Max,
A UAT, as designed by Jeff Seymore and marketed by BVM does not contain a "Clunk weight" of any kind.
Instead, it contains a filter "sock" membrane, as found on the inlet of submerged automobile fuel pumps, with a waffle type plastic separator to keep the sides of the sock apart. The fuel saturated sock supplies the engine with the fuel, both acting as a filter, and an air separator. A large enough bubble will shut a turbine down immediatly.l

An "Air Trap", as is used on ducted fan applications, is a small tank with the pickup tube located in the geographic center of the tank. No clunk weight either. It is supposed to remain submerged in fuel to eliminate the possibility of sucking air.

If the jets you are looking at do not contain the BVM type UAT, (and there are several manufacturers selling very similar items) they are using what I would call a a "Header tank". That's what you are using in your heli's.

No matter how you do it, or what you call it, the pickup must remain submerged in the fuel, or you will suck up air. That will make the engine very quiet all of a sudden.

See [link=http://www.bvmjets.com]BVM Jets[/link] for more information on the UAT.

Cheers,

Harley Condra
BVM REP
JetCat REP