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Getting the projectile to go further

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: Recruit » Fri Jan 19, 2007 7:18 am

BL4K_}-{4WK wrote:i saw a video of a guy wit a launcher that was made to perfect specs and was running it on oxy/accedilene n it wne toff wit a big bang, what he did was get the oxy goin to the right mix of O/A the he would put it out n then open up his gun n put that mixture n the chamber, this gives a perfect mixture n accedilene is extremely flammeable so. knock yoursef out.


P.S DO NOT USE WITH PVC!!!


Please dont do this if you want to live.
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Unread postAuthor: CpTn_lAw » Fri Jan 19, 2007 7:43 am

a mini pneumatic pumped up to 20 bars with .177 lead pellets shoots at about 550 fps...it is very silent (use a ball valve...) for perfect fit with .177 projectiles, you can use 14/16 aluminium arrows.
Can someone here explain to me why a 3 bars combustion is louder than a 20 bars pneumatic (of the same size) ?
I've never understood why a combustion is louder...
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Unread postAuthor: Pete Zaria » Fri Jan 19, 2007 1:36 pm

CpTn_lAw wrote:Can someone here explain to me why a 3 bars combustion is louder than a 20 bars pneumatic (of the same size) ?
I've never understood why a combustion is louder...


This is just an educated guess but I'd think....

In a combustion, when you pull the "trigger" and create a spark, you're igniting a pretty accurate fuel/air mixture. This mixture has to combust, turning certain gases into other gases, producing byproducts and exhaust. It's a very inefficient process, and two big byproducts of this combustion are heat and noise. This is because not all of the energy can be used in the form of gases expanding and creating pressure (which is useful for launching spuds), so some of that excess energy escapes as heat and noise.
Basically, I think the answer is, because of the combusting, expanding hot gases, and inefficient combustion process, a lot of noise is produced that isn't produced by simply letting lots of compressed air out of a tank - like in a pneumatic.

BLB, confirm or rip apart my idea please? :D

Peace,
Pete Zaria.
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Unread postAuthor: th3p0p0 » Sun Jan 21, 2007 4:14 pm

use .12 bbs thay sell at wall mart for $3.95. for 2000 thay give you more power and range
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Unread postAuthor: FiveseveN » Sun Jan 21, 2007 6:35 pm

BLB, confirm or rip apart my idea please?


While BLB is on vacation, can I have a go?
Sound is a consequence of pressure (or, rather, the dynamics of pressure over time) and heat is aftually desirable, as more heat=more pressure.

The deflagration happens a lot faster than the opening of a ball valve, so a more concentrated "wall" of pressure (shockwave, if you must) is created. Higher SPL=higher percieved volume. A high-pressure pneumatic with a good valve (like a paintball marker) makes a louder "pop" than a cannon using the same pressure, but releasing it through a ball valve.
Materials also play some part. That's half of the noise. The other half is generated when the projectile leaves the barrel. This has been discussed in threads regarding silencers. Different projectiles, barrels and muzzles will create different levels of noise.
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Unread postAuthor: Zimdale » Sun Jan 21, 2007 10:27 pm

haha well ya did better them me. I just tried to make one few hours ago and the bb went maybe 1-2 feet. Only when it would fire which was not often.
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