Fuel tank sizes

[fly boy3]

Hi all, my current build can only take a blue slec 4oz fuel tank,42mmx42 mm. I would like to have a longer flying time. I have always used slec square tanks, but I wondered if there are other tanks out there with different dimentions  ie longer and thinner, not over 42 mm wide,if there is such a thing. Cheers.

Edited By fly boy3 on 02/11/2018 16:48:21

[Don Fry]

I think you might struggle to find one. Can you fit a header ( chicken hopper) tank?

[fly boy3]

Hi Don. a header tank, you got me beat now ? Cheers

[Denis Watkins]

FB, a header tank, is a small tank elsewhere in the model, where there may be room

And is plumbed in

[alex nicol]

Gents, the slec tanks can be joined up. I've never tried it but it mentions this on the tank spec page if it's any help

[fly boy3]

Hi Alex, well spotted, I do have room to fit 2tanks one behind the other, Any chance of a connection diagram for an old guy. Lol Cheers

[Roger Marshall]

Hi,

Something I`ve done with two SLEC tanks is to cut them and rejoin to the length required, ie front of one tank and rear of the other. Make sure both cuts are square and meet each other nicely.

You then place them in a pan, joint side down of course, and heat gently on the hob, look closely and you can see them soften and melt ever so slightly. Adjust the heat as required

Place the two joins together on a level surface or simple jig, hold together until set. Pretty quick!

This is just a simple weld created, so you will get small bead at the joint. which didn`t cause a problem because the clunk weight extended past the weld to the rear of the tank.

Its easy to test the tank in the way you choose

If you don`t get it right first time then recut/clean the join and try again.

I hope I`ve explained this well enough for you to see the prosess.

Roger

[Don Fry]

Roger does not use water in the pan, and waits till SWMBO is out. And I bet he has a trough, the width of the tank, to align them. Cunning idea.

[Don Fry]

If Alex does not come back I can work out the plumbing for two tanks one behind the other, or a hopper tank. But, both have complexities in the plumping, and a good engineer says KISS ( keep it simple, stupid).

Roger's idea is simple. And you get to choose your tank size.

[fly boy3]

What a forum, great ideas everywhere. Thanks Don a dia.would be helpful. Thanks

[Bruce Collinson]

There’s a diagram of a chicken hopper installation somewhere on this forum which my club mate Steve Dunne posted a couple of months back and knowing him he will spot this (hi Steve) and link it. Having said that, I recall it’s all to do with having the smaller tank correctly aligned with the carb where an adequate tank won’t fit and probably too complex for a simple capacity issue.

Plan B, Mick Reeves’ website has some delightfully robust advice where tanks are concerned and you may want to take another look at, and a caliper to, coke bottles/ bean tins etc.

Plan C; put two SLEC tanks in tandem, seal the outlets in the rear one and add two new tubes between them, one at the top and the other at the bottom. Wouldn’t they then perform as a single tank (Newtonian physics, liquids finding their own level etc)?

BTC

[Barry W]

Du-Bros sell a range of tanks that may suite.

https://www.dubro.com/products/fuel-tanks

[Don Fry]

For Roger's idea, a hopper, or two tanks one behind the other?

And if between two and three, a hopper needs space above the tank position you have. One behind the other, you have space. It's a more complex plumbing installation, and will make filling, emptying, a bit more complex, and makes for more leak points.

What will work for you.

If it were I, I would weld the tanks. Done well, and it does not sound difficult, it's KISS endorsed.

But not my airframe. I will supply as requested.

Edited By Don Fry on 02/11/2018 21:00:26

Edited By Don Fry on 02/11/2018 21:01:56

[fly boy3]

Cheers Don. You are right, I'll have a go at welding tanks, or fly more reservedly on one ,lol. It feeds a 40 4stroke. Cheers

[cymaz]

Could you not make your own from brass / copper sheet?

Edited By cymaz on 03/11/2018 05:38:43

[onetenor]

Make one in card first to obtain patterns for the TIN PLATE (soup ,Beans etc tins.) If you want a simple way to get a slim one look for the bigger versions of sardine or pichard tins .Tinned herrings and kippers are bigger if you can find them.Solder a plate over the tear out place but fit your tubes in first. Easier when you can see inside. Oh yes don;t forget to boil them in detergent to remove the oil etc first. Test with a magnet as some are aluminium unless you fancy trying the alloy low temperature solders first 300 C solder available. I got some a while back but you will have to look on Amazon E bay for it I'm afraid as my memory is not good at present since losing my darling wife last month.

[Nigel R]

Rogers idea is a nugget of genius. I would certainly try that over separate tanks.

A pair of 4oz turned into a long thin 6oz would be just right for a 40 4str.

[Steve Dunne]

Hi Bruce! No hiding place eh?.

My chicken hopper design would be no good here, it is for feeding a lower small tank from a larger and higher-positioned reservoir.

I like Roger's suggestion of welding two tanks together, but I would cold-weld (glue) them with a suitable plastic weld adhesive (experiments required with old tank material) then bandage the weld with a ribbon soaked in Foam-tac or UHU Por. This gives you lots of time for playing and manouevering, and probably is much easier to create a non-leaky joint.

I have not tried this with a fuel tank, but used exactly this method some years ago to create made-to-fit bottles for thinners etc. in a home-made en-plein-air painting kit. They are still working...

Good luck - and have fun experimenting

Steve.

[fly boy3]

I too like this adhesive join method. Can anyone say what actual material tanks are made from ? Cheers

[Don Fry]

Now I would make a trough, in wood, close fit to the width of the tank, so the glued ends are butted very accurately and quickly together by simply sliding them together in the trough, and the trough makes it easy to hold the halves still until set

Glue might not be a goer, as I think these tanks are polythene.

To melt, a plate of heavy metal on the stove would work, not too high a heat. Experiment with scrap bits first.

Remember, the smell takes an hour to dissipate. Don't use a non stick pan. Sharpen a good chefs knife first, so if caught, at least you don't suffer.

[Steve Dunne]

"I too like this adhesive join method. Can anyone say what actual material tanks are made from ?"

Perhaps call SLEC and ask them?

[Don Fry]

Sorry, senile double post.

Edited By Don Fry on 03/11/2018 13:00:00

[Steve Dunne]

"Glue might not be a goer, as I think these tanks are polythene"

Don, polythene is no longer un-gluable. A couple of ads picked up from google:

Permabond POP Primer
**LINK**

Loctite:
The Loctite All-Plastic Super Glue includes a tube of bonding agent and a bottle of surface activator. It bonds with hard and soft plastic. The glue works well with polyethylene and polypropylene surfaces.

And there are others - not particularly cheap, but will do the job.

Steve.

[Don Fry]

I have rumbled this about my head for a day. And I think;

Heat weld, Pro, not complicated, will work for ever, because it's ancient technology. Against, needs some experimenting, needs speed, and confidence. All to get the correct weld temperature. Will work if there is a gap.

Glue. Pro, easy, less need for speed. Against, not cheap. At flight 60, will the new technology still keep the fuel in. You might contact the company, but they will say that the exact use criteria are beyond their control, and users are advised to conduct suitable tests. I.e., see if it lasts 60 flights. No data as to gap filling qualities,

As I said above. Not my airframe, therefore not my decision.

[Steve Dunne]

On reflection, I agree with you, Don.