Tuesday, March 6, 2012

A retractable Pitot Tube on an ultralight aircraft

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One really cool feature we've been shipping on our ultralight aircraft is a retractable Pitot tube.  The old fixed pitot tube was a royal pain, and tended to get bent everytime we shipped an airplane in our trailer.

Solution:  a retractable pitot tube.  Credit for this idea:  Gene comes through again.

Here's photos as to how we do it:

First of all, this is what it looks like when it's extended.  We've placed the pitot tube through the leading edge of the wing, which is also our front spar.  Although this photo shows a carbon fiber spar, it works equally well with aluminum spars.  Also note that the location of the pitot tube is very close to the wingtip, so there is very little stress on the spar at this point.  (I have to have a very good reason to drill through a spar.)

Retractable Pitot Tube in Ultralight Aircraft

Here is the same Pitot Tube, retracted into the wing.

Retractable Pitot Tube, inside ultralight aircraft wing
The Pitot Tube is constructed of 1/4" 6061T6 aluminum, to which we've tack welded a washer to the front.  An alternative to welding would be a good metal bonding glue, such as 3M 2216 (ScotchWeld) or JBWeld.

My shop foreman, Gene, has also fabricated some very nice boots and 'Remove Before Flight' flags for the Pitot Tubes.  Simply made out of nylon webbing, a metal clip, and rubber tubing, it slips over the front of the Pitot Tube.

Rubber Boot, "Remove Before Flight" on front of Pitot Tube on ultralight aircraft
We supply plenty of Pitot Tubing with every kit we sell.  It is mated to the Pitot Tubing using a scrap length of fuel line tubing.  I'm sure you'll be able to find something to make this work:

Mating the Pitot Tubing
I hope you find this helpful in your experimental airplane or ultralight aircraft.

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