Because they only have their main engines for propulsion, today's massive modern jet liners can burn hundreds of kilos of fuel just taxiing from the boarding gate to the runway. That translates to multiple tonnes of wasted fuel every year and more than £675 million in added operating expenses. But with this new electrical wheel drive, airliners will finally only need their engines for flying, not driving.
The WheelTug e-taxi system from Borealis Exploration Limited is a nosewheel-mounted, induction motorised ground propulsion system. Measuring less than five inches in diameter and weighing about 136 kilos, this system produces roughly 6,000 kN of force—more than enough to push a 91,000 kg 737 around the tarmac.
"The idea of putting an on-board electric drive system on aircraft is not new, since there are so many clear advantages," Isaiah Cox, WheelTug President and CEO, said in a press statement. "But until recently there was no electric motor technology with the capability to produce the required high torque for its small size, weight and safety profile to make it possible."
And since it doesn't require the plane's engines to work, powered instead by the aircraft's APU (auxiliary power unit), the flight crew only needs to rev up the main engines upon take-off, thereby saving time, fuel, maintenance, and money. Lots and lots of money. The system is expected to reduce the operating cost of each aircraft by as much as £307,000 per year or about £430 per flight.
"We believe on-board electric motors have a great many advantages," added Bob Carman, Chorus Motors' WheelTug program manager. "They could reduce the need for ground tugs and their associated costs, allow faster flight turnarounds and increased fuel efficiency per trip, and reduce airplane noise and emissions at airports, to name just a few advantages."
Short-haul flights are expected to see the largest savings since they spend a higher proportion of their time on the ground than longer flights. However airport traffic in general should improve if these become widely used as planes will be able to queue themselves rather than wait for a taxi cart. The first version, designed for the Boeing 737NG, and has just entered service with El Al airlines. [Wheel Tug 1, 2 - Wiki - Flight Global, Boeing ]