Hi all,

Was flying my heli, happily blasting it round the sky, seeing how fast i can do a figure of eight and seeing how high I can do stall turns when i banked a little too far on the entry to a left hand turn to intentionally go slightly inverted and pull it round in a sort of half loop and my engine slowed down to almost stopping. I managed to pull out but not quick enough so managed to land on my skids but my tail isn't exactly straight any more.

What everyone is telling me is that when i did that, the clunk in my tank took a bit of air and that's gone straight into my engine and caused it to pretty much stop. I have a caliber 30 and don't have a header tank (although I'm now getting a Raptor 30 one to fit). I just wanted to know if anyone knows how they work.

They work great!


The main tank works essentially the same but the header acts as a wide spot in the fuel line that makes it more difficult for the "air bubble" to get to the carb.
How does it work?
Fueling ...
You send fuel from the carb line into the header tank (much the same as fueling the main tank). The incoming fuel fills the header tank and displaces air into the vent line into the main tank. When the header tank is full, the fuel exits the header tank vent line and starts to fill the main tank, again displacing the air into the muffler pressure line.

At this point, the header is solid full and the main tank has whatever you put in it.

Flying...
Pressure from the exhuast line is applied to the air/fuel in the main tank, which pressurizes the header tank and pushes fuel to the carb.
The main tank replaces the departed header tank fuel with more fuel ... so the header tank "should" stay full throughout the entire flight as long as there is fuel in the main tank.
When the main tank is empty (or when you fling it's clunk into the air, or you have crappy clunk line and it has holes), the main tank will replace the departing header tank fuel with air instead of fuel. At this point, the header will start to empty ( or at least trap momentary air bubbles. The clunk line in the header tank has less of a chance to pass air to the carb.

^--- Thank you for that, that was nail-on-the-head.

- Chaz

Thanks for that!!

Cool picture Tippy!

I can only take a tiny bit of credit for it. Can't remember where the original came from but I added the filler tee ... so only that parts mine