The local speed of sound, denoted as “a_local,” represents the speed at which pressure waves (sound waves) travel through the air at a specific location, altitude, and temperature. It’s a critical parameter in aircraft design and flight operations because it affects various aspects of aerodynamics and aircraft performance.
Formula: The formula for calculating the local speed of sound is based on the standard speed of sound formula and adjusted for the local conditions:
- “a_local” is the local speed of sound (in meters per second, m/s).
- “γ” (gamma) is the adiabatic index or ratio of specific heats, approximately 1.4 for dry air.
- “R” is the specific gas constant for dry air, approximately 287.05 J/(kg·K) in SI units.
- “T_local” is the local absolute temperature of the air (in kelvin, K), which varies with altitude and atmospheric conditions.