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Sound barrier

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Can you sent something supersonic with ONLY compressed air?

Yes! Ive done it!
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I havent done it, but I think its possible...
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I have absolutely no clue
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I dont think so...
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Total votes : 14
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Sound barrier

Unread postAuthor: Tidbit77 » Wed Dec 03, 2008 4:08 pm

How many of you have sent something supersonic out of a pneumatic spudgun using only compressed AIR? If you think its not possible, or if you do... I want to hear your opinons.
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"i wonder if i can do that a little lowe- oh apparently no"

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Unread postAuthor: Brian the brain » Wed Dec 03, 2008 4:35 pm

Can't be too many people.
I've heard of two claims, I believe.

There have been numerous discussions about this, and therefor I don't think you'll get a lot of response.
It gets kinda old...and discussing the subject some more doesn't really get us anywhere.

build one, and you will get a lot of response....not now...
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Unread postAuthor: rp181 » Wed Dec 03, 2008 4:44 pm

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Last edited by rp181 on Wed Dec 03, 2008 5:54 pm, edited 1 time in total.
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Unread postAuthor: Ragnarok » Wed Dec 03, 2008 4:53 pm

It's entirely possible - it has been done (As rp181 has linked, the Airforce Condor rifle manages it), and the effect can be explained, mostly by shock heating.

However, it's a real challenge, requiring favourable conditions, so I personally automatically question it. I know GGDT gives supersonic results reasonably easily, but it's not that easy in real life.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: Tidbit77 » Wed Dec 03, 2008 5:02 pm

i am currently working on a (hopefully) supersonic spudgun. It has a 10' long tennis ball barrel (2.5") and two 4"x 5' air tanks, the valve is a SGTC supah+ valve (this is my 1st gun, so i didnt want to build my own piston), and the SGTC muzzel velocity calculator estimated it at 1400 fps with a tennis ball (tanks at 120 psi)
thanks for all the info
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Unread postAuthor: twizi » Wed Dec 03, 2008 5:13 pm

wow big cannon
should be very cool shoot it at a tile see what happens :twisted: :twisted: :D
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Unread postAuthor: Brian the brain » Wed Dec 03, 2008 5:15 pm

Look up S.W.A.T. cannon and watch your hopes fade...


Only shock heating will do it, that or swithing to helium, but that wasn't your question.
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Unread postAuthor: Tidbit77 » Wed Dec 03, 2008 5:15 pm

thanks...I cant wait till the weather warms up (im in ohio) so I can shoot it
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"i wonder if i can do that a little lowe- oh apparently no"

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My last words: "Ooooo! what does that do!?!?"
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Unread postAuthor: MrCrowley » Wed Dec 03, 2008 5:18 pm

Tidbit77 wrote:i am currently working on a (hopefully) supersonic spudgun. It has a 10' long tennis ball barrel (2.5") and two 4"x 5' air tanks, the valve is a SGTC supah+ valve (this is my 1st gun, so i didnt want to build my own piston), and the SGTC muzzel velocity calculator estimated it at 1400 fps with a tennis ball (tanks at 120 psi)
thanks for all the info


I got closer to 800ft/s with GGDT.

I don't see a tennis ball going supersonic with only 1 x 2.5" piston valve and 120psi. I'd imagine it'd be quite a challenge to send a tennis ball the speed of sound using air and a barrel only 10' long.

BTW, I don't think the second 4"x5' tank is required. Just one will give similar performance and save you a lot of hassle with filling it with compressed air.
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Unread postAuthor: twizi » Wed Dec 03, 2008 5:22 pm

i agree with mr c it would have to be at 270 psi that would take along time to pump up but it is possibole at the right psi :)

recomendation tie a bag to the front of the barrel then vaccum the barrel out so no air is in there :D
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Unread postAuthor: MrCrowley » Wed Dec 03, 2008 5:26 pm

270psi still falls short, just. I was very generous with my parameter variables too. BTW, if you have just the one chamber, you lose about 15ft/s. I really don't think it's worth it, unless you have a 20ft barrel.

Even if you did get it to 270psi like twizi said, you wouldn't be able to use PVC or Joel's Piston Valve. Even if it was all made of steel, I have my doubts it'd break the sound barrier at that pressure.
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Unread postAuthor: twizi » Wed Dec 03, 2008 5:30 pm

but u could put a 15 foot 1/2 barrel and stick in a musket ball that would be gonin very very fast :twisted: about how fast mr. c
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Unread postAuthor: Tidbit77 » Wed Dec 03, 2008 5:32 pm

Im probably gonna make a 10 foot golfball barrel too
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"i wonder if i can do that a little lowe- oh apparently no"

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Unread postAuthor: twizi » Wed Dec 03, 2008 5:34 pm

a cheap gb barel is 1 1/2 thin wall pvc have tons in backyard 20 feet
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Unread postAuthor: Brian the brain » Wed Dec 03, 2008 5:34 pm

Slower than a tennis ball.
More mass compared to the surface area.

Lots more.


Forget going supersonic with a pvc aircannon.

Subsonic velocities can do a lot of damage anyways...
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