The present invention provides a turbulence model that has been developed
for blade-element helicopter simulation. This model uses an innovative
temporal and geometrical distribution algorithm that preserves the
statistical characteristics of the turbulence spectra over the rotor disc,
while providing velocity components in real time to each of five
blade-element stations along each of four blades, for a total of twenty
blade-element stations. The simulator system includes a software
implementation of flight dynamics that adheres to the guidelines for
turbulence set forth in military specifications. One of the features of
the present simulator system is that it applies simulated turbulence to
the rotor blades of the helicopter, rather than to its center of gravity.
The simulator system accurately models the rotor penetration into a gust
field. It includes time correlation between the front and rear of the main
rotor, as well as between the side forces felt at the center of gravity
and at the tail rotor. It also includes features for added realism, such
as patchy turbulence and vertical gusts in to which the rotor disc
penetrates. These features are realized by a unique real time
implementation of the turbulence filters. The new simulator system uses
two arrays one on either side of the main rotor to record the turbulence
field and to produce time-correlation from the front to the rear of the
rotor disc. The use of Gaussian Interpolation between the two arrays
maintains the statistical properties of the turbulence across the rotor
disc.
The present simulator system and method may be used in future and existing
real-time helicopter simulations with minimal increase in computational
workload.