Flop tube installation in RV-14

[Treedy]

I’ve searched this forum without success. Has anybody installed flop tubes in the RV-14 tanks? If yes, what brand / supplier did you use? Any modifications to the standard tank?

It appears to me that the fuel gauge sending unit would interfere with a “regular” flop tube.

Thanks
Tom Reedy

RV-14
Tail complete
Fuel tanks next
Waiting on LCP issue resolution!

 

[RV8JD]

One Thing to Consider ...

I would really ask yourself if you REALLY need a flop tube.. unless you are intending extended negative aerobatics, they are must not needed. Are you also planning inverted oil? Flop tubes are rubber and need to be changed every few years.. I don’t know anyone who really changes them as preventative maintenance, but over time, they’ll get stiff and reduce your usable fuel. You can still do all the good aerobatic maneuvers without flop tubes, the engine won’t quit from just a momentary negative maneuver.

+1. From this post by Jon Thocker: https://vansairforce.net/community/showpost.php?p=1180965&postcount=1

"A data point for anyone considering fuel tank flop tubes.

Decided to see how long my engine would run while inverted and on the NON inverted tank.

I have a flop tube in the right tank and a standard pickup in the left. From "experience" I've noticed I can fly for quite some time inverted and on the wrong tank!

Today, I decided to find out just how long! With only 4 gallons in the left tank and the left tank selected, I rolled inverted and started a timer. At 25 seconds I rolled upright and at the 30 second mark the engine stumbled for about 2 to 3 seconds then it smoothly regained power.

Hope this will convince guys to bite the bullet and install that inverted oil system. There is absolutely no need to put in a flop tube unless you intend to fly inverted for more than 20 seconds."​

 

[wirejock]

Flop tube

Check the 7 plans. The float moves to the baffle.
If the tank is similar, the Vans flop tube might work. If not, TS Flightlines can fab the hose. You would just need the weight fitting for the end.
I just happen to have one if you want it. The flop tube timed out before she is airworthy so I swapped it for a standard pickup. The hose isn't useable but the weight is fine. I haven't checked but it should come off like any other fitting.
You pay shipping and its yours.
Shoot me a PM.

 

[Treedy]

RV14 flop tube

+1. From this post by Jon Thocker: https://vansairforce.net/community/showpost.php?p=1180965&postcount=1

"A data point for anyone considering fuel tank flop tubes.

Decided to see how long my engine would run while inverted and on the NON inverted tank.

I have a flop tube in the right tank and a standard pickup in the left. From "experience" I've noticed I can fly for quite some time inverted and on the wrong tank!

Today, I decided to find out just how long! With only 4 gallons in the left tank and the left tank selected, I rolled inverted and started a timer. At 25 seconds I rolled upright and at the 30 second mark the engine stumbled for about 2 to 3 seconds then it smoothly regained power.

Hope this will convince guys to bite the bullet and install that inverted oil system. There is absolutely no need to put in a flop tube unless you intend to fly inverted for more than 20 seconds."​

I am definitely installing inverted oil but after reading this I’m reconsidering inverted fuel. Don’t plan extended inverted - 25 seconds is more than enough!

 

[Treedy]

Check the 7 plans. The float moves to the baffle.
If the tank is similar, the Vans flop tube might work. If not, TS Flightlines can fab the hose. You would just need the weight fitting for the end.
I just happen to have one if you want it. The flop tube timed out before she is airworthy so I swapped it for a standard pickup. The hose isn't useable but the weight is fine. I haven't checked but it should come off like any other fitting.
You pay shipping and its yours.
Shoot me a PM.

Thanks Larry - I appreciate the offer. I’ll keep you in mind but based on the other post I’m rethinking the inverted fuel

 

[Ralph Inkster]

Just measured up a 7 & 14 tank side by side.

The 4/6/7/8 flop tube are about 13" long, reasonably allowing it to flex enough (noting it gets stiffer with age) to reach both the top & bottom tank skins.

The 14 tank has a forward tank mounting bracket which is part of it's structure, this would be an obstacle inside the tank to mounting a flop tube the same way as was done in earlier RVs. Using a shorter flop tube and mounting it behind this mount structure might not leave a flop tube flexible enough to reach all the way to both top or bottom tank skins & affect fuel pick up potential. Additionally you would have a major challenge to route your fuel lines around the aileron control bell crank & linkages.

If you do figure out a successful 14 flop tube setup - Post Pictures!!