Began the fuel vent install - 6 hours

 This is a part of the build that I was never really looking forward to. From what I've been reading this isn't the most simple and straight forward process. Then again, what did I expect....were building an AIRPLANE!

I have been looking at the option of F1 rocket style fuel vents that are coiled tubing contained within the wing root. Lots seem to report they work well. However I met an F1 Rocket owner and he didn't seem all that enthused about how they perform when I asked him about them. I ultimately decided to face the tricky tube bending head on. 

1/4" tubing is way more easy to work with and tweek versus the 3/8" tubing. So straight off I knew this would be less challenging then I thought. I decided that I will work the tubes from aft forward. Starting with the most difficult bends first and then leave the most simple and straight forward bends at the end.

Rather than eat up long lengths of tube, I choose to fabricate each bend making a template out of small sections of tube. This would allow me to "stitch" together a complete fuel vent with a precise example to follow.  I should note that all bends are been done with a tube bending tool, and only slight tweeks are being performed by hand. I also use a 1/4" tubing straighter to get all the coiled tubes straight before I start the bends. Both tools are fantastic and easy to use.

The first challenge is to sort the first section which turns out to be the most complicated portion of the vent. My first attempt clearly shows that I have distance issues between the 90deg fitting and the side stiffener angle.

The tube makes contact with the angle. So to solve this...I need to shorten the distance between the flair and the bend. Learning from previous samples I have shaved down the AN fitting sleeve. The result is that I can move the sleeve out of the way and get a much tighter distance between flair and bend. 

The result is excellent. Great spacing to go up and over that angle.

That solved, the next hurdle is to get the tube bent under the rudder cable. Simple enough... Using a piece of hinge pin strung through the rudder cable holes and attached to the rudder pedal with tape, I can easily see clearances.

At this point things look really good, but now I need to get this tube to offset enough so that it sits closer to the F-902 bulkhead and can attach with an adel clamp. That part of the bend is a pain. With my current setup, getting that offset bend is difficult and takes up a lot of space. It also looks awful. So, the way to fix that is to start my offset bends further down as the tube slips under the rudder cable. The result, while still tricky is a much more clean bend.

This is the exact 'recipe' for this section of bends (Keep in mind, that these work with my particular brands of tools);

1. Start the tube by bending 45deg a couple of inches from the end.

2. Flip the tube 180deg and then bend the tube 90deg immediately.

3. Measure 1" (Measured from the end of the previous bend to the start of the next bend).

4. Make a 45deg bend. (At this point you are now slipped under the rudder cable and the tube is pointing straight up from the fuel vent fitting).

5. Rotate the assembly 45deg in the tubing bender and bend the tube 60deg. (This now angles the tubing toward the bulkhead).

6. Measure 1" and then bend 60deg. (At this point the tubing should now be straight up to follow the F-902 bulkhead as shown in the picture above.)

7. At the end you have started on. The tubing can be cut and flaired. The exact length is 3/4” from end of the bend to the end of the tube.

8. Some slight tweeks will be required to get it all straight and aligned.