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
