An interesting proposition for a blade Lu.. .. .But even with the coanda effect, which I can see eliminating stall at higher pitch angles than typically found in todays systems, and retreating blade stall, how much more of a cushion would it provide?. .. .Dave,. .. .On the negative, I only brought that up for my model heli's fly with negative for inverted flight, the model having much more power thrust to weight thamn most full scale operations. In a model set to auto I typically have anywhere from -3-4 degrees set in there, likely more to maintain model Nr than anything else. some in the model commumnity feel you need negative to "get it down from alt" normally, however I have disproved that in demonstration.. .. .I was thinking the nearest thing that might fly that could demonstrate what we might be looking at would be an X plane derivitive. Having a spinning rotor that would lock down at some point and those airfoils then providing conventional lift in forward flight. If we placed that aircraft in the hover and then brought down Nr (or increased pitch allowing it to stall, I wonder if it could handle such loads, already having to have to handle the loads of having the blades locked down.. .. .Ooh, is there $$$ involved in that promotion? <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />. . . . <small>[ 21 March 2002, 20:54: Message edited by: RW-1 ]</small>