Showing papers on "Landing gear published in 1990"

Hypersonic Aerospace Sizing Analysis for the Preliminary Design of Aerospace Vehicles

Abstract: A review of the hypersonic literature indicated that a general weight and sizing analysis was not available for hypersonic orbital, transport, and fighter vehicles. The objective here is to develop such a method for the preliminary design of aerospace vehicles. This report describes the developed methodology and provides examples to illustrate the model, entitled the Hypersonic Aerospace Sizing Analysis (HASA). It can be used to predict the size and weight of hypersonic single-stage and two-stage-to-orbit vehicles and transports, and is also relevant for supersonic transports. HASA is a sizing analysis that determines vehicle length and volume, consistent with body, fuel, structural, and payload weights. The vehicle component weights are obtained from statistical equations for the body, wing, tail, thermal protection system, landing gear, thrust structure, engine, fuel tank, hydraulic system, avionics, electral system, equipment payload, and propellant. Sample size and weight predictions are given for the Space Shuttle orbiter and other proposed vehicles, including four hypersonic transports, a Mach 6 fighter, a supersonic transport (SST), a single-stage-to-orbit (SSTO) vehicle, a two-stage Space Shuttle with a booster and an orbiter, and two methane-fueled vehicles.

F-106B airplane active control landing gear drop test performance

Abstract: Aircraft dynamic loads and vibrations resulting from landing impact and from runway and taxiway unevenness are recognized as significant factors in causing fatigue damage, dynamic stress on the airframe, crew and passenger discomfort, and reduction of the pilot's ability to control the aircraft during ground operations. One potential method for improving operational characteristics of aircraft on the ground is the application of active control technology to the landing gears to reduce ground loads applied to the airframe. An experimental investigation was conducted on series-hydraulic active control nose gear. The experiments involved testing the gear in both passive and active control modes. Results of this investigation show that a series-hydraulic active control gear is feasible and that such a gear is effective in reducing the loads transmitted by the gear to the airframe during ground operations.

Landing gear for a tail sitting airplane

Abstract: A tail sitter aircraft of a type that takes off and lands on its tail section with the fuselage pointed vertically upward has landing gears located on its rearward end. Each of the landing gears is mounted on a support axis which is offset from the fuselage axis and which intersects a wheel axle at a 90 degree angle. The landing gears are located on the tail section and spaced around the fuselage axis. Two of the landing gears which are opposite each other will be locked so that they can roll only along a single straight line. The other two landing gears, which are also spaced opposite each other, are locked so that they can roll only on a single straight line. The straight lines are perpendicular to each other.

Aircraft landing gear having wheels that swivel while the landing gear is being retracted

Abstract: The landing gear of the invention comprises a strut in which a sliding rod slides, the strut and the sliding rod are connected to each other by a scissors linkage having a top branch and a bottom branch which are connected to each other by articulated means capable of moving between a folded position in which the branches of the scissors linkage are adjacent to each other, and an unfolded position in which the branches of the scissors linkage are moved apart from each other, thereby causing the sliding rod to pivot about its own axis.

Aircraft tractor without tow-bar

Abstract: The present invention pertains to an aircraft tractor without tow-bar. The arrangement avoids relative movement between the nose wheel of the aircraft and the tractor lifting platform by making the lifting platform (24) rotatable around a longitudinal axis (30) of the chassis, which axis is horizontal when the chassis is extended, and by making displaceable the transverse tow arms (38) and/or the holders (42) at right angles to this longitudinal axis (30). The tires of an oblique nose wheel landing gear of an aircraft being towed in a curve are handled very gently, because the tractor parts (24, 38, and 42) that are in contact with the nose wheel landing gear are able to follow the movements of the nose wheel landing gear and to adjust to its instantaneous position.

Raisable landing gear

Abstract: A retractable landing gear is arranged so as to provide, in use, a highly inclined shock absorber while avoiding high shearing stresses on the shock absorber. The landing gear includes a pivoting panel fixed to an aircraft structure to pivot about a raising axis; a shock absorber including a strut fixed to the pivoting panel so as to pivot relative thereto about a tilt axis, and a sliding rod mounted to slide in the strut and carrying a set of wheels at its bottom end; and a coupling member connected to the pivoting plate and to the bottom end of the sliding rod. Also included is a mechanism for raising and holding the landing gear.

Aircraft landing gear systems

Abstract: Topics presented include the laboratory simulation of landing gear pitch-plane dynamics, a summary of recent aircraft/ground vehicle friction measurement tests, some recent aircraft tire thermal studies, and an evaluation of critical speeds in high-speed aircraft. Also presented are a review of NASA antiskid braking research, titanium matrix composite landing gear development, the current methods and perspective of aircraft flotation analysis, the flow rate and trajectory of water spray produced by an aircraft tire, and spin-up studies of the Space Shuttle Orbiter main gear tire.

