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What's your Holy Grail of Spudguns?

A place to ask general spud cannon related questions.
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Unread postAuthor: DYI » Thu Jan 03, 2008 7:23 pm

@Rag: Who was the other person you were referring to in the plasma rifle comment? And why would HEAL not have supersonic capabilities with helium? With 30 bar helium supersonic muzzle velocities should be easily attainable with lighter ammo. And if they're not, then I just wasted $200 on parts for my BB gun...

I've always wanted to build massive launchers, but essentially, as they grow in size, they become less and less practical, and less fun to shoot because of horrendous reload times (and dealing with recoil :roll: )

@Spudmonster: although such a powerful launcher may seem good initially, it wouldn't be half as fun in reality unless you had a fully automated loading system, a multitude of targets, a massive, easily accesible firing range, and servants to prepare the ammo and burst disks.

I probably will attempt a 20 - 30x hybrid in the summer, but the size remains an issue. On further consideration, I may go for a smaller design that is extremely powerful for its size, while being relatively safe to fire in my yard. Of course, the ignition and fueling systems could certainly be adapted to a rather more massive launcher if a suitable target arose...
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Unread postAuthor: Hotwired » Thu Jan 03, 2008 8:03 pm

I'm sure you could count on the fingers of a blind butcher the number of people on this site that took the recoil of their large bore launchers sufficiently seriously before it broke something.

Still, we all learn by experience :)

Ah, all this grail talk is just daft.

My aim is to have a new cannon built this year. As unique as the last one.
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Unread postAuthor: Ragnarok » Thu Jan 03, 2008 8:51 pm

DYI wrote:@Rag: Who was the other person you were referring to in the plasma rifle comment? And why would HEAL not have supersonic capabilities with helium? With 30 bar helium supersonic muzzle velocities should be easily attainable with lighter ammo. And if they're not, then I just wasted $200 on parts for my BB gun...

I wrote the post, then realised I'd forgotten to talk about helium,and for the finale went about making a mess of re-writing it. I might be able to get supersonic with 30 bar air, but it's going to be hard. 30 bar helium would of course be a pushover to get over Mach 1 with.

There is only one person mad enough that they thought enough about building a plasma launcher that they asked about acquiring plans and assistance for a possible attempt. I think you know who that is.

I've always wanted to build massive launchers, but essentially, as they grow in size, they become less and less practical, and less fun to shoot because of horrendous reload times (and dealing with recoil)

I always wanted to go bigger when I first started, then my designs had to change to the resources I had, which was low bore copper, so that's what I'm now working with, and I'm perfectly happy with that. It's enough power to put holes through just about any target I can get my hands on without being too much I can't use it. And of course, I can shoot through the most humble of targets without it being boring - part of the fun of a moderately sized launcher (with a scope).

@Spudmonster: although such a powerful launcher may seem good initially, it wouldn't be half as fun in reality unless you had a fully automated loading system, a multitude of targets, a massive, easily accesible firing range, and servants to prepare the ammo and burst disks.

Which is why I try to keep my aims small in scale, but damned crazy - an airsoft minigun will be hugely fun, but I could use it almost any day. Just getting a cardboard to shoot at would be enough entertainment.

I probably will attempt a 20 - 30x hybrid in the summer, but the size remains an issue. On further consideration, I may go for a smaller design that is extremely powerful for its size, while being relatively safe to fire in my yard. Of course, the ignition and fueling systems could certainly be adapted to a rather more massive launcher if a suitable target arose...

Bloody Nora, that's going to take some serious containment. That's a lot of pressure to be handling. I wouldn't want to be around if any mishap should happen.

@Hotwired: And I'm probably the only person that has ever been concerned about recoil when there is little potential for it to cause any damage.
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Unread postAuthor: octane89 » Thu Jan 03, 2008 8:56 pm

If i could decide on my catridge fed,5 shot rifle or minigun project I think Id be fine for a while. But I haven't found a suitible idea for the minigun that I think is "legit" in a way.
However the cartridge fed cannon has been finalized and may start soon.
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Unread postAuthor: Ragnarok » Thu Jan 03, 2008 9:01 pm

Hotwired wrote:My aim is to have a new cannon built this year. As unique as the last one.

Actually, that would be a good one for me to try out. I seem to just keep modifying my old ones at the moment, not that there is any major problem with that.

*Gets out little red book... make new launcher this year*
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Unread postAuthor: Fnord » Thu Jan 03, 2008 10:17 pm

For an average hybrid launcher running on high mixes, all potential problems aside, it is a huge hassle to change burst disks, tighten the union sufficiently to form a seal, fuel, pressurize, fire, and repeat. My hybrid launcher manages 2 - 3 shots per day at most. These shots will on average span over a period of about 10 minutes.


*cough*piston*cough*
You could make a safe piston out of copper fittings, and copper is nice in that it doesn't crack like steel. Almost any piston valve will work as long as it can handle the pressure, and the piston itself uses o-rings.

With a bicycle pump, I can get a shot off every minute or so.
1. meter propane/inject, 5-10 secs
2. disconnect meter, hook up pump, fill, 15-20 secs
3. load ammo, 5 secs
4. charge igniter, fire, 10 sec
5. vent, ~15 secs

With a compressor and stungun, I could potentially cut that in half.



