Quote:
Originally Posted by Jetstream Rider View Post
Ground effect reduces drag, and hence increases L/D, giving a gain in performance. Its not a "lift increaser", its a "drag decreaser".
Sorry, have to disagree with that.
There's a definite shift in the lift-curve slope, with increased CL at a given AoA (at least at low AoA), in ground effect. It's not just a drag effect.
I stand corrected.
The particles bouncing off the lower surface theory does not account for the fact that around 4/5 of the lift comes from the top surface (see Kermode, early pages). Have a look here:
Incorrect Lift Theory
Forwards and backwards on the arrows at the bottom give more good info.
To sum up, the wing throws air at the ground. No downwash, no lift.
I disagree. Look at the flow sim and lift over a spinning cylinder. Up = down, especially on the cylinder, yet you get a large amount of lift. We only don't use that for aeroplanes as the drag is very high.
The maths of flow is by nature an approximation, or a "trick" to get the world to work. Bernoulli's equation is a description, not the whole text.