Pitot Tube Plumbing   June 28th, 2010

The pitot tube comes with very long aluminum tubing.  You can’t really bend it and be able to take it in and out of the mount.  So, I cut it down to a more reasonable length, added some clear platic hose (from Home Depot) to protect against the two tubes rubbing against each other, and installed the required connectors to go from aluminum tubing to the clear plastic tubing provided by Safeair (http://www.safeair1.com)

With the pitot inside the mount, I tried to route the two plastic hoses from the grommet in the rib to the pitot.  The problem is that these hoses have a minimum turning radius of 2″, so there was no way I was getting the tube to do what I wanted without putting kinks in it.

I figured I could use two 90″ connectors on each line (only one of them is shown below).  These are over $5 if you buy them at the usual aviation places.  However, if you go to AutomationDirect and search for Union Elbow under Pneumatic Components, you can find them for $5.50 for a 5-pack :-).  I bet they also have the plastic tubing for them at a much lower price.

Once the tubing is pushed fully into the fittings, they will look a lot more straight than they do below.

Finally, this is what it will look like from the outside…

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Pitot Tube Screws   June 16th, 2010

Before mounting the pitot mast to the wing, we need to drill and tap four holes for screws that hold the pitot tube to the pitot mast.  Drilling the holes was a bit tricky, since the pitot mast is a curved surface.  I used a leather glove to sort of hold the pitot mast in place, and did my best to drill a hole perpendicular to the pitot mast.  Dynon recoments using 6-32 screws, so I drilled the holes with a #36 bit.

I then match-drilled the pitot tube through the mast, and used a 6-32 tap to cut the screw threads on all four holes.

I was not sure which kind of 6-32 screw to use, so I ordered three different kinds from Aircraft Spruce (They are something like $0.05 each, so I figured it was worth the investment…)  The one on the right was the ‘safe’ choice, but it kind of looks like crap.  I ended up using countersunk screws like the one shown on the left.  I was not sure if the mast would be thick enough to countersink, but I decided to try it out anyway.  The hole did end up slightly enlarged, but there is plenty of material in the pitot tube for the screw to grab on and hold on to the pitot mast.

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Installing the Pitot Mast   April 11th, 2010

The pitot tube included in the RV kit is just a bent piece of aluminum tubing.  Nothing wrong with that, but I wanted a “real” pitot tube like any other grown-up plane.  In addition, I am still leaning towards using Dynon for my instrument panel.  They have a pitot tube with an Angle-of-Attack, which I would like to use instead of a stall warning horn.

So, I ordered a pitot mast from SafeAir.  It gets riveted to the main spar and to the bottom skin.  It comes with a paper template, which you simply tape up to the bottom skin and then cut out.  One important thing to point out is that the template was originally drawn for an RV-6.  For an RV-7, the template needs to be slightly offset outboard.  This allows the pitot mast’s plate to clear the rib that sits next to it.

The bottom of the template is aligned with the edge of the bottom skin and then you just got at it to make the hole for the mast.  I used a unibit to remove as much material as possible.

After I couldn’t take any more material out with the unitbit, I used a dremel tool with a little sanding drum to finish shaping the hole to match the template.

It took a bit of trial and error, but finally the hole was just the right shape for the pitot mast to slip through.

The template is supposed to be held by three rivets through the main spar and two other rivets at the opposite corners.  This wasn’t as solid I would have liked, so I added a little piece angle.  This angles has three rivets going through the pitot mast plate and the bottom skin, and three blind rivets to the adjacent rib.  This makes things a lot more solid.

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