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PostPosted: Sun Nov 18, 2012 5:17 pm 
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Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8989
Location: Coalmont BC
You reduced the pressure in your springer by allowing the air out quicker, thereby reducing the velocity.... springers need pressure to work properly....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
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Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
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PostPosted: Sun Nov 18, 2012 5:29 pm 
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Joined: Sun Aug 24, 2008 3:22 pm
Posts: 87
Location: norway
In springers, Compression ratio- the relationship between swept volume and the lost volume in the transfer port, plays a big role.

I have had good results sleeving ports that vere oversize, just like your Meteor became after drilling.

When your port is drilled and tapped, you can play around with different sleeves!


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PostPosted: Thu Apr 25, 2013 4:47 pm 
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Joined: Thu Sep 13, 2012 2:29 pm
Posts: 35
Threaded sleeve/ports. . .

Veery eenteresting.

I hope this does not break any forum rules, but here is an neat article on optimum port size. . .
part I:

http://www.pyramydair.com/blog/2008/10/ ... art-1.html

part II:

http://www.pyramydair.com/blog/2008/10/ ... art-2.html

part III:

http://www.pyramydair.com/blog/2008/11/ ... art-3.html

^One idea I have not seen is have a reverse funnel shaped port, with the largest diameter at the breech opening, and the smallest diameter at the piston end.

If you go by the Bernoulli effect, if you have a pipe with large diameter, then small diameter, then larger diameter again, with flow going from left to right, the fluid has high pressure and low velocity on the left, high velocity and low pressure in the middle, then high pressure and low velocity again on the right.

If you think about how a springer is designed, you have the cylinder with the piston causing the fluid flow when the trigger is depressed [high pressure, low velocity],, the transfer port reducing the fluid pressure and increasing fluid velocity, then on the right you have the air leaving the transfer port and entering the relatively large diameter of the barrel behind the pellet, (high pressure, low velocity of the fluid?)

However:

the bore of the cylinder is relatively large compared with both the transfer port and the bore diameter.

Now we are getting into the gas laws (there are quite a few), which are fun to countenance.

*To say nothing of all the variables that can have an effect on an air gun performance, such as energy lost to heat, energy lost to sound, energy lost to vibration and so on and so forth ad infinitum.*

Very interesting research and opinions (professional and non professional :D) in the above article comments - don't start reading them or you will be there for some time! :p


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