erikpmort

My Feedback: (52)

Why don't giant scale planes use header tanks like helicopters do?

DMcQuinn

My Feedback: (13)

Gasoline engines use a carburetor that has a built-in pump and regulator. So the fuel tank can be anywhere (usually on the CG) and the fuel flow to the engine is always perfect.

krayzc-RCU

My Feedback: (31)

yeah baby give me a Gas engine like its kewl

erikpmort

My Feedback: (52)

yeah true, but there are still moments when your tank is 1/3 full and the clunk might miss the fuel for a moment. what do you think?

krayzc-RCU

My Feedback: (31)

the clunk is never still when running along with there is about 6 or more inches of fuel line that has gas in it. just keep an eye on the old gas tubing that gets stiff after a year or so. that is why most of us use the soft blue aerotrend stuff....

erikpmort

My Feedback: (52)

but wouldn't someone agree with me that bubbles in the line will occur?

sweetpea01

My Feedback: (10)

Never had a problem in my GS planes

DMcQuinn

My Feedback: (13)

Never a hiccup on a gas engine with a proper clunk. I can fly until there's less than an ounce in the tank. I think the gassers are more tolerant of a few bubbles.

erikpmort

My Feedback: (52)

sounds good

as722

My Feedback: (1)

They are not a necesity on a heli either, in fact there's air on the header tank as well after a flight.

Albert

bodywerks

My Feedback: (4)

The pumped gas carbs are not affected by small bubbles in the fuel line like nitro engines are. Simple as that. Still, if you want to run a hopper, go for it, it won't hurt anything. I did it on my QQ102" Yak - saw no improvement, but also didn't have additional problems, either.

Rcpilot

My Feedback: (78)

I'm assuming your worried about bubbles in the lines causing a lean condition, as on a glow engine?

The answer to that question can be answered by studying the internal workings of your standard Walbro carb. You might get bubbles in the line between the tank and the carb--if it gets low on fuel or you haven't padded your tank with any foam, but those bubbles have about a 0.0000000000001% chance of ever reaching the carb venturi and actually causing a lean condition.

The pump will suck the tank dry--down to the last drop. But, it doesn't pump fuel directly into the carb venturi. It pumps pressure up to the main jet and from there, the diaphram raises and lowers the jet to fill the bowl. The venturi sucks fuel from the bowl. Not a chance of a bubble getting past that pump, past the jet and into the bowl and from there, going down the venturi to make the engine run lean.

If it's lean--you didn't tune it right, or you have some other problem in your fuel system.

erikpmort

My Feedback: (52)

i was just wondering if there was a big enough gap in the line that it could hiccup enough to mess you up, but it sounds like it doesn't happen. Just thinking a?

Rcpilot

My Feedback: (78)

Nope. The pump just keeps on pumping and putting pressure on the jet. The jet is held shut by a spring. If there was to be a bubble in the supply line from the tank, doesn't matter to the pump. As long as the piston is going up and down--the subsequent sucking and pushing in the crankcase is going to make the pump do it's job. A bubble isn't going to do squat.

When the bowl gets low--the atmospheric pressure pushes down on the diaphram. When the diaphram goes down, it pushes against the spring that holds the jet shut. When there is enough pressure to overcome the spring--the jet opens and lets more fuel into the bowl. The bowl is emptied via the vacuum in the carb venturi. Bowl gets low--diaphram pushes against spring--jet opens--bowl fills. The pump just keeps on pumping it's little heart out to keep the pressure on that jet.

A bubble isn't going to do a thing to impede, interupt or stop that process.