..............Plus a bubbleless clunk:

http://www3.towerhobbies.com/cgi-bin...&I=LXXF25&P=RF

Foam cannot isolate the tank from vibration if:
1) It is crunched.
2) There is another non-isolating connection to the airframe (tie-down, velcro, etc.)

JohnBuckner explained the radical solution to fuel bubbles, assuming the silicone tubes are hermetic to air sucking.[sm=thumbs_up.gif]