Document
NASA
Reference
Publication
r l r l on I 1 0 3
October 1987
Langley Aircraft Landing
Dynamics Facility
NASA
Reference
Publication
Langley Aircraft Landing
Dynamics Facility
n---1 A n,,,;, L aiiiu2 n. u a v a o , Sandy M. Stubbs,
and John A. Tanner
Langley Research Center Hampton, Virginia National Aeronautics and Space Administration Scientific and Technical Information Office Contents
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Historical Overview-Langley Landing Loads Track Facility. 1955-1981 . . . . . . . 1
Langley Aircraft Landing Dynamics Facility . . . . . . . . . . . . . . . . . . . 2
Propulsion System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
High-speed Test Carriage . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Track . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Arrestment System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Data Acquisition System . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Photographic Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
F, eferer?ces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
iii Summary Track was constructed and became operational in 1955 (ref. 2). Many of the design features of the The Langley Research Center has recently up- LLT described in the following paragraphs were later graded the Landing Loads Track (LLT) to improve incorporated into the ALDF. Table 1 lists the key the capability of low-cost testing of conventional and characteristics of the LLT.
advanced landing gear systems. The unique feature The LLT is shown in figures 1, 2, and 3. The of the Langley Aircraft Landing Dynamics Facility major components of the water jet catapult, identi- (ALDF) is the ability to test aircraft landing gear sys- fied in figures 1 and 2, included the L-shaped water tems on actual runway surfaces at operational ground vessel (identified as L-vessel), compressed air storage speeds and loading conditions. A historical overview tanks, a quick-opening valve, and the reaction bucket of the original LLT is given, followed by a detailed de- at the rear of the test carriage. Figure 3 is a pho- scription of the new ALDF systems and operational tograph of a typical run of the test carriage being capabilities.
catapulted at the LLT. The L-vessel was sized with a volume that would allow only the water contained Introduction in the horizontal leg, about 3000 gal, to be expelled during a maximum-speed catapult. This design fea- The Langley Aircraft Landing Dynamics Facility ture minimized turbulence within the jet and thereby (ALDF) became operational in 1985. It has the ca- enhanced jet integrity over the 400-ft catapult stroke.
pability of testing full-size aircraft landing gear sys- The LLT test carriage ahnwn in figures 1: 2: and tems under cioseiy controiied simuiateci iakwil' iilld 3 was a space truss structure constructed of tubular landing conditions on actual runway surfaces. Test- steel. The carriage was about 60 f t long, 30 ft ing landing gear systems on the ALDF is advanta- wide, and 30 f t high and for most test applications geous over flight testing for reasons such as safety, weighed about 106000 lb. The main features of the economy, parameter control, and versatility. Virtu- carriage were the reaction bucket, the drop carriage, ally any aircraft landing gear system or subsystem and the nose block. The carriage reaction bucket, can be accommodated on the ALDF test carriage.
which turned the water jet through about 177O, was New and novel landing gear concepts can also be in- based upon the efficient water wheel design of Pelton vestigated, and the versatility of the facility permits (refs. 3 and 4). The bucket design maximized the testing on a variety of runway surfaces under many impingement thrust on the carriage and produced a different simulated weather conditions.
water exit which did not interfere with the water jet.
The purpose of this paper is to give a brief The air storage tanks, L-vessel, and valve area were historical overview of the Langley Landing Loads all sized to provide about 350000 lb of thrust on the Track (LLT), the facility preceding the ALDF, and carriage and to catapult it up to test speed in about to discuss how the older facility was upgraded to 3 sec over a maximum distance of 400 ft. The drop the present ALDF configuration. The paper de- carriage rode on a set of vertical guide rails located scribes the main features of the ALDF, including the in the middle of the test carriage. The landing gear high-pressure propulsion system, the test carriage, test article, attached to the drop carriage, could the track, the arresting gear system, and the data be lowered at a predetermined location and rate to acquisition system.
simulate a landing impact.
The nose block on the front end of the car- Historical Overview-Langley Landing riage was shaped to capture five arresting gear ca- Loads Track Facility, 1955-1981 bles which spanned the track at the end of the test section. For the LLT, the 5 cables were attached The need for a facility to conduct landing gear to 20 energy absorbers which dissipated the carriage tests on actual runway surfaces was identified by re- kinetic energy over the last 600 ft of track. The searchers at the NACA Langley Aeronautical Labo- energy absorbers were hydraulic rams which dissi- ratory in the late 1940's. Reference 1 presents the pated the carriage energy by forcing hydraulic fluid results of an early study to define the most cost- through orifices. The arresting gear hardware, pro- effective catapult system to accelerate a 100000-lb cured from Navy surplus, had previously been used test carriage to a speed of 130 knots (1 knot equals onboard World War I1 vintage aircraft carriers.