Twin-rotor synchropter helicopters, with variable position of the engine central unit

Abstract: Two-seat, light, medium or heavy combat and reconnaissance twin-rotor synchropter helicopters, using the CdG to pilot and also to alter the position of the engine unit on the fuselage, between the cabin 1 with vertical-scanning radar 2, and the empennage with a ducted-fan turbine-engine unit 5 and an air-air or ground-air missile launcher 4. The panoramic radar 3 is in flight position. Under the engine central unit two motor cycles 8 are suspended when the main landing gear is in low position 6 and the landing gear well 7 open.

Aircraft arresting system and method

Abstract: An aircraft arresting system providing a controlled, gradual aircraft deceleration is disclosed. The system includes an arresting barrier comprised of a triggering net/parachute combination. The triggering net is aligned transversely to the runway and is actuated by contact with the aircraft nose landing gear. An engaging cable, releasably retained on the triggering net, is then thrust upwardly to entangle the aircraft main landing gear. A pair of parachutes, attached to the engaging cable, are deployed as a result of the continued aircraft motion. Once deployed, the parachutes provide the desired gradual decelerative force to slow the aircraft. The preferred embodiment of the aircraft arresting system includes three arresting barriers spaced a distance longitudinally on the runway to provide a reliable aircraft engagement and a controlled rate of arrest. An associated method is disclosed wherein the rate of arrest of the aircraft is determined after deployment of the first set of parachutes, and the second or third barriers deployed to provide a greater rate of arrest when desired.

Contour lounger with floor-contacting landing gear

Abstract: A contour lounger with floor-contacting landing gear is disclosed which provides rocking and reclining capability. The contour lounger is constructed of a standard legless rocking chair and has added thereto a footrest, footrest linkage, a landing gear, and landing gear linkage.

A theoretical and experimental investigation into the prerotation ofaircraft tires

Abstract: Excessive tire wear due to the spin-up of tires a t landing has forced NASA to abandon space shuttle landings on the concrete runway at the Kennedy Space Center in favor of the dry lake beds of Edwards Air Force Base. This cxccssive tire w a r , causcd by large landing speeds and tire loads, will likely gct worse with the even heavier and faster aircraft of the next century such as the National Aerospace Plane. This paper investigates the feasibility of using the frcestream air flow around the lowered 1;mding gear of an aircraft to acrodynamically rotate tha t aircraft's tires prior to landing; thus reducing wear on the tires. Wind tunnel expcrimcnts were performcd on a model whcel and the results scaled to predict shuttle wheel performance. The experimentation and aualysis showed that aerodynamic inducement of rotation prior t o landing is a feasible option for the space shuttle and may rcsult in a 50% rcduction of tire wear. Such a reduction would enable the shuttle to resume la,ndings at the Kennedy Space Center. Various references indicate that the prerotation devices might find useful application in commercial aviation through thc reduction of landing gear strut dynamic loads, runway pollution, and tire wear. Finallv. these devices could liavc a rolc in allcviating the AFI

Advanced Technology Landing Gear. Volume 2. Test

Abstract: : This report describes the development of retractable, crashworthy, main landing gear system for an LHX-size helicopter. The landing gear is of a tricycle configuration and is designed to absorb 60 percent of the energy from a 42 fps level impact condition. The landing gear extends automatically in less than two seconds in an emergency. In the event that the hydraulic and electrical systems fail, the gear is extended with the hydraulic accumulator that primarily supports the helicopter APU. Five sets of landing gears were fabricated in the program. The tests included single-gear platform drop tests with level and simulated roll and pitch conditions, and combined pitch (+15 deg) and roll (10 deg) conditions with an iron-bird fixture simulating a helicopter. The tests were conducted for five impact velocities from 10 to 42 fps. The crashworthiness analyses were conducted using program KRASH. The correlation between test and crashworthiness analysis results was very good and demonstrated how analyses can be used to predict the response of landing gears without utilizing expensive tests. The cost of 5000 shipsets over a 13-year production cycle has been projected from the cost of landing gears fabricated in this program. (Author) (KR)

A computer module used to calculate the horizontal control surface size of a conceptual aircraft design

Abstract: The creation of a computer module used to calculate the size of the horizontal control surfaces of a conceptual aircraft design is discussed. The control surface size is determined by first calculating the size needed to rotate the aircraft during takeoff, and, second, by determining if the calculated size is large enough to maintain stability of the aircraft throughout any specified mission. The tail size needed to rotate during takeoff is calculated from a summation of forces about the main landing gear of the aircraft. The stability of the aircraft is determined from a summation of forces about the center of gravity during different phases of the aircraft's flight. Included in the horizontal control surface analysis are: downwash effects on an aft tail, upwash effects on a forward canard, and effects due to flight in close proximity to the ground. Comparisons of production aircraft with numerical models show good accuracy for control surface sizing. A modified canard design verified the accuracy of the module for canard configurations. Added to this stability and control module is a subroutine that determines one of the three design variables, for a stable vectored thrust aircraft. These include forward thrust nozzle position, aft thrust nozzle angle, and forward thrust split.