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Hypersonic for ~$200?

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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Think it would work?

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No
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Total votes : 4
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Hypersonic for ~$200?

Unread postAuthor: SpudStuff » Mon Oct 30, 2006 12:36 am

I think i may have found a simple yet effective design that uses a 3000 PSI helium sorce in a SCH 160 Steel chamber with a 1" Rupture disk. The barrel would be 79 feet of 1/4" Sch 80 Pvc pipe. The entire assembally from McMaster minus the rupture disk and helium tank is ~$180, quite reasonable. GGDT estimated the speed at over 10000 FPS! I may have found a summer project!

Part #
8 x 48925K41
7 x 4881K711
1 x 43455K95
1 x 43455K163
1 x 7818K215
1 x 7818K211
1 x 7733K177
Simple yet effictive!
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Unread postAuthor: rna_duelers » Mon Oct 30, 2006 1:21 am

Ahhh 10,000fps but with what weight projectile?Werent you banned from these forums or were they nice and let you back?If you build this i would love to see it fire.Hint `cough' `cough'
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Unread postAuthor: SpudStuff » Mon Oct 30, 2006 1:35 am

Yes I was banned. But I don't want to talk about that. The 10000 FPS is with a 4 Gram teflon projectile. It probably will never get built but possibly...
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Unread postAuthor: SquishY » Mon Oct 30, 2006 2:54 am

One gram is equivilant(sp) to that of the powder in a sweetner packet like Sweet n Low or Splenda or what ever the fork it is that people think is better than real sugar.
Now, compact the ingrediants of four packets and blast it off.
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Unread postAuthor: Hotwired » Mon Oct 30, 2006 6:09 am

Well I see Sch40 pipe listed there.

If you can find a way of supporting 79' of pvc pipe then its worth a try.

Might be a good idea to not be too close to it on firing though.
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Unread postAuthor: joannaardway » Mon Oct 30, 2006 7:31 am

The words simple and effective don't seem to go with this.

It would be possible (with a little work) to get a golf ball up to Mach 1 with 7 feet of barrel and (only) 300 psi air (not helium).

That could be done for a little less than $200 equivalent, with UK materials, which are relatively more expensive.

Personally, I would consider the Mach 1 golf ball cooler. But if you want to go hypersonic, then do it.

A 1/4" chunk at 4 grams isn't a lot. You'd probably get higher speeds with a 3 gram ping-pong ball because of the larger cross sectional area and lower mass.

I would have guessed that you come damn close to liquifying the helium, hard though it may be, so just don't touch the thing afterwards, because you may well freeze your hand off.
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Unread postAuthor: Recruit » Mon Oct 30, 2006 7:55 am

The ping pong ball would be flattened if you shot it at Mach1.
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Unread postAuthor: CS » Mon Oct 30, 2006 9:59 am

As joannaardway, and others have exploited, such a gun would not infact be 'simple' and 'effective.

Although such has no dealings with these forums, and discussion of such is acutally prohibited, but a solid propellant based system would be much cheaper, and smaller for use in acclerating a small projectiles past Mach1.

79' of barrel is ridiculous. I mean if I were you I would rather spend my money, resources, and time on a fast opening piston valve(s) pneumatic using compressed air, or another foreign gas. Such could project a GB. In every aspect such a cannon would be satisfactory. Id reconsider.
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Unread postAuthor: joannaardway » Mon Oct 30, 2006 3:18 pm

Recruit, People have put ping pong balls past the sound barrier.

Maybe not to Mach 10, but certainly past Mach 1.
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Unread postAuthor: boilingleadbath » Mon Oct 30, 2006 5:48 pm

The speed of sound in helium is about 2.8 times that of air... so I'm severly doubting the GGDT's prediction regarding this proposed mach 10 (mach 3.5 in He) golfball.
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Unread postAuthor: joannaardway » Tue Oct 31, 2006 6:38 am

I never said that the golfball would reach Mach 10. I said a fraction over Mach 1, which is achievable with standard air.

I would believe it totally do-able...
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Unread postAuthor: SquishY » Tue Oct 31, 2006 6:52 am

Do it, Joann. BUT if you do you'd better post damage pics 'cuz it would be just completely incredible.
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Unread postAuthor: joannaardway » Tue Oct 31, 2006 7:22 am

I plan to try the golf ball cannon. (Currently it's project name GBH - golf ball howizter)

The damage should be fun. The golf ball should have a minimum of about 2750J of energy (2040 ft lbs) which would punch holes through well - some pretty tough stuff.

It'll need to wait for me to find a space to keep it, because I can't obviously think of a spot to store it. I also need to consider the horrendous noise it'll make.

Oh yeah, and I need to find the budget amongst all of my other plans.

Watch this space. (Well, not this space specifically, but you know what I mean)
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Unread postAuthor: boilingleadbath » Tue Oct 31, 2006 2:51 pm

Damn, did I say golfball?

Typo!

I ment spudshot's proposed 4 gram whatever.
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Unread postAuthor: joannaardway » Tue Oct 31, 2006 3:39 pm

If that's what you meant:

I suspect even GGDT gets inaccurate when you get to that kind of speed, if only because the .25 ms time interval becomes rather a long time (and distance) to a projectile that fast.
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