Telemaster- the math works against what you are saying, plus I think your gravity concept errs too since it is only pushing down on the bullet and not opposing travel.

The prop efficiency formula, which leads to prop performance, contains velocity and Velocity. One is what we call static thrust, so you can see that static thrust is only half the story. The other velocity is all the air being rammed through the prop disc area by forward airspeed. The hovering example is valid and is only static thrust. Plus, you have some rotary wing aerodynamics robbing the prop of thrust. The main thing is tip vortices and the other is ground effect when close to the grass.