*Gets out little red book... make new launcher this year*


I'd personally like to see the combustion bbmg before the plasma rifle, but either of them would be a huge leap for the hobby. You would be famous on youtube also, but I'm not sure that's a good thing.
"lol thta gun is swet do u use harspray also cud u send me plans plz??? lol"


If I have a working welder over the summer I may try a hybrid vortex bbmg. It seems like such a simple concept I don't see how it couldn't work. And, if the power compares to an equivalent sized hybrid I might try cutting down a small tree with it (That sounds like something BTB would say!).
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Unread postAuthor: SpudBlaster15 » Fri Jan 04, 2008 12:25 am

The problem with piston valved hybrids is the difficulty of building a valve that opens near peak combustion pressure, then stays open for the entire duration of the projectile's travel down the barrel. If the valve opens significantly below the peak potential chamber pressure, the actual peak pressure will be much lower, meaning that unless the chamber to barrel ratio is perfectly optimized for energy efficiency, the average acceleration of the projectile will be lower.

When using burst disks, peak chamber pressure is much more easily controlled.
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Unread postAuthor: SpudMonster » Fri Jan 04, 2008 1:52 am

It would NOT be a piston valved hybrid. They are still far to experimental in my opinion, still too slow to open, and too damn complex. I'd be worried about possible valve seat erosion, and the fact that they force the gases to go through a series of turns, along with a nice amount of dead space is very unappealing to me. Besides, I wouldn't trust a piston to work with 2,000 to 2,500 PSI combustion pressures that occur in tenths, or even hundredths of a second. I'd either wind up machining a 3,000 PSI union to accept and seal burst discs (probably), or wind up building a completely new fitting to hold the discs (very unlikely).

As for the speed and reloading time, fork it. If it takes me 10 minutes to set up one shot I'll be happy. This isn't about rapidity, it's about raw, unearthly power and precision. Small cannons are nice, and I agree, a small hybrid running 20x-30x mixes would be very attractive. I'd love to have one. But I'd prefer something with serious long-range capability. That, and discovering whether or not a golf ball will survive hypersonic speeds.
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Unread postAuthor: MrCrowley » Fri Jan 04, 2008 2:17 am

3000psi rated cam-locks that could hold burst disks would be nice and convenient
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Unread postAuthor: jackssmirkingrevenge » Fri Jan 04, 2008 2:22 am

Hybrid cartridges would solve all the reloading issues plus would give enough impetus for a semi/full auto launcher.

Pneumatic burst disc cartridges would be even easier to charge and setup and still provide decent power at high pressure, if I had a machine shop at hand this would be a doable project.
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Unread postAuthor: SPG » Fri Jan 04, 2008 7:51 am

SpudBlaster15 wrote:The problem with piston valved hybrids is the difficulty of building a valve that opens near peak combustion pressure, then stays open for the entire duration of the projectile's travel down the barrel. If the valve opens significantly below the peak potential chamber pressure, the actual peak pressure will be much lower, meaning that unless the chamber to barrel ratio is perfectly optimized for energy efficiency, the average acceleration of the projectile will be lower.

When using burst disks, peak chamber pressure is much more easily controlled.


One word - damper.

See HERE for more details, it'd work perfectly on a piston hybrid. A variable rate damper will allow movement in one direction very quickly and will slow the movement in the other direction... just like a car's suspension in other words. Put one in behind the piston and voila...
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Unread postAuthor: ALIHISGREAT » Fri Jan 04, 2008 7:56 am

hmm holy grail... well for me it would have to be a realistic looking (looks like a gun) piston valved marble gun with awesome power that ran at ~400psi and used a super quick opening valve with a high flow and it would be able to hit a gypsys nose from 200yards 8)

so basically awesome power and accuracy :)
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Unread postAuthor: Hotwired » Fri Jan 04, 2008 7:58 am

@SPG: How quickly would that be? Oil flows rather less readily than gas :?
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Unread postAuthor: Ragnarok » Fri Jan 04, 2008 10:49 am

jackssmirkingrevenge wrote:If I had a machine shop at hand this would be a doable project.

Well, if I had machine shop at hand, just about anything would be an achievable project. I'm sure I could probably make people's jaws bounce off the floor - finally, with the capacity to make my mad ideas.

@_Fnord: I think they probably will come in that order. I don't have the resources to handle plasma cannons just yet (not that surprising), but the BBMG will still either need some machining, or some grade A improvisation on my part.
Expect them in this sort of order: HEAL mods, Gauss rifle, BBMG or preloaded cartridges, then plasma will probably be some significant time in the future.

Well, talking about youtube, I found a very important trick on Youtube to get more views for my old HEAL video, which sort of slowed down after 1000 views.
A couple of days back, I noticed potatoflinger's paintball sniper was a few thousand views ahead of me - although it was older, it was getting many more hits a day. Making an educated guess based on the comments left there, I just casually put the word paintballs into the side text, and lo and behold, my hits per day has been a good deal higher.
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Unread postAuthor: DYI » Fri Jan 04, 2008 11:18 am

@Spudmonster: Unfortunately, it is very unlikely that any conventional (i.e. non detonation) hybrid could achieve hypersonic (Mach 5+) muzzle velocities. The speed of sound in a post combustion hybrid chamber is about Mach 3. However, I don't know how the massively higher combustion pressures in a 30x hybrid would affect things. And you wouldn't need to machine a custom union, McMaster sells unions rated for 3000 psi in up to 4" sizes. And you wouldn't need a union any bigger than 2" for a golfball barrel.

I still don't really know if I will try a detonation gun. While the novelty would be nice, I suspect that the hypersonic capabilities would only be possible with very light projectiles, which would get carried along at the same speed as the shockwave. And for the amount the machining would cost to build it at a useable size, I could build an uber-powerful coilgun with Mach2+ injection speeds to achieve higher efficiency. (seriously, the cost of machining and parts for a decently sized detonation gun would be in the thousands :shock: )

@Rag: It seems like you have a lot of interesting projects on the go. I look forward to seeing the combustion BBMG, and the gauss gun, as well as your modified compressor. After a little research, I think I've figured out exactly how it will work.
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