Where is everybody? Wing trammel?

[lawheelock]

I have been checking this site nearly daily for more than a week. It usually, in the past, was pretty active.
There has been almost nothing or very little posted the last week or two.
Where did everyone go?

Would someone please post their method of trammeling a Taylorcraft wing? I have done several searches and can find nothing.
Any guidance would be appreciated. I am putting the left wing back together after making a new rear spar.

Larry Wheelock, BC12 D N96179; former owner of BC12D N96927 from 1964 until about 1969 (flew it over 500 hrs all over the area east of the Rockies)

[Steve Green]

Re: Where is everybody? Wing trammel?

Try searching the forum for the word [trammel]. It will bring up a bunch of threads that have useful information in them. The one started by "rdwater" in 12-22-03 is pretty complete.

[Guest]

Re: Where is everybody? Wing trammel?

hi Larry,
I guess we are all pre-occupied being frightened by the election.

Trammeling is strange word that really means that you are making every section or bay between compression ribs into a rectangle with 90 degree corners.

To start off you have to make sure that spars are parallel. Use shims at the end of the compression ribs to do that.

After the spars are parallel mark the spars on the narrow face with an "X" or dot at each intersection of the spar centerline and the compression rib centerline on the side of the wing that you plan to work from.

Use those marks with your trammel bar to compare the diagonal distances across a bay and make them equal by adjusting the drag and not_drag wires (or is that the !drag wires ).

Start at one end, I like the root to start from, and work bay by bay to the other end then go back and check where you started.

Repeat until all the bays are ok. When you repeat you may find that a bay that you adjusted has changed and needs another adjustment.

For now just make the wires tight enough to prevent movement.

You are only trying to make the diaganols of one bay equal, that's what makes it "square". Don't compare the diagonals from one bay to another.

If you had a giant trammel bar then when you were done you could compare the first set of marks to the last spanning the entire wing and if you did the job well then these diagonals would be equal.

Dave

[Guest]

Re: Where is everybody? Wing trammel?

two other related things:

1) there are posts that remind us to put the drag wire on top of the not_drag wire this prevents them from interfering with each other when the wing is washed out

2) check your front to rear spar distance and the distance between the root fitting on the spar, then compare them to the fuselage. make sure that the wing will comfortably fit into the fuselage. Adding those shims to the compression ribs will effect this distance and fit. So what I am saying is that the distance between the spars must fit the fuselage first, then proceed with trammel.

Dave

[lawheelock]

Re: Where is everybody? Wing trammel?

Dave,
Thank you. Yes, the potential outcome of the election is frightening to all of General Aviation.
Thank you for a very detailed and easy to follow description of how to trammel the wing. I basically knew what we are striving for, but had not seen a detailed description of how to do it like you just gave. It is obviously very time consuming to do it correct since adding or removing shims at the compression struts means loosening bolts, removing, inserting or removing shims and then tightening again which could easily involve loosening and tightening the wires.
I have a way to go as I am just now getting the stamped ribs in position to re-rivit and then nail to the new spar. I don't get to spend a lot of time on it at any one session and will have to leave it in a couple of weeks to head south for the winter and spring.
Again, thank you. I have already saved and printed your comments for future reference.
Larry Wheelock, repairing left wing for BC12D, N96179

[Hank Jarrett]

Re: Where is everybody? Wing trammel?

Wow Dave, That is about the simplest and best explanation of how to trammel a wing I have seen. When I read your first message I was ready to jump in with a comment to set the distance between the front and rear spars first, but you beat me to it. I would also ALWAYS start at the root end. You even caught the washout trick to get the wires in the right order.
What we need now is a nice set of photos of the process (NOTHING helps as much as seeing how it is done!) and a way to mail a nice set of trammel beams through the mail. I would REALLY like a beam long enough to check from root to tip! Where the heck would you store it? :-)
Hank

[N96337]

Re: Where is everybody? Wing trammel?

I second Hank's comments! Nice explanation, Dave!! The one thing I also do is to center a black thread on top of both spars at the root as well as the place where the spar tapers, keeping them just off the surface of the spar so they can move freely. It will give you a good spot to reference for your measurements and also tell you quickly which way the spar needs to move (forward or back) to keep straight.
John

[mikerice]

Re: Where is everybody? Wing trammel?

I agree a few photos would make a nice howto. Daves explanation was great... complete and easy to follow.

As to the need for super long trammel bars, I am trying to picture how several perfect squares sharing common sides (trammel end points) could result in anything but a true rectangle over the length of the wing.

Its a geometry thing, but stacking rectangles should geometrically make a another rectangle...

[Guest]

Re: Where is everybody? Wing trammel?

I agree a few photos would make a nice howto. Daves explanation was great... complete and easy to follow.

As to the need for super long trammel bars, I am trying to picture how several perfect squares sharing common sides (trammel end points) could result in anything but a true rectangle over the length of the wing.

Its a geometry thing, but stacking rectangles should geometrically make a another rectangle...

sure Mike and that was my point.

and...

if you did have a super trammel you could check the goodness of your work and if it was good that first to last point check of diaganols would yield the expected result

[Hank Jarrett]

Re: Where is everybody? Wing trammel?

The reason you do a final trammel over as many bays as you can is to check for additive errors. Statistically errors should be small and cancel out, BUT if there is something in the process that causes the same error to always apply to one diagonal and not the other they will add up and cause a total error that can be significant. If you were going to be totally anal about it you should do things in measurements like measure twice, once from each end and flip the trammel over for the second check. That is overkill for something like a Taylorcraft wing, but become really important if you are trammeling something like a suspension bridge.

