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Old 09-08-2010 | 01:41 PM
  #76  
Top_Gunn
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Joined: Jun 2005
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From: Granger, IN
Default RE: Downwind Turns!!

If you can explain dissymmetry of lift (helicopter) without punching a hole in your 'wind has no effect' theory than I'll admit I was wrong and might enroll in one of your classes.
This wasn't addressed to me, but I can't resist. Dissymmetry of lift has nothing to do with whether the wind is blowing or not. Like anything else that happens to flying aircraft, it turns on airspeed, not groundspeed. When a helicopter is flying forward, the forward-moving blade has more airspeed than the backward moving blade, and so develops more lift. It happens in calm air, or in a wind. It exists because the helicopter is moving forward relative to the air, not because it is moving relative to the ground.

Nobody has ever claimed that "wind has no effect." It has a lot of effect on the motion of a plane relative to the ground. A steady wind cannot, however, have any effect on the motion of a plane relative to the air. How could it? The wind is the air, in motion. That would be like picking yourself up by your own bootsraps. Consider a plane flying due north at 100 miles an hour in a steady east wind of, say, 30 miles an hour. This wind will carry the plane (sideways) toward the west at a rate of 30 miles an hour. this feels exactly like flying at 100 miles an hour in a dead calm. So a turn, in either direction, will have the same effect on the plane, provided the control inputs are the same. The air molecules on the east side of the airplane aren't moving toward it, and those on the west side moving aren't moving away from it, while the plane is flying north. These two turns will look very different from the ground, however. That's why RC pilots have trouble with something that doesn't exist for full-scale pilots: they tend to think of tthings in relation to the ground. But, except for gravity (which plainly has nothing to do with wind), the ground cannot have any effect on a plane not touching it (or, strictly speaking, and not in ground effect conditions). That's why a constant wind speed, which has meaning only relative to an observer on the ground, cannot affect the way a flying airplane turns.

I cannot resist noting that saying "inertia, time, gravity, acceleration, etc." is making a list, not a reasoned argument.