"Steve Foley" wrote in message
news:NYDfh.5004$%T5.3873@trndny05...
Sure, any airplane could take off from a treadmill in a wind tunnel.
But climb out is a real pain.

No, it's not. Airspeed is airspeed. If the airplane can take off in the
wind tunnel, it can climb
(to the physical limits of the wind tunnel, of course).

I think that's the 'pain' part.

Maybe. Though, if so then I'd say that *any* operation of an airplane in a
wind tunnel could be characterized as "a real pain". I don't see how
climbing is any different than, say, getting to some actual destination for
example.