Lateral and Directional Stability and Control in Air-to-Air Refuelling

Abstract

Application of a wake roll-up method coupled with the vortex lattice method and approximate expressions for the receiver fuselage effect have been used to determine the induced loads on a Hercules receiver aircraft behind a KC10 tanker. The induced loads depend strongly on the vertical position of the receiver wing and fin relative to the tanker wing wake. In the case of steady sideslip there is a large decrease in the directional stability of the receiver as quantified by the gradient of the rudder angle versus sideslip. This is due mainly to the combined effects of the yawing moments due to bank, yaw and side displacements. Minimum directional stability corresponds to the tip of the receiver fin intersecting the tanker wing wake. The associated aileron angle is two to three times the value in free air in agreement with flight test data. Solution of the linearized equations of motion gives three lateral characteristic oscillations for the air-to-air refuelling case. These include the usual Dutch roll oscillation, a highly damped rolling oscillation and a divergent oscillation involving mainly bank and side displacements.

Derivation of the Dynamics Equations of Receiver Aircraft in Aerial Refueling

“…This operation might be needed to sustain/complete some critical flight missions that require an endurance or range beyond what the aircraft, either military or commercial [1], was designed for. The important modeling and control problems studied in the context of aerial refueling [2,3,4,5,6,7] include models of the tanker-receiver interference, stability of the receiver aircraft and design of an autonomous refueling controller. There has been a great interest in the research community [7] to develop an autonomous and efficient control algorithm that would enable a successful aerial refueling, with least disturbance effect on the receiver aircraft during the whole operation.…”

Optimum design of three-dimensional behavioural decentralized controller for UAV formation flight

“…Recently, research on control system design for formation flight has been performed extensively to support various aircraft missions, such as reconnaissance, precise air-to-ground strikes, and aerial refuelling (Giulietti et al 2000, Patcher et al 1996, Bloy and Jouma'a 1995, Dogan and Venkataramanan 2005. The formation-flight-management methods can be divided into two categories: centralized and decentralized management (Giulietti et al 2000).…”

“…With this approach, conflicting decisions among multiple UAVs should be avoided, because the distributed decision-making algorithm may cause a problem. 200 S. Kim and Y. Kim Most studies of UAV formation flight have focused on the leader-wingman approach (Patcher et al 1996, Bloy and Jouma'a 1995, Dogan and Venkataramanan 2005, which is based on centralized management. This approach may not satisfy some formation-flight requirements, such as prompt reactions to large external disturbance, various threats, and battle damages.…”

Flight Control and Simulation for Aerial Refueling

“…While the effect of the leader's vortices on the follower in a formation flight is beneficial in reducing drag/fuel consumed, 1 the influence of a tanker's vortices on a receiver aircraft during aerial refueling 2,3 can be detrimental to the stability of the receiver aircraft. There has been some recent work [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] dealing with demonstration of the benefit of and issues with the control system development for aerial refueling. However, they do not study the effect of the tanker's trailing wake vortex on the receiver aircraft.…”