Thank you Gengis.
I'm no mathematician, so much of it is going over my head.
Asking a gliding instructor once for the formula to calculate lift, he said "Half Ro V squared". Yes all very well, what units? Pounds? Kilogrammes? Miles per hour? Feet per minute? Not very helpful. It took me a while to guess at the speed of light?
No wonder my car doesn't fly like bird at 60!