Accurate Measurements of Free Flight Drag Coefficients with Amateur Doppler Radar

Effects of Sound Suppressors on Muzzle Velocity, Bullet Yaw and Drag

“…The Doppler radar measurement system for measuring free flight drag coefficients with an accuracy close to 1% has been described previously [6]. Briefly, a LabRadar unit (www.mylabradar.com ) is used to measure Doppler velocities at regularly spaced intervals from the muzzle out to 91.44 m (100 yards).…”

Accurate Radar Measurements of Drag Coefficients in Free Flight

“…While many units are prohibitively expensive for amateur and educational uses, the LabRadar (www.mylabradar.com) device is affordable (~$600 US) and has been validated for its capabilities to accurately measure drag coefficients for numerous projectiles. 4 However, firearms are poorly suited for classroom use due to safety considerations. This paper reports results from measuring drag coefficients of plastic spheres 6mm in diameter and weighing much less than 1 g. While classroom use is ultimately a matter for the instructor and school administration, Airsoft projectiles are used for game play where participants routinely shoot at each other (similar to paintball) with appropriate protective equipment.…”

“…6 Air density can be determined from available atmospheric data with various methods. 4,5 Here, a Kestrel 4500 weather meter is used to measure ambient pressure, humidity, and temperature, and these values were entered into the JBM ballistic calculator (http://www.jbmballistics.com/ ) to determine air density with an accuracy better than 0.3%. Rather than use masses and diameters given on the product containers, masses are determined with an electronic balance, and diameters are determined with a dial caliper.…”