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Date: Wed, 04 Nov 2009 17:39:20 -0500
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From: "John Schroeder" <jschroeder@perigee.net>
Reply-to: jschroeder@perigee.net
Subject: Re: [LML] Re: AOA installation question
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Ralf

I installed one in an ES.. Take a look at my pictures here.

http://w1.lancair.net/pix/jschroeder-Angle_Of_Attack_System

They are annotated and may hep you to locate the pressure ports on your
wing.

John


>Ralf,
>
>First of all, I think you are making a very good decision to install an
AOA.
>The AOA Pro you are apparently planning to install has other good
>functions...such as warning of gear not extended in landing
>configuration...if you chose to hook them up. I have an AOA Pro in my IV-P
>and really like it/find it useful.
>
>Your idea on sensor port installation below is close, and probably good
>enough--I don't think the upper and lower wing locations are super
critical,
>as you'll calibrate it in flight to the pressures actually observed, and
>this should offset any installation error. For the "technically correct"
>answer, read on.
>
>The "equal chord" point on a Lancair wing (not symmetrical) will be
slightly
>closer to the leading edge on the bottom than the top. As I said before, I
>don't think the location is that critical, but you might check with
Advanced
>Flight Systems (new owners) just to confirm. They've always been most
>helpful and courteous when I called: Rob Hickman, (503) 263-0037. Second,
>you'll want to mount the upper and lower sensor ports approximately the
same
>distance from the wingtip (span-wise). This is more significant if  you're
>mounting the ports near the wingtip where the flow is not completely
>longitudinal. Lastly, the tubes provided in my kit for moisture trap, etc,
>are porous. They need to be sealed inside and out with epoxy or
>similar...ask me how I discovered this... :-(
>
>Bob Pastusek
>
>
>Ralf wrote:
>
>Based on the discussions on this list I am putting an AOA indicator in.
>I am putting it in the right wing outside of the fuel tank.
>
>The unit calculates the angle of attack taking the pressure from the top
of
>the wing, the bottom of the wing, the static pressure and ram air
pressure.
>
>You are required to make a hole in the top and bottom of the wing. The
holes
>are supposed to have the same % of cord dimension from the leading edge
(see
>attached sketch).
>
>Question: is someone able to provide a procedure to determine these two
>points? How accurate does that have to be?
>
>My idea was: guess and mark the leading edge, take the half dimension of
the
>thickness of the tailing side. Roll the wing that I get a horizontal plane
>through these two points by using a water level. Take a led on a string
and
>mark top and bottom surface of the wing (see sketch).
>
>Thanks for your help
>
>
>
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