Maneuvers During Automatic Formation Flight of Transport Aircraft for Fuel Savings

Abstract

Formation flying techniques, demonstrated by migratory birds, have the potential to significantly save energy when two or more transport aircraft fly the same route at the same time. In fuel-saving formations, aircraft are flying straight trajectories for most of the time. For proof of concept, however, how vertical and lateral maneuvers can be flown has to be investigated. Those investigations require a flight simulator that is equipped with adequate flight mechanical models. Not much research exists on maneuvers of formation. The paper addresses the components that are needed to perform this research with real-time flight simulations. They are, first, a method to model wake vortices on curved trajectories; second, a formation flight control system, which comprises a method for the relative position determination, the design of control laws, and suitable cockpit displays; and third, techniques that allow vertical and lateral flight maneuvers. Two different strategies to position the following aircraft relative to the wake vortex during turns are described, and simulation results show their differences in terms of fuel savings and passenger comfort. Piloted flight simulator tests confirmed the usability of the proposed flight techniques for formation maneuvers, and the participating airline pilots indicated general consent to the concept.