Landing gear

About: Landing gear is a research topic. Over the lifetime, 3403 publications have been published within this topic receiving 25370 citations. The topic is also known as: landing gear & gear.

Implementation of tonal cavity noise estimations in landing gear noise prediction models

Abstract: Landing gear noise is considered the dominant airframe noise source on aircraft during approach. Previous studies indicated the presence of a strong tonal sound on flyovers of several commercial aircraft types, and suggested that it was caused by the interaction of open cavities in the nose landing gear (NLG) system with the flow. Airframe noise prediction models, however, do not account for parasitic noise sources, such as cavities, which can lead to severe underpredictions of the noise levels generated by NLG systems. In this paper, a method to improve the well–known landing gear noise prediction methods of Fink and Guo is suggested. The study is based on aircraft flyover measurements performed with a microphone array which, together with acoustic imaging techniques, allows for the separation of the noise emissions coming from the NLG. Flyover recordings from several Airbus A320 aircraft under operational conditions are analyzed and, based on the tonal frequency observed, potential cavity dimensions are suggested. The sound pressure levels of the narrowband tones were found to scale with approximately the 9th power of the airspeed. A simple correction formula for accounting for this type of cavity noise in the prediction models, depending on the aircraft velocity, is proposed. By applying this correction, the overall noise level predictions of the updated noise models become more accurate, reducing their average difference with the experimental data from 5 dB to just 1 dB.

Safety forced landing device

Abstract: PROBLEM TO BE SOLVED: To make soft landing possible of an aircraft without extending a landing gear at landing time. SOLUTION: In a safety forced landing device, an air bag 2 and a carriage 4 are used to serve as a principal constitutional element. In a lower part of the carriage 4, wheels 5 are mounted. Needless to say, a quantity, position and a structure of the wheel are determined so as to endure weight of a jumbo aircraft and a shock at landing time. The air bag 2 has strength resisting against kinetic contact friction of an aircraft 1, to be made by, for instance, waterproof cloth, wear resistant sheet, etc. While watching by a driver a mirror 10 in an upper part of a driver's room 7 provided in a tip end of the carriage 4, its speed and running direction can be matched with that of an approaching aircraft. The running direction is determined by a steering wheel 8. Propulsive force of the carriage is obtained from each engine 6 connected to each wheel 5 through a propeller shaft. The air bag 2 may be formed as a water bed method water pillow type.

Aircraft landing gear control

Abstract: This invention relates to retractable landing gear for aircraft and is directed particularly to an improved safety control system and switch through which the landing gear is actuated. In conventional landing gear systems of the type which are now commonly in use, a master control switch is...

Multibody rigid models and 3D FE models in numerical analysis of transport aircraft main landing gear

Abstract: Dynamic analyses of a transport aircraft landing gear are conducted to determine the effort of such a complex system and provide capabilities to predict their behaviour under hazardous conditions. This kind of investigation with the use of numerical methods implementation is much easier and less expensive than stand tests. Various 3D models of the landing gear part are defined for the multistage static FE analysis. A complete system of the main landing gear was mapped as a deformable 3D numerical model for dynamic analysis with the use of LS-Dyna code. In this 3D deformable FE model, developed in a drop test simulation, the following matters were taken into consideration: contact problems between collaborating elements, the phenomena of energy absorption by a gas-liquid damper placed in the landing gear and the response of the landing gear during the touchdown of a flexible wheel with the ground. The results of numerical analyses for the selected drop tests and the results from the experiments carried out on a real landing gear were used for verification of FE models and a methodology of the landing gear dynamics analysis. The results obtained from the various simulations of the touchdown have proved the effectiveness of the 3D numerical model and how many problems can be solved in the course of only one numerical run, e.g. geometric and material nonlinearities, a question of contact between the mating components, investigation of the landing gear kinematics, investigation of the energy dissipation problem in the whole system and the stresses influence on the structure behaviour, which can appear in some elements due to overload.