Originally Posted by
asgelle
Thanks, but you really should be sure in your own mind before teaching others. To cut through a lot of words. Force is a vector, speed is a scaler. Check your work.
The direction of the drag force is understood to be aligned with the freestream velocity. Much like weight (a force) is in a known direction in everyday applications so one need not explain the direction of the weight of an object on the surface of the Earth. It is understood. Since the direction of the drag force is known the specification of a single scalar quantity will define the force vector. The communication problem that we are having is that you want to make the drag force go in a direction other than in the direction of the freestream velocity. You want to align the drag force with the wheel instead and that is not the correct direction for the drag because the wheel is yawed and not aligned with the freestream. You are talking about a component of force, but it isn't the drag.
So, it is theoretically possible that there is an force in the plane of the wheel that pushes it forward if the wheel is yawed with respect to the freestream? Sure. Is it due to negative drag? No way. That is my main complaint. If it is true it must be due to lift.