You will not start moving over the ground until you have applied sufficient power to overcome the 50 kts of airspeed (not quite true - if you do not have brakes on, a smooth surface and insufficient power the wind could blow you backwards!) so to start moving you need more than power for 50 kts, especially as you are still on the ground so have ground resistance as well, so to fly you need power for 60kts PLUS enough to overcome the ground resistance.
As someone said, is this serious or are you just yanking our chains?
Foxmoth - I am not yanking anyones chain! I was just having trouble rationalizing two seemingly paradoxical statements.
Your explanation has actually helped me the best!!! If I picture the aircraft with the brakes off with the required thrust to 'hold' against a 50kt wind so has not to go backwards it really helps me rationalise the fact that the aircraft is then able to fly once airborne or "on the train" or in the "goldfish bowl", "in the flowing river" etc.. etc... (to quote the various analogies)
It was the statement that, "once in the air, an aircraft is not affected my wind (except relative to ground)" which was confusing. It made me picture the aircraft suddenly having the headwind flow of 50knots over the wings removed as it is now "in" the body of air rather than having the body of air flow over it.
Now if I picture the ground removed and the aircraft having the 50knots to "hold against" the wind + the 10knots forwards into it, equaling the required 60knots to lift off I can deal with the aircraft being airborne with 60 knots relative to a now "still" body of air.
Sorry if this does not makes sense, I am very tired!
I really do appreciate all of the responses and help and apologise for being a dimwit. This is a great forum.
btw: The Tramontana are in Mallorca, where I live and the winds are far from mythical!