The bung for my fuel tank has 2 lines going through it (3 on my new one) and they are plastic. The plastic bits can slide in and out and turn very easily. I believe this might be a source of a plumbing leak so I want to seal it up. I guess a tube of silicon would work - do I apply inside, outside, or both? What about using CA or epoxy?

Thanks.

Does your stopper assembly look pretty much like this picture? But, it has plastic tubes rather than brass? If so, getting the center screw good and snug should compress the rubber stopper so it seals around the tubes and seals the neck of the tank. You could put silicone sealant on it but you should not need it. CA and Epoxy should be avoided.

Yeah it's really similar but the brass parts in the pic are pre-bent plastic pieces on my assembly.

So this would explain why I've had less/no problems since I took everything apart and reassembled - I must have snugged down the bung screw a bit more. I was so worried I wouldn't be able to start my engine at the pattern meet, so I took everything apart and reassembled. and I was able to start with one flip, literally, for each of the 6 flights!

I love AX

HI JOE!!!!!! Couldn't help myself.
Is that an ARF tank ?? Just wondering. When you said pre bent tubes it got me to wondering. I have never even seen that on an ARF tank before.
Cool that you had the nerve to fly the event. I was being taught the fine points of pattern flying not too many years ago until my instructor had A problem and couldn't fly or go to the field any more. I didn't care for it myself but I was being taught serious so it wasn't all that much fun. It really did make me A much better pilot and A lot smoother.
We have two big/good events here every year and I go and watch, it has crossed my mind to get involved at least in basic. I do have A couple of good planes for the lower class and A closet full of plans for some smaller pattern planes.
Glad to hear you liked it.

Carrellh has your answer. When you tighten the screw it compresses the rubber of the stopper which causes it to seal around the tubes running through it and also seal to the tank. You really shouldn't need to use anything else to seal the tank.

Ken

I've seen some of those tanks with the plastic tubes cause a ton of trouble. They typically come with Phoenix ARF's. The airframes are great but the tanks and other hardware can sometimes be problematic. I would try t make a Sullivan or Du-bro tank fit. You may have to make some bracing from balsa or stuff it in there with foam. You'll never have a problem again though.

Another, possibly easier option might be to find a similar size and shape ARF tank from another manufacturer with a more traditional stopper. This might be easier to make fit. You could also try just buying a stopper and tubes at the hobby shop and see if it fits your existing tanks.

Yep, they're both Phoenix tanks. I'm definitely not going to use the setup that came with the Decathlon - because of the plastic parts and because it's a TINY tank for a bigger plane and engine than all my other planes.

Ken, I'll have to check this out. I don't remember seeing how tight the seal was after I cranked down the screw, but what you said makes sense. The only thing I can think of is if the plastic tubes are soft enough that they are deforming rather than a good tight seal being made.

Graybeard, I had one caller for most of the event, then this other guy came and thought he could 'fix me'. He was like 'do this, do that, then do this' before I even started flying. I want to learn, but it lost it's fun (with him) quickly. After that round I went back to (Scott) my original caller and told him to just call the moves and let me have some fun with this one =)

I think it's just all about stick time, flying in different conditons and trying different things before, during, and at the end of a maneuver.

If this is the case then I would recommend replacing the plastic tube with brass or aluminum tubes before using any sealants.

Ken

I just used the bung and tubing from a dubro tank in the Pheonix Fun Star. I went for the whole tank, but it was to long, so I had to use the tank that came with the plane. The Dubro bung fit well. A Sullivan one will fit also.

Don

Another very important point!!!

Don't tighten the plug TOO tight or it can split the neck of the tank!

And it won't happen right away... It'll happen a week or so later while you're in the air and leak fuel all over the inside of your plane. (Murphy's Law)

Truer words were never spoken. It's quite a shock to take the wing off your trainer to see a lake inside.

