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mcheesey · Mon May 15, 2006 5:36 pm

is there any equation i should use to find how big to make my chamber and barrel?

zvallance1 · Mon May 15, 2006 5:46 pm

the equation i like to use is called the seaerch button.
search bar + you = answers galore.

however, you'll want a 1.5:1 CB ratio if you're using a pnuematic, and a .8:1 CB ratio with a combustion.

use the volume formula to determine the volume of both your chamber and your barrel, and adjust each accordingly to match the ration best suited for your gun.

mcheesey · Mon May 15, 2006 5:52 pm

but what does that mean?

zvallance1 · Mon May 15, 2006 6:00 pm

what does WHAT mean?
...if you took middle school math you'll know the volume formula...just plug in the dimensions of your pipe...

unless that wasnt what you dont get...
please reply with something more than 5 one-syllable words...

sgort87 · Mon May 15, 2006 7:52 pm

\Generally the bigger the Chamber:Barrel ratio, the better for a SET barrel length (combustions unfortunately actually lose power after a point).

It is said to use AT LEAST 1.5:1 for pneumatics or you will lose a significant ammount of power. Many people argue to use 2:1.

For propane combustions we use .6-.8:1 for the best results.

For aerosol combustions it is said to be 1.5:1 but I really have my doubts on that one. I am certain that it really depends form one aerosol type to the next. No official tests have been done to prove anything to my knowledge.

mcheesey · Mon May 15, 2006 8:12 pm

if im goin by the 1.5:1 ratio and my chamber was 3in my barrel would be 2ins? how do i find the right length? or does it not matter?

mcheesey · Tue May 16, 2006 3:14 pm

can someone help me i need to kno this for building my cannon

Pete Zaria · Tue May 16, 2006 3:33 pm

What size (diameter, not length) pipe do you intend to use for the chamber, and what size for the barrel?

When people talk about 1.5:1 or .8:1 ratio, they're talking about VOLUME, not LENGTH.

For instance, the volume of a chamber made from 4" pipe, 12" long would be roughly (my math is a bit rusty, been out of school for too long) 143.4 cubic inches. So, if you wanted a 1.5:1 chamber-to-barrel ratio using this chamber, you'd want your barrel to be 95.6 CI.

Boilingleadbath, is this correct?

Here's a handy tool I found for calculating the volume of pipe. You can do it with a calculator in a few seconds, of course, but if you're crunching a lot of numbers this is a bit quicker.
http://www.online-calculators.co.uk/vol ... volume.php

Peace,
Pete Zaria.

sgort87 · Wed May 17, 2006 12:53 am

Actually his chamber volume would be 150 cubic inches. His barrel would then need to be 100 CI for the best performance. (according to the "1.5:1 Law") BLB wasn't the only one who passed Grade-School Math.

Don't just "go with" the 1.5:1 ratio. What type of fuel are you using for this? Or is it pneumatic?

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