Why I believe coaxials are opposite of what is best fps etc.
Posted: Fri Apr 09, 2010 11:08 am
by boyntonstu
In a coaxial, the chamber is large in diameter than the barrel.
Larger diameters are weaker than small diameters when it comes to chamber design.
The smaller the barrel/projectile the less the force on a projectile for a given pressure.
IOW A coax is working against itself design wise.
For example my Trom-Boyn uses 3/4" Copper type L for both the chamber and the barrel.
The barrel is 38" long and the chamber is effectively 17" in length.
If I changed the barrel to 1/2" Copper type L and used the same 600 psi pressure the force on a projectile would be reduced by ratio the squares of their diameters.
If you wish to throw away force, acceleration, and fps, build a coax.
It makes zero sense to build a cannon/rifle to me unless I MUST have the most compact design to fit a small space.
Posted: Fri Apr 09, 2010 11:24 am
by SpudBlaster15
Coaxial launchers were never designed to offer maximum performance; they were intended to provide a neat appearance and a high power to length ratio, which the coaxial design accomplishes quite effectively. Clearly, if you're looking for raw performance, an inline cannon design is best.
Posted: Fri Apr 09, 2010 11:26 am
by Bluetooth
It's not like you often max out the pressure of the pipe anyway. if you need more strength, use stronger pipe. Coaxials look sweet, are compact, and make it easy to implement a powerful diaphragm valve. It is ypur choice if you want to make a coax or not. I personally love them.
Posted: Fri Apr 09, 2010 11:30 am
by Crna Legija
im pretty sure coax are more powerful than barrel sealers because air come from all around the barrel than just the bottom
Posted: Fri Apr 09, 2010 12:28 pm
by Mr.Sandman
Well that may be true but no need to put coaxials down, they have feelings to you know. For one thing coaxials are easier to make, cost less, and can be easily made with epoxy and whatever you have on hand. So if you are a beginner and want to make a quick piston valve then coaxials are indeed whats best. Then again everyone has their own opinion of whats best.
Posted: Fri Apr 09, 2010 1:15 pm
by clemsonguy1125
I agree that tee valves are better if performance is what you want but you you can't make tee valve pen guns so both have pros and cons
Posted: Fri Apr 09, 2010 1:26 pm
by boyntonstu
-_- wrote:im pretty sure coax are more powerful than barrel sealers because air come from all around the barrel than just the bottom
I disagree.
The diameter of the barrel is the key to power, not how the compressed air feeds into it.
Posted: Fri Apr 09, 2010 1:31 pm
by Gippeto
Well, that's a can of worms split wide open.
If we're going to start throwing opinions around...
I believe that the co-axial configuration has some advantages other than "space saving".
Consider that drag increases as the square of velocity...now think about mass flow rate. The larger volume available at the valve in a co-ax should result in lower air velocities inside the chamber...reducing drag/wasted energy, and eliminating any formation of shock waves within the chamber itself (another big waste of energy). This I believe will net out higher velocities at the muzzle. The larger the chamber diameter at the valve for a given barrel id, the greater the effect.
Wonder about the benefits of mass flow rate? Check out Techs qdv builds...they take full advantage of it. It's not just a good valve.
Without side by side builds to quantify it...it's just a theory, but one with which I'm content.
As to co-axials being low fps pieces, my own personal experience says otherwise;
And I have to agree with Bluetooth...if you need a stronger tube...use one.
Posted: Fri Apr 09, 2010 1:41 pm
by POLAND_SPUD
I don't think you concentrate on the most important thing here... coax can't be breech loaded
Posted: Fri Apr 09, 2010 1:44 pm
by boyntonstu
Gippeto wrote:Well, that's a can of worms split wide open.
If we're going to start throwing opinions around...
I believe that the co-axial configuration has some advantages other than "space saving".
Consider that drag increases as the square of velocity...now think about mass flow rate. The larger volume available at the valve in a co-ax should result in lower air velocities inside the chamber...reducing drag/wasted energy, and eliminating any formation of shock waves within the chamber itself (another big waste of energy). This I believe will net out higher velocities at the muzzle. The larger the chamber diameter at the valve for a given barrel id, the greater the effect.
Wonder about the benefits of mass flow rate? Check out Techs qdv builds...they take full advantage of it. It's not just a good valve.
Without side by side builds to quantify it...it's just a theory, but one with which I'm content.
As to co-axials being low fps pieces, my own personal experience says otherwise;