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'Regulating' a springer


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#1 Guest_Nigey42_*

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Posted 25 August 2007 - 08:07 PM

I'm probably displaying my airgunnig engineering ignorance [again] here but is there any benefit in 'regulating' a springer in a similar way to PCPs? I am assuming the transfer port is an unrestricted 'tube' simply joining the cylinder to the breach.

I'm just thinking that a PCP releases its payload of compressed air all of a sudden - and the regulator makes sure it's a consistent payload irrespective of what's left in the tank. A springer - I am assuming - releases its store of air throughout the sweep of the piston, and that is a relatively long and fluctuating curve.

Would an spring airgun perform better if its air could be compressed by the piston...but then reserved until it had reached a critical pressure, at which point it would be permitted through a valve in the transfer port and delivered all of a sudden?

Cheers

Nigel

#2 Guest_TheSmallHolder_*

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Posted 25 August 2007 - 08:12 PM

I suppose you could, but then you're changing a fundamental part of springers - they're simple. OK, there are various innovations in them, e.g. the TX200, but they're nowhere near the complexity of a PCP system.

The point of regulating PCPs is more to do with ensuring that over the course of a tank, the muzzle velocity is constant, whereas what you're suggesting is simply to improve the airflow for a single shot. As long as that remains the same BETWEEN SHOTS, then variation within a shot shouldn't matter I don't think.

I have no real technical knowledge of air rifle technology, so I might be about to get shot down, but that's how I see it.

#3 Guest_Nigey42_*

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Posted 25 August 2007 - 08:27 PM

Makes sense I guess - I think I was wondering more about efficiency of air use; if you could harness all of the cylinder's air and ensure as much as possible that all of it was being used to expel the pellet, then perhaps you would need less volume, smaller pistons, less cocking effort, faster lock times etc. I wouldn't have thought it would add a great deal of extra technology - I was thinking of something like a simple valve which opened only at a set pressure - so the air 'backed up' as it compressed until it burst through the valve.

Perhaps this effectively happening already - maybe the pellet skirt itself is acting as the valve. And perhaps the air is delivered so quickly that any pressure 'curve' is negligable. Anyone know how efficient/important the compressed air 'power curve' is on a typical springer? At what point of the piston's sweep does the pellet start to move - once it's started to move along the barrel, how much is the remaining air from the sweep adding?

Cheers

Nigel

#4 1 0f 5

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Posted 25 August 2007 - 08:52 PM

A pcp actually releases it's air relatively slowly compared to a springer. 2000 psi is a common pcp pressure but 18,000 psi is a common springer pressure. This is bourne out by barrel lengths. A springer can often make do with a 7 inch barrel but a pcp will need a longer one as the air is still shoving the pellet up it. There is already precious little air volume (comparatively) in a springer compared to a pcp so restricting it would cause big problems. Given a springer usually delivers far more consistent chrono results I'd say it was a superior powerplant to a pcp (recoil excepted).

#5 Guest_Nigey42_*

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Posted 26 August 2007 - 06:35 AM

Every airgunner instinctively knows a springer is the superior powerplant awink.gif

Nigel

#6 Guest_dvd_*

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Posted 26 August 2007 - 07:15 AM

x


Hi,
look at it this way,
when the air in a springer is very very rapidly compressed, an important thing happens.
Its temperature rises immensely , enough to ignite any combustible material in the cylinder, which results in a further pressure increase.
At this point, we are way above PCP pressures and PCP air velocity.
It is this immense pressure rise due to Dieseling that gives the pellet in a springer its considerable velocity.
On the other hand, temperatures in a PCP are too low for spontaneous ignition to occur because though the air is compressed, any heat generated during its compression was transfered to the device used to compress it initially.
When used to propel a pellet in a PCP, it is at ambient temperature and no form of combustion can take place. It is simply expanding and pushing a pellet in front of it.It is the larger air volume at a relatively low pressure coupled with the time acting on it, that gives the PCP pellet its comparable performance to a full power springer.
So in my opinion, the fundamental difference is the combustion taking place in a springer due to the rapid rate of compression.
This is what generates a springer's power from such a small volume of swept cylinder.
For these reasons, I do not think it is possible to create a usable airgun that uses a spring driven piston to compress air and then use it in PCP fashion.
David

#7 Guest_Nigey42_*

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Posted 26 August 2007 - 04:02 PM

Cheers David - that's interesting. I wasn't necessarily thinking about compressing the air and retaining it for future use as with a PCP, but was more thinking about fractions of a second...retaining it until the piston was at its furthest point and the air as compressed as it could be before sending it through the transfer port. It would retain most of its heat. Looks like this might be a moot point anyway however.

