The performance and longitudinal stability and control of large receiver aircraft during air to air refuelling

Extract

The aerodynamic interference between typical tanker and large receiver aircraft during air-to-air refuelling was modelled using a simple horseshoe vortex representation of the tanker wake whilst the aerodynamic forces and moments acting on the receiver were calculated using the vortex lattice method. For each combination of tanker and receiver, the aerodynamic loads depend mainly on the vertical separation, whilst the receiver tailplane position on the fin strongly effects the pitching moment acting on the receiver due to the tanker downwash. Particular attention was given to a high T-tail receiver aircraft. The predicted increase in the receiver drag compares favourably with available flight test data. Changes in trim in pitch of the receiver were analysed and related to the static stability of the aircraft. Aerodynamic derivatives due to the position and attitude of the receiver aircraft within the tanker downwash field were calculated and solutions of the linearised equations of motion obtained for the high T-tail receiver refuelling from different tanker aircraft at different flight conditions. Typically the receiver exhibited a divergent oscillation at the normal refuelling position. The dynamic stability characteristics are consistent with the trends observed in flight tests on the tendency of the receiver to oscillate in pitch.