1. What is Mach Number?

Definition: The Mach number is a dimensionless quantity representing the ratio of flow velocity to the speed of sound in the surrounding medium.

Purpose: It's crucial in aerodynamics to determine compressibility effects and classify flight regimes (subsonic, transonic, supersonic, hypersonic).

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( M \) — Mach number (dimensionless)
• \( v \) — Velocity of the object (meters per second, m/s)
• \( a \) — Speed of sound in the medium (meters per second, m/s)

Explanation: The velocity of the object is divided by the speed of sound in the medium to determine how many times faster than sound the object is moving.

3. Importance of Mach Number

Details: Mach number determines when compressibility effects become important in fluid dynamics. Different flight regimes require different aerodynamic considerations:

• Subsonic (M < 0.8)
• Transonic (0.8 ≤ M ≤ 1.2)
• Supersonic (1.2 < M < 5)
• Hypersonic (M ≥ 5)

4. Using the Calculator

Tips: Enter the object's velocity in m/s and the speed of sound (default 343 m/s at sea level). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the speed of sound important?
A: The speed of sound varies with altitude and temperature, affecting the Mach number calculation for aircraft.

Q2: What's a typical speed of sound at sea level?
A: Approximately 343 m/s (1,235 km/h or 767 mph) in dry air at 20°C (68°F).

Q3: How does altitude affect Mach number?
A: The speed of sound decreases with altitude (colder temperatures), so an aircraft flying at the same true airspeed will have a higher Mach number at higher altitudes.

Q4: What is Mach 1?
A: Mach 1 means the object is traveling at exactly the speed of sound in that medium. This is also called the sound barrier.

Q5: How is Mach number used in aircraft design?
A: Critical Mach number determines when shock waves form on aircraft surfaces, affecting drag, lift, and control effectiveness.