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Small fuel tanks


John  Tee
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Not R/c related really. I have a single channel model powered by an Indian (copy) Mills .75 diesel. Mine hasn't got the attached fuel tank. My local model shop hasn't had free flight tanks for years and that is what I need. I have one but it is too small and would probably only supply enough fuel for 1 minute if lucky. I tried to convert one of my Insulin syringes but is even smaller. I could use a small clunk tank but not easy to retro fit as the tank bay is now blocked in and would be too high sitting on the ply engine plate and would require major surgery to alter. I am informed that diesel fuel is not good for silicon tubing. I have some yellow tubing suitable for glow, diesel or petrol There must still be free flight supplies available somewhere but does anyone know where?

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If you have a reasonable size soldering iron (nothing special) then it’s pretty easy to make your own. Tradition calls for recycling a Colman’s mustard tin but thin tin plate is available from model shops or model engineering suppliers (e.g. K&S). 
 

2 square U shaped pieces form the basis of an oblong tank but you would be free to make any size/shape that you need. 
 

Peter Miller has a great tip when adding the brass pipes - use a suitable sized nail to punch holes and it forms a useful flange/well for the solder. 
 

Use flux and lead/tin solder and you’ll find it surprisingly easy to produce a leak-free job. 
 

In the best traditions of Blue Peter, here’s one I made (a lot) earlier:

 

DE57C049-D8CF-43E0-8022-0689D8AC4C7A.jpeg

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6 hours ago, John Tee said:

Not R/c related really. I have a single channel model powered by an Indian (copy) Mills .75 diesel. Mine hasn't got the attached fuel tank. My local model shop hasn't had free flight tanks for years and that is what I need. I have one but it is too small and would probably only supply enough fuel for 1 minute if lucky. I tried to convert one of my Insulin syringes but is even smaller. I could use a small clunk tank but not easy to retro fit as the tank bay is now blocked in and would be too high sitting on the ply engine plate and would require major surgery to alter. I am informed that diesel fuel is not good for silicon tubing. I have some yellow tubing suitable for glow, diesel or petrol There must still be free flight supplies available somewhere but does anyone know where?

 

Can not help you, but posting this to correct a factual error 

Any and all Mills, other than the original, Indian and the Irvine made were 'copies'. 

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Thanks for the pointers Mike and Peter.  Did try to make one years ago like that Martin didn't turn out too well  but willing to try again.  DaveyP as an ex gasman I have plenty of copper pipe in my scrap bin. Hadn't thought of that though may be a bit heavy on a 32 inch w/span model but wouldn't need that big a bit I suppose.

Have found a tablet tube which could be adapted if it is diesel proof (plastic).

Thank to all for your replies.

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Inkjet printer refill bottles are pretty useful for small fuel tanks.

 

Typical sizes are 25ml and 40ml and they even have a useful nozzle in the cap.

The ones that I have tested are not affected by diesel or nitromethane glow fuel.

 

Poke a vent hole with a small soldering iron, force (melt) a brass tube into the nozzle from the inside and bend for fuel pick-up.

 

So the pick-up is fixed but then so is your Mills tank so no loss.

 

* Chris *

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Tin tanks are very easy to make. They can be made to virtually any size or shape. Don't use them for glow fuel as it rust the insides pretty quickly. Thin gauge tin plate can be sourced from biscuit or chocolate tins and is a good excuse to eat more of them ?. Use the inside surface to solder together as it easier to solder the tin side than the steel side when the printing is cleaned off. Cellulose thinner cans are an excellent source if you need bigger sheets.easily cut to size with a pair of scissors. Ordinary flux cored solder works fine but don't try the lead free stuff it useless. 

Fuel tube to use is black nitrile , neoprene or Tygon yellow tubing or its variants. Nitrile and tygon tubing stay flexible but the neoprene quickly goes hard . Silicon is not suitable as it hies soft and swells up then falls off if used with diesel.

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20 hours ago, Engine Doctor said:

Very interesting to see the  exhaust stubs on the Mills. Only ever saw them fitted to the marine version.

Well spotted!

 

Originally the engine was bought as a marine unit.  When the owner moved from boats to aircraft, he fitted it with an aero head but kept the stubs.  Now in his late 70s, he passed the engine on to me last year (as he's all electric nowadays).

 

I've subsequently fitted an RC throttle from an Indian Mills, and it works just fine!

 

Tim

IMG_4986.JPG

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Do be careful as those stubs screw into modified exhaust ports cut in the crankcase. They may in a crash, damage the crankcase casting . Unlikely in a vintage rc type model but possible. The standard ex ports are smaller oval shape but the marine conversion required them to be drilled and threaded for the stubs to screw into. Apart from the mod I think the cases are the same . Never actually examined one but someone on here may be able to confirm ?

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11 hours ago, Engine Doctor said:

Do be careful as those stubs screw into modified exhaust ports cut in the crankcase. They may in a crash, damage the crankcase casting . Unlikely in a vintage rc type model but possible. The standard ex ports are smaller oval shape but the marine conversion required them to be drilled and threaded for the stubs to screw into. Apart from the mod I think the cases are the same . Never actually examined one but someone on here may be able to confirm ?

 

Thanks for the advice, Doc!

 

The stubs were actually quite loose when I received the engine, and seemed to have a tapered thread on their inner ends. If I tightened them fully, then their inner ends appeared to  actually touch the piston, which suggests that the liner's ports were also enlarged!  I took the precaution of adding a little bit of thread locking compound as I gently tightened them up.  The model has had dozens of flights since then, and they're still firm.

 

Tim

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  • 2 weeks later...
On 23/08/2021 at 21:24, Tim Hooper said:

I'll second the use of syringe bodies.

 

My Mills .75 runs for several minutes on a cut-down 5ml syringe.  The top can be anything that fits, but has a hole in the centre!  The tank is secured to the firewall with a brass strap.

 

Tim

IMG_4943.JPG

IMG_4976.JPG

 

@Tim HooperI've bought a small syringe for my latest creation, but where did you get that yellow top?  Is it 3d-printed (and if so, got a link to the file?)

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On 06/09/2021 at 13:28, Mike T said:

 

@Tim HooperI've bought a small syringe for my latest creation, but where did you get that yellow top?  Is it 3d-printed (and if so, got a link to the file?)

 

Mike, 

 

I'm using the top from an old FF fuel tank.

 

However, on a similar set-up on another model (using a cut down 20ml syringe), I just used a tightly fitting washer pressed into place as a top, helped with a bead of CA glue.  Works well!

 

Tim

IMG_5423.JPG

Edited by Tim Hooper
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