I purchased a 4oz. tank from RSM on a recommendation from another modeler. Dennis will remain nameless. 

It's for the Flite Streak, Skyfall 007.

Better "flite" time with the 4oz. and the Fox .35.

The tank is really nice, well made and shiny. Great tank RSM, way to go. Absolutely no complaints, I highly recommend these RSM tanks! 

Interesting though, the copper tubes, I was thinking brass, but I guess RSM uses copper. No big deal there.

Anyway, the tank was to long, just a tad, for the FS. I know bummer. 

I was going to send it back for the 3.5oz shorter tank, but decided to cut this one down instead.

Taking a tad less than .25" off the back end, I'm guessing I now have 3.75oz.? Close.

Yes, I also shortened both the uniflow tube and the fuel pick-up tube. One thing that wasn't really necessary, I straightened the overflow vent tube.

The task? Not as easy as one might think, but I did get it done.

Oh, by the way, that wire wing tip skid, the one I said could be used as a tool, it's in the photo, I did use it as a tool. 

Took just under one hour.

Quick note here. I can't quite grasp how you benefit from the uniflow tube being so close to the pick-up tube in the tank? Actually soldered to it.

One would think it would disturb the fuel entering into the pick-up tube?

 

That is a uniflow tank, designed by Edme Mariotte, of Dijon, France, in the 1600s.  A uniflow tank will give you a steady run.  The engine thinks it is sucking fuel from the submerged end of the uniflow. When the uniflow uncovers, the engine will go a little rich, then lean out as it runs out of fuel.  Brass does not hold up as well as copper in glow fuel.

I will expand a bit on what Jim T explained about copper vs brass tubing for fuel tanks.  Brass tubing has a tendency to split when subjected to the environment of these tanks, namely being submerged in fuel and the vibration.  Copper tubing generally gives a much longer service life than brass tubing for these tanks. It has to do with brass tubing often has a longitudinal seam while the copper tubing is generally an extrusion or some such thing.  People who work with this stuff will be able to explain it better.  Any article on making your own tanks will recommend copper tubing over brass.

Keith

Keith,

Link to your article?

Charles

Here are some articles.  No particular order.  I will leave it to you to find what you want to look at.


Frugally fabricated fuel tanks by Milton Dicky.  FM, Oct 2004
Super Tanks From Simple Change by Robert L. Anje.  Air Trails Annual, 60
Krueger Hopper Tanks in Brickhaus CL Stunt Column, FM, April 99
How to Make Your Own Fuel Tank by Robert Baron, AAM, Nov 74
Custom Controline Stunt Fuel Tanks by Dave Rees, FM Jan 77  (THIS IS ONE OF THE BEST!!)
Control Line Fuel Tanks, Part I, Part II, Part III, by Bob Balsi, FM Nov, Dec,90, Jan 91  (ANOTHER GOOD ONE)
The Aldrich Uniflow Tank by George Aldrich, MAN Dec 90
Metal Control Line Tanks by Charles Frizell, Aeromodeller, Jan 81
Uniflow Tank by M Harvey, Aeromodeller, Jan 71
Make a Custom Fuel Tank by Randy Randolph, MAN Nov 83

There are more in the various speed and Team Racing columns over the years as well as the various stunt columns for the past 40 years.  Most of these specify the use of copper tubing.  Every now and then, there is an article that mentions brass tubing, but most experienced stunt fliers will tell you to shun brass tubing.  The brass tubing will fail in time.  My collection of tank articles includes the above and about again that number of articles or more that talk about our model airplane tanks for control line.

Keith

an easy way to take the back off a tank is to tput a thick pan on the stove on high and set the tank on end the solder will melt and u can just tap the back and it will drop right off  ,u can even do the same thing to re solder it back on

Bob,

Thanks for that info, I will remember it.

There's the tank with the same ears that were on the smaller tank.

It will fit the same holes already drilled on the fuselage. Now, no holes will need to be filled and no re-drilling of new holes to fit this tank.

I allowed for a .125" offset at the rear of the tank.

Bob, thanks for the reply.

Charles

Hi Charles,

Do you have the ability to move the tank up and down?

Bill

Bill,

Hey! Hey! Thanks for the reply.

Moving the tank up and down for adjustment was brought to my attention in the New American build. That model is now electric, so it's a non issue there.

I do understand, somewhat, why some engines require the tank not to be dead on center. Somewhat?

I'm allowing for movement with "egged" slots in the ears for up and down adjustment. I will do that next. I need to get a small file or attempt it with a drill bit. I don't want to ruin an ear.

Thanks for pointing that out to me.

Did you see I have the rear corner kicked out a tad?

Charles