0.5 m/sec). The study considered many catapult op- The test carriage rode on steel rails that were 30 f t tions including a dropping weight, flywheel, blow- gun, high-pressure piston, and rocket power. Yet, the apart. The carriage was supported at each corner by most promising and cost-effective concept appeared a two-steel-wheel bogie which also had two wheels for lateral constraint against the track rail system.
to be a high-pressure water jet catapult system. As The operating sequence of the LLT was simple and a result of this study, the Langley Landing Loads carriages from a second set-up building to the test resembled what is used today. The catapult system track. Table 2 provides quantitative specifications propelled the test carriage to the desired speed over concerning the major component capabilities of the the first 400 ft. The carriage then coasted through ALDF which are described in the following sections.
the 1200-ft test section where the landing gear test article was tested on the runway surface. Finally, the Propulsion System test carriage engaged the arresting gear system and was brought to a stop within the last 600 f t of track. The propulsion system uses the stored energy of The versatility of the LLT has been demonstrated compressed air acting on water as a carrier medium over the years by a variety of test programs (refs. 5 to impart energy to the test carriage. The major through 17) ranging from taxi tests over runway components of the propulsion system shown in fig- lights to the tests of the Space Shuttle Orbiter nose ures 5 through 12 are the air storage tanks, the gear tires.
L-vessel, the internal nozzle, and the high-speed Most design features of the LLT catapult] car- shutter valve.
riage, and track rail system have been incorporated The air storage system consists of three tanks, a into the design of the new Langley Aircraft Land- manifold, and piping to the top of the L-vessel. Com- ing Dynamics Facility. In fact, the LLT test carriage pressed air is stored at a maximum system pressure has been retained as a second test carriage for the of 3150 psi in the three tanks which have a total of ALDF. The main drawback of the LLT was its lim- 4800 ft3 of air storage volume. Each tank feeds into ited speed capability. When the LLT facility became a manifold and then into a gooseneck-shaped pipe operational in 1955, the maximum speed capability of which carries the air to the top of the L-vessel. (See 110 knots was adequate to cover the landing speeds of fig. 8.)
most commercial]propeller-driven aircraft. With the The steel L-vessel has an 8-ft inside diameter] advent of the commercial jet aircraft in the 19601s, with a wall thickness of 7.25 to 9.5 in. It weighs a p landing speeds climbed above the speed limitation of proximately 720000 lb and is mounted to a massive the facility. This progressive increase in touchdown pile-supported concrete foundation. The L-vessel speeds is shown in figure 4 for several commercial air- contains 26 000 gal of potable water and can be pres- craft. Some military aircraft have touchdown speeds surized to 3150 psi. To accommodate an effective higher than those shown, especially when there are propulsion distance of 400 ft, the horizontal leg of failures in the flap or swing wing mechanisms. In the L-vessel is oriented upward 0.75O so that a slight addition, the Space Shuttle Orbiter lands at speeds upward water jet stream trajectory is produced. The between 190 and 220 knots. Thus, a facility up- water expelled during the catapulting process is con- date was required to enable testing at landing speeds tained initially in the horizontal leg of the Gvessel.
up to 220 knots which would cover all current and As high-pressure water moves out of the horizontal proposed aircraft. leg during the catapult process, it is replaced by the water initially contained in the vertical leg. This is done so that no water turned by the elbow section of Langley Aircraft Landing Dynamics the L-vessel flows out the nozzle and no air escapes Facility through the nozzle. The maximum water system flow rate during catapulting is 72 100 ft3/min at 3150 psi.
