Transonic Regime
Definition
The velocity range from approximately Mach 0.8 to 1.2 (272 to 408 m/s at sea level, 15 degrees C). Wave drag peaks and gyroscopic stability can degrade, causing unpredictable projectile behaviour and trajectory errors.
- Velocity range
- Approximately Mach 0.8 to 1.2
- Speed at sea level
- About 272 to 408 m/s at 15 degrees C
- Effect
- Wave drag peaks, gyroscopic stability can degrade
- Consequence
- Unpredictable projectile behaviour and trajectory errors
Common questions
Why is the transonic regime especially problematic for long-range shooting?+
A bullet slowing through this speed band can experience sudden, uneven drag and destabilising forces as shockwaves shift around it, which can throw the projectile off its predicted path in ways that are hard to model precisely.
How do ballisticians try to avoid transonic problems in trajectory reconstruction?+
Where possible they choose loads and ranges that keep the projectile supersonic or subsonic throughout its flight, avoiding the unstable transonic band, or they apply drag models specifically validated for that velocity range.
Related terms
- Aerodynamic Drag
- The retarding force exerted by air on a moving projectile. Proportional to air density, the square of velocity, the drag coefficient, and...
- Ballistic Coefficient (BC)
- The ratio of a projectile's sectional density to its drag relative to a reference standard (G1 or G7). Higher BC means less...
- Drag Coefficient (C_D)
- A dimensionless number characterising the aerodynamic drag force relative to the dynamic pressure and the projectile's cross-sectional area. Varies with Mach number;...
- G1 Drag Standard
- The Gavre Commission reference projectile: flat base, round-nose ogive. Established in the late 19th century and codified at Aberdeen Proving Ground. Standard...
- G7 Drag Standard
- A long, boat-tailed secant-ogive reference projectile developed by Bryan Litz at Applied Ballistics. More accurate for modern spitzer-BT precision and military rifle...
- Hatcher Rule
- A simplified wind-drift estimation formula from Major General Julian Hatcher's Hatcher's Notebook (1947). Useful as a field check and courtroom cross-reference; diverges...
- Litz Wind Drift Model
- The velocity-integrated wind-drift calculation method from Brian Litz's Applied Ballistics for Long Range Shooting (2015), implemented in AB Quantum and Hornady 4DOF....
- Sectional Density
- A bullet's mass divided by the square of its diameter (in consistent units). A component of BC; higher sectional density generally produces...
- Wind Drift
- Lateral deflection of a bullet by a crosswind component. Grows with time-of-flight (faster than range) and is the most variable error source...