GGDT Design Library


The Condor airgun by Airforce Airguns is an interesting beast. It was the first non-driven-piston, non-heated-gas, air-powered airgun that I'd seen believable supersonic claims from. It was this gun that forced me to re-examine the methodologies used in GGDT v3 and look for theories that explained supersonic capabilities in airguns.

As you can imagine, however, detailed data on the Condor is something that I'm not likely to be able to come up with short of coughing up the dinero and buying one; something I'm not likely to do.

Still, I wanted to test GGDT's ability to model the Condor. So I threw together a model using what technical data I could find. The only real data I couldn't find was data on the valve. I knew it was a high efficiency hammer valve, but that was about it. My course of action was to make what I felt were reasonable guesses concerning the valve's properties and then "tweak the numbers" until I felt there was a reasonable agreement between the simulation and the published data. At that point, I modified the ammunition, held the gun data constant, and compared the new scenario against more published data (of a different flavor, of course).

More precisely, I went to this site and tweaked until I hit the first average velocity. I looked at the pressure drop (32 psi per shot) and dropped the pressure 160 psi to simulate 5 shots (ie, halfway into that first 10 shot group described on the other page). I made a final teeny tiny tweak and I "locked in" the design. I sim'ed the gun. I dropped the pressure to simulate 10 more shots and sim'ed it again, hoping to match the test data....

Shot Number Pellet Published
5 (1-10) 22.1 gr 1121 1121 (cal shot)
15 (11-20) 22.1 gr 1083 1189 0.6%
25 (21-30) 22.1 gr 1036 1039 0.3%

Needless to say, I was very pleased with those results. However, for bonus points, I decided more data was required. I went to this site, where they a velocity of "around 1,250 fps for the first five shots" for a 14.3 gr pellet. I fired up GGDT again. I dropped the pressure 60 psi (to 2930 psi) to simulate two shots having already been fired. I lowered the projectile mass to 14.3 gr and gave it a shot. That site also stated that 29.6 gr pellet would be fired at "just faster than 1,000 fps" so I gave that one a whirl as well.

Shot Number Pellet Published fps GGDT fps Deviation
3 (1-5) 14.3 gr 1250 1279 2.3%
20 14.3 gr 1175 1212 3.1%
1 29.6 gr 1000 1036 3.6%

Obviously, I would have liked a closer match. But it still isn't bad, and the published muzzle velocity wasn't exactly precise. So while I would have liked a closer match, I'm still not disappointed; especially given that I wasn't even sure of something as basic as the valve diameter!

If you'd like the model I used, right click on it and save it as a file...


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