I'm new at this discussion room business, but following this discussion has been both informative and entertaining. Entertaining in following the line of everyone's opinion and point of view and informative in that its confirming my understanding of aerodynamics.

HarryC is emphatic about the dangers of trying to turn a plane with rudder with very good reason. I believe he's got the classic stall/spin accident on base to final in mind which in full scale is fatal most of the time. If you're not lining up right on base to final don't use rudder to correct the situation - go around! That's true both full scale and models.

Bigheavy really hits it on the head though. We're not talking about one control surface. Its a coordination of all the control surfaces. Turns need to be coordinated and there are so many variables involved. No one has mentioned the effect of elevator in a turn but its involved too. Some have maintained it is the main turn control surface. Its just a matter of the way one chooses to look at the many forces acting on the plane in a turn. Horizontal component of lift makes the plane turn, but to get that one must bank (roll) the plane with ailerons and use rudder to counteract adverse yaw. When that happens, vertical component of lift is reduced (because the plane is banked) and one must do something to increase that component to maintain altitude. Ususally that is done with a touch of back elevator to slightly increase angle of attack and total lift.

Its a marvel that humans can take this screaming machine moving through the air at breakneck speed and balance it (with all control surfaces) on a pinhead called the CG while navigating, talking with ATC, conversing with passengers or fighting other aircarft.

Very interesting discussion


Roodester