ishu4u,

True, a standard header tank can be used with a geometrically centered fuel pickup. The difference is the fabric membrane in the JMP and BVM "air trap" style tanks. As an air bubble appears in the header tank, the surface tension at the air bubble's surface causes the membrane to adhere to it. Since the clunk is inside the fabric, it is never exposed to air and should never be starved of fuel...

If a membrane-less fuel tank is used, David Gladwin recommends at least 14 oz in capacity. The reason not to use a 2 oz tank is that a geometrically centered pickup would be exposed to air after a bubble displaced only 1 oz of fuel. If a 14oz tank was used the likelihood of displacing 7oz of fuel with air is much less... A heli's piston engine can live with a bubble or two and keep running, unlike a turbine.

If $$$ is a problem when purchasing a tank, Woketman is a good one to ask about making your own.:thumbup:

Later,
Kelly