Originally Posted by no4
The Velocity twin looks magnificent!
Twin Kawasaki motorcycle engines would provide over 400 hp total, and 200 hp single engine. It would be a small problem to introduce a clutch or neutral gear to allow the prop to windmill freely and improve single engine performance. Likewise Ivoprop's are readily available, as are certified pushers with constant speed props ( hello Dust).
Instead of going through the expense, etc of the clutch-- consider that there is a twin Ez with coaxial drive shafts, pushing two props, somewhere in south America. Additionally, Consider the Twin with C/S props with full feathering capability. Every certificated twin has such props. Feathering the prop drops the drag to the lowest possible factor.
When the Twin Comanche came out in the mid 60's, one of the marketing ploys piper did was to remove one of the props, put it in the baggage compartment and fly around the country on one engine. With the prop installed and non-feathered, the thing probably wouldn't get off the ground.(due to my faltering memory, the plane may have been the aztec, however I think it was the TC)
The Learfan was also a twin engine with one prop using some sort of magic in the gear box to allow running on one engine without penalty.
For over the water flying w/o being able to glide to land, I also favor twins or better.
The guy that developed the Europa did develope twin EZ (I think it was a long). He used two small 100HP rotaries (Norton)in the pusher configuration mounted to the strakes. Perhaps you could look that up. I used one of those engines in my Dragonfly.