# Wind resistance on an airsoft BB

#### chip92us

Hey, I have a question pertaining to the effect of wind resistance on a 0.2 gram plastic, spherical airsoft bb over a given distance. I know it has something to do with drag coefficient, and I’ve been having a little trouble calculating it myself, so I would really appreciate any ideas and/or help.

I would like to construct a chart of distance (m) vs. instantaneous velocity (m/s). Distance will be in increments of 5m, starting at 0. Similar to these charts, but with a different initial velocity and distance as the independent variable instead of time:

http://www.swatairsoft.eu/37.html

Here’s some data:

Mass of bb: 0.0002 kg
Initial velocity of bb: 125 m/s (410 fps)

Since the bb is a sphere, it would have a drag coefficient of 0.47, correct? (neglecting any spin).

An air density value is also required: I was thinking of using 1.204 kg/m^3 (density of air at 20 degrees Celcius).

If needed, the cross-sectional area of a bb is 0.0000281 m (5.98mm diameter).

If any more information is needed to make it more accurate, please let me know. Anyone know how to go about doing this?

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