SpudFiles

Ragnarok wrote:

farcticox1 wrote: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 first stage actually has a *lower* volume, so it's doing nothing useful. It just means the pump is drawing in most* of its air on the compression stroke rather than the return stroke, but I don't see any benefit to doing so.

*As the internal volume of the cylinder actually increases as the rod slides out, it would actually still need to draw in some air on the return stroke.

Ah, of course, but if I flipped the cylinder round

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

sorry but this is where i have to ask, what actually is a coaxial config and how it Works..?

farcticox1 wrote:Ah, of course, but if I flipped the cylinder round

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.

Jude wrote:sorry but this is where i have to ask, what actually is a coaxial config and how it Works..?

Coaxial configurations are those where the chamber is around the outside of the barrel. In terms of how they work, they generally use what is effectively a barrel sealing piston valve (although they have occasionally been seen with things like QDVs instead).

It's a quite compact layout, but it tends mean less chamber volume, usually means you can't breechload* (although some people have gone out of their way to disprove this), and occasionally have problems like like aligning the barrel inside the chamber and making sure that muzzle loading doesn't accidentally push the projectile into the valve. (Although, to be fair, barrel loaders can have different problems).

* Which means I personally take issue with their safety. No breech-loading means either means pressurising a loaded cannon, or trying to muzzle load a pressurised cannon. (Both of which are more dangerous than loading the projectile only at the last step, while you're safely not anywhere in front of the muzzle).
However, many people would consider me overly paranoid about that, but I'd rather that I not be responsible for any news articles that include any permutation of the words "died of potato inflicted head trauma".

Thanks for the information, I've seen coaxial all over the forum but couldnt find this info.

Muzzle loading a pressurised system seems nowhere near safe.. but the one in the youtube video i earlier posted looks like it can be modified for a breech load.
To be sure, can we say the break barrel air rifles are also coaxial..?

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).