Simulation of Atmospheric Turbulent Gusts and Gust Gradients

An improved three-dimensional, nonrecursive model for atmospheric turbulence has been developed that provides for simulation of both instantaneous gusts and gust gradients along the flight path of the Space Shuttle. The one-dimensional gust and gust gradient spectral models, which form the basis for the simulation scheme, are developed from three-dimensional, von Karman spectra, integrated over finite limits based on the characteristic dimensions (length, width, and thickness) of the flight vehicle. By means of the simulation process, nondimensional time series for both gusts and gust gradients have been generated and stored on a series of magnetic tapes for four altitude bands ranging from 0 to 10,000 m. These Shuttle Simulation Turbulence Tapes (SSTT) have been validated by means of spectral and statistical analyses with very satisfactory results. The dimensionless form of the time series, coupled with the use of a von Karman spectral model (as opposed to a Dryden model), distinguish the SSTT from earlier turbulence simulation concepts.