Don

Very true. But even worse is not seeing the lake, which weakens the wood and you see a wing pull loose from the fuselage in the air!!! [X(]

Ken

I usually managed shaking the wings loose hitting the pump house fence, testing the hardness of the soil on either end of the runway, and sending a plane into the deep dark creek bed behind our field to not be seen for several months. Slow soaking fuel damage didn't get a chance to happen.[sm=lol.gif]

Don

Thanks guys, i have spare tubes from the Nexstar, and ordered a new, bigger tank with brass tubes for decathlon.

I went through this bung tightening issue a while back. What I finally found out is that when putting these things together, a big thing is that many people (including me at that time) thought that it should be tight enough so that the tubes don't move. If you do this, it will actually be over tightened and may cause the splitting mentioned above.

The right way to do it, from what I was told, and I believe read here on RCU is to tighten it so that the tubes are snug, but still rotate, but with some effort. This is sufficient to both seal the bung in the tank inlet and to seal the tubes inside the bung. It will not leak if done right and won't split because it isn't tightened to the point where it stresses the neck of the tank.

I read your post about the Pattern meet. Great job!! Now, the key to this is to practice, practice, practice. Have someone stand behind you with the Sportsman sequences and do them over and over again, start to finish. If you run into a stumbling point, like perhaps you are not happy with your Split S or 1/2 Reverse Cuban 8, or whatever, do the entire sequence (get that down so that it's totally automatic as to "what comes next".. you don't want to be thinking about what you are going to do just prior to doing it, you should be a maneuver or two ahead of that and planning on your exit from your maneuver so set up the next.

Anyway, after you complete your maneuver sequences, and get ready to land, you can do a touch and go, then go back up and do, oh, 5 to 10 of the maneuvers that are giving you problems, or that you are not happy with.

Eventually, you will be doing each and every maneuver as though they were animated and all you are doing is watching. Well, perhaps not that easy, but you get the idea.

Best of luck at your NEXT outting!!! Hey.. now you have experience so you're ready for the NATS!!

CGr.

One more thing. Get some brass or aluminum tubing at the LHS or via Tower, and get a tubing bender and do your own tank plumbing. Just a suggestion. That's what I did.

One of our guys that flys Intermediate Pattern does some pretty elaborate plumbing in his pattern plane. He swears by his method, and he never has a dead stick due to poor fuel flow nor tank fuel foaming. And he does not use a pump.

CGr.

Carrellh, "CA and Epoxy should be avoided".

What is the problem using CA on fuel lines? I had a problem with the tubing staying tight on the brass tube and put a drop of thin CA on tubing and it held great.

Gary

Another nice trick is to get some 1/8" COPPER tubing from you local Auto Parts store. I't only about 50 cents per foot and it bends MUCH better than brass or aluminum. To prove the point, I once looped a piece around a nail (see pic)

I often use long pieces so I can send them right through the firewall so that there is no "Metal-to-silicon" connection behind the firewall.

CG, thanks, sounds like good advice (tank and pattern stuff). I'm gonna use my pre-bent Nexstar lines for my Dolphin, and will be bending my own lines for the Decathlon. I've got to work on finding a caller too, though the pattern doesn't take much time so that shouldn't be hard.

OH!!! You were SO RIGHT about my engine, too! I was using an 11x5 prop 'cause that's what came with the Nexstar, so I got used to the high rpm's and the NOISE! During the pattern meet I switched to a 12x5 'cause my caller wanted me to slow down and fly closer, and it worked great, and is so much quiter! Must be easier on the engine too spinning at less RPM's, and being tuned right it's not getting hot or using too much fuel.

I'm gonna fly as much as I can with this stupid fuel shortage. I'm trying to stock up, but here's it's $30+ per gallon, so I've only got 2 gallons, and I can't get my 10% Nitro which annoys me (have to use 15%). Tower is even out of 0% and 5%, and their shipping surcharge is a killer.

So, if Nats wasn't this week I might think about going. Definitely next year. I plan on flying in Sayre and Jackson this year, and maybe the other one in our division. Maybe I'll get to meet you in Jackson?