Interesting fuel tank

Some of you may be interested in this tank. I built it for a fellow club member. The tank is intended for a PAW 35 or 40 powered Eifflaender 'Freebird'. The Freebird is an inline design with the engine mounted 'sidewinder'. The tank fits between the engine mounts, so there is a range of vertical adjustment. The tank was built from Tony Eifflaender's sketches and plans drawings with some slight modification on my part.

Fred

LAST EDITED ON May-13-04 AT 12:43 PM (CDT)
 
"Reflections" is what I am seing so many of, and a couple of extra tack-solder spots scattered around, too? Looks more complicated than it actually is? (The included mounting flanges took an additional look to be sure what they were, but those I'd figured out before admitting my confusion about reflected tubes.)

.

Kiwi

I have little understanding of what you are showing me. Could you post a diagram which does not have reflections? I'm sorry to say that my first impression is of a very strangely overdesigned chicken hopper.

Jim,

As I figger this tank, you pegged it. Tom Dixon's Little T-Bird article in Model Aviation (?10-12 yrs back?)gave layout sketches for a similar tank. The L'il TBird used a PAW .8cc, upright or inverted,if I recall. Tom D said this uniflow/sorta-chicken hopper gave him good stunt runs. I've never had much success with upright/inverted PAWs... Even Tony Eiffelaender, PAW mfr, turned his Freebird 4's PAW 35 sidewinder rather than fight this quirk in his earlier Freebirds.

Described for clarity(?),
--this is a rectangular tank with an added hopper chamber at the rear of the outside wall.
--The four 'corner' holes into the hopper allow fuel in, upright or inverted.
--The short 'vertical' tube from the rectangular chamber into the hopper sets where uniflow vent air is released into the tank interior.
-- The fuel supply tube exits the forward 'wall' of the hopper chamber.

It should have the run consistency of a usual uniflow tank, with the slosh damping of a "chicken hopper." And, it is a lot of work.

Another UK technique shown may confuse us colonials -- the extended tank inner wall, top and bottom to form a built-in mounting flange.

Sorry about the reflections. I will try to scan in the tank drawings from the plans tomorrow. This is just a simple chicken-hopper design. The fuel pick-up to the engine is obvious (straight off the hopper tank). The over-flow vent is tack soldered to the top of the tank near the front and exits straight out the side. The wierd one is the uniflow vent, which is tack soldered to the overflow vent. It faces into the airstream, enters the main tank, runs down the side and bends 90 degrees to enter the hopper tank. So, there are only 3 pieces of copper tubing: uniflow (and fill), overflow and engine feed.

The main tank is actually quite easy to build as it is just 2 U-shaped pieces of metal. As they are soldered together, the solder forms a fillet on both sides of the wall and is quite strong. I believe George Aldrich's pinch-corner tank was designed similarly.

I thought this would be a welcome diversion from that @#$%@*! blasted ARF thread.

Fred

Hey Fred,
Breathe easy and count to three!

OK, I understand. A few dozen well chosen words is better than several pictures with lots of reflections. (A new Texas proverb)

LAST EDITED ON May-14-04 AT 09:43 AM (CDT)
 
Hi Jim,

We sure miss you up North (and your Texas proverbs!). Hope all is well.

I scanned the tank drawings from the Freebird plans. Tony Eifflaender ran the uniflow tube externally, where I chose to run it internally. That, plus the height adjustment slots are the only changes. I did NOT show the sheet metal layout for the hopper tank as it is a fairly normal design.

So, to restate the new Texas proverb: "A few dozen well chosen words (AND A DECENT DRAWING) is better than several pictures with lots of reflections."

Fred