wing trammelling

[rdwater]

This topic has been started on other threads that have diverged into other subjects before we got to the answer. I've got a '46 BC12D with rear spar work done. The spar is back in the wing and we need to re-tighten the drag and anti-drag wires. Can someone please describe the proper procedure for this? My IA is white-haired, but still wasn't sure! Thanks, Bob

[taylorcraft078]

Bob,

If you get any replys that aren't posted to the web site please copy me in. I am hoping to have to do one panel before the end of the holidays. Today my wife made me take off my clothes in the cellar. Something about being covered with varnish dust. I figure that any varnish that smells like gas, urine, or mold when I hit it with the sander should probably come out of the plane.

Dave
N36078 ' 41 BC-12-65 in pieces

[mredpath]

I have built a bunch of wings and there is nothing to trammeling. All you are doing is making sure each bay is square. Where it gets fun is when there is two sets of wires in a bay but that is a story I don't have time to tell. I used a piece of one inch tubing slightly longer than the outboard wires for the trammel bar. Take another short piece of tubing that will slide over the bar tube and drill a hole in one side.The less play the better. Braze a nut over the hole and install a screw for a lock. On the other side braze a rod approx. 1/8 inch in diameter and about 6 inches long that will drop in the empty hole right below the compression bolt. You need to make two. Adjust the points until they will drop in the front of one compression member and the back of the next one over. Once you lock the points, reverse and check the other wire. If they are the same the bay is trammeled square. If it is not then you need to adjust the lengths of the wires until they are the same. It will take some practice to know which wire to shorten or lengthen because I still confuse myself sometimes. Once the first bay is done, lock the adjusting nuts down and proceed to the next bay. till you are done.

[Ron Greene]

Wing trammeling

How tight do you tighten the drag and anti-drag wire?
Ron Greene

[mredpath]

tighten both wires as evenly as possible and as tight as possible with a 3/16 offset ignition wrench. You won't be able to overtighten with the little wrench.

Mike

[Grant S. Bailey]

Also make sure drag wires are installed on top of anti-drag wires.

[rdwater]

Thanks everyone for these great suggestions. Another dumb question...which one is the drag and which one is the anti-drag wire?

[Robert Lees]

Drag wires are the ones resisting rearwards air loads in forward flight.

Anti-drag wires are those trying to stop the wings moving forwards under their own inertia when you stomp on the brakes at the end of that extremely short runway with a large hedge at the end.

[Acroeric]

How important is the sequencing of the wires. I will have to look but I think I did not have mine positioned as stated. I really do not want to re-trammel!

[Grant S. Bailey]

I hate to admit it, but I had mine all reversed (i.e. anti-drag wires on top of drag wires) and after tightening the wires I noticed my wing starting to twist. The next day it had one heck of a twist in it. I immediately loosened all of the drag wires and the wing returned to normal. That is when I discovered "install drag wires on top of anti-drag wires" on the very difficult to read printing on the wing plan in the service manual. I can't explain why the wing would twist, however on second try the wing has stayed very true with the drag wires tightened and in the proper position (drag on top of anti-drag).

[Jim Baker]

Make sure to start your trammmeling with the inside (root) bay.

[Forrest Barber]

wires

When doing the wires go out to the tip with the wing in a normal upright condition on the saw horses.. raise the rear spar a bit like it will be when installed and rigged, ( wash OUT) you will see that the wires should move away from each other.........

Sooooo you now see that we do not put tape around both wires hooking them together...you merely put a few wraps of tape around the lower wire as a rub strip ; original was good old black friction tape with shellac there are better tapes now....

How tight? I use low G on the tail wires and make the wing wires quite snug , I still have a wing wire tool from the factory
and it has a very short lever arm ; about 1 inch or less. So do it as tight as you can with a short wrench and your little finger!!

[taylorcraft078]

Forrest,
I have been removing that old black tape. Some of it was even used to hold ribs together. Varnishing the spars today. The wing panel is sitting in the driveway in the sun.
Dave
N36078 '41 BC-12-65

[Forrest Barber]

Probably that tape was put on at the second or third recover

e-mail me direct if you ahve any particular questions... Have fun warm stuff went away down here today.

[Guest]

When I did my last set of wings with new spars I found it helpful to start by by adjusting the front to rear spar fitting dimension so it matched the fuselage fittings.

Had to add/remove shims under the compression struts to do that.

The previous worker had them misaligned and the deformation in the old wood was apparent. Assembly of wing to fuselage has to be easier if the fittings align well.

Dave.