My background is electrical engineering, but I have a question regarding the mechanics and physics regarding plane propellers. The purpose of a plane propeller is meant to provide thrust to the plane. Similar to a plane wing, the propeller generates lift but does so in a direction that is parallel to the ground. Looking solely at the rotational speed and torque of a propeller, is the speed of the plane limited by the maximum speed at which the propeller can rotate? Say for example the plane increases its speed. Will the plane reach a speed at which the propeller can't keep up with the incoming speed, thus transitioning the propeller from something that generates force to something that resists a force (similar to a wind turbine)? Furthermore, I've been looking into plane designs that involve two propellers that might be stacked one in front of another. Does a propeller accelerate the incoming wind speed? And could this acceleration in wind speed affect the thrust that the secondary propeller could achieve, similar to the issue described in the question above? For a visual idea of what I'm trying to describe, refer to the helicopter below, but imagine this set up on a propeller plane instead. http://www.guncopter.com/images/ka-50-large2.jpg Thanks for any responses!