gus

I am building my first ever plane, a Great Planes PT40. The recommended fuel tank is either a 6 or 8 oz tank. At the LHS, the assistant assured me that the 10oz will fit, and the extra capacity would be beneficial. So, armed with the 10oz tank, I began construction.

Now, with a slighe bit of modification to the tank compartment floor, the 10oz tank DOES fit, but it is pretty tight (about 1/4 inches free on either side... just enough to squeeze some of the latex foam in. My problem is with the throttle, and nose-gear steering push-rods. These run along the sides of the fuel compartment, near the top, and are in contact with the tank when installed (and need to be removed to get the tank in and out...),

I know that the easy answer to my question is to get an 8oz tank, which will fit (and is not a wallet-breaker), but the tank manual indicates that the tank can be re-formed with a heat gun.

So my question is, does anyone have any tips, techniques, cautions about re-forming the tank so that there is more space around the control-rods?

gus

flap

Dont know about reshaping the tank, sorry.
Are you using sleeves for the controll rods? possibly glued to the fuse side?
I like to use cable for the throttle when possible, its great for sharp curves ect..
Just looks like, if theres room to install any foam, you should be able to fasten sleeves to the side or bottom of the fuse, understand what I mean??

den1tjb

I have never heard of re-forming a tank with a heat gun, but it the instructions say you can, then go ahead and do it. Watch out for the CG change during flight though. A larger fuel tank may push the CG out of acceptable ranges when full. Not something you want right after takeoff! Most .40 size birds can handle the 10oz, so don't worry, do as flap suggested with the control rods/foam, and take her up already!

JetAwithPrist

It sounds like you have a sullivan flex tank. I have had one of those also but never needed to reshape it. I can't help you as far as the reshaping goes but it sounds like you just heat it up with a heat gun and squish it a little further than you need to and let it cool. I bet you can do it as many times as you need to get it to fit. Let us know how it goes.

ramcharger

I tried this years ago. I had a round DuBro or Sullivan tank and needed to reduce the tank diameter so it would fit between the rear portion of the 2 hardwood motor mounts and the cutout in the fuselage formers behind the firewall (Aeromaster Too). I wanted to heat the tank and stretch it longer. I immersed it in boiling water but it wouldn't stretch. I was going to then try cooking oil but decided that was to dangerous. I tried my Hobbico heat gun but heat was to local and it got hot in spots. I think all the messing around ruined the tank because later when tightening the screw to seal the lid/plunger assembly the nozzle of the tank split open.

gus

I guess I will try, and post results as they occur.

If I break it, well it needed to be replaced anyway!

gus

gus

Reforming seems to have worked. The back end of the tank is now mor "conical", and the entire tank is a little narrower.

but, I have decided to kill the idea anyway, and get an 8oz replacement.

Reforming the tank was quite easy, (it is a sullivan). Heat gun it until the plastic goes transparent, reshape it (without burning your fingers), and then let it cool.

My concern is that the clunk will not get to move around quite as much, or will not be able to get to all the fuel. The back end of the tank is pretty clearly shaped so that the clunk can move around to all the extremes.

So, I may just go get an 8oz, and not have any of these worries.

gus

JetAwithPrist

thanks for the update, i'll keep that in mind in case i need to do that sometime