TF P-47 fuel tank issue.
07-05-2005, 07:56 PM
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TF P-47 fuel tank issue.
I like my .60 size P-47 a lot. It flies great and I took my time building it so it looks awesome. Here's the problem.
I've got a great planes 24 oz fuel tank with a three-line set up and an inverted Satio 1.50. When I was breaking in the engine in, it ran fine extra rich and I have about a dozen flights on it. Now that my engine is breaking in and I'm trying to lean it, I find that I can't! The engine likes to flood!
The carburetor is filling up with fuel and it spits out when I flip the prop. Although the carb line is approximately in line with the carburetor, I'm thinking that the fuel tank needs to be lower. If I pull carb line off I get a stream of fuel flowing out, suggesting I’m force feeding the engine. I've tried running the tank without the fuel pressure line and with the third line unplugged and I still get the same thing, flooding. Simply put, my fuel tank is either getting over pressurized or it’s being gravity fed. To lower the tank I'd have to cut that nice little box the kit has you build because the fuel tank protrudes into it. The tank is as low as I can get it, I've got it stiiting on the wood! I highly doubt that this is an engine problem, it seems more of a configuration problem so I'm soliciting you people at Top Flite if you've ever come across something like this with this kit in particular. Before I start my quest of searching for a tank with a different configuration or settling for a smaller capacity tank, do you people know of the best and biggest tank for this kit? Any other suggestions would be appreciated. - Mike
I've got a great planes 24 oz fuel tank with a three-line set up and an inverted Satio 1.50. When I was breaking in the engine in, it ran fine extra rich and I have about a dozen flights on it. Now that my engine is breaking in and I'm trying to lean it, I find that I can't! The engine likes to flood!
The carburetor is filling up with fuel and it spits out when I flip the prop. Although the carb line is approximately in line with the carburetor, I'm thinking that the fuel tank needs to be lower. If I pull carb line off I get a stream of fuel flowing out, suggesting I’m force feeding the engine. I've tried running the tank without the fuel pressure line and with the third line unplugged and I still get the same thing, flooding. Simply put, my fuel tank is either getting over pressurized or it’s being gravity fed. To lower the tank I'd have to cut that nice little box the kit has you build because the fuel tank protrudes into it. The tank is as low as I can get it, I've got it stiiting on the wood! I highly doubt that this is an engine problem, it seems more of a configuration problem so I'm soliciting you people at Top Flite if you've ever come across something like this with this kit in particular. Before I start my quest of searching for a tank with a different configuration or settling for a smaller capacity tank, do you people know of the best and biggest tank for this kit? Any other suggestions would be appreciated. - Mike
07-06-2005, 09:41 AM
#2
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RE: TF P-47 fuel tank issue.
The fuel tank IS a bit high, but that's because of the wing's location. The tank could be lowered if it was mounted transversely, but that causes other problems. So does side-mounting the engine.
Usually, in cases like this, the siphoning is halted by using a clamp on the fuel line to the carb. Once the engine's running, it usually isn't a problem. The main difficulty resulting from a high fuel tank is the leaning that will happen as the tank drains. A lower tank position will give you less of a needle change.
Usually, in cases like this, the siphoning is halted by using a clamp on the fuel line to the carb. Once the engine's running, it usually isn't a problem. The main difficulty resulting from a high fuel tank is the leaning that will happen as the tank drains. A lower tank position will give you less of a needle change.
07-06-2005, 03:49 PM
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RE: TF P-47 fuel tank issue.
Well at least my diagnostic skills seem to be on target! I have clamped the carburetor line during fill up, but if I wait too long before starting the engine, it floods again! I’m not sure what I’m going to do about this problem yet. I guess I’ll try and find a fuel tank with a lower profile, but I’m also considering re-engineering the nose so the tank sits lower. Thanks for your response!
07-08-2005, 10:41 PM
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RE: TF P-47 fuel tank issue.
I'm considering something else. Fuel pumps are essentally regulators right? Would a fuel pump meter the fuel and prevent it from flooding?
08-26-2005, 03:56 PM
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RE: TF P-47 fuel tank issue.
Well a Perry VP-30 regulated pump did not prevent flooding. Clamping the fuel line only prevents the carburetor from flooding during fueling; as soon as the clamp is released, the carburetor floods. It would appear that the fuel pump is primarily designed for two stroke engines. Four-Stroke usage simply requires simply placing a tee in the crankcase vent line to power the pump diaphragm. I had to resort to using a 16 oz Slimline Hayes fuel tank in place of the Great Planes 24 oz fuel tank. The tank opening is considerably lower on the Hayes tank. This set-up requires that the tank be vented. I’ve had a few flights and the problem seems to have been corrected. For reliable operation, it’s important to use very flexible fuel tubing in the fuel tank.
I think Top-Flite could easily improve the kit but I’m not going to hold my breath waiting for them to make improvements. My business is probably going to gravitate to Skyshark. Anyway I just wanted to pass this information on so the next poor S.O.B. will have some answers.
Things a TP-47 owner should know beforehand:
The Bad:
1. Fuel tank deck is high, fuel siphoning may be a problem for inverted engine installations. The larger the tank the bigger the problem.
2. Retracts will not retract flush into the wing. I used Robart 650’s and find them problematic. Personally , I think rib-spacing in the wing cold have been relocated to better handle near-scale wheel size and the thickness of the wing increased to accommodate a flush fit.
3. Many of the accessories have been discontinued, such as drop tanks, static props, etc., even though they are advertised with them.
The Good:
1. The plane is an easy build and hiding the equipment simplified inside a relatively large fuselage. Even the Saito 1.50 with a stock muffler is completely hidden.
2. Flights are tame and predictable, even with my Saito 1.50
3. Landing are very slow and stable with flaps.
I think Top-Flite could easily improve the kit but I’m not going to hold my breath waiting for them to make improvements. My business is probably going to gravitate to Skyshark. Anyway I just wanted to pass this information on so the next poor S.O.B. will have some answers.
Things a TP-47 owner should know beforehand:
The Bad:
1. Fuel tank deck is high, fuel siphoning may be a problem for inverted engine installations. The larger the tank the bigger the problem.
2. Retracts will not retract flush into the wing. I used Robart 650’s and find them problematic. Personally , I think rib-spacing in the wing cold have been relocated to better handle near-scale wheel size and the thickness of the wing increased to accommodate a flush fit.
3. Many of the accessories have been discontinued, such as drop tanks, static props, etc., even though they are advertised with them.
The Good:
1. The plane is an easy build and hiding the equipment simplified inside a relatively large fuselage. Even the Saito 1.50 with a stock muffler is completely hidden.
2. Flights are tame and predictable, even with my Saito 1.50
3. Landing are very slow and stable with flaps.