The major components built or refurbished for The stainless-steel internal nozzle, 18 in. in diam- the Langley Aircraft Landing Dynamics Facility are eter] is mounted to the end of the Gvessel as shown shown schematically in figure 5 and pictorially in in the photograph in figure 8. The nozzle provides figure 6. The new propulsion system utilizes a water jet concept similar to the original system. A new, a smooth contour from the end of the L-vessel and larger L-vessel with an 18-in-diameter nozzle and forms the 18-in-diameter water jet. The valve open- a high-speed shutter valve are mounted on a more ing is centered over the nozzle to give unobstructed massive foundation. A new test carriage, with a flow. The valve shown in figures 7 through 11 is a larger open bay, was constructed to withstand the high-pressure, quick-acting valve with a hydraulic- nitrogen actuation system. In figure 8, the high- water jet maximum thrust of 2200000 lb. The speed shutter valve is shown beside the L-vessel be- existing test track was extended 600 ft, resulting in a test section of 1800 ft, to provide additional test fore installation and the internal nozzle can be seen time at the higher speeds. A new arresting gear protruding from the end of the L-vessel. The valve system was installed to bring the carriage to a safe shown schematically in figure 9 consists of a spheri- stop within 500 ft. The calibration building was cal valve body, inner shutter, outer high-speed shut- rebuilt at the end of the extended track and a transfer ter] dual hydraulic actuator, linkage system, and system was modified to transfer either of the two associated control systems. The inner shutter and long, to facilitate testing of large test articles. At the valve body provide the primary pressure boundary rear of the carriage, a reaction bucket with a 104% and watertight seal for the valve. This seal allows opening captures the high-velocity jet of water from operational checkout of the high-speed shutter with- out losing water from the valve. During a typical the propulsion system. The reaction bucket turns the water jet approximately 177’ before releasing it catapult operation, the high-speed shutter seal is ac- rearward and downward away from the test carriage.
tuated and the pressure equalizer valve is opened At the front of the carriage is a nose block assem- to allow water to flow into the cavity between the bly which engages the five pendant cables that are shutters (equalizing pressure across the inner shut- ter). The inner shutter translates axially away from part of the arresting gear system. The nose block its sealing surface and rotates into the top of the is a segment of a cylinder, approximately 30 in. in radius and 5.5 f t high, with internal ring-stiffened valve body. The high-speed shutter seal is then re- tracted, and the high-speed shutter is opened by the bulkheads. Five V-shaped grooves on the face of the hydraulic actuator and linkage system. The high- cylinder catch the arresting cables. The entire nose speed shutter opens in approximately 0.4 sec, is held block structure is made of 0.25-in. steel and is welded open for the dwell time necessary to obtain the de- into a single unit.
sired carriage speed, typically less than l sec, and The test article drop carriage is shown at the then returned to the closed position in approximately top of the test carriage in figure 14. It is also 0.3 sec. The high-speed shutter opening and closing made of tubular quenched and tempered low alloy I .
J t - - & - I . . ’ - --
n-.n cmt tn mntml thp water 61IIlBS are 8 U J U ~ b c l U l G aut! uic. u b u u v VY------ ---- steel and i s located in the open test bay of the jet acceleration rate on the carriage. By controlling carriage. The test article, such as a landing gear the propulsion system pressure and the dwell time strut or a test tire mounted to a dynamometer, is of the fully open jet valve, the operator can mod- attached directly to a mounting flange on the drop ify both the peak acceleration and the velocity of carriage. The drop carriage with a dynamometer the carriage. At a maximum pressure of 3150 psi, weighs 14 000 lb. It travels vertically on four vertical the water jet will produce a thrust on the carriage rails with two hydraulic lift cylinders being used 200 OOO lb. With the new car- of approximately 2 to control the vertical motion. The drop carriage riage weight of approximately 108000 lb, this thrust can reach vertical velocities up to 20 ft/sec for tests creates a peak acceleration of approximately 209.
of landing gear systems, and simulated wing lift Figure 10 is a photograph of the high-speed shut- can be applied to the drop carriage just prior to ter valve fully assembled and ready for mounting tire touchdown. Four hydraulic load cylinders can prior to attachment on the L-vessel. The shutter be used to obtain additional vertical loading up to approximately 65000 lb on the test article. The valve linkage mechanism used for opening and closing the high-speed shutter is shown. Near the top of the hydraulic system is powered by onboard hydraulic accumulators. Solenoid valves are used to actuate the valve are the hydraulic and nitrogen supply system controls which regulate the pressure and flow of oil hydraulic system, to lower or raise the drop carriage, and nitrogen in the dual actuator which opens and and to apply vertical loading during a test run.
closes the high-speed shutter. These systems also The carriage wheel truck assemblies which pro- control the flow of oil to the inner shutter actuators vide vertical support and lateral restraint are located and several mechanical safety pins around the valve. at each corner of the carriage along with hold-down outriggers to prevent the carriage from lifting off the A water flow straightener mounted at the exit of track rails during catapulting. Additional hold-down the high-speed shutter valve is shown in figure 11.
