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Old September 1st 03, 09:33 PM
David Megginson
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"Wayne" writes:

Since the airspeed indicator (pitot tube) is pointed the same as the
wing, then "indicated airspeed" does mean something. For instance,
if you were to put the wing at a 90 degree AOA to the relative wind,
then the airspeed would also read nothing or almost nothing correct?

So I agree that airspeed doesn't matter, but indicated airspeed
does.


His point was that the stall speeds marked on the ASI (Vs and Vso) are
applicable only at 1 G, maximum gross weight, and the appropriate
flap/gear configuration. That's why an angle-of-attack indicator
would be nice.

If you're doing anything that increases the G-load on the plane, like
turning or pulling up from a dive (i.e. anything that presses your
behind into the seat), the stall speeds will be higher; if the plane
is loaded below maximum gross weight, the stall speeds will be lower;
and so on.

It's a bit of an overstatement to say that stall speeds don't matter,
but you do have to take them with a big grain of salt. Let's say that
you have just recovered from a stall or spin and are now in a dive
heading quickly towards the ground. If you pull up hard, you might
stall the plane at close to double the Vs marked on the ASI.


All the best,


David
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