pitot tube 7ac

powers · Post by **powers** » Mon Oct 06, 2008 21:51

Anybody have any good pics of the pitot tube on a 7AC. I'm trying to install mine but its been years since I've seen a Champ fully together. Thanks in advance.

james gevay · Post by **james gevay** » Tue Oct 07, 2008 14:52

I hope these pictures help.
The first is from my parts out in the garage. The assembly is pretty easy once you know how they go together.
The pitot tubes are screwed to the front jury strut about 1/2 down from the top. Then it gets screwed to the horizontal jury strut with the 2 holes near the front. Remember to have the 10 degree bend at the end of the horizontal strut, and angled inboard. Look closely at the picture, I think you can see the holes and the angle.

Both of the front and back jury struts have a slight bend on the ends, and I think both are on the bottom, I know the front goes on the bottom, it can fit only one way.
I always look at Champs and Chiefs and it amazes me how many I see without any bend in the horizontal strut, and the front and back "tweaked" to fit.
The second is from Oshkosh and shows the tubes and how they go through the fabric.
This person did a fantastic job with the covering, but I would make the tubes go through behind the strut, not off to the side.

powers · Post by **powers** » Tue Oct 07, 2008 17:02

Thanks for taking the time to put that together. I got this project in pieces, and the little things like this have haunted me. I made the tubes come out of the fabric on the side of the brace as well. But I put them up tight to the brace. I seem to be missing the little bracket on the pitot tube. That was throwing me off a little. What angle does the pitot tube have to be with relationship to the wing or strut? Or does it just need to be close?

james gevay · Post by **james gevay** » Tue Oct 07, 2008 18:46

The top one is just a small "U" shaped bracket thats soldered on the tubes. The bottom one is curved to meet the round horizontal strut.
As for the angle, I have no idea, I've always just left mine the way it came when I bought the plane. Mine looks like it's at a very slight angle. My only guess would be to make it parallel to the bottom of the wing.
Although I've seen some that were obviously bent at some larger angle from the wing.
When I repainted my struts years ago I put some inner tube rubber under the brackets so they don't scratch the paint.

Mikek · Post by **Mikek** » Tue Oct 07, 2008 20:59

james gevay wrote:The top one is just a small "U" shaped bracket thats soldered on the tubes. The bottom one is curved to meet the round horizontal strut.
As for the angle, I have no idea, I've always just left mine the way it came when I bought the plane. Mine looks like it's at a very slight angle. My only guess would be to make it parallel to the bottom of the wing.
Although I've seen some that were obviously bent at some larger angle from the wing.
When I repainted my struts years ago I put some inner tube rubber under the brackets so they don't scratch the paint.

OMO
I would say parallel to the bottom of the wing. 99 % of the ones out there also have a disk (see picture above) is positioned just in front of the static hole (about 3/8 in.) this disk can be move to adjust the indicated airspeed but the Champ still will not catch a Chief.

Mike K

Post by **joea** » Tue Oct 07, 2008 21:28

The small disk that Mike is talking about is shown in the top photo on the bottom tube. It is needed to adjust for an accurate airspeed reading.

WWhunter · Post by **WWhunter** » Wed Oct 08, 2008 07:27

Anyone have a spare set of these tubes? When I bought my Champ the lower tube that is supposed to have that disk on it is broken. It is broken just above the bend and juts straight down. I have jabbed my back on it many times!!! OUCH!!! I never knew a difference until after I had the plane for awhile. The airspeed registers correct though....at least it sure is close to my GPS reading most of the time.
Keith

Post by **joea** » Wed Oct 08, 2008 09:06

Keith,

You could make one of these disks without too much trouble. Would not look for the entire pitot assy just to get a disk. The tubing is plain metal tubing and you could replace the one broken tube easily without buying a new one.

Take some bar stock the right size or a bit larger, cut a slice out of it, file or turn it down a bit then drill and tap for a set screw. Could be done in 30 minutes with a descent workshop, or an hour with basic hand tools (hacksaw, file and drill and tap) that I know you have to have at home.

Wonder if ACA or Wag-Aero has these disks for sale? Bet that Wag would have the complete pitot assy if you really wanted it.

Joe

Mikek · Post by **Mikek** » Wed Oct 08, 2008 09:30

joea wrote:Keith,

Wonder if ACA or Wag-Aero has these disks for sale? Bet that Wag would have the complete pitot assy if you really wanted it.

Joe

Joe would you (NAA) have the drawing for the Ass'y 3-535, also I noticed that that the service manual shows the Airspeed tubes on the left wing, with the indicator on the right side of panel.

Also the tubing in the wing is soft alu.

Mike K

Post by **joea** » Wed Oct 08, 2008 09:36

Mike,

Just looked and its one of the drawings that we do not have a copy of this drawing.

Joe

Nathan K. Hammond · Post by **Nathan K. Hammond** » Wed Oct 08, 2008 13:36

For what it's worth, I'm planning on putting the pitot/static lines on the left side. More than once I've run into them while slipping behind the struts after propping, and I'm afraid I'll break them off if not careful.

nkh

powers · Post by **powers** » Wed Oct 08, 2008 13:41

Ya thats a good idea. I thought about doing that but chickened out.

Post by **joea** » Wed Oct 08, 2008 14:44

On the LEFT side? More proof about Nathan and backwards, two peas in a pod I guess!

Joe

PS Actually I do not see any reason not to and it would keep it out of the way of getting in and out. The Sedan has the pitot on the left wing.

james gevay · Post by **james gevay** » Wed Oct 08, 2008 15:07

This is just what I do when proping my plane.
I always go around the entire length of the struts, I never cut half-way through.
I don't want the habit of cutting through and getting too close to the prop disc. I think it may help some day when you get complacent and just take the short cut.
I know that cutting through is not that close but that's the habit I developed.

Paul Agaliotis · Post by **Paul Agaliotis** » Wed Oct 08, 2008 15:14

ACA has moved the position to the rear spar on the right wing. The original location is prime for getting it bent out of shape. We have a remove before flight streamer with velcro attached for installation on the Citabria. This saves coming out of the cafe to a broken pitot tube.
Paul