As the high-speed shutter is in the process of being rails are located below the reaction bucket because opened, the developing water jet is deflected down- of the significant uplift that occurs during initial de- velopment of flow in the bucket while the valve is ward and the flow straightener redirects the water into the carriage reaction bucket. A photograph of opening. Once the carriage is arrested at the end of the carriage during a low-pressure catapult is shown the test run, an antirollback brake system located at in figure 12. The valve is fully open and a coherent jet the rear of the carriage prevents the carriage from can be seen shooting through the flow straightener. rolling backwards.
Electrical power on the carriage is provided by High-speed Test Carriage a pair of aircraft-type batteries. They are used to power the onboard cameras, data systems, and The high-speed test carriage shown in figure 13 electrical controls (e.g., solenoid valves). All carriage is a welded space truss structure made of seamless test data from onboard instrumentation are routed quenched and tempered low alloy steel tubes. The through a signal conditioner in the instrumentation carriage is 30 ft wide, 70 f t long, and 26 f t high. It box, identified in figure 13, and telemetered to a a centrally located open bay, 20 ft wide and 40 ft has recording station in the command center building. attach the pendant to the nylon tapes. The tapes (See section “Data Acquisition System” for more which are 8 in. wide, 0.344 in. thick, and 483 f t long informat ion. ) are shown after an arrestment in figure 21. The top and bottom edges of each tape are reinforced Track with extra nylon to accommodate wear and abrasion The ALDF track, as shown in figure 15, has a during the arrestment operation. Each tape is coated with a black resin polymer to resist the degrading total length of 2800 ft. The maximum effective jet effects of ultraviolet radiation and moisture.
propulsion distance is approximately 400 ft, and the The cable system has a minimum breaking strength of test section is 1800 ft, which allows for 5 sec of test 150000 lb.
time during a maximum speed test. The carriage Figure 22 is a photograph of one energy absorber arrestment section is 600 ft. A cross-sectional view before installation. Each absorber assembly consists of the track is given in figure 16.
of a tub, rotating shaft, and spool. The tub is filled The track rails are 6 in. square and are welded with a mixture of water and glycol as a work medium.
together forming one continuous rail. Each track rail Rotor vanes are located between top and bottom sta- is supported by chair units which restrain the rail tor vanes inside the tub and are connected to a rotat- along its length by friction clamping only allowing thermal expansion of the rail at each end. The chairs ing shaft which protrudes through the top of the tub.
are spaced 3 to 4 f t apart at random intervals on The spool is connected to the rotating shaft and the a pattern that repeats every 81 ft or after 22 chair nylon tapes are wound about the spool. The energy units. The purpose of this random support spacing absorbed in the carriage arrestment process is con- is to prevent buildup of harmonic frequencies that verted into heat and dissipated into the water/glycol mixture.
could excite the natural frequencies of the carriage.
The transfer dolly, shown in figure 17, is located The arrestment system is equipped with subsys- at the end of the track just ahead of the calibration tems that pretension the cable assemblies before ar- building. It is 72.5 f t long and is used to transport the restment such that the catenary deflection does not exceed 6 in. at the center of the track. A safety in- carriages from the calibration building to the main terlock system prevents the opening of the jet valve support building. The same tug which tows the test carriage back to the L-vessel after a run is used to unless arresting gear system parameters, such as ca- move the transfer dolly holding a test carriage. ble tension and position, and water levels and tem- perature in each turbine are within allowable limits.
Arrestment System Buildings A photograph of the carriage arrestment system is shown in figure 18 and a schematic of the sys- The control room for the ALDF is located on tem is shown in figure 19. The system is located the second floor of the command center building at approximately 600 ft from the calibration building the propulsion end of the track. (See fig. 6.) The at the end of the track. The major components of control console graphically displays all facility oper- the system include five independent sets of energy ational safety interlocks and houses all the controls absorbers. Each set of energy absorbers is connected needed for regulating the operating sequence of the by a cable/tape assembly. The system can routinely high-speed shutter valve. A process controller checks absorb 167000000 ft-lb of energy which is sufficient all safety interlocks just prior to valve actuation to energy-absorbing capability to successfully arrest the confirm that all systems are ready before a launch. A carriage in the event of a failure of any two sets of communications cystem consisting of a public address energy absorbers. system, intercom system, and portable handheld ra- The gantry tower, shown in figures 18 and 19, dios is used to secure the area of all but essential supports the five cables and is used to position the personnel prior to and during a test run. The instru- cable assemblies at the proper elevation for carriage mentation room, which is located on the first floor of nose block engagement. The gantry is also used to the command center building, contains the telemetry raise the cables above the maximum height of the receiving equipment and all the computer and record- carriage so that the test carriage can be towed the ing equipment necessary to reduce the data received entire length of the track without interfering with the from the test carriage and test article. (See section arrestment system.
