Hybrid velocity

Harness the power of precision mixtures of pressurized flammable vapor. Safety first! These are advanced potato guns - not for the beginner.
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D_Hall
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Sat Mar 30, 2024 3:45 pm

Pennywise wrote:
Sat Mar 30, 2024 2:37 pm
Very interesting. At those velocities, does the sabot shatter on exit?
I would be lying if I said I haven't been thinking of ways to pack a 2 stage gun into a rifle-esque design.
Well, they're multi-piece designs that are literally held together by the bore of the gun. The moment they're clear of the bore they fly apart due to aerodynamic forces. It's also pretty bad ass because at those velocities they're burning just due to the extreme temperatures on the backside of the shock wave. The point being that in high speed photography they appear as balls of fire spreading from the muzzle like some psycho roman candle.

As for 2 stage designs, the biggest issue is that the piston in your pump stage will be single use and will extrude itself at least part way down the barrel. Very cool toys, but reloading them.... Well, that depends on the size of the gun. The smallest 2-stage I've seen took about an hour or two to reload. The largest I've seen took as much as a month to reload. That said, if you're making one small enough to be shoulder fired, it would be smaller than the smallest I've previously seen so maybe there's a way to make it work well?
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Sat Mar 30, 2024 4:16 pm

Yeah I noticed the multi-piece design, I was just wondering if the air hitting it broadside at ~6000mph would vaporize it. Though thinking if it now, if it can withstand the gforces of the initial shot, that should have been obvious.

I've been working through a design that wouldn't necessitate a sacrificial piston. It would have considerably less power than a mounted large design, but my goals are typically 'get this thing going as fast as possible', preferably without losing any kind of practicality.

I'm thinking of a design using a small piston-hybrid (to avoid burst discs in this region(powered by H/O)), which would propel another very light piston down a relavitvely long length of tube (filled with H) to a mating surface, at the center of which is a transfer port the same diameter as the barrel. The hybrid discussed in this original post uses ammunition with a burst disc built into it, so I'd probably use a similar design for this idea as well. (Or just another piston design for the final pressure release as well).

This design would require tweaking both the 'burst' pressure of first the piston-hybrid (to achieve maximum pressure built prior to release, and then the actual burst disc ammunition. Unfortunately, this means the design would need to be built for one specific mix rather than be adjustable. That's the trade-off for quick action, o suppose.

Would a design eliminating the chamber-taper still work? Or does the Lab-designed gun work because of the leverage of pressure pushing on the larger surface at the rear of the piston to compress the gas in front of the smaller side?
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Sat Mar 30, 2024 11:10 pm

Well, the biggest issue is "How do you STOP the piston in the pump stage?" If you're soft stopping it, that implies your piston velocities aren't very high which in turn implies that your pressures aren't very high which in turn means your velocities won't be very high which in turn begs the question of why bother with a 2-stage design? Unless, of course, you've got some wicked special/cute/unique/etc. to stop the piston.
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quinn whitsitt
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Sun Mar 31, 2024 5:01 pm

okay I will as soon as I get a alt account that's not on my school Chromebook trust me it is pretty hard to post images on a school chromebook so I will as soon as I get a computer of my own which might if I am lucky happen in 1 week to 2 weeks
quinn whitsitt
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Mon Apr 01, 2024 1:37 pm

i will a soon as i get a pc that can put photos on here since i am running on a old school chromebook
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Wed Apr 10, 2024 8:07 am

once I get my own PC I will since I am running on school chromebook
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