1. What is a Subsonic Mach Number Calculator?

Definition: This calculator determines the Mach number, which is the ratio of an object's speed to the speed of sound in the surrounding medium.

Purpose: It helps aeronautical engineers, pilots, and physics students understand how fast an object is moving relative to the speed of sound.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( M \) — Mach number (dimensionless)
• \( v \) — Object speed (m/s)
• \( a \) — Speed of sound (m/s, ~343 at 20°C sea level)

Explanation: The Mach number indicates whether the flow is subsonic (M < 1), transonic (M ≈ 1), or supersonic (M > 1). This calculator focuses on subsonic conditions (M < 1).

3. Importance of Mach Number Calculation

Details: Mach number is crucial in aerodynamics for determining compressibility effects, shock waves, and aerodynamic heating.

4. Using the Calculator

Tips: Enter the object speed in m/s and speed of sound (default 343 m/s at 20°C sea level). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does a Mach number less than 1 mean?
A: It indicates subsonic flow, where the object is moving slower than the speed of sound in that medium.

Q2: Why is the speed of sound set to 343 m/s by default?
A: This is the approximate speed of sound in dry air at 20°C (68°F) at sea level.

Q3: How does altitude affect the Mach number?
A: The speed of sound decreases with altitude (colder temperatures), so the same true airspeed would result in a higher Mach number at altitude.

Q4: What's the difference between true airspeed and Mach number?
A: True airspeed is the actual speed through the air, while Mach number is this speed relative to the local speed of sound.

Q5: When does compressibility become significant?
A: Compressibility effects typically become noticeable around Mach 0.3 and must be accounted for above Mach 0.5.