I've just make a blank for one of the fuel tanks of my Westbury Hunter out of blue foam. I plan on molding my own tanks (or at least the custom shaped ones).

To maximize the volume, I've made it to fit between the intake ducting. I have a question regarding it's shape though. I am worried that the clunk will be constrained to move only in the very tapered back section and not work as well as it should. Does anyone think this will be a problem or am I worrying about nothing.

I do have the space to fit two of these tanks, plus a cylindrical tank as well. Theoretically I could have about 140oz of fuel if I use all three tanks. Given the large capacity I could shorten the taper on the tanks to give more freedom of movement to the clunk.

Thanks

Paul

Looks ok to me, a tip I was given recently on the vent line, just stub in the brass and bend it up, then strap on a short piece of tygon with a 45 degree tip at the end that will bump the top of the tank.

Should give you a very high overflow in there.

I don't think you're gonna have a clunk problem from what I see.

Sean

Paul,

It looks to me like the clunk can go where the fuel is going to be. There should be no reason for any side to side movement since the fuel is funneled to the center. The only movement will be up and down which looks un-obstructed to me.

John

Paul,
As long as you have enough space to fit that tank in there I can see no reason to make it any shorter. It appears that the total length of that tank is around 10-11", I would suggest that you simply make the rear bottom of the tank taper upward to prevent the fuel from pooling in the back and make the clunk line about 7-8" long (with a length of brass tubing to keep it from whipping to the front of the tank under harsh decelerations). I think it is impossible to keep the clunk in a large tank covered in fuel under all conditions but as long as you have smaller tanks (UAT, or some other type of air trap) between the main tank and the pump it is not going to be a problem if you get momentary burps of air. Just be sure that when the airplane is experiencing positive Gs the clunk is always submerged.

Just remove the area outlined in yellow to keep the fuel from pooling behind the clunk, and have the clunk end just in front of the bottom of the ramp.

Thanks guys, great info.

Paul