The firing mechanism worked perfectly and it didn't explode, but the rifling is so worn that it was keyholing like crazy, the bullets weren't stabilizing at all. I'll probably re-barrel it at some point. You may be able to fix this with different loads. Suffice to say.... I have an 1895 Mauser (7mm...

The 0.8:1 ratio comes from burntlatke's testing where chamber volume was held constant and barrel volume was changed, which effectively found the longest barrel length that could efficiently use a certain chamber size.. It is worth noting, however, that latke was using potatoes for projectiles and ...

Late to the thread here (and I've only read the first post) but one of the things I've seen with VERA is that the burst pressure doesn't really make much difference (at least, not on her). Why? Simple, really... Once the disk bursts and the gases start to move, everything becomes very turbulent. Wit...

My gut says we're on to something.... You need something to induce turbulence!

Late to the thread here (and I've only read the first post) but one of the things I've seen with VERA is that the burst pressure doesn't really make much difference (at least, not on her). Why? Simple, really... Once the disk bursts and the gases start to move, everything becomes very turbulent. Wi...

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...

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...

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.

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...

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...

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...

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...

Not really a question but some commentary.... Obviously, it's been a very long time since I wrote GGDT/HGDT. I've learned a lot since then and I think I could do a better job. I've spent a lot of time thinking about things. If I rewrote them, how would I do it? Well, first and foremost I would creat...