Message-ID: <000b01c1b06d$7fa491a0$4930b43f@f3g6s4>
Reply-To: "Dan Schaefer" <dfs155@earthlink.net>
Reply-To: lancair.list@olsusa.com
From: "Dan Schaefer" <dfs155@earthlink.net>
To: "Lancair list" <lancair.list@olsusa.com>
Subject: Stall Warning/AOA
Date: Thu, 7 Feb 2002 22:54:45 -0800
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>Has anyone used the mechanical tab style angle of attack warning that is
used on most light general >aviation airplanes on a lancair?

Not advisable. After going to all the trouble of building an airplane which
incorporates a relatively high-tech NLF airfoil (Natural Laminar Flow),
sticking something like a stall-warning-tab out in front seems quite
counterproductive. You can get the tech paper on the NLF series of airfoils
from NASA (a lot of the development work on these airfoils was done there,
in the '70's or '80's, I think). You will note that it is too easy to
disrupt the laminar, flow resulting in a sudden increase in drag.

I've related this story before, but for those who haven't seen it, I'll say
again. I encountered a cloud of bugs on climb-out from Tonopah, Nev. a
couple of years ago. didn't realize it at the time but I had coated the
leading edge of my wings with a gazillion of the critters. When I leveled
off and tried to accelerate to cruise speed, no soap! I actually thought
that maybe my nose gear door had closed before the gear was all the way up
(I had had that problem early on) so I slowed to gear speed and cycled the
gear. Still couldn't get to more than about 140 MPH IAS and the airplane
felt odd - it just wasn't as crisp on the controls as I was used to.

Deciding that I must have a very large problem that I couldn't diagnose in
flight, I landed at the nearest airport. When I ran my hand over the forward
third of the wings, they felt like sandpaper! Looking close, I could see
that the sticky little bug-guts (they were about the size of gnats) had
glued themselves to the wing surface by the untold (previously mentioned)
gazillions.

After a very thorough inspection of the rest of the airplane and finding
nothing amiss, I got out my trusty Formula 409 and cleaned off the
passengers. The rest of the flight home was normal and uneventful. No
problem attaining normal cruise speed, etc., etc.

>From this I conclude that one may not want to stick a protrusion into the
airstream ahead of the wing.

Dan Schaefer

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