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From: RWolf99@aol.com
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Date: Tue, 8 Aug 2000 23:08:53 EDT
Subject: Computed AOA
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>>
<<You give up a little with the SFS angle of attack because, as I understand
it, there is no compensation for weight change and it rather gives you data
based on gross weight to be conservative.  However, it does a great job of
computing G forces, angle of bank, airspeed and so on.>>

Hmm....

Does the SFS unit actually know how many G's you're pulling?  If so, the 
accuracy you credit it with should be good enough for stall warning, even if 
it assumes a gross weight.  If not, it's no better than an airspeed indicator.

I disagree with Marv when he says that only Jim's AOA indicator shows actual 
angles.  In the flight test world, we used little tiny AOA vanes on long 
booms -- they were pretty good.  Any system measuring the position of a vane 
should give a consistent reading and thus be good enough for stall warning, 
with the correction that must be applied when flaps are extended (which Jim's 
does).

To put all this in perspective, I bought one of Jim's units when it first 
came out because I think it's an excellent product -- probably the best thing 
out there short of a vane on a flight test noseboom.  However, I am begging 
him not to invent any more stuff.  My airplane is getting heavier and my 
wallet lighter!

- Rob Wolf


[Hmmm, maybe I missed one of my own editorial comments... I don't remember
saying that Jim's AOA instrument is the only one that shows actual angles.
What I did say was that "Jim's AOA indicator is the only one that
actually uses the wing to generate the AOA information" and as far as
commercially available angle of attack indicators go, I still believe
this to be true.  Just to keep the record straight.     <Marv>     ]
 
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