How to calculate propeller delta v

[kellven]

Trying to get a simple algorithm for propeller thrust.

-Has to work inside KSP, so the ridiculous quadratics, blade sections, and look up tables are out.

-Also has to work from static to stall, and operate in atmospheres with different densities.

The first part I got from http://www.grc.nasa.gov/WWW/k-12/airplane/propth.html

Momentum theory:

force = PropArea * dPressure

dPressure = 0.5 * AtmDen * PropDeltaV

Already much slower than existing engine calcs, but it should still be workable.

Problem is how to calculate the PropDeltaV, or change in air velocity caused by the propeller.

Could derive this from a given power, or thrust, but I can't find a straightforward equation relating either:

-power with "propeller efficiency",and air data yielding imparted delta v

-thrust with some system of coefficients accounting for air data yielding imparted delta v

This probably isn't too difficult, but I have the spatial reasoning skills of a blind infant, so any help would be appreciated.