Regulated HPA and Hammer Strike

[rsterne]

This is just a short post about how hammer strike affects a regulated HPA gun.... There is an optimum balance between regulator setpoint and the hammer strike, just as in a non-regulated PCP.... Adding spring preload (or hammer travel or weight) past a certain point will result in the gun using more air, but no increase in velocity.... Here is an example....



You will note that there is no change in velocity past a certain point as you increase hammer spring preload.... but the efficiency goes down (number of shots per fill goes down) because you are just wasting air.... However, if you go too light on the preload for a given regulator pressure, once the pressure drops below the setpoint, the velocity will actually increase instead of falling off like it normally does.... Here is an example....



You will notice that when the tank pressure is above the regulator setpoint (in this case 1500 psi) the velocity slowly creeps upwards.... and then once the pressure drops below 1500 psi it climbs quickly before falling off again.... Most regulators have a small amount of "creep", which means that the output pressure is very slightly higher when there is 3000 psi in the tank than when there is less.... Since the hammer strike is very light, that slightly higher pressure keeps the valve from opening quite as far, resulting in a slightly lower velocity.... Once the pressure drops below the setpoint, the valve opens more and more, and the velocity increases, just as in a non-regulated PCP.... Once the velocity peaks, then the velocity drops as the pressure once again falls.... If you are in this situation, the ideal solution is to lower the regulator pressure to where the peak of the velocity occurs, or even less if that is still more velocity than you want/need.... In the above example, the velocity peaks at 840 fps at 1200 psi, so if you want velocities in the 800-820 fps range that would be a good choice for the setpoint....

I hope that understanding this relationship will enable you to get the most out of your regulated HPA gun....

Bob

[airpuffhunter]

good info. interesting as allways.
thank you Bob.

[bradyman1]

Thanks for the info. Your testing is very intriguing.

[RatRacer]

Interesting. I really need to get a chrony and see how my Rainstorm acts when it comes off the regulator.

[renowntwo]

thanks for sharing the infor. I noticed the same thing happen to me.
 

[william71743]

OK... probably a dumb question, but a disco is not a regulated hammer strike...right ? Unless their is a orfice somewhere, in the valve i guess ?........        

[RatRacer]

OK... probably a dumb question, but a disco is not a regulated hammer strike...right ? Unless their is a orfice somewhere, in the valve i guess ?........        

No. The M & P-rods have 2 adjustments that you can do thru where you put a power adjustment screw on a Disco. One for the spring tension, like the Disco, and one for the hammer travel. It basically makes the hammer longer or shorter, adjusting travel space.

[william71743]

OK Steve, but my dumb I guess, I still don't quite get the regulated part ?   

[william71743]

I really need to look at the valves and all I've never even seen a disco valve, I kinda understand , but I think if could see it I could put it all together . The hammer and valve combination has to operate kinda like a pilot operated valve .

[RatRacer]

A regulator is a user add on item. It goes between the valve and reservoir, and only allows a preset amount of air pressure at the valve to flatten a shot string, until the res pressure drops below the reg preset.

[rsterne]

Disco are NOT regulated, neither are MRods or PRods.... unless you purchase an add-on that fits inside the tube or convert to a regulated HPA tank.... The information in this thread only applies to regulated PCPs....

Bob

[SquirrelSniper25]

Disco are NOT regulated, neither are MRods or PRods.... unless you purchase an add-on that fits inside the tube or convert to a regulated HPA tank.... The information in this thread only applies to regulated PCPs....

Bob

How much do you think a regulator that goes inside the tube would cost me for a Marauder Bob?

[rsterne]

I'm guessing over $100.... no idea where to get one but I seem to remember that much....

Bob

[SquirrelSniper25]

I'm guessing over $100.... no idea where to get one but I seem to remember that much....

Bob

Aiight. Thanks!

[ronbeaux]

Joe Korick (sp) put a regulator in my old NJR 100 and it would not vary more than 3fps over a 20 shot string with a full charge. I had to blow off the first one and then the next 20 were all almost the same. Very important when in a comp so the only variable was the pellet itself. Once you size and weigh them then you were set.

I had to send it to him in CA and it cost about 200.00 way back when.

He might even be still around for all I know.

There is very little out there on regulators construction and what there is I have no clue how to even understand the engineering behind it other than it only allows a certain amount of air to charge a chamber in a slow rate so that when you shoot the gun you have a known amount of air to work with. Almost like a nail gun that cycles so quick that all of the air is used each shot and recharges between shots.

[william71743]

OK, I found a regulator for a Discovery. It sells for $100.00 from Airguns of Arizona ....