At What Speed Does A Bullet Go Subsonic

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Understanding at what speed does a bullet go subsonic is crucial for a variety of reasons, from predicting its trajectory and impact to designing effective suppressors. The transition from supersonic to subsonic flight dramatically alters a bullet’s behavior, making it a critical point to understand for ballistics experts, firearm enthusiasts, and anyone interested in the physics of projectiles.

The Science Behind Subsonic Transition

At what speed does a bullet go subsonic? The answer isn’t a single, fixed number. It depends primarily on the speed of sound, which itself is influenced by several factors, most notably air temperature. Under standard atmospheric conditions (around 68°F or 20°C), the speed of sound is approximately 1,125 feet per second (fps), or 343 meters per second. However, this speed changes with temperature. The speed at which a bullet transitions to subsonic is vitally important because the aerodynamic forces acting upon it change drastically at this point.

Here’s a breakdown of key factors impacting this transition:

• Temperature: As temperature increases, the speed of sound also increases. This means a bullet will remain supersonic for slightly longer in warmer conditions.
• Altitude: Higher altitudes generally mean lower temperatures and air density, influencing the speed of sound.
• Humidity: While humidity has a minor effect compared to temperature, higher humidity can slightly increase the speed of sound.

Therefore, a bullet doesn’t “go subsonic” at a universally defined speed. Instead, it transitions from supersonic to subsonic when its velocity falls below the local speed of sound. Consider these different atmospheric conditions, a simple table is show below.

Want to learn more about the specific calculations involved and how different ammunition types behave during this transition? Check out reputable ballistics resources for in-depth information on trajectory calculations and the effects of transonic drag.