J

jdmunzell

Well Known Member
OK... reading the other post "Fuel Tank Hints" leads me to ask this now of everyone.

Who has installed the flop tube tube system and who has installed the regular fuel pick up? Next any known issues with either system, regrets on installing one system over the other? ..or satisfaction with what you installed?

Also, who has installed the fuel return lines during construction of the tanks, and who hasn't? Any regrets or otherwise?
 
Standard fuel pick-ups. No flop tubes. No return lines. Regular acro. No problems, no regrets in 14 years.
 
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Flop tubes in both tanks. It is a little more work with the antihang brackets and moving the fuel sender to the second bay but nothing to fuss about. Haven't got to the flying stage yet but looking forward to it.

Jim Kinsey
7A Fuselage
 
Flop tubes both tanks. NO fuel return.
(1/2 gallon UNUSABLE each tank)

First flight September 1997. 1,981 hobbs hours.
 
One flopper, one normal pickup.
Not flying yet, and don't plan on any inverted oil system. If my next RV is not a -10, I will probably skip the flopper - really not needed for positive G aerobatics, and there's the whole issue of service life / stiffening over time.

I installed returns to both tanks, a simple straight line into the second bay. Not much extra work, and they don't get in the way of anything. I don't know which FI system I'm going to use. If unused, they will be capped.

Thomas
 
Installed a flop in the left tank of the 6A. Would I do it again? No. It was a difficult installation on my 6A (see photo) and not needed for most acro unless you plan on staying inverted for awhile. I've frequently thought about the pickup end of the flop moving or vibrating about on the inside bottom of the fuel tank skin in normal flight. If I were to do it again (which I didn't on the -8 fuel tanks) I would bond a reinforcing doubler plate beneath it just to put my long term chafing concerns...real or imagined...to rest.

fa02720ru6.jpg
 
Wish I would have done the fuel return during the construction. Now , I have to add it after the fact. I would put a return fitting in. You can always cap it if you don't use it.
 
Standard

Mel said:
Standard fuel pick-ups. No flop tubes. No return lines. Regular acro. No problems, no regrets.......
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Mine is the same as Mel's....(without the 14 years of experience!)
 
Tank Choices

- Standard pickups (Van's fancy ones with screens)
- Return lines plumbed nearly per http://www.rv8.ch/article.php?story=20040704204434728
- Vent fitting oriented for vent completely in wing root ala Rocket http://www.vansairforce.com/community/showthread.php?t=5437
- Float senders
- Wings on rack still

I figured that unless you put in full inverted fuel and oil, that doing any part of it was a waste. I really don't like to fly 0 or negative g's for more than a couple of seconds anyway :cool:

Return lines will be capped if not used. They're AN5 since, apparently, the Andair stacked valve uses AN6 for the feeds and AN5 for the returns. Mine are also towards the top at the root and plumbed into the bottom of bay 2

The "Rocket" vent just looks slicker, easier, and equally effective to me.

George
 
1 flop hose, 1 normal pick up. No problems, would do it again.

Fuel return line in right tank with carb engine. Used .040 drill restrictor at carb and it drained the left tank in a little over 20 minutes! Capped return line and would not do it again. I guess we should post under "Close Calls" also.
 
Put return lines in!

I put return lines in, same size as the feed lines, they end in the third bay of the tanks. I need them because I am considering a Diesel engine. I thought it be best to mix the warm and the cold fuel a bit before picking it up again, this will solve any problems of diesel freezing over at high altitude and low temps. Also diesel may foam a bit when returned in the tank (depending on what kind of fuel I am going to use), this way the foam will stay away from the pick-up.

Andair double stack valves come in two types! one with same feed and return and one with a larger feed (for engines over 200 bhp).

I would recommend to put return lines (or at least fittings) in, just in case you decide to go for FI or Diesel later on.

Regards, PilotTonny
 
Mel said:
Standard fuel pick-ups. No flop tubes. No return lines. Regular acro. No problems, no regrets in 14 years.
Click to expand...

