Rick Cavallaro wrote:

On Oct 3, 3:34 pm, Ronald Raygun wrote:

If you're wanting to get 10lb thrust in those circumstances using only
1/2hp, then (if my calculations are right) this is possible only if you
play the same silly game as you've done with the static case, i.e. you
would end up with prop air output speed the same as air input speed, i.e.
zero speed difference and hence a need for infinite air throughput.

What on earth are you talking about. What sort of silly math are you
using to compute 1/2 h.p. for zero acceleration of the air!?

I've just shown my "silly" math in a parallel posting.
It doesn't purport to compute 1/2 hp for zero acceleration, rather it
*starts with* the 1/2hp your friend gave, together with the given values for
thrust and air input speed, and tries to solve for air output speed.

I had thought that the purpose of your discussion which included the
analysis was to try to persuade unbelievers (who no doubt think the whole
DDWFTTW idea is impossible, and that your documented demonstrations of it
nevertheless actually working must therefore be elaborate hoaxes). I
would comment that an analysis which only works with infinitely large
propellers is hardly going to be terribly persuasive.

It would appear that you're now dedicated to not understanding the
basic analysis. So be it.

No, I'm not, please don't dismiss me as a "dennis". I'm genuinely trying to
understand why I can get the energy budget to add up using your result.

If there's a mistake in my maths or my arithmetic, please help me find it.