Wren 44 Gold Helicopter Owners Manual
Page 17
Hopper Tanks and UAT’s
Hopper tanks and UAT’s (originally the Ultimate Air Trap from BVM Models but others are
available now) are a popular choice and can help with continuity of fuel supply – especially
on aerobatic or 3D helis. The standard hopper tank is simply a small capacity fuel tank which
is fully sealed and has a single fuel-in pipe and a fuel outlet positioned centrally so it can pull
fuel from any attitude the heli finds itself in without the possibility of pulling in air.
The UAT is similar to the hopper tank except it has a membrane type pickup on the fuel-
outlet which acts as a sponge and allows fuel to pass but without allowing air into the
system.
Fit the UAT or hopper tank as close as possible between the fuel tank and fuel pump – take
great care to ensure a totally fuel tight pipe run from tank to UAT/hopper and then onto the
fuel pump. Purge all air bubbles from the UAT or hopper before use. Monitor the remaining
fuel level in the UAT/hopper as this is a good indication of air getting into the system. If this
level drops noticeably during a flight and there is still fuel remaining in the tank, then suspect
an air leak, find and cure it before it causes a stoppage and enforced autorotation practice.
UAT’s are very helpful, but keep the tank capacity well above the flight time requirement so
the system never runs out of fuel and the tank clunk is not chasing the last dregs of fuel
around at the bottom of the tank. The UAT will not cover up a poor fuel installation.
The regular fuel tank does just fine for Greg Goncalves Align T-Rex 700 shown here – neat!
All in weight of 5.2kg plus 630ml of fuel – enough for about 6-7 mins flying.