Me too...except no acro yet. ;)

Waiting and watching for the big truck with fuselage...
 
Mel said:
Standard fuel pick-ups. No flop tubes. No return lines. Regular acro. No problems, no regrets in 14 years.
Click to expand...


That's what I thought.. Will probably add return lines though and just cap them if I wind up not using them. Ya never know though what with the new technologies ie. diesel or FI.
 
I'v got the flop tube on one side and regular tube on the other, just in case I decide to go with inverted oil.
You know, instead of sending a return line back to the tank, you could also tee it in at the "in" side of the fuel pump.
 
No Flop

Anything with "Flop" in the name picking up fuel kind of scared me. ;) Standard pickups here.
 
[Insert title here]

Standard pickups, no regrets, not flying yet but my mission profile is mostly cross country anyway. I was looking for good speed and fuel economy plus lowest cost of ownership. The 7 was the way to go! :)

Chris....
http://www.n212s.com
 
Inverted everything

Gradually spending more and more time upside down...Almost up to 5 seconds now before I chicken...:)

Frank 7a
 
I've got inverted oil + fuel injection, so I put in one flop tube. Having a flop adds a new failure mode - flop tube hung up inside tank, so it doesn't go back to the normal position. This could result in a significant increase in unusable fuel. If you only have one flop tube, you can mitigate the risk of this failure mode by running that tank low on fuel first, while you still have a reasonable quantity of fuel in the other tank. If the flop tube is hung up, the engine will quit when the fuel gets down to the critical level. You then can restart your heart by switching fuel tanks and landing, maybe having to land short of your intended destination.

I didn't install two flop tubes, as then you have no way to completely mitigate the risk of a hung up flop tube, as you have no way to know in which tank the flop tube could be hung up.
 
IF your engine has a carburetor, The engine will quit during neg portion of aerobatics because of float in carburetor long before a flop tube in the tank would matter anyway.

My opinion is if you aren't fuel injected why bother.

I have the standard pickup tubes.
800 hrs, 5 years, ton's of hard acro, never a problem.
 
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jdmunzell said:
OK... reading the other post "Fuel Tank Hints" leads me to ask this now of everyone.
Click to expand...
I'm not yet there but I've parts for wing already: flop tubes for both tanks and 3/8" return lines as I yet don't know which engine to have. Regrets? Not yet, I'm just trying to do everything right from the beginning. I'm sure it is much easier to install these when building tank rather than retro install them later if needed. The cost can't be issue here, it just adds a little more work.
 
made the tubes in the plans. My thoughts are with simplicity. Also, I don't want any debris caught in the screens in the tank. I want to blow air into the fuel lines on anual and clear out anything stuck in the slots I cut in the al. tubing. I'd rather have a filter get pluged than a screen. I plan on fi and will tee in a return at the fuel valve.
 
Four tanks, 75 gal, 1000nm w/reserves (also, the most comfortable seats I will be able to afford. ;) ) Three tanks with standard pick-up tubes, one with flop tube, still debating whether left or right inboard would be better. Any ideas?
 
One Flop, one standard, Silverhawk FI but no return lines. Not flying yet (getting closer) but already have decided I would not do the Flop next time as I don't plan on sustained negative G's.

Larry
 
Paul said:
IF your engine has a carburetor, The engine will quit during neg portion of aerobatics because of float in carburetor long before a flop tube in the tank would matter anyway.

My opinion is if you aren't fuel injected why bother.

I have the standard pickup tubes.
800 hrs, 5 years, ton's of hard acro, never a problem.
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1 flop tube installed in my carbureted, pos-g oil equipped -8 for future negative g use.
 
Right tank flop

longranger said:
Four tanks, 75 gal, 1000nm w/reserves (also, the most comfortable seats I will be able to afford. ;) ) Three tanks with standard pick-up tubes, one with flop tube, still debating whether left or right inboard would be better. Any ideas?
Click to expand...

Isn't the default standard with certified planes to take off using the Left Tank if both are full? Sort of makes sense if only one person is on board...

So the flop tube goes on the right tank...

gil in Tucson
 
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