SpudFiles

A few days ago some one was asking about a combustion with a breach loading feature. I was thinking about it and since a combustion requires a burst disk, a breach load is kinda of useless if your using loose fitting ammunition. So I was thinking of this, if you could find the max pressure the gun would make and then have a sprinkler valve piloted by a regulator set to that pressure you could essentially have a high ROF combustions. What do you think?

i don't know about you but my combustion doesn't require a burst disk

Ok, let me rephrase that, a combustion that uses propane or some other gas in which you pressurize the chamber. So I don't know about you but unless there is a burst disk or tight fitting projectile that gas goes bye bye.

I think you mean a hybrid

Nope no hybrid.

umm yes if you have hybrid, then you need a burst disk, if you just have an advanced combustion, then you dont.

So the propane just chills inside the chamber and doesn't leave it because?

No, your projectile stops the propane from exiting the barrel.No burst disk just the necessity of a tight fitting projectile or firing fast.

If you're using loose fitting ammunition then your spudgun simply won't work (or at least not very well). The pressure will just bypass the projectile.

ShowNoMercy wrote:So I was thinking of this, if you could find the max pressure the gun would make and then have a sprinkler valve piloted by a regulator set to that pressure you could essentially have a high ROF combustions. What do you think?

I wasn't understanding the first half but I did understand the second half. It sounds like a really good idea but there are some obvious issues.

1 - the rubber diaphragm in the valve may not be able to handle the heat generation and pressure spike. This can be fixed by making a metal diaphragm using Noname's sprinkler valve mod (minus the blowgun portion).
2 - Measuring the pressure in the chamber may be an issue due to the pressure spike. From my understanding, the temperature rises and falls pretty quick, thus making the gauge fairly inaccurate. This could be solved by using some type of liquid with a check valve.
3 - Instead of using a regulator, which may or may not work, why not find a pop-off valve to do the same?

The injection of propane will increase the chamber pressure to 0.6 psig, so as long as the projectile can prevent that from escaping, then all is well. With a loose fitting, not sealing projectile like a golf ball in SDR 21, some air/propane will escape, but not enough that it will throw off the ratio to the extent that the gun will not fire. Burst disks almost always help a combustion's performance though, because they allow a faster pressure release. Kind of like switching from a ball valve to a burst disk valve on a pneumatic.

Ah I guess I misunderstood just how much pressure was put in first. Well then cancel that idea. Thanks for the help though.