On clunk tanks, I’ve had good success raising and lowering the uniflow inside the tank as an alternative to raising and lowering the entire tank. However, I’ve never tried that technique in a regular metal tank with a fixed pickup and fixed uniflow vent – well, because they’re soldered in, ya know.

Suppose you wanted a stunt ship with a conventional metal uniflow tank, but were concerned about tank height. Typical inverted engine installation; either lower the engine or build a new tank if it is rich inverted; as you can only shim one direction – down!
   What is wrong with moving the uniflow up a tad from the normal middle of the tank to start with? That is, build a tank that has the fuel pickup in the middle of the wedge (normal) with the uniflow a little above the fuel pickup. Say, .090 higher than center? Worst case, it is lean inverted, but heck, I can shim the tank down with no problem. In clunk tanks, I’ve had fixed uniflows higher than that, but, of course, the fuel pickup is moving in those cases.

I know, there are about 47 (probably better) ways to skin this cat, but what might keep my idea from working? Or does everybody do it that way and I didn’t know?

      Larry Fulwider

   What is wrong with moving the uniflow up a tad from the normal middle of the tank to start with? That is, build a tank that has the fuel pickup in the middle of the wedge (normal) with the uniflow a little above the fuel pickup. Say, .090 higher than center? Worst case, it is lean inverted, but heck, I can shim the tank down with no problem. In clunk tanks, I’ve had fixed uniflows higher than that, but, of course, the fuel pickup is moving in those cases.

I know, there are about 47 (probably better) ways to skin this cat, but what might keep my idea from working? Or does everybody do it that way and I didn’t know?

    We do a lot of them that way. I built a tank for Uncle Jimby that had the wedge, pickup, and uniflow 1/4" from the top of the tank. Oh, and it went from 1" deep at the front to 1 3/4 at the back, and tapered in plan view as well. That's how you get 7 oz of gas in 4 3/4" long tank compartment. As long as you keep the wedge angle the same it runs just like a symmetrical tank.

    Brett

Larry   I just did that on my Tempest. We will see how it works this week.
Ed

    We do a lot of them that way. I built a tank for Uncle Jimby that had the wedge, pickup, and uniflow 1/4" from the top of the tank.  . . .
    Brett

Ed, Brett –

Thanks! I was afraid I was overlooking something, as I had never seen this specific approach (in a non-clunk tank) published on any of the forums or columns. Your responses were indeed a pleasant surprise   

Ed –
   Since we’re working with the same size hole (and about the same size tank) we’ll have to compare Saturday. I’m scratch building, so mine is (or will be) tapered ¼” front to back.
   Well, no excuse to delay now, time for the origami solder game. This should be a piece of cake – my first shot at using the Jim Lee tank bender. Might actually make some bends on the score lines for a change. 

       Larry Fulwider

I kept my answer short to Larry as we are flying today. Ted Fancher explained it to me back in 1987 and have used it many times since.
Ed

You mean kind of like this? Used a high uniflow vent, centered in wedge 3/8” from top of 1” tank, truncated 2 ½” from rear of tank (my first time for less than full length uniflow vent in a metal tank). Curved the fuel pickup around the end of the uniflow, keeping uniflow snug in the wedge. Also placed the pickup in the center of the wedge. However, centered the pickup vertically at the front of the tankTomorrow, we'll see how well it works.

   That might be OK, but the wedge angle on the bottom is shallower than the wedge angle on the top. if the angle is sufficient it will work, but I would be concerned that the shallow side will allow the fuel to run away from the pickup towards the end of the flight.

     Brett