Accession Number : ADA305456

Title :   The Design, Qualification and Maintenance of Vibration-Free Landing Gear (La Conception, la Qualification et la Maintenance des Trains d'Atterrissage sans Vibration).

Corporate Author : ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE)

PDF Url : ADA305456

Report Date : MAR 1996

Pagination or Media Count : 151

Abstract : Aircraft landing gears are crucial for safety, comfort (both for passengers and pilots) and for weight considerations. As the element responsible for safely moving the aircraft on the ground, the landing gear has to fulfill several, sometimes conflicting, requirements. Landing gears that shimmy (shimmy can be defined as a self-excited instability during take-off, landing or taxiing, involving up to three vibration motions: angular wheel motions about a vertical axis - yaw -, and a fore and aft axis - roll -, and lateral displacement of the wheel) are unacceptable. In fact, a severe occurrence of shimmy can damage the landing gear and its attaching structure, resulting in significant repair costs and airplane down time. Some assurance is therefore needed that landing gear designs will be free from shimmy under all operating conditions including the normal wear and tear experienced in service. One of the difficulties of shimmy analysis is that real landing gear systems exhibit many non-linear characteristics. Tests on life-size aircraft are obviously expensive and risky, and tests on test-rigs (namely drop-test facilities) allow only for limited information about the landing gear's dynamics; the interaction between aircraft and landing gear is especially difficult to assess. On the other hand, simulation offers a means to examine the behaviour of the landing gear as part of a complex system at a reasonable cost. Both rigid and elastic body motions can be modelled.

Descriptors :   *VIBRATION, *AERODYNAMIC STABILITY, *LANDING GEAR, SIMULATION, SYSTEMS ENGINEERING, YAW, AIRCRAFT MAINTENANCE, DYNAMICS, EXCITATION, PILOTS, ELASTIC PROPERTIES, MOTION, PROBLEM SOLVING, COSTS, NONLINEAR SYSTEMS, REPAIR, VERTICAL ORIENTATION, WEAR, WHEELS, FRENCH LANGUAGE, SELF OPERATION, LANDING AIDS, OSCILLATION, RIGIDITY, INSTABILITY, PASSENGERS, AIRCRAFT LANDINGS, ANGULAR MOTION, DOWNTIME, TAXIING.

Subject Categories : Aerodynamics
      Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE