Sat Aug 08, 2020 1:59 pm
A streamlined projectile could be interesting. I think the mass would have to be relatively low and use a sabot, like a dart or something. Could possibly go supersonic with some effort. It would be interesting to see how much pressure is needed to push past the sound barrier with a golf ball. I know the 10X hybrids are supersonic. I wonder if 5 or 6x would get there. I'd want an alloy steel cannon for any more pressure, even though the aluminum should be fine for 5 or 6x. It's beyond my comfort zone given my face is directly behind the backplate when firing. Gotta keep that safety factor high enough for my balls to drop so I can have the nerve to actually use the thing and have fun with it.
In my opinion, such a power class as anything around 10x starts to pull away from what a spudgun is in nature. You can't reliably fire fruits, vegetables and soda cans from something that powerful. They just vaporize or break apart. Something like that starts to bridge the gap between the spudgun and the black-powder cannon. If I wanted that much power I'd likely just start researching black-powder cannons. They can be made and used legally if done right. It would be more powerful than any spudgun, easier to make, much easier to use, and probably cheaper as well, lol.
I saw a youtube video of a guy who made one out of nothing more than an ugly piece of pipe and remote fired it. He got 1700fps from a goofball, lol. Probably cost him $20.00 haha. That's too easy and not for me though. Hell, I got a 12ga shotgun that I can go shoot slugs from any time I want. I'm all about the spudgun.
I feel that based on my experience shooting between 2 to 4x with different sized cannons, that 2 to 4x is the place to be for maximal power from a spudgun at any given size without destroying the potato. The design I'm toying with for a future build is a larger cannon but still operates up to 4X max. The greater chamber volume and longer barrel is needed to get the spud going at a greater speed without destroying it. It's the same principle behind why pumpkin cannons are very low pressure with MASSIVELY long barels and gigantic air chambers. Maximize the pressure the projectile can withstand and the performance is then governed simply by the size of the cannon.
For instance, with my larger hybrid, potatoes go 730fps at 2x, but at 3x they come apart, even with a very conservative burst disc. Sometimes even at 2X they break apart in that cannon. With my new, medium-sized cannon using the tennis ball barrel, giant potatoes stay together at 3x but break up at 4x. Using the small barrel potatoes stay together pretty well at 3x although I haven't tried a small spud at 4x. So it depends on the specific design characteristics of the cannon, such as port and barrel size, opening pressure etc. But the general limit seems to be around 4X for spudgunning based on my experience.