How to Install the Pitot Tube in a QB Wing

[Rolly LSA]

I am reluctant to just start cutting holes in the Leading Edge of the Wing. Sooo I thought I would ask for advice from builders how they installed their pitot tubes. It looks like it ought to go in the area where the lift strut comes into the wing. Thx. Rolly Clark

[N942VT]

The idea is to keep it out of the prop wash and flap disturbance areas. Otherwise put it where you will have access to install / remove / inspect. Mine is in the outboard bay, others have put it in the bay just outboard of the strut attach with good results.

[John Massaro]

Something I saw, albeit on a Kitfox IV, on pitot placement was locating it ahead of, and near the strut attachment point.
The thinking behind this was so that the strut would provide some protection to the tube as people walked around and under the wing.

[Enewton57]

Here is how I did mine on the Patrol QB
(link removed due to URL change)


Eric Newton
Bearhawk Tailwheels LLC

Http://bhtailwheels.com

Bearhawk Builder Manuals

Http://mybearhawk.com

[Rolly LSA]

Thanks to all, and to Eric for the great fotos and parts list. RC

[Zzz]

Eric, I noticed your pitot tube looked to extend about 12" past the leading edge. Is there a minimum length for that? Is there any aeronautical principle that requires a minimum distance from the leading edge? Maybe for "clean" air?

[Battson]

Eric, I noticed your pitot tube looked to extend about 12" past the leading edge. Is there a minimum length for that? Is there any aeronautical principle that requires a minimum distance from the leading edge? Maybe for "clean" air?

At low speed air is incompressible, so provided it's clear of the higher pressure area around the LE, there should be no problems I'd have guessed. Lots of gliders I see have quite short pitot tubes, often bent to sh*t too. Still seem to work just fine provided the front still points forwards.

[Enewton57]

Eric, I noticed your pitot tube looked to extend about 12" past the leading edge. Is there a minimum length for that? Is there any aeronautical principle that requires a minimum distance from the leading edge? Maybe for "clean" air?

Yes - a previous builder who was an engineer type had said a long time ago that 18" was ideal - but o went with 12" and mine seems to be accurate. It has to do with air building up at slow speeds and high angle of attack.


Eric Newton - Long Beach, MS
Bearhawk Tailwheels LLC
Bearhawk Manuals

http://mybearhawk.com

[N942VT]

Dynon boom type recommends 18" for the same reasons. Seemed like a lot to me but works well.

[AKKen07]

Has anybody installed the leading edge boom type pitot? I would like to do so but haven’t found any references for installation. I’m not sure how to seal up the hole in the front, support the boom, etc. Any pictures/experience would be greatly appreciated!

[jaredyates]

I did, but I don't think I would do it again.

[AKKen07]

Oh? Have you run into problems because of it?

[jaredyates]

It just seems that the underwing pitot is much better supported. There are plenty of mounting masts available, and it looks like if you want to have heat, that may be the only way to go. I have a heated under wing pitot standing by for installation, but just haven't had a chance to swap it out yet. When I get back to a computer I can look at my building log to try and find the photos of how I mounted the boom style pitot. It works, but it isn't particularly elegant.

[AKKen07]

Thanks Jared, after a day of reading and hunting down answers I’m thinking of changing my mind to just what you’re saying. Your experience might have convinced me.

[James]

Hi AKKen07, I inherited my wing with a hole through the LE for the boom mount, and a combined P/S boom to match, so I thought I'd stick with it. Battson also convinced me about the merits of Dynon AOA probes, which only come with the under-wing type. So my plane will have both.

I'd always go with the under-wing type. It's easy enough to modify one of the inspection panels to accept it - search this forum and you'll see pictures of my effort, plus all the info I squeezed out of Dynon and the other builders about where to position this sort of probe. Haven't flown yet, but I'd definitely go underwing again, if only because if you change your mind / probe, you only have to change the panel, not patch the hole in the leading edge.

James

[AKKen07]

Thanks James! Your thread was part of the reason I changed my mind to go underwing. A Dynon pitot/AoA it is! Cheers