M

Millionrivets

Member
Anybody have any advice/experience on going with flop tubes in the -4? I'm inclined to install them in mine just for the versatility, but wondering if they're more trouble than they're worth, i.e. subject to wearing out over time, extra installation considerations, etc.

Thanks,
Chris
 
Having a flop tube adds another failure mode - it is possible for the flop tube to get hung up inside the tank so it is no longer resting on the bottom. You only discover this when the engine quits from fuel starvation. You can get a restart if you switch tanks, but only the fuel in the other tank is now available. So, I would only add a flop tube if you will actually have full inverted flight systems, and you would actually do negative g manoeuvres. Otherwise, there is no point.

If you do have a flop tube, and you plan to use most of the available fuel on this flight, I recommend to run the tank with a flop tube down before you run the other one down. That sequence leaves you in a better situation in the event that you discover the tank with the flop tube stops feeding early.
 
Flop Tubes in my -4

I put flop tubes in both tanks of my -4 and have had no issues. I originally did both tanks because I did not like the design (at least at the time I built my tanks) of the fixed pick-up tube.

When I built the tanks, I had been planning on an inverted oil system, but ended up skipping it as there is so little space under the cowl of a -4.

Good luck,

Dean Pichon
RV-4/400 hrs
Bolton, MA
 
I built with a flopper in the left tank just in case I went for inverted systems. I didn't. As for the tube getting hung up, it's a non-issue if built properly. Regarding wear, yes they do wear out and stiffen over time. If I were building again I would not put one in. Live and learn.
 
Thanks for the input. The consensus seems to confirm my instincts--a nice feature, but probably not worth the trouble just to have the option. And so, the first real casualty to reality on my list of dream airplane features. No flop tubes. That means I can cross the inverted oil off my list, too. Still holding on tight to the turtle deck slider idea, though.

Chris
 
flop tube

You got to be kidding me; you need one! My flop tube, 18 years old-that's right eighteen years old, has never hung up, has not gotten brittle, and allows me to fly any outside maneuver, from level flight inverted through rolling 360's to outside loops. The only thing I would change is to put a flop tube in each tank so that I don't have to think about which one is the acro tank.

SPUDS
 
Changed my mind, went ahead and ordered a flop tube from Van's, and I have to say, now that I've seen it, there's no way I can't install this thing. It's a nice component. The only problem is that it does make me feel a bit...inadequate... But I'll get over it *

Hmmm, not sure I'll be doing any outside manuevers, Spuds, but your input is well taken.

Chris
 
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