Adam Dershowitz wrote: > On Jun 14, 2006, at 8:23 PM, Jon S. Berndt wrote: > >>> Maybe said a different way, imagine your wing is riding on the >>> edge of >>> the amount of air it can push down without stalling. Now you deflect >>> the aileron down and try to push the air down even more. >> Stupid me. I forgot something. OK, deflecting an aileron is like >> deflecting >> a flap. If you look at a lift curve from a wing section you can see >> that >> deflecting a flap (aileron) increases the lift coefficient, but you >> also >> reduce your stall angle. That would be enough to do it for that >> portion of >> the airfoil. >> >> Jon >> >> > > There tends to be another issue here as well. And it might relate to > what Curt experienced. > When teaching students to do slow flight (near the edge of stall) the > temptation is to use aileron to correct. If they do that, what can > happen is that the down wing, that they want to raise, will get down > aileron, more lift, and an increase in induced drag. That increase > in drag will "pull" the wing "back". Thus there is a yaw induced, > that can have the same affect as using rudder...a spin! > As an additional complication, wings don't stall all at once, instead > it is a progressive event. When a wing is on the edge of stall the > trailing edge is where the stall will start. So it is possible that > a wing that is nearly stalled will have have some flow separation at > the trailing edge. That is also where the ailerons are. Down > aileron can cause flow separation and a decrease in lift, with an > increase in drag, and that wing can drop on you. > When in slow flight students have to be taught to use rudder instead > of aileron, or the CFIs get nervous ;-) > > --Adam > > > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel >
Hmm, so how would JSBSim model low speed control reversals like this? Could it be done in a way that would also be able to model transonic control reversals that are caused by shockwaves near the control surface hinge? Josh _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
