A study of the effects of Rotating Frame Turbulence (RFT) on helicopter flight mechanicsThe turbulence actually experienced by a helicopter blade-element significantly differs from the space-fixed free atmospheric turbulence. The turbulence in the rotor disk requires a rotationally sampled description in a rotating frame of reference. It is referred to as the rotating frame turbulence or RFT which exhibits a striking phenomenon. The RFT spectral density versus frequency shows high peak values at 1P,2P, or 3P, frequencies. The energy increase at these peaks is balanced by an energy decrease primarily at the lower-than-1P frequency range. Particularly for low altitude flight regimes of pure helicopters, such as the nap-of-the-earth maneuvers, the conventional space-fixed description of turbulence is not a good approximation, since the turbulence scale length can have values comparable to the rotor radius. Accordingly the flight mechanics characteristics with RFT description are compared with those based on the conventional space-fixed turbulence description. The results demonstrate that the RFT qualitatively and quantitatively affects the prediction of helicopter flight mechanics characteristics in turbulence. Such comparisons should play an important role in the new development of handling qualities specifications for helicopters.
Document ID
19900005742
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Schrage, D. P. (Georgia Inst. of Tech. Atlanta., United States)
Prasad, J. V. B. (Georgia Inst. of Tech. Atlanta., United States)
Gaonkar, G. H. (Florida Atlantic Univ. Boca Raton., United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1989
Publication Information
Publication: AGARD, Flight in Adverse Environmental Conditions