Remember to take into account the vena cava
flow.

Paul Lipps.


ROFL. Sure Paul. I did not know you studied medicine :)
Your not serous. (you're, a contraction that means you are)

The propeller flow is deemed vena cava, which means it starts out larger in
diameter than the prop disc, contracts as it flows into the prop disc, then
continues to contract and pick up velocity as it goes to the rear. At a
point many diameters behind the prop, the delta v is twice as much as at the
prop disc. That's the delta v you have to use in calculating thrust
horspower.

Paul Lipps

Paul


So this is the main reason it is advantageous to put the prop
farther out away from the cowling  or make it as slim as possible?
Perhaps  alleviate much of the high pressure area between the prop
and cowling.


DougFir

You would think so but the pusher prop so far has not been
proven to be that much more efficient.

There are at least two ways to model a propeller.
One is use the momentum theory as alluded to above and one
is the pressure difference theory on the prop blade for
lack of a better term.

Klaus and I were having a discussion on what keeps airplanes
up the sky. I said it was the pressure difference on the
wing and Klaus said "Shame on you Paul. You are wrong!
Don't you know anything?":) He said it is the mass
of air accelerated downward.

Both are true.


Paul Lamar ...No rotor no motor.

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