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Engine basics => Engine set up tips => Topic started by: dagored on November 25, 2014, 09:22:59 PM
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used a plastic tank with clunker inside on a sig Banchee profile motor is an old fox .35 no muffler and it seems the clunker in the tank cant keep up when the fuel gets less then half full when your doing stunts , the tank is a 4oz . just getting back into control line after 20 + yrs , should i just put a 4 oz wedge tank on it.....Thanks
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sounds like the fuel line is too stiff, find a softer fuel line
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The clunk should touch, or almost touch, the outer wall of the tank when the plane is held with the wings vertical. If you have a Hayes tank and this is not happening then your line is too stiff. If you have a DuBro or Sullivan tank, then either your line is too stiff or (particularly if you have a slant tank) the brass tubes are not bent correctly.
I've never been fully satisfied with regular tanks -- even the metal tanks that find their way into my airplanes end up being clunk tanks. Clunk tanks can and do work very well.
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In this regard, where can a fellow buy some soft tubing that works well in a clunk tank.
I have tried the Sullivan web site, but can't get info on softer tubing. Where else to find some sure would help.
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Back in my early R/C days we use to use surgical tubing as it is very flexible. The only thing is it does deteriorate pretty fast, and also will let the clunk go forward in a hard landing. We fixed that by using only a short piece of it to a length of brass tubing and the the clunk fixed to the end of the brass tubing with another piece of regular silicone tubing. That all worked pretty well as long as you changed out the surgical tubing every so often. I have not had much luck with plastic tanks myself on profile C/L models as I always seem to move the tubes one way or the other when fueling with my ham hands and it changes the motor run. They seem to work well for others though.
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In this regard, where can a fellow buy some soft tubing that works well in a clunk tank.
I have tried the Sullivan web site, but can't get info on softer tubing. Where else to find some sure would help.
I look for silicone tubing that's one size smaller in diameter than what I'd use externally. If there's a choice between thick wall and thin I go thin.
Remember that the stuff just needs to traverse the outside edge of the tank from top to bottom -- if the fuel isn't being thrown to someplace on that outside wall, then something is wrong with the plane.
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Does it shut off and then restart? Might just be the Fox burp instead of the tank.
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I just think the clunk can't keep up with the fuel....... D>K
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I bought this
http://www.ebay.com/itm/251549842581?_trksid=p2050601.m570.l4469&_trkparms=gh1g%3DI251549842581.N17.S2.M-16856.R4.TR6
limp as limp can be.
Phil
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I didn't register the fact that you're running a Fox 35. I think you'll be very happy if you shorten the nose and change out the engine to an OS 46 LA (best), Magnum 36, Tower 40, OS 40 LA (probably good, but some people hate 'em), OS 40 FP, etc. You'll need to run 'em the way they like, but when you do that they're much nicer than the Fox.
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shorten the nose and how much do i cut off , i could use a new 40 fp OS that i have of cores the OS 40 Fp with muffler weights much more than the old fox with no muffler .........
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shorten the nose and how much do i cut off , i could use a new 40 fp OS that i have of cores the OS 40 Fp with muffler weights much more than the old fox with no muffler .........
Shorten the nose enough so that the big heavy 40 FP balances the same as the Fox, of course!
I'd do it by experimentation: take off the Fox, put a prop and muffler on the 40 FP (APC 11.5 x 4, or a ThunderTiger 11x4.5), then rubber-band the thing to the fuselage. Move it back and forth until it balances. As long as there's meat to drill through in the motor mounts, you're ready to rock & roll.
If that sounds like too much work, just fix up the tank and fly it with the Fox -- but build the next one for the 40 FP.
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I might just do that .....thanks
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...Weight of engine times nose length = X. X divided by weight of new engine = new nose length. Cheers, John
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Thanks John....
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Thanks to all , Have a Great Thanks Giving
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Your description of can't keep up is somewhat vague. Is the clunk getting hung up on the side wall of the tank? Loosen the stopper screw and holding the neck cocked to the opposite side and re tighten. It may not hurt to pull the pickup line forward slightly. It sounds as if the clunk is floating up and out of the fuel and then the engine is leaning out and quitting. I would also consider shimming your tank out in the rear approx 1/4" with a scrap of balsa. Sullivan makes a larger clunk which can be most helpful. In addition, Dubro makes a sintered bronze clunk which is not only heavier than the standard brass clunk but it also prevent bubbles which can make runs on a profile most problematic. I certainly don't feel your plagued with a engine problem. While the hard tin tank may work, they don't come without issues at times as well. Ken
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Shimming of tank thats a good idea , Thanks Ken
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I'm probably repeating myself, but the important part of getting a clunk tank set up is to test it on the ground. On or off the plane, hold the tank so that the outside surface (the surface that points to the outside of the circle) is down. Then tilt the tank lengthwise. You should be able to see where the clunk is, and you should be able to see that it is (a) riding on that outside surface, and (b) smoothly riding to both rear corners as you tilt the tank. If you don't see that, figure out what's wrong and fix it. Sometimes it's stiff tubing, but sometimes it's the various other problems mentioned (I often start by cutting the tubing a bit long, so the clunk hangs up on the rear edge of the tank, and must be shortened).
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I'm not trying to insult anyone, but are you absolutely sure the clunk is at the back of the tank? A hard landing or any kind of a nose plant can flop the clunk to the front of the tank. Then the airplane will run fine and even take off but not for long. Ask me how I learned this lesson.
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Dirty Dan even found out that storing the plane nose-down was enough to put the clunk up front and mess up the first flight of the day...the one where you find out something just ain't right.
I'll do my part by suggesting (strongly) that the Hayes plastic tanks are foolproof and reliable as a tank can be. Whether to mount it "foot" down or "foot" against the fuselage is a bit of a problem. Foot down is just the way they're mounted in R/C planes. Foot against the fuselage makes it more difficult to fill with fuel. They are simple to assemble and more leak-proof than others, from my experience. y1 Steve
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I'll do my part by suggesting (strongly) that the Hayes plastic tanks are foolproof and reliable as a tank can be. Whether to mount it "foot" down or "foot" against the fuselage is a bit of a problem. Foot down is just the way they're mounted in R/C planes. Foot against the fuselage makes it more difficult to fill with fuel. They are simple to assemble and more leak-proof than others, from my experience. y1 Steve
I'll second that. The plug-style tanks can be made to work well if you know what you're doing and if you're careful. The Hayes tanks just work, period. I mount 'em foot down, and they work fine for me.
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OK foot down , what do you mean foot down ?.......... %^@
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If you look at a picture of a Hayes tank it'll be obvious. They're molded with a "foot" at the bottom.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK827&P=ML (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXK827&P=ML)
(http://www2.gpmd.com/image/h/hayq1000.jpg)
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Ok i see ..........