Later this year a propeller-driven aircraft will be used to test landing gear with in-wheel electric motor-generators for pushback, taxiing and braking.

Virginia-based Delos Aerospace has developed the in-wheel system, which uses axial flux disk motor-generators to replace friction braking disks. It is in talks with an undisklosed motor and controller specialist aerospace company and is looking at applications for very light jets and general aviation aircraft.

The in-wheel system uses nanotechnology-enhanced "ultra capacitors" developed under a US Defense Advanced Research Projects Agency programme for directed energy weapons. Delos claims that to move a Boeing 777 would need 4,500kg (10,000lb) of conventional capacitors, but only 230kg of ultra capacitors, located in both nose and main wheels.

For braking, the patented Delos system substitutes a magnetic disk system for conventional friction disks. With a magnetic disk, Delos says, braking generates electricity that is fed to the ultra capacitors and produces less heat.

"[In conventional] wheels and tyres, the [gear] mass has to cope with heat from braking and you can get rid of that [heat-absorbing mass with the electric system]. This will reduce the weight of the aircraft," says chief engineer and chief executive Steven Sullivan, a former nuclear power engineer whose work on axial motors gave him the idea.

Sullivan expects to come to some sort of agreement with Airbus, which he says told him it has been working on this technology for some time, but does not expect the European manufacturer to seek an exclusive licence. This is because Airbus expects the in-wheel system to become a required safety feature, he says.

Source: Flight International