Questions about pressure.
I know absolutely nothing on this subject, so please bear with me.
If the rifle’s main bottle had a smaller bottle inside it, couldn’t the small bottle take a charge of air from the big one and thereby deliver more consistent shots to the rifle? How much volume would be required? A matchbox-sized amount? More? Less?
If the main bottle is at 3000psi, and a smaller one inside shut off at a charge of, say, 2000psi, how big a volume of 2000psi would be required to give the pellet a velocity of 1200fps? I’ve no doubt there’s a simple formula…
Assuming it could be done, would it be possible to construct a valve that would automatically shut off at a given pressure?
I’m sure ya’ll can see where I’m going with this. No doubt I’m talking utter arse, so somebody please let me down gently. 😆
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I wish you and your brother well, but don’t pat yourselves on the back too soon. You’re a LONG way from having anything remotely useful. What you have right now is a concept. A concept that only a few hundred of us have thought of already. A few people have made it a reality though, and like Adam was saying, they ain’t sharing. Yet.
It would be worthwhile for you to read back thru every single thread in the modding forum here, dating back to the forum’s beginnings. It’ll take you an evening to cover it all, but you’ll find some threads that will prove very enlightening. And drawings and schematics, etc. What you’re hoping to design isn’t rocket science. But lacking the tools or possibly the skills to use those tools, you’d be hard-pressed to build anything remotely useable on your first few tries.
Don’t wanna sound like I’m pissing on your parade, but at the same time, I don’t hold out much hope that you’ll be successful. Not for a while.
I was going to post the rough drawing I’ve made but my brother reckons somebody would nick it and make a bunch of dough off our genius. 😆
Git Er Done….
We will be patiently waiting. 😀
Abe
We’ve got this so it works on air-pressure and springs, and can be fabricated using brass turned on a lathe and drilled & threaded. It’s so simple I can’t see why it’s not already been done.
There’s a main body, inside which there’s an air-tight piston bearing against a main-spring. As air at 3000psi is introduced into the body it compresses the piston against the spring until, at 2000psi, it exposes a port. The air at 2000psi enters the port and goes up a shaft where it forces a plug against a small spring across the aperture where the air is entering the main body, shutting it off.
When the rifle is fired the main body empties, including the air in the shaft which is holding the plug across the aperture. The aperture opens, but not before the piston has returned far enough to close the port to the shaft. The main body then fills again, until the port is exposed once more, shutting off the aperture again.
My brother says there are springs which are designed to compress at a given distance per psi, at a given OD. So it’s all about the position of the port in regard to getting the port closed by the piston before the aperture opens. Trial and error I guess, until a design works flawlessly.
Yeah. SCUBA regulators do this very well. The only problem you would have is that SCUBA regulators deliver about 200 psi through the first stage instead of 2000. I’m sure a little redisigning would give you what you want. Take a look at a cut away drawing and see what you think.
Abe
We think we’ve just worked it out. Kind of. 😆
The secondary reservoir needs to be filled to 2000psi from the main bottle’s 3000psi. If it had a sprung valve in it that was set to mechanically trigger a shut-off gate…
Upon firing the rifle the spring would force the valve back again, triggering the gate to re-open. Air rushes in at 3000psi (or 2990), forcing the valve back against it’s spring until 2000psi was achieved, closing the gate again.
We’ve got drawings and everything! 😆
People have made them. They just are not sharing 😉
Yep, that is exactly what we’ve been talking about.
Yeah, me and my brother are just re-inventing the wheel tonight. 😆
It’s pressure and volume. The reason the UK-spec rifle is so consistent is the pressure in the bottle drops by such tiny increments. US-spec rifles are chucking out bigger packets of air per shot, reducing bottle pressure by pretty big increments.
The only way to get a smaller bottle to hold a lower pressure than the bigger one is by means of a solonoid valve, which means introducing a battery and electronics into the bottle. Or so we think.
The UK spec rifle has a valve assembly that has a spring-retainer with a pin-hole. This effectively makes the assembly on the top-hat side of the spring-retainer a reservoir. The air within that reservoir is discharged and emptied before it can be refilled via the pin-hole from the bottle. The rifle ends up delivering around 12ft/lbs.
By enlarging the pin-hole one effectively negates the reservoir effect and gets a full-pressure blast straight from the bottle.
The UK-spec rifle is supposedly able to give 500 full-strength shots from one bottle (others say more likely 300).
What if one were to retain the pin-hole in the spring-retainer, but make the area on the top-hat side of the spring-retainer bigger?
We do that here as part of our valve modification. It increase airflow and thus velocity.
What you are looking for is a reservoir of air regulated at 2000psi from a 3000psi tank.
A pipe is no larger then its smallest restriction
I’ve just been talking this through with my brother.
The UK spec rifle has a valve assembly that has a spring-retainer with a pin-hole. This effectively makes the assembly on the top-hat side of the spring-retainer a reservoir. The air within that reservoir is discharged and emptied before it can be refilled via the pin-hole from the bottle. The rifle ends up delivering around 12ft/lbs.
By enlarging the pin-hole one effectively negates the reservoir effect and gets a full-pressure blast straight from the bottle.
The UK-spec rifle is supposedly able to give 500 full-strength shots from one bottle (others say more likely 300).
What if one were to retain the pin-hole in the spring-retainer, but make the area on the top-hat side of the spring-retainer bigger?
What you are alluding to is called a regulator. It can and has been done. But it is not readily available as of yet. And we do not know if and when it will be available.
We had a member working on it but he has slipped into the ether and it is rumored he is working with a MFG. on the project.
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It would be worthwhile for you to read back thru every single thread in the modding forum here, dating back to the forum’s beginnings. It’ll take you an evening to cover it all, but you’ll find some threads that will prove very enlightening. And drawings and schematics, etc. What you’re hoping to design isn’t rocket science. But lacking the tools or possibly the skills to use those tools, you’d be hard-pressed to build anything remotely useable on your first few tries.
Don’t wanna sound like I’m pissing on your parade, but at the same time, I don’t hold out much hope that you’ll be successful. Not for a while.
Don’t worry Chad, we’ve got our tongues wedged very firmly in our cheeks. 😉
But the morning has brought a fresh stroke of genius and I’ve already removed a major moving part from the design. Now I’ll do as you suggest and look through all the old threads and see if anyone stole our ideas before we’d even thought of them. 😆