Somehow I missed this thread until now. Nicely done!

If you want to jump through all those hoops with so many burst disks... Just go with a two stage design and use methane both as your primary fuel and as your second stage gas. Granted, hydrogen or helium would be better, but methane is still prettttty damned good and it's available in any house that...

Most of the danger will come from the construction of the Spud Gun, not the use, PVC being what it is, will be the main cause of failures, usually explosive. PVC is not air pressure rated. Adding to that.... And "putting too much fuel" into a spud gun generally results in a misfire. No bang at all....

This is the first photograph ever taken by the US NAvy using a FLIR: https://i.imgur.com/ePBTDxs.jpg And near as I can tell, it was taken from this location facing West: https://www.google.com/maps/@35.678051,-117.612751,256m/data=!3m1!1e3?entry=ttu&g_ep=EgoyMDI1MDMwMy4wIKXMDSoASAFQAw%3D%3D Obscure ...

I've seen people using them to throw pilot lines for rope handling. They seem to work well at that. I've used them to function check blast pressure gauges. I wasn't involved but I'm aware of them being used to simulate water spray when submarine launched missiles clear the water. That's three "non t...

It's not the money. It's the fact that it's something that needs doing. It would be something that once I was happy with it, I would release into the wild and probably never touch again; thus my concern for anything that requires ANY sort of upkeep. I haven't built a spud gun in a looong time. I sti...

Free web hosting or not is irrelevant. The money is a complete non-issue. The catch is that this is likely my last forray into spud guns. I'll likely write the new tool, put it out there for the community to do whatever it sees fit with it, and not really think about spud guns again. Having a web pr...

But now someone is on the hook for maintaining the web presence, no?

Yes, I actually looked at doing it in Python a couple years ago. The biggest issue was that Python is generally not compiled and you have to install the IDE for it. Well, that's all well and good except that only geeks actually have done so. Meanwhile, pretty much everyone and their brother has a sp...

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...

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...

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...

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...

Hint: Side 7 has the title "Typical FI Laboratory Gun Sabot" and photographs of 2 different sabot designs.

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...