[aerohead]

Originally Posted by CFECO

True, that is why my original X-Prize car had two, two cylinder outboard powerheads, which would run together or one only depending on load requirements. Think of a gas golf cart, the engine doesn't run until power is required, when you step on the throttle. Mine was to be; Electric to start driving initially, with one or both ICE power plants starting as the throttle was pushed farther down. If the car "Only Needs" 15HP to go 60 MPH, it can be done with a 15HP engine, passing or hills, the HP doubles or more. Harder, in some ways and not as efficient, as making one engine convert from 2 to 4 cylinders.

The Rutan Voyager used a similar strategy,using tractor and pusher powerplants for takeoff and climb,then going to either of the single engines for cruise,which would enable oil changes and servicing of one powerplant as the other just sang along the airways.