Angle of attack

toad wrote:


While I agree that understanding of AOA is crucial for a pilot. I
don't think that a AOA indicator would be very useful in gliders


Why would the best reference for the actual performance of the aircraft
be less desirable than an error-prone and very approximate indication
which, like a stopped clock, is exactly right about twice a day?



I think that stall accidents are caused by lack of awareness and lack
of attention. Letting the airspeed "creep away" and incorrectly
responding to the loss of airspeed. Substituting an AOA dial for the
airspeed dial, won't change that.


It is my understanding that one is supposed to be able to fly a glider
safely without reference to the ASI, and I suppose that should also then
apply to AOA as well. Obviously, not everyone can do so. And there are a
few each year that manage to demonstrate the inability to fly safely in
spite of the availability of a working ASI. It is also possible that the
fact that the stall speed of a given sailplane on a given flight could
be +/- 15%, or more, from book speed _in one-g flight_ should be given
more thorough consideration. Do we know then what it might be in a 30-60
degree banked final turn, or in a wind shear condition where the ASI
reads considerably below the book stalling speed? "More" is an answer,
in one case, and "Less" in the other. How much more or less we find by
trial and error, guesswork and luck--or not. An AOA would tell us
instantly and throughout the normal operating range of the glider, and
beyond, just how close to the stall we are operating.



AOA gauges seem best suited for heavy aircraft flown by reference to
instruments. Where you might have to wait a couple of minutes after
setting the AOA and power lever to get the airspeed to respond.
Gliders will change their airspeed much quicker than a 747 or F-14.


I can't use the F-14 or the 747 as a reference, because I have not flown
either. My understanding is that the F-14 can accelerate rather rapidly
and slow down pretty quickly as well. High performance military aircraft
which I have flown certainly exhibited that capability. To say that any
of them, or even a 747, could not accelerate more rapidly than an
unpowered glider in a specified attitude seems an incompletely
considered statement, but perhaps you can provide some evidence to
support your claim.



We also only really fly at 2 or 3 different weights. So we only
really have to remember the best L/D speed for these conditions.

Be my guest--memorize as many speeds as you like. You'll still be
guessing at how close your ASI is to the actual stalling speed at any
particular moment. AOA never lies: any g-load; any altitude; any
attitude; any airspeed.



Jack