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Building Tips and technical articles. => ARF'S => Topic started by: Bill Heher on October 19, 2010, 06:45:17 PM
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Finally got a few flights in on the Score / Super Tiger .56 combo. Big difference over the LA.46 it had in it when I bought it. The engine had not been run much in the last 10 yrs so 1st couple flights were spent getting it running right. Finaly got a good solid needle setting, and tried inside / outside loops / horizontal and overhead 8s.
Plenty of power, decent tension and good response, but engine goes way lean inverted. Still have the stock plastic tank - what is a better option that fits without having to do major surgery?
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Bill,
I use a 6 oz. Sullivan, plumbed for uniflow in mine-------but you may just need to adjust tank height to get the upright/inverted run correct.
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I have a 6-oz cylindrical plastic clunk in mine, all tubes forward in center of tank, uniflow with ram air to the uniflow, overflow line plugged during engine runs. I had to build a cradle to hold it in position (simple, two ply bulkheads with semicircular cutouts to hold the tank). Held in place with zip ties that work like with the stock (weird) tank. By rotating the uniflow tube inside the tank you effectively raise or lower the "tank level." I get nice even runs upright and inverted with the Enya 61 CXS. Oh, and I had to enlarge the hole in the firewall to get the tubes to exit into the engine compartment with the new tank, elongate the hole more accurately.
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So a 6 oz Sullivan round fits - I should have one in the tank box. I don't like the stock triangle one - seems like wasted space and I've had arf tanks split too many times.
Thanks for the set-up info.
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Bill i got one of those RST 6 oz tanks they are soft plastic and conform to the score's tank area
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Now that Geoffrey mentions it, mine is the 6 oz. RST. No problems for almost three years.....and counting.
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Is RSt a different brand- or a type of Sullivan tank?
If Sullivan I would guess RST is Round Soft Tank....
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Is RSt a different brand- or a type of Sullivan tank?
If Sullivan I would guess RST is Round Soft Tank....
Hi Bill,
I think it may be a Sullivan "SRT" tank. Their ads say This stands for "Standard Round Tank". They are pretty soft. As many have said: they are perfect for CL because you can rotate them to effectively change the "head" position of the pick up and uniflow tubes for perfect runs flying in both directions. ;)
Here is a link to their tank details: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFU36&P=7
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The Sullivan RST is "rectangular soft tank"----can be squished a bit to fit tight spaces. The one in my Score is the RST 6 oz.
Check the link, scroll to bottom of the page.........
http://www.brodak.com/shop_productdetail.php?ProductID=6443
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Did you set your tank up as clunk w/ muffler press ala R/C,
clunk w/ uniflow tied together, but still free to move up and down in flight,
or rigid tubing uni-flow where you rotate the whole stopper assy to change the pick-up / uni-flow vent height in the tank?
Got a tank, just need to know the best plumbing set-up so I can steal an hour or so tonight to work on it.
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Bill,
I set my tank up as uniflow, vented to atmosphere (no muff pressure).
Clunk with uniflow line about 3/8 to 1/2 in. shorter than pick-up line; both flex fuel tubing. I used very small dia. SS wire "twister" to secure the uniflow and pick up lines together, close to the end of the uniflow vent line. I used a short (1/2 in.) piece of aluminum tubing inside the back end of the uniflow line to make sure the uniflow vent line didn't collapse because of the "twister".
Has been trouble free for two or three seasons.......
Cheers,
Jim
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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?
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I am trying a Sullivan 8 oz. (exactly fits cavity) slant type tank. Had to bend tubes on inside.
From comments I gather the ST51 is not strong enough? GaryFrost
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I am trying a Sullivan 8 oz. (exactly fits cavity) slant type tank. Had to bend tubes on inside.
From comments I gather the ST51 is not strong enough? GaryFrost
Hi Gary,
Not meaning so sound weird, but it depends on how you run the ST G.51, if it's stock or reworked, and more importantly, how heavy the Score is.
I had no problems whatsoever with a T&L ST G.51 in a 64 oz. SV11. And that was with flying once in a meet with very high winds at Norfolk back around 1992.
How heavy of a plane will the ST G.51 fly in good conditions? I don't know.