stunthanger.com
Engine basics => Engine set up tips => Topic started by: frank mccune on December 24, 2019, 09:11:41 AM
-
Hi All:
Before I disassemble a new tank to attempt to diagnose what may be a tank problem. Perhaps somebody can offer a solution.
I put a new chicken hopper Uniflow tank on my Tudor that was powered by an OS .35 Stunt. Notice the use of the past tense in describing the Tudor. We could bot get a good needle valve setting for a consistent engine run. The engine did not respond well to the changes of the needle. At first there were many bubbles in the fuel line but this was alleviated by using muffler pressure on the tank. Still failed to get a steady run. The engine quit in the most unfortunate place and speared into the ground.
What tests may I do prior to unsoldering the tank to see what is wrong? This tank is the only change that made since the last flight. I went to a smaller chicken hopper due to a severe over run. The tank was purchased from a popular CL supplier.
Comments/Suggestions
Have a Cool Yule and a Frantic First,
Frank McCune
-
Hi All:
Before I disassemble a new tank to attempt to diagnose what may be a tank problem. Perhaps somebody can offer a solution.
I put a new chicken hopper Uniflow tank on my Tudor that was powered by an OS .35 Stunt. Notice the use of the past tense in describing the Tudor. We could bot get a good needle valve setting for a consistent engine run. The engine did not respond well to the changes of the needle. At first there were many bubbles in the fuel line but this was alleviated by using muffler pressure on the tank. Still failed to get a steady run. The engine quit in the most unfortunate place and speared into the ground.
What tests may I do prior to unsoldering the tank to see what is wrong? This tank is the only change that made since the last flight. I went to a smaller chicken hopper due to a severe over run. The tank was purchased from a popular CL supplier.
Comments/Suggestions
Have a Cool Yule and a Frantic First,
Frank McCune
Hi Frank,
Many, many years ago I had an OS 35 Max on a profile that behaved very similar. I could not get a decent engine run. I tried all kinds of different fuel tanks (vented, uniflow, muffler pressure, clunk, etc.) and at various locations. No matter what I tried I could not get the engine to run properly. The biggest problem was on outside maneuvers, it would go very rich to the point of almost quitting. Very similar to the Fox 35 burp.
I mounted this engine inverted in a full fuselage plane and it purred like a kitten! Go figure. I never again ran this engine on profile after that.
Now I have several profiles and I run OS LA 25 or 46 depending on the model. They run great on profiles!
Dennis
-
Frank,
To address your question, you can try drawing fuel out of the tank with a syringe, rotating the tank to various positions to try to ascertain where the pickups are really located. You would do this at various fill levels.
A whole different idea is to go back to the good tank, but deal with the overrun by only filling it to the amount you really need for your stunt run.
Sorry about the spearing,
Peter