When I set up my Score's front end, I followed the directions in Tom Dixon's Time Machine kit . He wrote (I'm recalling fuzzy memory now) that if a ST (Super Tiger) .60 is used a 7 oz. tank might be needed, but the nose should not be stretched to make room for a longer metal tank. Instead he recommended a Sullivan plastic tank (probably 8 oz.) with the engine mount modified as shown in the attached photo, to achieve proper height.
The mod is a short length of 1/2" X 3/8" maple (or 1/2" square) epoxied on the main (long) mounts. The engine rests on these. With the plane upright the tank can be a full 1/2" above the level it otherwise would be, without this mod. It can always be shimmed down if needed. The long mounts should probably be raised a nearly equal amount, so the vertical CG is not altered. The Score's fuselage was deep enough to do this (it was also necessary so the cowl and spinner would still match up). Other designs might require tweaking of the fuselage layout.
At first I tried a ST .56, then a Stalker .60 in the Score. Those engines needed only about 6 ounces of fuel. I used a 6 oz. Magnum vented metal tank (shimmed to appropriate height). They ran well, but didn't have the right kind of power to haul the 5 pound Score through a pattern. I then tried a ST .60 which was strong enough to fly it reasonably well, but needed 7 ounces of fuel.
Even with the mods I made the nose was too short for a traditional 7 oz. metal tank, so in went the plastic tank. With the ST .60 and Sullivan 8 oz. Flex-Tank on muffler pressure I get nearly equal engine speeds upright and inverted. Actual height difference is about 3/8 inch. I had to shim it down 1/8" for the tank tubes to clear some internal structure and not pinch on the rear of the engine. In hind site, I should have lengthened the nose to accept a 7 inch long metal tank, since I ended up needing 2+ ounces of nose weight.
The tank is set up according to an old Bob Hunt/Dean Pappas video. I may try this with a 6 oz. Sullivan tank on a .46 powered model. I'd make sure the front end could still accept a metal tank, just in case. Plastic tanks have issues, but they are lighter and cheaper and they don't rust. Has anyone else experienced the need for such a huge height difference when using a plastic tank? Perhaps the ST .60 draws fuel so strongly that tank plumbing and height are not as critical, relative to other engines. Is it working because its set up this way, or in spite it?
Topic: TF Score w/ ST .56 flies - need different tank. (Read 2626 times)