Get things straight from the start

In order to get the fuselage started straight and  level you will need to minimally have the following bulkheads in place:

• F-401 The Firewall
• F-404 The Wing Spar
• F-407 The Back Seat
• F-412 The Tail

Starting from the front, be absolutely sure that F-401 is level, at the correct hieght (there was an error on earlier plans of a 5/1/8 vs. 5 7/8) and square or vertical on the jig. Then mark the center of that bulhead on the upper (lower on jig) aluminum angle (need term). This is the alignment point on the front which will be used in conjunction with the alignment hole in F-412.

In my case, I had to center F-404 on the jig, without the string because the crossmember I used was taller than all of the other crossmembers in order to hold both F-404 webs in the correct position. By utilizing the sides of the jig, a carpenter's square, and measuring carefully from F-401, I was able to center F-404. In retrospect, I suppose you could cut out the center section of the F-404 crossmember to allow the alignment string to run the full length of the fuselage.

I next marked a center line on the F-404 crossmember and drilled an alignment hole at a height that kept the string 1/8" - 1/4" above all the other crossmembers. Turns out that this is a much simpler connection point, I am not sure how one would connect to the stainless steel or aluminim angle of F-401

NOTE: Unless you keep the string off  the crossmembers slightly you will not get a true reading along the length of the fusleage.

This photo shows where I fastened a string from the center alignment hole in F412. Then I stretched it to the alignment hole just drilled in F-404 and checked to make sure there was nothing touching the string while measuring the distance between the longerons at each crossmember.

I'm not sure it matters, but I placed the remainging bulkhead into position on the longerons, with the exception of F-410.

Due to the palcement of the holes in  F-410, there is no way to run th alignment string. Well actually there is a way - I discovered it by accident. By putting F-410 in upside down, the string just barely clears both the crossmember and the F-410 bulkhead. Probably best to just leave it out until everything is locked down and centered along the jig.

Using the alignment string as your guide, you can now easily straighten the longerons and attach (clamp per instructions or of your own design) them securely to the crossmembers. In theory, if all of your crossmembers are the same height, your longerons will also be perfectly level at this point. In my case there was a slight variation between F-412 and the remaining crossmembers, so I had to make an adjustment.

Here is what it looked like when I was finished.  The longerons are perfectly level along their entire length until F-404 where they bend down (up jigged). They are also secured to the crossmembers such that there is an equal distance from the alignment string to each respective longeron, thus creating the basis for a straight fuselage.

By definition the bulkheads are mostly vertical because the longerons pass through the notches in each bulkhead. And assuming the crossmembers are place at the correct distance from F-401, the bulkheads are also very close to their final resting places. So far I have not yet drilled one hole, just clamping things together until final measurements are verified.