One question though - how much of a springer's power relies on a small amount of dieseling? Isn't all dieseling to be avoided or is a small amount crucial? At what stage does it become 'bad'.

Cheers

Nigel

#8 bulsaye

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Posted 28 August 2007 - 03:56 AM

Even fractions of a second added to shot cycle could play hell with accuracy.. and the ability of the shooter to stay "welded on target" during that time. IMO, nothing would be gained by such a contraption, and several things could be lost.. most notably accuracy and power, but I'm sure reliability could be an issue as well. RB

#9 bulsaye

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Posted 01 September 2007 - 11:31 PM

I probably should have written this reply first. Why would you want to regulate a springer? A decent springer is already pretty consistent when measuring shot to shot velocity, plus I've been able to tune some guns that fired with an extreme spread of 1.5 fps over a ten shot string! You just can't get things better than that !!! Find a regged PCP that does that for several strings!! Regards, Russ

Edited by bulsaye, 01 September 2007 - 11:32 PM.


#10 raygun

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Posted 02 September 2007 - 04:09 PM

With springers you get combustion. If you've got dieselling you or your gun has got it wrong.

The Cardews said that the combustion of the minute amount of lube would contribute up to 30% of a springers power.

If you have dieselling (explosion of the lube) you will certainly damage your gun if continuing with it's use whilst dieselling. You will certainly burn your piston seal and quite possibly break your spring.

The HW Barracuda's with ether injection didn't last long abiggrin.gif

ATB
Ray.

#11 Guest_Andy Westcott_*

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Posted 07 September 2007 - 06:23 PM

Back to initial post:
"I'm just thinking that a PCP releases its payload of compressed air all of a sudden"

The way a springer works is interesting, as it doesn't act like a blowpipe, as many may believe.
The key is in obtaining a pellet which matches the barrel - this means one where the pellet's skirt is slightly too wide to fit down the barrel.

Once the gun has been fired and the piston is on its way down the cylinder, the air pressure increases rapidly although at this point the pellet is still wedged firmly in the breech.

In an ideal situation, the pressure would continue to increase to the point where the back pressure is way greater than the spring's force, and yet it continues to compress - this is due to the weight and momentum of the piston assembly. Eventually the piston will 'bounce' on the cushion of highly compressed air it has built up in the compression chamber and it is (in an ideal world) at this point that the pellet's skirt gives way and allows it to be spat down the barrel, accelerating to full velocity in a very short distance.

This is why a pellet which slides into the barrel easily won't reach a very high velocity - you need that 'skirt resistance' to allow the full pressure to develop, and this is why matching the pellet to the gun is important to get the best out of it.

That's how I understand it, anyhow. smile.gif

#12 stillair1

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Posted 08 September 2007 - 10:08 AM

QUOTE(dvd @ Sun Aug 26 2007, 08:15) <{POST_SNAPBACK}>
x
Hi,
look at it this way,
when the air in a springer is very very rapidly compressed, an important thing happens.
Its temperature rises immensely , enough to ignite any combustible material in the cylinder, which results in a further pressure increase.
At this point, we are way above PCP pressures and PCP air velocity.
It is this immense pressure rise due to Dieseling that gives the pellet in a springer its considerable velocity.
On the other hand, temperatures in a PCP are too low for spontaneous ignition to occur because though the air is compressed, any heat generated during its compression was transfered to the device used to compress it initially.
When used to propel a pellet in a PCP, it is at ambient temperature and no form of combustion can take place. It is simply expanding and pushing a pellet in front of it.It is the larger air volume at a relatively low pressure coupled with the time acting on it, that gives the PCP pellet its comparable performance to a full power springer.
So in my opinion, the fundamental difference is the combustion taking place in a springer due to the rapid rate of compression.
This is what generates a springer's power from such a small volume of swept cylinder.
For these reasons, I do not think it is possible to create a usable airgun that uses a spring driven piston to compress air and then use it in PCP fashion.
David

In ultra high power pcp's there are other factors which come into play. awink.gif

#13 gedfinn

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Posted 08 September 2007 - 02:33 PM

QUOTE(stillair1 @ Sat Sep 8 2007, 11:08) <{POST_SNAPBACK}>
In ultra high power pcp's there are other factors which come into play. awink.gif



Yes I have Done this, ( And posted threads on the same ) ?
Its not difficult on some gun,s & A little harder on others ! The Basic,s are not to go for the
Transfer port, But to machine a " New " Cylinder end block,

This would be threaded and the spring " Tension " Increased, ( Or the other, by external means !)
Power could now be controlled by an " External " Allen screw !
I have done this a couple of times, Bsa Meteor, Relum Tornado, Etc, Webley Vulcan,
( As long as it does not have a Piston/Sear rod )
Cheers,




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