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Alain et al,
Thank you for your replies to my original post. This is the reply I received from Dynon.
"The recommendations are based on the typical pressure fields around a typical wing, and represent where we'd expect there to be both good pitot and AOA performance. The general requirement there, by the way, is that the air look like free stream air. For example, if the pitot snout is too close to the wing surface, you can get into the boundary layer flow, where the flow is more attached to the wing and AOA may not be as sensible (since the air travels in the same direction), and the pitot may become less reliable (since air near the surface of the wing maybe faster or slower than the surrounding airmass). But, those are just guidelines. I'd do the easiest drop-in install first, do an AOA calibration, and see how it goes. You'll probably be okay."
I bought the Safe Air pitot mast... http://www.safeair1.com/Pmast_1.htm ... to increase clearance between the wing and pitot tube in view of their comment about the boundary layer, though obviously any of us could fabricate something similar from E-glass. I'l keep the original location but will put a large flag on the pitot head when it's on the ground. After many years building I'm in a hurry to get flying.
Anyone out there know the boundary layer thickness?
Regards, Chris.
----- Original Message -----
Sent: 1/10/2009 5:23:17 PM
Subject: Re: [LML] Re: LNC2 AOA Pitot tube location?
Chris ;
I am interested too with the location of the Dynon AOA probe on a L320.
Let's all LML fellows to know the answer you'd get from Dynon or anyone else .
Alain Noireaux L320 F-PSDV
Robert Pastusek a ?crit :
Chris Skelt wrote:
I was persuaded by the arguments cited on the List in favor of an AOA indicator and just received a Dynon AOA Pitot tube to replace the standard AN5812. It's 2 1/4 inches longer than the AN5812, and so sticks out a couple of inches in front of the leading edge. In the installation instructions Dynon recommend that the tip should be between 2 and 12 inches aft of the leading edge, which would mean I need to move the mount aft to outboard of the gear doors. This would be a pain, and would also result in a longer and circuitous route for the pitot and AOA plumbing, as would mounting it at the wingtip, etc...
I don't believe I'm the first to retrofit an AOA probe, so does anyone have views or experience on whether it would function well aerodynamically?
Chris, I have this system installed in my Lancair IV-P, and have been very pleased with its performance?except for a computer failure?which Advanced Flight Systems replaced under warranty. I believe having the pitot tube extend forward of the wing leading edge will not affect its performance, and may, in fact, improve it. Not being an authority on such, however, I?d suggest that you call Rob Hickman at Advanced, (503) 263-0037, or email info@advanced-flight-systems.com about this. I?ve found them to be most helpful and am sure they?d be willing to discuss.
Good Luck; your decision to use an AOA is a good one!
Bob
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