You would still need to know IAS, or some measure of dynamic pressure, to know how to avoid exceeding operating limitations. And you write that you might still need to do a cosine correction for large inclinations, to be sure we are measuring free-stream velocity as closely as possible. This is essentially the same type of processing that is currently done, either automatically or manually using CR or E-6B computers, or read from charts, using pitot-static systems, and applying gas formulas and trig to get TAS, and windspeed, when ground velocity is known. I don't see why it wouldn't work, you are just starting at TAS, and computing everything else the opposite direction of what is currently done, if I read your post correctly.

My question, since you still haven't defined a mission, is what would be the benefit to such a system? Would such a system be light and small enough to fill the gap between zero and 30 mph (I guess that is what you are asking)? Pitot-static systems have served well thus far, and are simple and accurate enough when their limitations are understood.

I really see two parts to my question. Could such a system be made light and inexpensive enough to be used on small UAVs? And, why would it be better than what we are using now? I guess I'm mainly referring to UAVs here because I don't know of many recreational RC models that have ANY type of speed sensing.

BTW, I assumed when you first mentioned 30 mph (or knots, whatever) as a lower limit, I assumed you were indirectly relating that to AOA and x-component loss. I think I see now that you were referring to the sensitivity of the diaphragms used in pressure sensing.