math refresher

[Bootlegger]

 Guy's I am wanting to build a 5 oz metal clunck tank and I need some refreshment on the dimentions, the length is limited to 3", so I am thinking about 2" vertical and "X" is the width...

        Thanks...

[Jim Carter]

Howdy!  Assuming you're not looking at creating some sort of trapezoidal or dodecahedron shape, wouldn't you be safe just using the dimensions published on the Brodak web site for their tanks or on the BMJR web site for a particular volume?     (jus' askin')

[Bill Johnson]

That's probably the smart way to go as liquid volume will change with temperature......


But you can always use this formula......
https://www.google.com/search?num=30&site=&source=hp&q=cubic+inches+to+ounces&oq=cubic+inches+to+&gs_l=hp.1.6.0i20l2j0l8.1302.6281.0.10617.17.11.0.6.6.0.188.1803.0j11.11.0....0...1c.1.64.hp..1.16.1730.0.S9_DylRz6ng

So 3" X 2" X 1.5" =4.987 ounces, which I would assume is at 59F / 15C

Add another 1/2" for thermal expansion and a 3X2X2 tank should work.

[John Kelly]

   ...Hey Bootlegger, I use 1.8 cu. in's per ounce. 5 ounces x 1.8 cu. in.'s = 9.0 cu. in's. 2" x 3" is 6... so X = 1.5 . I'd go 2 wide and 1 1/2 high...if it'll fit.  Cheers,  John

[Trostle]

There are two ways to approach this.

If you go metric, just figure that 29.4 cc of fuel will be approximately 1 ounce.

If you go English units,  figure that 1.80 cu in will hold 1 ounce.  

I have found it is easier when sizing a tank to measure in metric rather than working with fractions of an inch.  It is easier to calculate volume when I change a dimension a couple of mm than measuring in fractions of an inch.

When using the old Veco tanks, it was convenient to use their factors that when you had a wedge tank, 4" long, 2" wide, and 1" high, that it was "about" a 4 ounce tank.  A 5" long tank was "about" a 5 ounce tank.

Keith

[Randy Ryan]

Guy's I am wanting to build a 5 oz metal clunck tank and I need some refreshment on the dimentions, the length is limited to 3", so I am thinking about 2" vertical and "X" is the width...

        Thanks...

A fluid ounce is about 1.8 cubic inches which gives you a total of 9 cubic inches. so 3x2=6, 9/6=1.5". Proof; 3x2x1.5=9 Cubic Inches for a rectangular tank. It gets a bit more complex if its a wedge tank, you'll have to develop an end that is 3 square inches with the triangular section, it will get a bit taller depending on the angle you want.

[Perry Rose]

Yup, 3 x 2 x 2 will be plenty big.

[FLOYD CARTER]

Since I'm a fan of rectangular tanks, the calculation is simple.  Most commercial stunt tanks are 2" wide and 1" in height.  The "wedge" at the long end is mild, and can be accommodated by using half the width of the "wedge" for converting into a rectangle for calculation.  Those commercial tanks have length= volume in oz.

[Tim Wescott]

   ...Hey Bootlegger, I use 1.8 cu. in's per ounce.

Me, too.  And the tank always ends up a bit bigger or smaller than you planned, so design it a bit big.

[Clancy Arnold]

I like to make the tank as large as will fit in the space available.  You can short tank it when filling which is much easier than replacing the tank if it is too small.
Clancy

[Randy Ryan]

I like to make the tank as large as will fit in the space available.  You can short tank it when filling which is much easier than replacing the tank if it is too small.
Clancy

Me too, I've made tanks that extend between the bearers to get extra capacity. I just pinch the outside rear corner to a wedge and they seem to work fine.

[Clancy Arnold]

Here are pictures of a tank replacement I did in a Super Ringmaster from 2 Oz to 4 Oz.  
The new tank was required after an engine change from a Forster 29 to an OS 25 FSR.
The new tank is made from .005 In Bronze shim stock and is lighter than the original tank.
Clancy

[Paul Smith]

If want to use all the fuel and quit clean you need a taper and also the have the pickup outboard.

Volume = L x W X H.  If dimension a has a taper, use the average.   

Start out with the wood block a little oversize and grind it down to fit.
Plan B: If it's undersize, glue on sheet wood to build it up. 

[Bootlegger]

  Thanks Paul, that is a good idea, I pan to "kick" the rear out by 1/8" of an inch for the same reason..