Clunk Tank Question ?

LAST EDITED ON Feb-11-04 AT 01:39 AM (CDT)
 
I have a Sullivan RT-1.5 oz clunk tank
and while setting it up I cannot figure out how to make
the clunk drop or sink when holding it upside down as
in simulated inverted flight, I tried adding some thin
solder coils around it (the clunk end) for weight but it does not want to droop.
larger tanks allows longer silicone tubing to cause it to fall under it's own weight, but with such a short piece of silicone tubing and the small tank, it just won't work on it's own. I also tried the cheaper silicone tubing knowing it's a tad more
flexible but still won't drop. Any ideas would be neato!

The picture below shows the tank upside down as in inverted flight.
I also shortened the length of the brass tubing to allow the silicone
tubing to extend as far as possible.

The clunk doesn't need to drop to the bottom of the tank when inverted, centrifigal force should keep it near the middle of the tank both upright and inverted. During maneuvers the clunk will be forced to the side of the tank on the outside of the maneuver as the g-forces are many times normal.

There are some brands that are "thin" wall, if you can find them you might have the clunk move as you want.

>The clunk doesn't need to drop to the bottom of the tank
>when inverted, centrifigal force should keep it near the
>middle of the tank both upright and inverted. During
>maneuvers the clunk will be forced to the side of the tank
>on the outside of the maneuver as the g-forces are many
>times normal.
>

Actually you will find the fuel to form a triangle that is, perhaps, three times as high as wide (depending on the lap speeds, line length--you know, centrifrugal force). With a wedge tank the angle of the wedge is approximately the same as the hypoten, er, the hyoptenu...well, you know, the "big" side of the triangle so the pick up can stay in the center. On the clunk tank it would be important for the pickup to fall to the bottom or you will have trouble pulling the last part of the fuel out. There is some tubing that is a lot more flexible than others. Has anyone tried surgical tubing for this? You might have to replace it fairly often, but if it works...???

Try the white translucent tubing that come with the Sullivan tanks. It is supposed to be more flexible. But at that short length, it might not help much. Like the others have said, centrifugal force should keep the fuel and clunk on the outside. Just fly it and see how much fuel in left in the tank to see if you really need to be concerned about it.

I know it looks bad, but this tank and clunk can work.

You mention cutting the brass tubing extending from tank stopper back, but as shown you can obviously cut it more; you're not even using all the tubing available for attachment of the clunk line.

Cut brass tubing as short as possible, when installing fuel line use spit for lube, do not contaminate with any fuel or oil at all, wrap with serving wire.

Ferrule on clunk can be shortened for the same reason and with the same techniques intended to keep all secure.

If this is a Sullivan tank they probably included much better clunk-to-stopper tubing than shown; you can also get it in some sort of repair kit. Very flexible.

Surgical tubing is an option, but of limited value. The stuff just rots away, ending up being a maintenance hassle.

Again, this can be made to work.

Thank you gentlemen for all of the input, I'll put it
to use and see what happens.