Ira Rampil wrote:
>
> Greetings all,
>
> Having recently watched with interest the traffic on AOA I thought I would
> mention another choice, the DIY choice which I selected.
>
> A prominent commercial AOA device uses a probe made of a small block of
> metal providing a known leading edge geometry which can me positioned in
> angle to match the wing to which it is attached. Plans for a "quite"
> similar device can be found at:
>
> www.snyder.on.ca/pages/angle%20of%20attack.jpg
I just now noticed in this .jpg that the 2 ports are drilled parallel,
and how that best reads AOA is escaping me. There may be differential
pressure as relative wind varies, but perhaps too small for a reliable
instrument. It may _appear_ to work, if it's basically an ASI - which
reads out a stall speed, but not true AOA.
One of the AOA makers uses similar design, but ports are angled to
each other. There, as rel. wind varies, the differential pressure
changes a lot.
I'd prefer electronic transducers to read the diff., to add an aural
alarm. But I've wondered whether you could use like a 2-1/4" UMA ASI,
and plug the lines into the pitot and static ports. Play with the
angle on the ports with first some kind of mockup on the wing.
Repaint the face for AOA indication.
How do you drill a 5-7/8" long hole in 1/2" thick ali. stock? I'd
just pot some flox around tubing and fittings, in an aerodynamic
shape, before going through 10 feet of 'lumnum stock trying!
Regards,
Fred F.
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