ThinAirDesigns wrote:

We subtract the 1/2hp that the prop needs to produce its 10lbs of
thrust from the 1.0hp that the wheels can produce from that same 10lbs
and you have 0.5hp left over for the system losses.

Thanks for the numbers and your skateboarder examples, I think I can
grasp it now, but I'd hate to have to explain it down the pub from
scratch ...