“Data Acquisition System” for more information.)
Each cable assembly spanning the track consists The calibration and setup building, identified in of a steel wire pendant, as shown in figure 20. Each figures 5 and 6, is also a storage building for either f t long.
pendant is 1.25 in. in diameter and 100 carriage. A rail system to support the carriage, a test Special connectors, shown in figure 20, are used to a massive concrete structure for model assembly pit, calibration and drop tests, and an overhead crane The the carriage to photograph the test articles.
are contained in the building. General maintenance cameras on the carriage are contained in watertight service for the carriages and installation of test ar- boxes with plexiglass windows.
ticles can be performed in this building as well as carriage instrumentation calibration.
Concluding Remarks Data Acquisition System The Langley Aircraft Landing Dynamics Facility has been described. This unique facility, which be- The carriage onboard battery-powered instru- came operational during the summer of 1985, is ca- mentation system uses signal conditioners with a pable of testing various types of landing gear systems telemetry system for data transmission. The data at velocities up to 220 knots on a variety of runway system is versatile enough to accommodate a wide surfaces under all types of weather conditions. The range of sensors which are located on the carriage facility has a track 2800 ft long with a test section and send analog signals to the signal conditioners.
1800 ft long, which allows 5 sec of test time at maxi- The signals are amplified or attenuated and sent to mum speed. Test articles can be subjected to vertical an analog to digital (A-D) converter and then mul- loads of up to 65000 lb or sink rates of 20 ft/sec.
tiplexed (i.e., each channel is sampled and then sent This facility significantly increases the capability to one data channel). The multiplexed data are sent to conduct low-cost testing of conventional and ad- to the microwave transmitter and telemetered to the vanced aircraft landing gear systems. The capabil- g r w ~ d statinn in the inat~riimcntation room. The ities facilitate testing at speeds and sizes pertinent signal is demultiplexed and sent to a 2&megabyte, to large transport aircraft, fighter aircraft, and the 12-bit hard disc computer and to a digital to analog Space Shuttle Orbiter.
(D-A) converter. The computer processes 28 chan- nels of data directly and can provide output to a printer or multipen plotter. The digital data that NASA Langley Research Center goes to the D-A converter is recorded on an FM Hampton, Virginia 23665-5225 magnetic tape recorder. Magnetic tape data can be August 24, 1987 played into a multichannel galvanometer oscillograph system for quick-look purposes of the raw data. The system has a 1600/sec sample rate capability and ap- References proximately a 1-percent error on vertical, drag, and lateral load measurements. Speed measurements are 1. Joyner, Upshur T.; and Horne, Walter B.: Consid- accurate within f l knot.
erations on a Large Hydraulic Jet Catapult. NACA Forces developed by the test tire are measured by TN 3202, 1954. (Supersedes NACA RM L51B27.)
strain gauge load beams that make up the force dy- 2. Joyner, Upshur T.; Horne, Walter B.; and Leland, namometer as shown in figure 3 and schematically in Trafford J . W.: Investigations on the Ground Perfor- figure 23. The dynamometer has five beams measur- mance of Aircraft Relating to Wet Runway Braking and ing the axle loads with two in the vertical, two in the Slush Drag. AGARD Rep. 429, Jan. 1963.
fore-and-aft, and one in the lateral direction. The 3. Durand, W. F.: The Pelton Water Wheel. I- load transfer between the drag-load beams gives a Developments by Pelton and Others Prior to 1880.
measure of aligning torque, and the load transfer b e Mech. Eng., vol. 61, no. 6, June 1939, pp. 447-454.
tween the vertical-load beams gives a measure of the 4. Durand, W. F.: The Pelton Water Wheel. II- overturning torque. Torque links are used to measure Developments by Doble and Others, 1880 to Date.
the brake torque. Strain gauge type accelerometers Mech. Eng., vol. 61, no. 7, July 1939, pp. 511-518.
