Showing papers on "Landing gear published in 1974"

Airplane landing gear shock absorber

Abstract: An aircraft landing gear shock absorbing strut of the telescopic pneumatic/hydraulic type having a two stage pneumatic spring, with one stage only functioning during the absorption of landing impact, and both stages functioning during taxiing. The strut includes improved means for controlling its damping characteristics such that its motion during the initial landing impact and subsequent rebound is heavily damped, but motion during taxi is damped to a lesser degree providing a more comfortable ride while taxiing.

Two-speed trailer landing gear safety arrangement

Abstract: A two-speed landing gear arrangement for high and low speed operation thereof including a landing gear drive shaft having a high speed detent position and a low speed detent position, a landing gear handle having a handle shaft in longitudinal abutting relation with the landing gear shaft, a coupler housing surrounding and slidably disposed in reciprocable relation on the abutting ends of the handle shaft and the landing gear shaft, the handle shaft having axially spaced drive dogs each mounted by a shear pin and respectively received in an opposed square interlocking recess in the outer end of the housing, said housing at the inner end thereof having a slotted portion with an inner end part in abutting relation with a fixed portion of the landing gear, the outer end of the landing gear shaft having an outer end including a landing gear pin therethrough in lost motion coupleable relation with the slotted portion and further including a slide portion outwardly of the pin cooperative with a reduced bore in the housing, a detent groove on the handle shaft outwardly of the drive dogs and cooperative with a detent means in the outer end of the housing for limiting longitudinal reciprocable movement of the handle shaft with respect to the housing during pulling out of the landing gear crank handle whereby pushing of the handle into the landing gear pushes the landing gear in low gear through the low gear shear pin in the low gear driving dog and pulling out of the landing gear crank handle causes high gear drive of the landing gear through the high gear shear pin in the high gear driving dog.

Landing gear truck pitch damping

Abstract: A device for damping the post-landing angular oscillations of the bogie or axle beam on a multi-wheel bogie-type aircraft landing gear. The device employs a sensor for sensing rotational motion of the bogie about its pivotal mount on the landing gear shock strut and supplying a hydraulic pressure proportional to any such rotation to a frictional braking mechanism which acts to damp out the motion.

Preliminary measurements of aircraft aerodynamic noise

Abstract: Flight measurements of aerodynamic noise were made on an AeroCommander airplane with engines off and a JetStar airplane with engines at both idle power and completely shut off. The overall sound level for these airplanes in the landing configuration varied as the sixth power of the aircraft velocity. For the JetStar airplane, the overall sound level decreased as the inverse square of the distance in the lateral direction. The aerodynamic noise was approximately 11 decibels below the FAR Part 36 noise level for the JetStar airplane. The landing gear were a significant contributor to aerodynamic noise for both aircraft.

Retractable landing gear

Abstract: A retractable landing gear assembly capable of being mounted as a unit in a wing of a model aircraft, including a relatively movable cam and cam follower to operate the landing gear between its fully retracted and full down and locked position, and wherein the same includes means to move and retain the landing gear in its full down and locked position.

Drop Testing Naval Aircraft and the VSD Landing Gear Dynamic Test Facility

Abstract: This paper describes a laboratory facility developed by Vought Systems Division (VSD) of LTV Aerospace Corp. and techniques used to realistically simulate landings of full scale aircraft under precisely controlled conditions. Capabilities are included to evaluate effects of running over deck obstructions during carrier landings or other types of bumps that might be encountered in rough field operations of aircraft. The project provided VSD with the most accurate method known for dynamic simulation of aircraft landings and safe evaluation of the structural adequacy of airframes and landing gear systems for landing loads. Operational characteristics of the facility are predictable and repeatable. A deck obstruction or bump can be repeatedly passed under the landing gear wheel within */2 in. of any preselected point in the stroke of a landing gear strut at any sink speed or landing velocity to 120 knots. Tests performed in the facility have shown that running over a bump can increase both main gear and nose gear loads significantly and can also result in tires being cut and rims bent at lower sink speeds than previously anticipated. Comparison of data shows the laboratory data to be characteristic of flight test data.

Landing gear foot

Abstract: A landing gear foot pivotally mounted at the lower end of a vehicle landing gear leg. The landing gear foot comprises a body having a curved outer surface, two spaced apart bearing journals having aligned axes, and two gusset plates, each connecting a different one of the bearing journals to the curved body. An aperture is formed through the curved body between the gusset plates. The landing gear foot is pivotally connected to the landing gear leg proximate the free end thereof by means of the bearing journals and appropriate shafts.

Airframe noise - The next aircraft noise barrier

Abstract: Progress in quieting the commercial aviation fleet has been achieved by reducing the noise generated by jet engines. Recent tests have indicated that noise produced by airflow over aircraft surfaces (lifting surfaces, landing gear, flaps, and cavities) is only 8 to 10 EPNdB below certification requirements for current aircraft and will likely be a design consideration for aircraft of the future as engines become still quieter. This paper reviews the state of the art for understanding, predicting, and control of airframe noise. Levels and spectral content of the noise, correlation with important variables, and noise generation mechansims are discussed. The noise floors for future aircraft, the direction of research projects, and likely impact of this new technology on aircraft design are indicated.

