Thorp Air Command - T18.net

Hey guys,

Today's question: How to bend my pitot tube? Static ports are on fuselage sides behind baggage compartment per newsletter. I know there are lots of types and places for pitot tubes. I put a fitting for a simple 1/4" tube under the end of the left wing, inboard about 1 ft. from the wingtip joint, just ahead of the spar. Making a guess at it, I'll extend it down 8" and forward 4", putting the tip about 10" back from the leading edge. Can I get some comments if that's reasonable? I know others have similar setups but didn't see any in the old newsletters.

Close to the finish line...
Les Krumel, Albuquerque

Close to the finish line... congrats, Les! If anyone is taking bets between me and you, I'll put my money on you.

Mine is about 5" down and 4" fwd, and more like 30" inboard from the left tip.

Les,
My pitot is mounted through the most outboard rib flange about 3" behind the leading edge and extends forward approximately 7". The vertical distance is the radius of the tube bender plus enough straight for the sleeve that mates with the B nut. By pulling the wing tip I have access to the pitot pumbing. Just another data point.


You just need to get the end of the tube far enough away from the wing to be out of the boundary layer, a couple of inches is probable enough. For reference, take a look at the pitot on a Piper Cherokee.

It'll be great to see another Thorp take to the air.
Get er done!

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Speaking of Piper Cherokee, I use the baloney slicer pitot used by Piper. Mounted it just aft of the main spar. It, s right on with my GPS speeds.

As Bruce said; out of the boundary layer. The main thing is to not have it where it will get bent when folks mill around the plane, as they will when you bring it out. I use the Piper baloney slicer as well. I found that I had to use cabin air as the static to get truly good readings. I had a plane with a probe out of the left wing and it was always getting bent.

_________________
Bob Highley
N711SH
SN 835
KLAL

Thanks again guys. I like simple. Now on to the next question... Les.

I used the "L" shaped tube from Vans . It came with the mounting flange and I think at the time it was around $10.00 ? I placed the tube in the same bay as the LED landing lite and installed an access cover on the last rib . I did improve on the appearance of the tube by installing some model aircraft streamline tubing over the pitot tube . Nothing magical about the pitot tube . Just a 1/4" piece of alum. tube with a 90 in it .

RB