Hi a
(we'll call dClbydalpha "a" and substitute)
I am afraid you are wrong
I am trying to get an important point across.
Please analyse your friend crab responses and see if he is helping get the point across. That is where the frustration comes from.
I think your assumption that downwash remains constant is incorrect. Really the downwash in your scenario would increase with RRPM so there's the RRPM term on top that you 'accidentally' left out.
ie it still cancels.
But that's not the point, the point is there is an interesting way to look at an Ultimate Coning Angle
Yes there is some bathwater (like Airspeed, which would reduce the UCA)
but it is useful to think of UCA being dependant on the terms left in my previous math
You can see it is useful because there is a frequent error made in thinking that coning of 'say' 45deg might be acheived.
In 'layspeak':
This 'can't' happen because if a blade is going slowly enough to make feeble Cf then it's going too slowly to make enough lift (and the attempt to make more lift by increasing AoA will have resulted in stall prior to that point (actually at (or close) to the UCA)
dCl/dA I hope that you can find the valuable point here, and help me explain it. (rather than showing that you learnt some maths once, it's nice that you did, why not use it for the forces of good, truth and the American way? Instead of encouraging that moronic oaf.)
AscendC quite right