The foam clunk acts like a "fuel Magnet" the heli guys sue this. It becomes a buffer of fuel so if an air bubble hits the pickup line it will not go directly to the engine. The foam stays wet all the time it is in fuel so it acts to absorb air bubbles without letting them get into the line.

The foam is fairly fragile. if you leave fuel in your tank all the time. You should replace it about once a year. If you drain your tank when not flying it then it will last for a long time.

Troy Newman
Team YS