5. Dreher, Robert C.; and Batterson, Sidney A.: Landing are used to measure the axle acceleration along the and Taziing Tests Over Various Qpes of Runway Lights.
three axes so that inertial loads can be isolated. Typ- NACA RM L58C28a, 1958.
ically 10 channels of data are recorded from the dy- Batterson, Sidney A.: Investigation of the Mazimum 6.
namometer. Additional measurements include test Spin- Up Coefficients of Friction Obtained During Tests wheel vertical displacement, angular speed, and an- of a Landing Gear Having a Static-Load Rating of 20,000 gular acceleration together with carriage position and Pounds. NASA MEMO 12-20-58L, 1959.
velocity.
7. Batterson, Sidney A.: Braking and Landing Tests on Some New Qpes of Airplane Landing Mats and Mem- Photographic Coverage branes. NASA TN D-154, 1959.
High-speed motion picture cameras can be placed 8. Horne, Walter B.: Ezperimental Investigation of Spin- Up at various positions around the track, near the Friction Coefficients on Concrete and Nonskid Carrier- Deck Surfaces. NASA TN D-214, 1960.
propulsion and arresting gear systems, and onboard 9. Horne, Walter B.; Joyner, Upshur T.; and Leland, on Water, Slush or Ice. AIAA Paper No. 65-749, Trafford J. W.: Studies of the Retardation Force De- Nov. 1965.
veloped on an Aircraft Tire Rolling in Slush or Water. 14. Yager, Thomas J.: NASA Studies on Effect of Grooved NASA T N D-552, 1960. Runway Operations on Aircraft Vibrations and Tire 10. Dreher, Robert C.; and Batterson, Sidney A.: Coef- Wear. Pavement Grooving and lfaction Studies, NASA ficients of Friction and Wear Characteristics for Skids SP-5073, 1969, pp. 189-201.
Made of Various Metals on Concrete, Asphalt, and 15. McCarty, John Locke: Effects of Runway Grooving on Lakebed Surfaces. NASA TN D-999, 1962. Aircraft Tire Spin-Up Behavior. NASA T M X-2345, 11. Horne, Walter B.; and Leland, Trafford J . W.: Influence 1971.
of Tire Dead Pattern and Runway Surface Condition 16. Stubbs, Sandy M.; and Tanner, John A.: Status of Re- on Braking Friction and Rolling Resistance of a Modern cent Aircraft Braking and Cornering Research. Aircraft Aircraft Tire. NASA T N D-1376, 1962. Safety and Operating Problems, NASA SP-416, 1976, pp. 257-269.
12. Horne, Walter B.; and Dreher, Robert C.: Phenomena of 17. Vogler, William A.; and Tanner, John A.: Cornering Pneumatic Tire Hydroplaning. NASA T N D-2056, 1963.
Characteristics of the Nose-Gear Tire of the Space Shuttle 13. Horne, Walter B.; Yager, Thomas J.; and Taylor, Glenn Orbiter. NASA TP-1917, 1981.
R.: Recent Research on Ways To Improve Tire Traction Table 1. Comparison of Capabilities of LLT and ALDF Parameter Maximum test speed, knots . . . . . .
Length of- Overall track, f t . . . . . . . . . .
Test section, ft . . . . . . . . . . . 1200
2200 I
2800 622 I
Arrestment section, ft . . . . . . . .
Test duration at- 100 knots, sec . . . . . . . . . . .
220 knots, sec . . . . . . . . . . .
7 1 5 1 Propulsion system: 400 400 Maximum catapult stroke, ft . . . . .
2950 3150 Maximum pressure, psi . . . . . . .
7.16 18 Exit nozzle diameter, in. . . . . . . .
Water consumption, gal . . . . . . .
Carriage: Maximum carriage acceleration, g units on carriage . . . . . . . .
Maximum carriage deceleration,
1.1 2o 6 I
g units on carriage . . . . . . . .
Maximum catapult force 350 000 2 200 000 on carriage, lb . . . . . . . . . .
10 x 15 20 x 40 Open bay size, f t . . . . . . . . . .
Maximum vertical velocity ~ &20 0-20 of test article, ft/sec . . . . . . . .
