You attach your 125kg petrol or diesel bike beneath a wing, retract its wheels and get into the plane, taking off from the suburban airport.
After a while, the plane’s batteries start to run low. To prevent touchdown, the motorbike’s 50kW generator kicks in, burning conventional fuel to boost the aircraft’s range. The plane is now a hybrid.
You land at the airport close to work and climb down on to the tarmac, detach the bike and ride off.
That is the vision of Richard Glassock from the Institute for Aerospace Technology at the University of Nottingham. Last year, he unveiled the RExMoto concept, the “modular electrical generation power plant” that doubles as a motorcycle or scooter and a range extender for two- or four-seater electric planes.
As the aerospace sector seeks to reduce the 5m barrels of oil burned every day, it is giving ever-greater attention to electric flight. Battery-powered aircraft could be cheaper to run and will cause fewer polluting emissions. They will also allow more suburban commuter flights thanks to quieter operation, says Glassock.
Electric plight
When it comes to energy density, however, lithium-ion batteries just do not cut the mustard – kerosene has 40 times more energy per unit weight than even the best batteries. The solution for range anxiety – a more conspicuous issue hundreds of metres above the ground than on the road – could well be range extenders, says Glassock. After he reached that decision, the RExMoto design just seemed to come together.
“I wanted to make it mobile so you could easily install and remove the range extender,” he says. “It was fairly clear the unit should have wheels, because it will weigh a substantial amount… It’s got an engine, a generator, wheels and practically suspension, so why not make it steerable?” He adds: “One of the big things with aircraft flying and commuting is arriving at the destination and being stranded, having to rely on some other form of transport, so it all comes together nicely as a concept.”
Imminent revolution?
The RExMoto could “help to solve some basic transport problems”, says Glassock, but inventors have been promising a revolution in personal short- to mid-range flight for a century or so. Unless we see a major shift in costs and regulations, it seems unlikely that the RExMoto or similar concepts could gain mainstream appeal. Security checks and air traffic control would also likely lead to longer queues with any increase in individual air travel.
The government sees potential, however – it has awarded a £30,000 innovation grant to the project, money that Glassock is using to build and test a 20kW proof-of-concept. If it works, his team will see if the product is feasible. It might be ambitious, experimental and just a bit weird, but it does sound like a lot of fun.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.