A Simulation Model for Computing the Loads Generated at Landing Site During Helicopter Take-Off or Landing Operation

Abstract

Summary The paper presents simulation method and results of calculations determining behavior of helicopter and landing site loads which are generated during phase of the helicopter take-off and landing. For helicopter with whirling rotor standing on ground or touching it, the loads of landing gear depend on the parameters of helicopter movement, occurrence of wind gusts and control of pitch angle of the rotor blades. The considered model of helicopter consists of the fuselage and main transmission treated as rigid bodies connected with elastic elements. The fuselage is supported by landing gear modeled by units of spring and damping elements. The rotor blades are modeled as elastic axes with sets of lumped masses of blade segments distributed along them. The Runge-Kutta method was used to solve the equations of motion of the helicopter model. According to the Galerkin method, it was assumed that the parameters of the elastic blade motion can be treated as a combination of its bending and torsion eigen modes. For calculations, data of a hypothetical light helicopter were applied. Simulation results were presented for the cases of landing helicopter touching ground with different vertical speed and for phase of take-off including influence of rotor speed changes, wind gust and control of blade pitch. The simulation method may help to define the limits of helicopter safe operation on the landing surfaces.

Vibroacoustic Helicopter Impact on Elevated Helipad

“…For example, the influence of the main rotor causes turbulent airflow [2] resulting in the helipad vibration [3] as well as the acoustic phenomena accompanying the main rotor operation. the Łukasiewicz research Network -Institute of Aviation conducts research on the aerodynamic impact of the helicopter on the helipads [4] and vibrations excited by the helicopter, as well as acoustic measurements. this paper contains selected results of research on helicopter vibroacoustic impact on the elevated helipad located on the building roof.…”

Fatigue Crack Propagation Estimation Based on Direct Strain Measurement during a Full-Scale Fatigue Test

“…The most comprehensive fatigue test is the actual usage, but due to possible critical damage FSFT are commonly used in order to predict any possible cracking [10][11][12][13] before the aircraft is certified to roll out. As with most tests FSFT is a representation of the actual service load conditions [14,15] and simplifies the complexity of the actual load spectrum by neglecting some effects. Moreover, due to discrete load application FSFT may cause some local effects that are absent from actual service.…”