Figure 11.- Comparison of stroking force of landing-gear struts during landings of test vehicle and theoretical model.
.
30 .-
0 Compression stroke
A Tension stroke
7 - *75
5 0 BLact agreement .25 O O 10 20 0 10 20 30 &cperimental stroke, i n .
1 I I I 1 I 1
0 -25 .50 o
.25 .50 9 75
Experimental stroke, m (a) Secondary struts. (b) Primary struts.
Figure 12.- Comparison of total stroke of landing-gear struts d u r i n g landings of test vehicle and theoretical model.
I I l l l l l I 1 l l l l l l
Pad friction, Pad friction,
0 . 4
Oo4 \
m
8 O f
x
! 3
0 . 1 5 bo
0 0
\
ii
al m
I
I I - 1 0 1 I 2-2 1-24 1-24 Gear orientation 2 2
- + 0
Pitch attitude +
Constrained 0.4, 0.15
Pad f r i c t i o n 0.4, constrained Constrained Type of landing Figure 13.- Maximum center-of-gravity normal and angular accelerations measured on test vehicle during landings.
0 Positive acceleration
A Negative acceleration
2.5 10
2 2.0
bo
d
0 1 . 5 d
ii PI
i !
V
8 1.0
7 4
rl
x
8 0.5
€l
I I I I I I I I I J
2 4 6 8 10
0 . 5 1.0 1.5 2.0 2.5 Ekperimental acceleration, g units Experimental acceleration, rd/sec (a) Normal acceleration.
(b) Angular acceleration.
Figure 14.- Comparison of maximum normal and angular acceleration of center of gravity d u r i n g landing of test vehicle and theoretical model.
W I I I I I I -12 . .
0 1 . 0 2 . 0 3.0 Time, sec Figure 15.- Pitching motion during 1-2-1 landings of test vehicle.
Experimental
- - - -Theoretical
c (D m (0
I
w c
r
a
$
R
+r h %
4 - 4
-8 -12 Region of maximum rock up I I I I I I I - 1 6 I 1.0 2 .
3.0 4.0 Time, sec Figure 16.- Comparison of pitching motion d u r i n g 2-2 landings of test vehicle and theoretical model.
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I I Date I I Please send, on loan, copy of film supplement L-1011 to I TN D-5029.
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