Breaking the Sound Barrier with An Air Gun- Impact on Accuracy



Posted: Monday, February 14, 2011

by John Davis
Qualprod

The earliest action that broke the sound barrier was not caused by a gun or airplane, but by the snapping of a bull whip. Is there an impact on hitting your target accurately when your shot (bullet, pellet or bb) breaks the sound barrier?

Because sound waves travel faster in liquids and solids than air, and objects travel faster in air than in liquids or solids, the only substance where the object can travel up to and through its sound wave is air. Although the speed of an object traveling through air is affected by pressure, density and temperature, the main effect is temperature. At 70 degrees Fahrenheit, with little humidity, the speed of sound is about 1,100 ft/sec. When an object catches up and breaks through its sound wave a loud cracking noise is heard, commonly referred to as "breaking the sound barrier". The turbulence caused does impact the trajectory of the object. The resultant impact (deviation from the desired trajectory) depends on the force (mass and velocity) of the object. The greater the force, the less the impact.

For a small (.177) pellet breaking the sound barrier would most likely send the pellet tumbling, missing the target completely. A larger pellet (.25) at the same speed would be much less impacted. The aerodynamic design of the pellet is also very important at high speed. Sub-sonic air gun pellets are less impacted by wind the slower they go, but this is due to the greater weight of the pellet.

Powerful pellet guns have to be concerned with these issues because their pellets travel near the sound barrier. They are either just below or above the speed of sound. Approaching the sound barrier (1100 ft/sec) the air starts bunching up in front of it and the turbulence increases right up to the point where the sound barrier is broken, which is the moment of violent turbulence (crack-bang). This bumps the pellet off course. That is why high-end pellet rifle manufacturers try to keep velocities below 1100 fps on most rifles, even if they have to use a heavier pellet.

The worst impact is felt at speeds around the speed of sound, just below and above 1100 ft/sec. The pellet is affected by the turbulence on the front of the pellet just below the speed of sound and the turbulence on the back of the pellet just above the speed of sound.

So, yes there is an impact on the accuracy of your shot if the pellet breaks the sound barrier, and you must know the projectile/pellet speed the air gun you select will generate.

The goal is to have the pellet stay below (800 ft/sec) or well above (1400 ft/sec) the speed of sound. A further negative is to endure the turbulence when breaking the sound barrier, and to have the pellet slow down enough to have its sound wave catch to the back of the pellet and endure more turbulence.

All this is very important to high power pellet guns that must hit targets 50 to 80 yards away. So the effects of the sound barrier on accuracy are important.

Yes, there is an impact on the accuracy of your shot if you break the sound barrier and the selection of your air gun is very important.

For safe war games and training airsoft equipment has become very popular and a wide selection of guns, protective gear, targets, grenade launchers, and ammunition can be found at http://www.airsoftstoreaccessories.com .
Worked for 48 years in Information Technology before retiring from industry. Employed by General Dynamics, AT&T, IBM, Worldwide Computer Services (Owner), Butler Technology Services, Advantage Professionals and Merritt Technology Solutions. Bachelor of Electrical Engineering from Manhattan College and Masters in Operations Research from NYU.

Has an airsoft equipment website at http://www.airsoftstoreaccessories.com .
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