GTA
General Discussion To Gateway To Airguns => Airgun Gate => : jberenyi May 25, 2009, 02:15:45 AM
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Roy, Utah has an altitude of 4436 ft. above sea level. I was wondering if I am loosing significant fps with my springers due to this and possibly dimimishing the life of my springers more quickly. Does anyone know at what altitude you should abandon springers and go to the dark side? I've heard of guys in CO that have terrible issues with their springers at 6000+.
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Good question about springer longevity at altitude. Awhile back I asked PeakChick about using an airgun at about 10,000' and she said it would be fine so long as I expected a significant loss of fps and dealt with it accordingly. However, I can't remember what kind of fps loss it would at 10000' be anymore, maybe 7 or 8%? For 6000' it would be less of a loss of course.
I didn't think to ask about longevity problems though. I believe PeakChick lives at around 7000-8000' and still uses springers; so off the top of my head she's the one to ask. I'm sure other higher altitude shooters will chime in too.
I asked about longevity too, and I think she said you just take care of the gun like you would normally, maybe pay more attention to proper lubing (as opposed to extra lubing?).
Basically what I remember from asking her is that the answer was reassuring and amounted to just a judgement call over energy loss and not possible damage. Sorry my memory is failing me, and thereby you too.
Given that my memory is hazy, better wait for the high altitude members to enlighten the both of us...
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Eric ( onemountain ) pretty accurately recounted what I told him. My house is at a bit over 6000.' I shoot air rifles, including springers at altitudes ranging from 6-9000.' You will experience some performance loss, it will vary, as a rough rule about 2% per thousand feet of elevation change.
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jberenyi - 5/25/2009 8:15 AM
... and possibly dimimishing the life of my springers more quickly.
What mechanism would cause damage to a springer (or any air rifle) due to altitude? Sure, the air is a bit "thinner" the higher you go, but why would an air rifle care about that (talking about damage, not performance)?
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the air is thinner therefore easier to compress. the piston moves faster, and it has less air in the way so it slams home faster, but with less air moving, it doesnt push the pellet as fast. thats my opinion anyways. who knows what actually happens.
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the air is thinner therefore easier to compress. the piston moves faster, and it has less air in the way so it slams home faster, but with less air moving, it doesnt push the pellet as fast. thats my opinion anyways. who knows what actually happens.
Man, our air's not THAT thin up here! I would guess that after that piston has moved 1mm it would have already compressed our thin air down to sea level pressure anyways. But who am I to speculate, I've never actually measured the difference. Just use a heavier pellet to compensate and "pad" the pistons push if thin air damage is a concern.
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What Brod Man said is most likely correct. As for using a heavier pellet....that will give the piston abit of "air cushion" but than the fps will suffer even more.
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All the guys from up there that used to come shoot with us down here in Baton Rouge did was re-zero their guns when they got here. Their guns worked fine when they showed up and worked fine when they left. PCP and Springers.
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I live at about 3000ft and sometimes go to up to 4500 ft and I do see loss in fps but I just subtract about 6% from what others get and its in the ballpark.
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The total level of compression we're talking about here makes the altitude difference almost miniscule. Standard atmosphere sea level pressure is 14.7 psi, 6,000 feet (where I live) is 11.8 psi, and 10,000 feet is 10.1 psi.
Compare those numbers to the final pressure under compression (I'm not sure what it is, but even if it was only 200psi...), and the difference is small. That is why a turbo charger works so well at altitude; not only does it give you additional power, it basically makes up for the loss as well. 4.6 psi is a small percentage of the final value.
As someone above already said, once that piston moves only a little bit, you are already back at sea level pressure.