Question

Which of the following instrument is used to indicate air speed corrected for compressibility effect?

• A. Altimeter
• B. Gyroscope
• C. Mach meter
• D. Pitot probe

Hint:

Above transonic speeds, compressibility effects make Mach number more useful than IAS.

Answer 1

The Correct Option is C

In aerospace engineering, understanding airspeed is crucial for navigation and safety. Various instruments are utilized to measure different aspects of flight conditions. One specific measurement is airspeed corrected for compressibility effects, which is critical at high speeds.

The Mach meter is the instrument specifically designed for this purpose. It measures the Mach number, which is the ratio of the speed of an aircraft to the speed of sound in the surrounding medium. Correcting airspeed for compressibility effects becomes important as an aircraft approaches and exceeds the speed of sound. This is because, at such speeds, changes in air pressure and density occur, affecting the accuracy of basic airspeed readings.

In contrast, other instruments serve different purposes:

• Altimeter: Measures altitude above sea level but does not consider airspeed or compressibility.
• Gyroscope: Provides information on orientation and stability, not airspeed.
• Pitot Probe: Typically measures dynamic air pressure to derive true airspeed but doesn't inherently correct for compressibility effects.

Therefore, for airspeed readings corrected for compressibility effects, the Mach meter is used.