US military research scientists at DARPA have asked Boeing for help in exploiting the aerodynamic benefits of formation flying to save fuel in military aircraft.
According to the report on those trials, significant performance benefits were obtained during the flight test phase.
Drag reductions of more than 20 per cent and fuel flow reductions of more than 18 per cent were measured at flight conditions of Mach 0.56 and an altitude of 25,000 ft.
The Register reports that the NASA project was intended to move forward and actually demonstrate fuel savings over a long flight, and develop autopilot equipment which could hold following jets exactly in the sweet spot for best results relative to the aircraft ahead.
However the NASA effort was shelved due to funds drying up.
Although not an entirely new concept, aircraft flying in formation could offer a way of increasing range of aircraft in formation without transferring fuel.
“This opens a new design space for aircraft conceived and operated as a networked system. As always, there are challenges to overcome. One challenge is precisely maintaining the relative position of two aircraft, or many aircraft, to take full advantage of the reduction in drag due to lift. Only birds now do this routinely, and they can’t explain it to us …” says the agency’s Dr Thomas Beutner.
The Boeing deal will see an initial simulation phase before flight tests in the wake of a large military transport aircraft. Later work could see autonomous self separation using stationkeeping equipment – possibly applied to manned or unmanned future aircraft fleets custom designed operated as networked systems.