How does air temperature affect critical Mach number (Mcrit)?

How does air temperature affect critical Mach number (Mcrit)?

• A. Increases with higher temperatures
• B. Decreases with higher temperatures
• C. No effect on critical Mach number
• D. Varies depending on altitude

Answer: (C)

The critical Mach number (Mcrit) is defined as the lowest Mach number at which airflow over some part of the aircraft reaches the speed of sound. Understanding its relationship with air temperature is crucial in aerodynamics and aviation dynamics. Air temperature indeed affects the speed of sound in the atmosphere. As temperature increases, the speed of sound also increases because sound waves travel faster in warmer air. The critical Mach number is calculated based on the speed of sound, and since it defines the Mach number at which local flow reaches that speed, higher temperatures actually lead to a higher speed of sound. When the temperature rises, for a given true airspeed, the Mach number will be lower than the critical Mach number derived at lower temperatures because the baseline changes due to the higher sound speed. Consequently, the critical Mach number itself does not increase or decrease independently; it varies with the conditions that affect the speed of sound. Thus, the characterization of critical Mach number having no effect from temperature changes can be misleading. Significant changes in air temperature will impact the Mach number relative to the local speed of sound, and therefore influence the critical Mach number experienced by the aircraft in flight conditions.

The critical Mach number (Mcrit) is defined as the lowest Mach number at which airflow over some part of the aircraft reaches the speed of sound. Understanding its relationship with air temperature is crucial in aerodynamics and aviation dynamics.

Air temperature indeed affects the speed of sound in the atmosphere. As temperature increases, the speed of sound also increases because sound waves travel faster in warmer air. The critical Mach number is calculated based on the speed of sound, and since it defines the Mach number at which local flow reaches that speed, higher temperatures actually lead to a higher speed of sound.

When the temperature rises, for a given true airspeed, the Mach number will be lower than the critical Mach number derived at lower temperatures because the baseline changes due to the higher sound speed. Consequently, the critical Mach number itself does not increase or decrease independently; it varies with the conditions that affect the speed of sound.

Thus, the characterization of critical Mach number having no effect from temperature changes can be misleading. Significant changes in air temperature will impact the Mach number relative to the local speed of sound, and therefore influence the critical Mach number experienced by the aircraft in flight conditions.