Not really my specialty so I'm willing to be wrong and corrected, but I don't think the propane will evaporate as air pressure is applied? That would also be my thoughts. From my general understanding, the phase change is based on partial pressure, and the partial pressure of propane will be the sa...

I have 2 questions of any one who has the time, is there an ideal ratio for barrel volume to air reservoir volume? And the same goes for the vacuum accumulator. It depends how you define ideal, but the likely answer is no. Two possible ideals are: - A chamber volume where acceleration falls to zero...

foot/pounds are a measure of torque, not velocity. Possibly slightly late and off-topic to answer this, but what the heck. While this part is sort of correct, both torque and kinetic energy use units of foot-pound force, being a force multiplied by a distance. (So foot-pounds, not foot/pounds. They...

I must have missed that part. No, it'd be very strange for coaxial pneumatics to be able to use any type of breech loading (including break action).

Ah, of course, but if I flipped the cylinder round :shock: It would, but unless the rod is a fairly large part of the volume of the cylinder (which would be unusual), you wouldn't see massive advantages in the amount of air moved or the pressures reached. sorry but this is where i have to ask, what...

In response to your PMed question (if it's not a question I specifically need to answer, it's better kept to the main forum): Generally the pilot volume on a piston hybrid is vented by a "spool"-type piston with two sealing faces (one between the chamber and the barrel, and the other connecting the ...

I'm not entirely sure. It's possible it's a coaxial configuration.

now I am wondering if this would work, the reduced bore rod side would act as a precharge pump It won't. In a double-acting configuration like this, the first stage would need to have a higher volume than the second, else you're not increasing the pre-charge pressure in the second stage. Here, the ...

Generally, hybrids are considered to be something of an "if you have to ask, don't ask" affair. Anyone who hasn't got the experience to figure most of it out on their own is likely to overlook something when following a tutorial. If you have more specific questions about how certain aspects work, fe...

I'd probably suggest a simple blow-forward bolt, as it's fairly reliable and works well for spherical ammunition like that, although it does increase the dead-space between the valve and projectile. Blow-back loaders tend to need more fine-tuning, and a pneumatically operated bolt would be rather ov...

The QB78/9 have a really long barrel, I rarely see one so long in modern PCPs, maybe because they are designed for CO2? It's possibly a factor. CO2 is after all generally less powerful, given the lower pressures available. Anyway, I do think that a PCP is going to be able to make use of a longer ba...

Yes, I did get accused of being involved in the JFK assassination. The Mythbusters did, as I recall, try small airguns as a possible way of delivering poisoned pellets, but they didn't give the airguns a chance with the ice bullets. Mind you, their air cannons were seldom very impressive. I figure s...

wyz2285 wrote:So for a PCP there would be such a sweet spot too right?

There will be, but it's difficult to say where that is.

My gut feeling is that taking that much off the barrel of a PCP will cost you velocity - a back of the envelope guess would be around 10-15%.

Something I cooked up in response to a snowball machine gun video a friend shared on Facebook:
[youtube][/youtube]

Oh, I'm sure I could, but by my count I've already got enough unfinished projects to last two lifetimes.