1. What is Mach Number at Altitude?

The Mach number at altitude is the ratio of an object's speed to the speed of sound in the surrounding medium at that altitude. It's a dimensionless quantity used in aerodynamics to characterize flow regimes.

2. How Does the Calculator Work?

The calculator uses the equation:

Where:

• \( M \) — Mach number (dimensionless)
• \( v \) — Velocity of the object (m/s)
• \( \gamma \) — Specific heat ratio (dimensionless)
• \( R \) — Specific gas constant (J/kg·K)
• \( T_0 \) — Sea level standard temperature (K)
• \( L \) — Temperature lapse rate (K/m)
• \( h \) — Altitude above sea level (m)

Explanation: The equation accounts for how the speed of sound changes with altitude due to temperature variations in the atmosphere.

3. Importance of Mach Number Calculation

Details: Mach number is crucial in aerodynamics for determining compressibility effects, shock wave formation, and aircraft performance characteristics at different altitudes.

4. Using the Calculator

Tips: Enter velocity in m/s, specific heat ratio (1.4 for air), gas constant (287.05 J/kg·K for air), sea level temperature (288.15 K), lapse rate (0.0065 K/m for standard atmosphere), and altitude in meters.

5. Frequently Asked Questions (FAQ)

Q1: What are typical Mach number regimes?
A: Subsonic (M < 0.8), Transonic (0.8 < M < 1.2), Supersonic (1.2 < M < 5), Hypersonic (M > 5).

Q2: Why does speed of sound change with altitude?
A: Because it depends on temperature, which decreases with altitude in the troposphere.

Q3: What are standard values for air?
A: γ = 1.4, R = 287.05 J/kg·K, T₀ = 288.15 K, L = 0.0065 K/m for standard atmosphere.

Q4: When does this equation not apply?
A: In non-standard atmospheric conditions or when temperature increases with altitude (inversion layers).

Q5: How does Mach number affect aircraft design?
A: Critical for determining wing shape, engine type, and materials to handle aerodynamic heating at different speed regimes.