I'm making a maap gas powered cannon that will shoot 2.6" 12 oz. projectiles (soda cans) . I'm trying to figure out the optimal, most efficient barrel length. Do you know how I could figure that out? Also, I'm wondering what the optimal barrel diameter to chamber diameter ratio is. I could only fin...

Have a look at hectmarr's projects, he has done a lot of valuable work in this field.

Get SCH 40 2 inch barrel (36 to 48 inches), 2 to 1-1/2 threaded bushing, a 2 inch coupling and some of these for a fun time. Check at your local dollar stores for best prices! Digging this up to say that this was user dewey-1's last post on this forum, ten years ago today. I believe he passed away ...

It's been over a decade since I first made this project and almost as long since I dabbled in hybrids so here is a recent project along the same lines: 20231108_233649.jpg Nothing particularly special about the design, chamber volume is around 34cc and it's currently fitted with a 490mm long 6mm bar...

One of the experiments I've done with this project to to see how burst disk strength influences performance. Intuitively one would tend to think that the stronger the disk, the higher the pressure it will burst at and therefore the better the performance will be; this might be true of a pneumatic bu...

As mentioned earlier what was presented as the Mini Hybrid II is actually a component of a wider project that I will attempt to detail here. I would first of all like to thank hectmarr with whom this project was a collaboration and without whose input would not have happened. Here is an animation sh...

I made a 0.177" barrel attachment for this thing, at a 20x mix it was pushing 0.35 gram BBs to just over 1800 feet per second :D that's 39 ft lbs of energy! https://www.youtube.com/watch?v=23-DWhJ0-MA The same barrel hooked up directly to the air cartridge at 2500 psi yielded 1143 fps, still impress...

Excellent post!!! You can see all the experimental work with a single glance!!! Thank -you- for this great collaboration :) There is room to investigate different fuels but one thing to take into account when making comparisons is the relative size of the cylinder that is a critical parameter in th...

I had doused it with oil several times to prevent wear, and made sure there were no sharp edges on the ports, but apparently that is not enough. The other draw back was the higher the chamber pressure, the harder it became to open at the o-rings are pushed into the cylinder walls increasing frictio...

An interesting question and I thought worth investigating, so I made the following modifications to the Mini Hybrid II : Blunt endcap insert: 20231123_211452.jpg Insert bore tapered: 20231123_214925.jpg I fired two shots each with both endcap variations, for each shot I used a 63cm long 0.177" barre...

Rheinmetall's Fly-K mortar operates on the same spigot mortar principle as much earlier weapons like the PIAT however it marries the idea with the captive piston principle to provide a relatively quiet shot: http://pds15.egloos.com/pds/200906/16/96/c0066396_4a3797df875d5.jpg With some imagination I ...

Something relevant to the original post, an animation I had made of the Russian 2B25 "silent" mortar that works on a principle similar to the Fly-K

This 1400 has languished in my parts bin for some years now, I'm wondering if it could be a candidate for a much more radical project. Here is roughly the concept I have in mind: https://i.imgur.com/farDIxq.gif The "blow open" idea and trigger are preserved, but the chamber and valve are moved in li...

It looks good and I think it's an interesting adaptation. I'm not sure how a sliding breech works... Think of it like the Huben K1 whose magazine feed functions on a similar principle: https://i.imgur.com/ufIaLpr.gif The projectile is placed inline with the valve and the barrel for minimum loss and...

Am I off my mark? The way I understand it, in a pneumatic the pressure is more or less constant while in a hybrid it's a brief spike. If we have a disk on a chamber that bursts at 1000 psi, then by filling that chamber until the disk bursts there will be 1000 psi of air to push the projectile. With...