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View Full Version : wind drift comparison, .22 vs .177



Numb Nut
24-05-2004, 04:07 PM
Its often been said that crosswinds affect 0.22 less than 0.177. I thought it'd be a suitably geeky waste of time to see what a wind-drift calculator would predict using a typical decent pellet in both sizes.

The outcome isn't a foregone conclusion, generally a 0.177 pellet is faster to the target than a 0.22 pellet but a 0.22 pellet has a higher mass per surface area (sectional density) meaning its more aerodynamic. Sounds like it could be a very close call...

Results were gathered using the following online calculator, but could have used Dave's excellent 'Chairgun' freeware program.

http://69.6.222.74/airgunjournal/calc_wdrift.cfm?action=00

For the pellets - Daystate FTs in 0.177, BC=0.022, 11 ft lbs, MV=766fps and AA fields in 0.22, BC=0.032, 11 ft lbs,
MV=556fps. Assume a crosswind of 10mph at right angles to the direction of fire.

So here are the results for a few distances, drift calculated in inches.

range - 0.177 - 0.22
15 yrd - 0.48" - 0.45"
30 yrd - 1.98" - 1.84"
45 yrd - 4.59" - 4.23"
55 yrd - 6.99" - 6.40"

Conclusion: we can see that 0.22 has marginally less drift than 0.177, a slowly increasing percentage as the range increases but still under 10% at 55 yards.

Any comments? :)

Beer Hunter
24-05-2004, 04:37 PM
Comments – only that I got vastly different figures using ChairGun V1.9.0:

range - 0.177 - 0.22
15 yrd - 0.66" - 0.51"
30 yrd - 2.74" - 2.06"
45 yrd - 6.38" - 4.72"
55 yrd - 9.75" - 7.14"

I wonder which program is correct.

TER…

Numb Nut
24-05-2004, 05:00 PM
Thanks TER. Dunno about Chairgun 1.9.0 but using an older version (1.8.0) I get figures closer to my earlier results.

55 yrd - 7.09" - 6.30"

Wonder if the wind calculator equations have changed between versions of chairgun?

Actaeon
24-05-2004, 05:09 PM
Using Chairgun 1.8.9 I get very similar results to Numb Nut

I must say - a 10inch drift at 55 yds in a 10mph cross wind does sound on the high side to me.

Maybe Chairgun 1.9.0 has a bug ??

Numb Nut
24-05-2004, 05:23 PM
Just installed Chairgun 1.9.0 (had the install file lying around on the hard disk) and get the same figures as 1.8.0!

If the results are accurate, I can't imagine many HFT shooters will be trading the flat trajectory of the 0.177 for marginally less wind drift! :)

Beer Hunter
24-05-2004, 06:29 PM
Weird, perhaps mine has a "bug". Are you calculating drift through the visualisation part?

TER...

Actaeon
24-05-2004, 06:48 PM
What environmental settings have you got TER. If I drop the temp to 10 degrees C that makes quite a difference - just over 9 inches drift at 55yds, 10mph wind 177 etc.

Actaeon
24-05-2004, 06:50 PM
Oops my mistake - 7.35" @ 10 Celcius - put the wrong BC in before

Beer Hunter
24-05-2004, 07:00 PM
20 degrees Celsius, gravity 32.20 Ft/s/s, pressure 30.00 inches Hg.
.177 = Daystate 4.51, 8.44 grains, BC=0.018, 10.999 ft lbs, MV=766fps
.22, = AA Field, 16.9 Grains, BC=0.032, 10.996 ft lbs, MV=558fps
Wind from right @ 10 mph

range - 0.177 - 0.22
15 yrd - 0.66" - 0.51"
30 yrd – 2.74" – 2.06"
45 yrd – 6.38" - 4.72"
55 yrd – 9.75" – 7.14"

TER…

Numb Nut
24-05-2004, 09:58 PM
TER, how very odd! Yup, calculating wind drift using the visualisation feature. Minor differences, I'm using 16 grains for 0.22 AA fields and am using BC=0.022 for Daystate FTs in 0.177.

The 16.9 grains in your earlier post is a typo, eh?

Beer Hunter
24-05-2004, 10:22 PM
Yep, typo - should have been 15.9.

I think your results are more accurate than mine though. I also use http://www.handloads.com/calc/ for centerfire loads and it shows results much closer to yours.

I'll try uninstalling ChairGun and manually deleting any remaining files / registry entries before re-installing to see if that makes a difference. (but not tonight! :rolleyes: :D )

TER...

lionel
26-05-2004, 06:24 PM
Fascinating thread. I'm wondering if 22s wind drift advantage is constant - ie what would happen at higher muzzle velocities - say 21 fpe with Bis Mags? My gut tells me the little pellet would start to come out in front.

The software doesn't seem to factor in the difference in rates of spin between the two calibres and what effect this has on wind drift,- if any. I'm guessing that a 177 pellet has a higher rate of spin at a given ME but I am by no means sure.

Lionel