Phoenix FS

Right Wing Fuel tank

Since the goal of our team is to fly on (liquid) hydrogen, there is no need for sealed fuel tanks on the wings. That's why we have decided not to seal the fuel tanks. Still they had to be build since they are an important part of the wing.

We did start out by making the fuel tank jig out of some mdf wood. but since they did not have to be sealed we soon figured out this jig was quite unnecessary. The fuel tank ribs where made as they are supposed to but any sealant, gasket or tubing was left out. We did however used the sealed rivets everywhere where they were supposed to be used since we would have a shortage of normal rivets if we would have used those.

After having cleco'd the ribs and fuel tank stringers to the rear fuel tank channel and the skin, we mounted it to the right wing with cleco's before riveting. This was to make sure that the ribs, stringers and channel were properly riveted into place and no misalignment issue would occur later.

After riveting the ribs stringers and channel the fuel tank was removed and the large channel together with the smaller fuel tank mounting channels were riveted onto the ribs from the back using sealed 4mm rivets. Getting to these rivets was hard even with a hand riveter. With normal rivets: if the rivet gun had a slight offset angle with respect to the surface the rivet would still pull itself straight but the sealed rivets are much weaker and unable to pull themselves straight even with the slightest misalignment of the rivet gun. Extra care has to be taken in holding the rivet gun perfectly perpendicular to the surface before pulling the sealed rivets!

Another notable thing with the sealed rivets is that once every +/- 50 rivets the mandrel will break somewhere in the middle instead of at the bottom as it is supposed to be. We thought about removing these, but one of our supervisors advised us just to file down the mandrel until flush with the head.

Eventually the fuel tank was attached nicely to the wing. 1 point if improvement would be at the leading edge where the fuel tank skin overlaps the non-fuel tank leading edge skin. There the fuel tank skin turned out a bit 'wavy' which is not that pleasant to look at. We hope to be able to fix this with some filler (which we also plan to use to fill up the rivet holes in the future)

Builders of the fuel tank:







This post is from Phoenix FS