On Sat, 22 Dec 2007 06:39:08 GMT, Eric Greenwell
wrote:

Nyal Williams wrote:
The inside wing; it travels a lesser distance while
sinking the same amount as the outside wing.

No one seems to have observed that the AoA is instantaneous
whereas the ASI indicates what the aircraft was doing
moments ago.

I don't think this is true: all the ASI I've had or checked seemed to
respond in less than a second. Surely that's fast enough to keep up with
the glider? Just try blowing gently into a pitot and see how quick the
needle is. If takes "moments" to respond, you should check the indicator
and the pitot line.

The reason we are told to "fly attitude and don't chase the airspeed" is
it takes the glider a while settle down to a steady speed, not because
the ASI is slow.

That's precisely his point. Change the AoA, and the drag changes.
Change the drag, and the glider accelerates (positively or
negatively). Then the airspeed changes, and only then does the ASI get
a chance to tell you about it.

"Fly attitude and don't chase the airspeed" really means "fly AoA and
don't chase the airspeed", but if you don't have an AoA indicator, you
have to use the attitude as a substitute for AoA. And it's a
second-rate substitute.

rj