‘Formation flying saves half the fuel’

Illustration: Piet van Rosmalen

Nine TU Delft students have won a Dutch aviation award for their idea of having airliners fly like geese: in formation. They calculated a 50 percent fuel reduction.

The inspiration came from geese, Hugo Dijkers and Joren de Wit, members of the winning student team, admit. These birds fly great distances, always in the typical V-shaped formation, which reduces their energy needs by as much as 60 to 70 percent. So why not learn from nature and have large airplanes fly in formation as well?

Dr Wouter Beelaerts van Blokland (Aerospace Engineering), who was the students’ principal supervisor, proposed the project to the students after having checked its feasibility. He discovered that for formation flying to work, the mutual position of the aircraft must be controllable within 10 centimeters. If so, that degree of precision navigation should indeed be achievable, he asserts.

The force behind formation flying comes from the quasi-static air currents originating at the wingtips during flight. These so-called vortices are normally feared, as they can drag other aircraft down, but a vortex also has a region that pushes other aircraft up and reduces their drag. That’s what geese benefit from.

“It’s a paradigm shift,” says Dr Beelaerts van Blokland. “When you don’t know exactly where the vortex is, you prefer to stay away from it. But once you can locate it precisely, you can benefit from it.”

The team proposes to pinpoint the vortex by using Lidar technology (a remote sensing technology that uses laser pulses to measure distances). Only one wing will be lifted by the vortex of the plane in front. This means that the other wing and the rudder must be especially equipped to deal with the permanent imbalance. The students propose to achieve this using morphing wing technology.

The organisers of the Nationale Luchtvaartprijs (National Aviation Award) called for innovative, energy-saving aviation proposals. The students reckon that the open rotor jet will save 20 percent on fuel, and formation flying, with the benefit of lighter aircraft carrying less fuel, will save another 30 percent.

In their vision, future airliners flying from, say, Paris, Amsterdam and Munich, will gather above Ireland, before crossing the Atlantic in formation, taking turns taking the lead, and then splitting up to their various destinations above the US east coast.

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