Maximum vertical load on
' &45 000 65000 at 200 knots
test article, lb . . . . . . . . . .
>65 000 at lower speeds
I
Table 2. ALDF Component Specifications Propulsion system: L-vessel:
Inside diameter, ft . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Wall thickness, in. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.25-9.5
Exit nozzle diameter, in. . . . . . . . . . . . . . . . . . . . . . . . . . 18
Weight, lb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 720 000
Concrete foundation thickness, f t . . . . . . . . . . . . . . . . . . . . . 12
Maximum operating pressure, psi . . . . . . . . . . . . . . . . . . . . . 3150
Maximum flow rate, ft3/min . . . . . . . . . . . . . . . . . . . . . . . 72 100
Maximum force on carriage, lb . . . . . . . . . . . . . . . . . . . . . . 2 200 000
Water reservoir, gal . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 000
Maximum water jet velocity, ft/sec . . . . . . . . . . . . . . . . . . . . 680
Gooseneck pipe inside diameter, f t . . . . . . . . . . . . . . . . . . . . . 4
Shutter valve:
Opening, in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Opening time, sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.38-0.4
Closing time, sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3
Dwell time, sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.40-0.86
Carriage:
Weight, lb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 000
Dimensions, ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 x 70 x 26
Open bay, f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 x 40
Drop carriage weight, lb . . . . . . . . . . . . . . . . . . . . . . . . . . 14 000
Maximum vertical load on test article, lb . . . . . . . . . . . . . . . . . . . 65000
Maximum vertical velocity of test article, ft/sec . . . . . . . . . . . . . . . . 20
Maximum test speed, knots . . . . . . . . . . . . . . . . . . . . . . . . 220
Maximum acceleration, g units on carriage . . . . . . . . . . . . . . . . . . 20
Maximum deceleration, g units on carriage . . . . . . . . . . . . . . . . . . 6
Track:
Catapult section, ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
Test section, ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1800
Arrestment section, ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . 600
Total length, f t . . . . . . . . . . . . . . . . . . - . . .. . . . . . . . . . . 2800
Test track runway foundation:
Thickness, ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5
Width,ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Arrestment system:
Maximum energy absorption, ft-lb . . . . . . . . . . . . . . . . . . . . 167 000 000
Maximum stopping distance, f t . . . . . . . . , . . . . . . . . . . . . . . . 545
Cable:
Diameter, in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.25
Length,ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Minimum breaking strength, lb . . . . . . . . . . . . . . . . . . . . . . . 150 000
Tape belt:
Width,in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Thickness, in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.344
Length,ft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
Minimum breaking strength, lb . . . . . . . . . . . . . . . . . . . . . . . 150000
ORIGINAL PAGE T S OF POOR QTJALTTY
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L a , cn .- T I & a , U m x m rr ORIGINAL PAGE I S OF POOR QUALITY E v .e c d E M , Report Documentation Page 2. Government Accession No.
. Report No. 3. Recipient's Catalog No.
NASA RP-1189 5. Report Date October 1987 6. Performing Organization Code . Author(s) 8 . Performing Organization Report No.
Pamela A. Davis, Sandy M. Stubbs, and John A. Tanner L-16293 10. Work Unit No.
'. Performing Organization Name and Address 505-63-41-02 NASA Langley Research Center 11. Contract or Grant No.
Hampton, VA 23665-5225 13. Type of Report and Period Covered 2. Sponsoring Agency Name and Address Reference Publication National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, DC 20546-0001 5. Supplementary Notes 6. Abstract The Langley Research Center has recently upgraded the Landing Loads Track (LLT) to improve the capability of low-cost testing of conventional and advanced landing gear systems. The unique feature of the Langley Aircraft Landing Dynamics Facility (ALDF) is the ability to test aircraft landing gear systems on actual runway surfaces at operational ground speeds and loading conditions. A historical overview of the original LLT is given, followed by a detailed description of the new ALDF systems and operational capabilities.
17. Key Words (Suggested by Authors(s)) 18. Distribution Statement Langley Aircraft Landing Dynamics Facility Unclassified-Unlimited Landing gear test Runway surface test Subject Category 09 121. NO. of Pages 122. Price 19. Security Classif.(of this report) 20. Security Classif.(of his page) -
1 A03
Unclassified Unclassified I NASA FORM 1626 OCT 86 NASA-Langley, 1987 For sale by the National Technical Information Service, Springfield, Virginia 22161-2171