Wing prep for cover 1946 BC12D

[jim34285]

We have removed the fabric, cleaned the metal, checked components and now are ready to trammel.
What we need is an accurate drawing of the wing structure, giving dimensions. Also could use a written procedure to use ensuring accurate alignment.
Is there anyone who can provide these or direct us to a source ?


Jim

[Ragwing nut]

Re: Wing prep for cover 1946 BC12D

measure the wing attach brackets to make sure of a slip fit when wing is reinstalled. All the rest of the bays just need to make sure they are square. Find the center line of the spar and compression member point. Once that location is marked, measure the distance along the drag and anti drag wires to make sure they are identical. If they are not, you will need to either lengthen or shorten the appropriate wire. To know how much, take the two dimensions, subtract them and then divide by two. that will give you how much it will need moved. Start at the wing root and work outboard. If you have not taken the wing apart, you should not have to do much changing if any at all.

[Pearson]

Re: Wing prep for cover 1946 BC12D

Here is a little blurb on trammeling from the Dakota Cub website. Also, I have helped an IA do this on an Aeronca and a short wing Piper. According to this guy, you really need to use a special tool for the measuring, instead of a tape measure. I forget what you call it, but it is one of those things with the pointers that slide on a bar. There are thumb screws that hold the pointers where you want them. The idea is that you put the tips of the pointers on the points you want to measure and lock the thumb screws. Then you use the pointers to compare that measurement with the diagonal of that same bay you are working on.

Here is the blurb.

Dakota Cub Aircraft
Wing Trammeling Instruction

The purpose of wing trammeling is to "square" the wing along its length. This is a very important process and if not properly squared, will not fir the fuselage properly. If improperly trammeled, it is possible the wing tip could lead or follow a line that is perpendicular to the fuselage. Problems with aileron or flap hinge alignment, and aileron end clearances with inboard
and outboard wing ribs can occur. These problems can be avoided if a little time is spent "laying out" the wing for the correct trammeling process.
It doesn't matter where you start the trammeling process on the wing as long as your spar layout is accurate! First you must make known the exact relationship of the butt end fitting holes to the centerlines of each drag/compression struts. To accomplish this, lay the front and rear spars next
to each other with the butt end fittings installed and align the fuselage attachment holes with each other. This is the basis for keeping the wing square. When these holes are accurately lined up
you can proceed by marking the spars "as they lay next to each other" at EACH compression strut location. Next mark the center of each spar on the line that you have drawn across the spar. If this is done properly you can start the trammeling process at ANY bay and it will come out
perfectly. Square is Square!

When assembling a wing from scratch I prefer starting at the "N" drag strut at mid wing. When installed first, this assembly tends to automatically square the wing to some extent, and with the strut attachment fittings located in this area, it is easier to slide ribs onto the spars from both ends. If the wings are already assembled without trammel marks, you must use an alternate layout process. A narrow width tape measure with the end removed can provide an accurate layout tool. Starting at the outboard tip rib, slide it under the rib capstrip and along the spar top cap aligning it with the inboard wing to fuselage attachment hole. Remember - measurements used on the front spar MUST be accurately transferred to the rear spar! Once marked, the wing can be accurately trammeled. This procedure works well when trammeling a wing in which only one spar has been removed & replaced. It facilitates the trammeling process, without complete wing
disassembly for spar layout.

[Robert Lees]

Re: Wing prep for cover 1946 BC12D

How to trammel a Taylorcraft wing.

If the attached is not detailed enough, send me an email address & I'll email a better copy.

Rob

[Buell Powell]

Re: Wing prep for cover 1946 BC12D

[QUOTE= I forget what you call it, but it is one of those things with the pointers that slide on a bar.
Aircraft Spruce sells them for 29.85-they are called trammel points.