Flight Data Analysis and Simulation of Wind Effects During Aerial Refueling

This paper presents an analysis of data obtained in an automated aerial refueling test flight conducted with a KC135 as the tanker and a Learjet 25 as the surrogate receiver unmanned aerial vehicle. The purpose is to identify the wind induced by the tanker wake and its effect on the receiver aircraft. From the available flight data, a direct computation of the winds experienced by the tanker and receiver is carried out. The mean variation of the receiver wind is compared with the tanker wind when the receiver is at the observation and contact positions. This results in the identification of the wake-induced wind. A spectrum analysis is conducted to characterize the turbulence and to identify the pilot effects. The paper also presents methods used to model 1) prevailing wind, 2) wake-vortex-induced wind, and 3) turbulence as the three sources of wind that the aircraft are exposed to and the approach used for incorporating the wind effect into the dynamic simulation of the aircraft. The test flight is simulated in various caseswithdifferentturbulencemodelsand flightcontrollers.Thesimulationresultsareanalyzedandcomparedwith the flight data in terms of the power spectral densities and mean variations to validate the wind and turbulence modeling techniques.