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Old October 3rd 06, 04:43 AM posted to rec.aviation.piloting
Dave Doe
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Posts: 378
Default Stalls - Angle of Attack versus Vstall

In article .com,
says...

wrote:
Hi,

I'm a student pilot, learning in Piper Warrior II's.

I'm hoping that someone can shed some light on stalls for me.

I understand that an aerofoil doesn't stall becauase of speed, it
stalls because it has exceeded it's critical angle of attack. It can be
stalled therefore at 100 kts (an accellerated stall?) just as it can at
20kts.

If this is the case, then why do they quote 'stall speeds' in aircraft
specs? For example (from Wikipedia), for the PA28 VS (stall, clean) =
50 kias. Is 50 kts the speed at which you would be unable to maintain
LEVEL flight? ie, at 50kts, in level flights, you would have an AOA of
16 degrees, therefore, any slower and you'd have to pitch back past the
critical angle?





If the normal stall speed is 50 knots, you can make it stall at 100
knots if you pull some positive g's, or you can make it stall at 25
knots if you pull some negative g's. On the same token, you can stall
the airplane at higher or lower airspeeds depending on the aircraft
weight.


I don't know why all primary aviation texts focus so much on AOA when
nearly all of the airplanes we fly do not have an instrument to measure
it.


??? - Stall warning buzzer - fairly common on most planes methinks.
(Next time yer up try a cruise speed max rate turn and pull back a bit
more - you'll hear it

--
Duncan