Papers Published

  1. Quackenbush, Todd R. and Bliss, Donald B. and Wachspress, Daniel A., New free-wake analysis of rotorcraft hover performance using influence coefficients, Journal of Aircraft, vol. 26 no. 12 (1989), pp. 1090 - 1097 .
    (last updated on 2007/04/09)

    Abstract:
    Free-wake analyses of helicopter rotor wakes in hover using time stepping have been shown to encounter instabilities which preclude convergence to valid free-vortex solutions for rotor-wake geometries. Previous work has demonstrated that these convergence difficulties can be overcome by implementing a new free-wake analysis method based on the use of influence coefficients. The present paper reviews this approach and documents its incorporation into a hover performance analysis called Evaluation of Hover Performance using Influence Coefficients (EHPIC). The technical principles underlying the EHPIC code are described with emphasis on steps taken to develop the single-filament wake models used in previous work into a multifilament wake valid for realistic hover performance predictions.

    Keywords:
    Aerodynamics--Wakes;Flow of Fluids--Wakes;