Landing gear position simulator

Abstract: A self-contained, landing gear position simulator for use in an aircraft includes first and second panels oriented in different planes. Five lamps and a manually operable switch are mounted on the first panel and four manually operable switches are mounted on the second panel. When the switch on the first panel is moved to a first position to simulate a control action of retracting the aircraft landing gear, a first lamp on the first panel is lighted, and when the switch is moved to a second position to simulate a control action of extending the aircraft''s landing gear, the first lamp is extinguished and second, third and fourth lamps are lighted. When one of the four switches on the second panel is operated, a corresponding one of the first, second, third or fourth lamps is prevented from being lighted. The simulator also includes apparatus responsive to a predetermined air speed indication of the aircraft for lighting a fifth lamp.

Drop testing naval aircraft and the VSD landing gear dynamic test facility

Abstract: This paper describes a laboratory facility developed by Vought Systems Division (VSD) of LTV Aerospace Corp. and techniques used to realistically simulate landings of full scale aircraft under precisely controlled conditions. Capabilities are included to evaluate effects of running over deck obstructions during carrier landings or other types of bumps that might be encountered in rough field operations of aircraft. The project provided VSD with the most accurate method known for dynamic simulation of aircraft landings and safe evaluation of the structural adequacy of airframes and landing gear systems for landing loads. Operational characteristics of the facility are predictable and repeatable. A deck obstruction or bump can be repeatedly passed under the landing gear wheel within */2 in. of any preselected point in the stroke of a landing gear strut at any sink speed or landing velocity to 120 knots. Tests performed in the facility have shown that running over a bump can increase both main gear and nose gear loads significantly and can also result in tires being cut and rims bent at lower sink speeds than previously anticipated. Comparison of data shows the laboratory data to be characteristic of flight test data.

Combat Traction II, Phase II. Volume I, Narrative

Abstract: : A sensitivity analysis of airplane braking distance was conducted on a hardware-analog brake control simulator for the Boeing 727-200, 737 Advanced, and 747-200, the Lockheed C-141A, and the McDonnell F-4E aircraft. Parameters affecting braking distance by at least 2% were identified. With the application of dimensional analysis, these parameters were arranged in dimensionless groups, and a braking distance prediction equation was developed for each airplane. A new methodology for predicting airplane braking distance is recommended, based on a dimensional equation, a suitable ground friction prediction system, and accurate weather data.

Helicopter Movement on Unimproved Terrain.

Abstract: : A brief review is presented of the current state of the art of criteria for determining the ground-flotation requirements for landing gear of aircraft, particularly fixed-wing aircraft, and criteria for estimating cross-country performance of military vehicles. Discussions are also presented of three soil strength parameters: California Bearing Ratio (CBR), airfield index (AI), and cone index (CI). Results of tests with three helicopter tires in prepared and natural soils are presented, and relations are shown among soil strength, towed motion resistance of some assumed helicopter configurations, and maximum-drawbar-pull capabilities of selected ground vehicles. Also presented is the distribution of terrain factors mapped in a selected West German transect and the probability of moving helicopters over the terrain. (Modified author abstract)

Landing Gear/Soil Interaction Development of Criteria for Aircraft Operation on Soil During Turning and High Speed Straight Roll

Abstract: : The continuing design and operational requirements for military aircraft to operate on unimproved runways has led to the need to investigate those landing gear/soil runway parameters which most significantly influence performance. This report summarizes those activities accomplished during the first year of a two-year research effort concerned with the development of criteria for turning, operation at high speed, and multi-pass operation. The work accomplished consisted primarily of a comprehensive investigation of the turned aircraft tire/soil interaction effects and how these effects should influence future criteria for aircraft turning operations on soil runways.

Experimental investigation of the landing dynamics of three-legged spacecraft models

Abstract: An experimental investigation was conducted to obtain accurate data from two three-legged spacecraft landing systems for purposes of validating current and future computer programs for legged landers. Two landing-gear systems were investigated: an inverted tripod system and a cantilever system. Tests were conducted for eight landing conditions chosen to obtain stability data, maximum loads, and maximum strokes for correlation with analytical results. Data from the two models are not directly comparable because of geometry and mass differences, but both are considered to be typical models of the respective landing-gear systems. Results indicate that maximum accelerations for both models, which occurred during a nearly flat landing on a horizontal surface, were nearly the same (approximately minus 18g). Maximum primary strut forces occurred for landings into a 20 deg slope and were 40 kiloNewtons (9000 lbf) and 47 kiloNewtons (10 500 lbf) for the inverted tripod and cantilever models, respectively; and maximum primary strut strokes for both models were 19 cm (7.4 in.). The inverted tripod model was slightly more stable than the cantilever model because of a larger ratio of footpad radius to center-of-gravity height.

Surface Effect Takeoff and Landing System (SETOLS)

Abstract: : An ARPA Program Report on its program to develop the surface effect takeoff and land system (SETOLS) for high performance naval carrier-based aircraft. The report discusses the program's back-ground and technical need, the detailed plan to develop and demonstrate the technique, the program results, allocated resource levels, the contractor's performance and the program's impact.

Laboratory Method for Evaluating Effect of Runway Grooving on Aircraft Tires.

Abstract: : The development of a laboratory technique which simulates an airplane operational touchdown on an existing representative grooved runway landing area is described. The laboratory technique demonstrates that chevron cutting of a 49 inch x 17 inch size tire (KC135, B727) landing on a dry 1/4 inch x 1/4 inch x 1 inch grooved concrete pavement slab is obtained which is representative of tire damage currently being experienced during airplane landings on grooved runways. A computer program is developed and used to analyze the method of approach and test results. Government and industry furnished tires, and eight different pavement configurations were tested. High speed motion pictures indicate that cutting occurs at the initial point of contact wherein speed is at a maximum. The test data is analyzed with regard to potentially critical parameters including energy absorption, forward velocity, and number of grooves traversed. (Modified author abstract)