One thing that could bite you on a wing is if the spars were curved, twisted or cupped. Over the length of a wing that could cause errors that would make measurement and adjustment really hard. Of course if you are assembling a wing with that kind of cupping, twist or warps in the spar you are way past problems you can solve with trammeling.

The next item to discuss probably should be how to trammel the sections of a fuselage to get the tubes straight and finally how to trammel the whole plane to make sure it goes together straight. I only know a couple of people who have bothered to trammel a fuselage or whole plane and it can raise the hairs on the back of your neck. Some of our planes are REALLY crooked! And yet, they still seem to fly pretty well.

Hank

Of course the straight ones seem to always fly a bit faster on the same power.

[Guest]

Re: Where is everybody? Wing trammel?

The reason you do a final trammel over as many bays as you can is to check for additive errors. Statistically errors should be small and cancel out, BUT if there is something in the process that causes the same error to always apply to one diagonal and not the other they will add up and cause a total error that can be significant. If you were going to be totally anal about it you should do things in measurements like measure twice, once from each end and flip the trammel over for the second check. That is overkill for something like a Taylorcraft wing, but become really important if you are trammeling something like a suspension bridge.

One thing that could bite you on a wing is if the spars were curved, twisted or cupped. Over the length of a wing that could cause errors that would make measurement and adjustment really hard. Of course if you are assembling a wing with that kind of cupping, twist or warps in the spar you are way past problems you can solve with trammeling.

The next item to discuss probably should be how to trammel the sections of a fuselage to get the tubes straight and finally how to trammel the whole plane to make sure it goes together straight. I only know a couple of people who have bothered to trammel a fuselage or whole plane and it can raise the hairs on the back of your neck. Some of our planes are REALLY crooked! And yet, they still seem to fly pretty well.

Hank

Of course the straight ones seem to always fly a bit faster on the same power.

Good points Hank depending on how stiff your trammel bar is you can get different "readings" depending on how and where you hold it.
You have to be consistent and willing to observe. Mine are made from 3/4" by 3/8" oak and it can get too flexible as you spread the points farther apart for big diagonal. I am thinking of finding a metal replacement one.

My Aeronca fuselage has has so many repairs that it had a 1 to 2 inch bow convex on the right side. I fixed it but it flew that way for years. You are correct; I am not sure that I want to look any deeper and know any more.

Dave

[dalijohn]

Re: Where is everybody? Wing trammel?

Hank, check you email. Tried PMing you, alas your account is full!

[N-43121]

Re: Where is everybody? Wing trammel?

The reason you do a final trammel over as many bays as you can is to check for additive errors. Statistically errors should be small and cancel out, BUT if there is something in the process that causes the same error to always apply to one diagonal and not the other they will add up and cause a total error that can be significant. If you were going to be totally anal about it you should do things in measurements like measure twice, once from each end and flip the trammel over for the second check. That is overkill for something like a Taylorcraft wing, but become really important if you are trammeling something like a suspension bridge.

One thing that could bite you on a wing is if the spars were curved, twisted or cupped. Over the length of a wing that could cause errors that would make measurement and adjustment really hard. Of course if you are assembling a wing with that kind of cupping, twist or warps in the spar you are way past problems you can solve with trammeling.

The next item to discuss probably should be how to trammel the sections of a fuselage to get the tubes straight and finally how to trammel the whole plane to make sure it goes together straight. I only know a couple of people who have bothered to trammel a fuselage or whole plane and it can raise the hairs on the back of your neck. Some of our planes are REALLY crooked! And yet, they still seem to fly pretty well.

Hank

Of course the straight ones seem to always fly a bit faster on the same power.

Hank,

This reminds me of a saying that would simply not be appropriate for our little birds; but maybe on the Maule or Shortwing Piper forums ... "mic-ing the brick".

Just saying'

Rod

[Hank Jarrett]

Re: Where is everybody? Wing trammel?

Dave,
got your email and am attaching the file you sent me at a text file and a PDF for everyone else. I had a copy of that page but no way at home to scan it.
Thanks

Hank

Rod,
Mic-ing a brick is only needed on a Taylorcraft if it is an original "Taylorcraft Brick" (anyone fine one in the tail of their plane? They are real collectors items!), but I didn't know that when I did the 45 fuselage. It is probably the straightest fuselage on any Taylorcraft. It was my first GA airplane and I thought it had to be to 0.001".
Just a hint for anyone who is thinking of trying it, you can never get there....but I got darned close!

[lawheelock]

Re: Where is everybody? Wing trammel?

Hank,

Thank you for posting the pdf file. The wing diagram is helpful too.
The text file had nothing in it.
Hank, maybe you are already familiar with this, but I bought the cheapest Canon printer/scanner I could find at Walmart a year or so ago. The price was basically what the price of a package of color ink plus a package of black ink was, so they were essentially giving away the machine. It was around $50 and came with ink. It even lets you set the default printing to print black and white (grayscale) and fast print automatically which saves lots of color ink when printing text like stuff from this T-craft site.
I have found this printer much more reliable than any of the many HPs that I have had. The HPs always default to "normal" quality, color which is designed to use up the ink fast so they can sell more. But the Canon scanner program works easier and better than any other that I have ever had. It gives several choices of scanning into jpg, pdf, and several other files.
I have scanned a lot of T-craft stuff using stuff using it.
Larry Wheelock, N96179