clunk tanks on profiles

Do I need to adjust the height placement of a clunk tank. I have a ringmaster with a clunk tank mounted on the left side of fusaloge. The engine on the ground is running lean and after take off the engine run turns very rich (too rich). Help?

LAST EDITED ON Nov-21-04 AT 05:49 PM (CST)
 
Yep...ya do...You need to mount that tank on the other side...same side as the engine...right side...if ur set up to fly counter clockwise...jim

I looking at Stunt News Sept/Oct 2004 page 104 and I see a clunk tank setup showing clunk tank on the opposite side of fuselage of engine mount.

Inboard mounted tanks work just fine. They go back as I recall to the Slow Combat rules in the early 70's. Rule said that tank must be forward of the wing LE. To get a large enough tank without the nose being too long they were mounted on the inboard side. We flew a lot of Flite Streaks with inboard tanks with no problems.

Several questions regarding your tank installation.
1. Is it set up for uniflow?
2. Is the vent directed into the airstream?
3. Are you using any kind of pressure to the tank ie muffler?
4. What engine are you using?

Steve
The older I get, the better I used to fly!

LAST EDITED ON Nov-21-04 AT 08:43 PM (CST)
 
like to see that pic

Hope this pic works

LAST EDITED ON Nov-23-04 AT 03:34 PM (CST)
 
guess i should have said unless ur usin a pressurized tank ...then it shouldn't matter that much..jim

1. Not uniflow

2. Vent tube is routed from left side and wraps around nose of fuselage and underneath engine, laying on side of fuselage pointing toward leading edge of wing.

3. No pressure.

4. The strange thing is this engine has no specs or name on it.

check out pic.

LAST EDITED ON Nov-21-04 AT 09:33 PM (CST)
 
I suspect the problem is in item #2. Your vent should stay on the inboard side, face forward, and be above the fuel level in the tank. Steve

Edit1: Due to addition of photo above.
Edit2: A closeup of the engine should allow identification. Maybe this engine has a big venturi and needs pressure fuel feed (not to be confused with muffler pressure). Sometimes an engine can sound to be quitting rich, when it is in fact, lean.
Edit3 (good grief): It looks like the tank may not be firmly enough mounted on the fuselage.

I will fly again next weekend and try your suggestion of reworking the vent tube. Thanks

One other thing you might try: get a short piece 0f 3/32" metal tubing and stick it in a piece of fuel line and fit the other end of the fuel line on your tank's vent. What you have done is to have effectively reduced the 1/8" tank vent line to 3/32". This MAY reduce the amount the engine is going rich. It may not either, but it is an easy thing to try. Be sure and plug the tank's overflow line when you do this.

I have seen it work many times.

While it might be an optical illusion due to the angle the tank appears lower than the engine. This will cause a leaner setting on the ground.

What size engine and prop are you using? Might be a case of the engine being overloaded on the ground. If the engine is like a Fox 35 and you are using low (20%) oil especially synthetic the engine might be overheating on the ground and going rich when it unloads and cools off in flight.

Switching the tank to the outside of the circle, should be enough room on a ringmaster, and using uniflow without muffler pressure will usually give a good engine run.

Let us know what you do and what worked

I don't know what kind of engine or size. See engine pics. I agree with your observation of tank is lower than it should be. I will raise the tank to position the vent tube above needle valve. Thanks

check engine pics

Your engine loks to be a fox 19 bb - produced early on in the switch to the new barn door engines - it was stopped in favor of the 25 -

That's my best guess

McCoy 40, It also appears to me also, to be the Fox 19 that the cylinder could be rotated any of the four positions and still run. I don't know if they ever produced a 25 size of that configuration or not . I do know that they intended to. The engine likes to run very hard and doesn't four cycle very good at all. Lowering the compression and choking down the size of the venturi would help the run, but then you lose a lot of power.

Bigiron

Charles,

Either Fox 19 or 25 BB... Only easily visible external difference is that the lower case bottom on the 25 has a double "step" where the diameter increases for the rear shaft bearing. (Makes room for the longer stroke crankshaft...)

Pretty high RPM-type engine, so a prop that lets it wind while keeping your airspeed reasonable should be the direction to go, say 9-4 for screaming revs, 9-5 or so to load it a bit more.

It IS an iron FOX, so think fuel with 23-25% oil, preferably all- or mostly-castor, too. Should be a good runner.

LAST EDITED ON Nov-23-04 AT 05:48 PM (CST)
 
lomax...theres no muffler on that engine...that tube goes on th muffler and pressurizes th system u cant get by without it...get a muffler and pulg on that line and u should be fine....jim