Brief Description: Joining the Rudder Skins - Part 1
Section 5.8 outlines the procedure for building a straight trailing edge, but I feel they could be written a little more clearly. I looked at what other builders were doing and decided to use a length of steel rectangular tubing 1 in. x 2 in. x 0.10 in wall thickness as a support to cleco the trailing edge during bonding. The tube was dead straight and very stiff.
I match drilled the tube using the trailing edge as a guide. The I clecoed the spar assembly in the right skin and set the trailing edge on the tube. When you do the bonding of the wedge to the skin you want to make sure you don't put a preload or twist on the assembly. I did this by using shims on the tube and assembly so that the TE would lie flat on the tube without clecos. It took a fair amount of fiddling before I got the TE to lay perfectly flat. To finish the process I clecoed the left skin in place and rechecked for twist.
I decided on using ProSeal instead of the VHB double sided tape partly for its superior adhesion and partly because I wanted to try out a method for applying sealant that I haven't seen mentioned anywhere in any builders logs or on the Vans air force website. I got this method from watching our AOG (aircraft on ground) team working the derilect 737 at work. Basically you use a common paint roller to roll the sealant on. This has the advantage of not getting any sealant in the holes and you get a very consistant thickness with very little mess. It goes only where you want it. They were using 3 in. x 1/4 in. fabric rollers. It's important you get the rollers with minimal "fuzz" on it. Anything more than 1/4 in. is too much. The fuzz comes off and mucks up the sealant. I also got some foam rollers and ended up using them.
The steel tubing is matched drilled to the trailing edge holes.
Setting up the rudder with shims so that no twist is induced when the TE is clecoed together.
Assembly is clecoed together and shimmed. Goal is the TE lays flat on the tube w/no twist in rudder.
