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Flop tube question

Larry DeCamp

Well Known Member
My project has a flop tube in the left wing. It will require extra elbows or sharp tubing bends to bring the tube to selector valve without routing it through the left footwell. Extra elbows are to be avoided due to vapor lock potential with FI.
The ship will only be configured for positive G aero (no inv?oil). So, is the extra elbows and bends a problem with FI ? I can convert to standard pickup or simply carry on with plumbing.
 
Larry,

The flop tube is not necessary for positive G maneuvers. I removed mine some 20 years ago when I realized the heavy brass fitting was putting a wear mark on the bottom tank skin. The O ring failed and allowed metal to metal contact.

https://www.youtube.com/watch?v=P8uJYaJFst4

This was done with the normal fuel pickup.

Cheers, Hans
 
I forgot to switch to my left wing with the flop tube and rolled inverted. Engine ran for a solid 30-45 sec before losing fuel pressure. I don’t see the need for a flop tube unless you have full inverted oil and plan on spending minutes at -2g. FYI I have Standard Bendix fuel injection on a Superior forward sump.
 
Larry---we've plumbed alot of inverted tanks for guys. At the tank we use a long drop 90* hose end that routes through the tank nose bracket and crimps to a teflon hose. At the side skin, we 'either' is a 90* bulkhead fitting to connect the valve lines or make a longer hose to connect to the valve with a grommet at the side skin. A bunch of them out there, no issues we've heard of.
Tom
 
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