Search found 1914 matches
- Sat Apr 13, 2024 1:39 am
- Forum: Pneumatic Cannons
- Topic: Couple quick Noobie Questions and advice.
- Replies: 4
- Views: 784
Re: Couple quick Noobie Questions and advice.
1) Any general thoughts or concerns to the overall design? Probably charge it to 100psi max. Always remember that PVC is prone to cracking if mistreated. In other words, while a PVC barrel can be done, the larger it is the more cognizant you have to be about its treatment. Be nice to it lest it gren...
- Sat Mar 30, 2024 11:10 pm
- Forum: Hybrid Cannons
- Topic: Hybrid velocity
- Replies: 20
- Views: 3017
Re: Hybrid velocity
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 questio...
- Sat Mar 30, 2024 3:45 pm
- Forum: Hybrid Cannons
- Topic: Hybrid velocity
- Replies: 20
- Views: 3017
Re: Hybrid velocity
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 t...
- Thu Mar 28, 2024 6:54 pm
- Forum: Hybrid Cannons
- Topic: Hybrid velocity
- Replies: 20
- Views: 3017
Re: Hybrid velocity
Hint: Side 7 has the title "Typical FI Laboratory Gun Sabot" and photographs of 2 different sabot designs.
- Thu Mar 28, 2024 12:17 am
- Forum: Hybrid Cannons
- Topic: Hybrid velocity
- Replies: 20
- Views: 3017
Re: Hybrid velocity
Yes, H and O are great. That's why you see 'em used in rockets. For bonus points, run it just a bit fuel rich and you get even lower molecular weight without much loss in temperature. And yes, that's why rockets run such. The same physics apply! That said, running H/O in a gun at anything that resem...
- Tue Mar 26, 2024 9:04 pm
- Forum: Hybrid Cannons
- Topic: Hybrid velocity
- Replies: 20
- Views: 3017
Re: Hybrid velocity
What are methods of passing beyond the local SOS? The previously mentioned exploitation of Maxwell-Boltzmann distributions. Highly inefficient and has it's own limitations. Not useful for much more than braggin' rights. I imagine things like raising temperature beyond that of standard combustion or...
- Sun Mar 24, 2024 7:43 pm
- Forum: Hybrid Cannons
- Topic: Hybrid velocity
- Replies: 20
- Views: 3017
Re: Hybrid velocity
A few thoughts in no particular order.... 1 - Post-combustion chemistry absolutely matters. It can drastically alter the local sonic velocity. 2 - Traditional powder-based guns can go much faster than OP's listed 5200 ft/s. I've personal experience with a gun that runs at 8,900 ft/s. 3 - I'm a bit b...
- Sun Jan 28, 2024 2:00 pm
- Forum: SpudFiles Discussion
- Topic: GGDT and HGDT
- Replies: 22
- Views: 35006
Re: GGDT and HGDT
Jack got it right.
- Sun Jan 21, 2024 7:26 pm
- Forum: SpudFiles Discussion
- Topic: GGDT and HGDT
- Replies: 22
- Views: 35006
Re: GGDT and HGDT
I didn't keep anything, but if you've a specific question I'm likely to be able to answer it.
- Sun Jan 14, 2024 2:03 pm
- Forum: Pneumatic Cannons
- Topic: Where to download GGDT
- Replies: 3
- Views: 8242
Re: Where to download GGDT
I don't remember where it's stashed, but it's actually on this site somewhere....
- Thu Jan 11, 2024 7:11 pm
- Forum: Off-Topic Hobbies
- Topic: My current hobby: Cowboy Action Shooting
- Replies: 24
- Views: 98042
Re: My current hobby: Cowboy Action Shooting
And as a minor brag, I set a new personal best last weekend....
...Still not going to win any championships, but I felt really good about that run.
...Still not going to win any championships, but I felt really good about that run.
- Sun Dec 17, 2023 6:09 pm
- Forum: Combustion Cannons
- Topic: Potato cannon not igniting
- Replies: 3
- Views: 7435
Re: Potato cannon not igniting
As hinted at in the previous post.... The most likely cause is incorrect fuel/air ratio. Unfortunately, this is not an easy thing to measure with a "spray and pray" potato gun. First things first? Ditch the hair spray (that is an affront to the potato gun gods!), and find a way to MEASURE how much b...
- Mon Dec 11, 2023 9:29 pm
- Forum: Combustion Cannons
- Topic: HGDT Guide
- Replies: 5
- Views: 4442
Re: HGDT Guide
Correct. I am NOT going to loop in PEP or any similar combustion codes!jackssmirkingrevenge wrote: ↑Wed Nov 29, 2023 3:29 pmI believe a stoichiometric mix ratio is assumed depending on the chosen fuel.
- Fri Dec 08, 2023 12:31 am
- Forum: Hybrid Cannons
- Topic: Hybrid disk burst pressure effect on performance
- Replies: 23
- Views: 34564
Re: Hybrid disk burst pressure effect on performance
That's enough experimentation for this session but I would also like to try cutting down the baffle to make the "second chamber" smaller to see if that makes a difference, I wonder if it will increase or reduce peak pressure at the disk. If my gut is right, making the baffle shorter (increasing vol...
- Fri Dec 08, 2023 12:28 am
- Forum: Hybrid Cannons
- Topic: Hybrid disk burst pressure effect on performance
- Replies: 23
- Views: 34564
Re: Hybrid disk burst pressure effect on performance
A mesh screen would kick up turbulence but also suck up a lot of heat. We have discussed before if running the chamber fan during firing might increase the burn speed. Way back when I measured burn speed in a closed chamber at 1x with/without the fan running and with one or three sparks gaps. There...