Unable to find a suitable engine or convince the government to order the development of one the Yakovlev bureau was forced to follow a different course.

The principal problem in development of the Maus was finding a powerful enough engine for its weight that could be carried in the tank.

They found an engine somewhat loose in the bearings, and there followed remarks which would not look well in print.

Maxim's father had earlier conceived of a helicopter powered by two counter-rotating rotors, but was unable to find a powerful enough engine to build it.

Other engines took to him because of his willingness to help out, or to find an engine who could.

Finding a suitable small engine proved difficult.

Lift up the rear hood and you find an engine not much changed from the one that Ferdinand Porsche designed in the first prototypes.

"We needed to find an engine that could fuel our growth," said Brett Shevack, chief executive at Partners & Shevack.

Under the hood, where you'd expect to find an engine, there was now only two big tanks, one for oxygen and the other for hydrogen.

In its place you will find a very ordinary electric engine - no steam, and no ear-piercing whistle to start the adrenaline flowing.