Airbus researches weight-shift control system

By John Croft

Airbus in investigating a backup flight control system that provides transport aircraft control by transferring fuel between separate tanks in the left and right wings for roll control and between belly and tail tanks for pitch control.

Such a system, detailed in a US patent application submitted 2 April, would be transparent to the pilot, with traditional controls sending inputs to a computer that would command the fuel flow using pumps.

"In the event of total failure of the aerodynamic surfaces, the transfer of fuel enables the control of the aircraft to be maintained in order to attempt a landing or splash-down even if one or more jet engines have just gone out of operation," the airframer says in the application.

The pictures below, from the patent application, shows how transfer of fuel would effectively shift the centre of gravity of the aircraft rearward and forward in the top picture to produce pitch, or side to side to produce or roll motion in the bottom picture. Airbus notes that combined pitch and roll maneuvers can also be accomplished.

Along with its use as a backup mode that would be entered for example if the traditional flight controls became damaged by hail or a bird strike, Airbus says the option could be used as a fuel-saving primary flight control system that would avoid the drag induced by the typical aileron and elevator movements used to control the vehicle in flight.