The new design would have to carry two people and luggage, have an empty weight of no more than 625 lbs. and use an 85-horsepower engine. The biggest different

The new design would have to carry two people and luggage, have an empty weight of no more than 625 lbs. and use an 85-horsepower engine. The biggest differentiator between cars and planes (as far as construction goes) is crashes. That changes both weight and price in a non-trivial way.