Stabilization of external loads in high speed flight usingan active cargo hook

Abstract

The use of an active cargo hook for stabilizing external loads during high speed flight is demonstrated in simulation. A CONEX cargo container with two rear mounted stabilization fins is used as the subject load. Significant nonlinearities in the dynamics of the external load result in multiple equilibria and limit cycle oscillations. A full state feedback linear quadratic controller is developed assuming an isolated load in wind tunnel model and shown to be successful in stabilizing the originally unstable load at a target airspeed of 100 kt. The design is then completed to cover the target carriage envelope from hover to high speed flight. Simulations of a coupled system incorporating a UH-60 Black Hawk helicopter with an actuated cargo hook and the external load show that the controller is successful in providing system stability throughout the target flight speed envelope.