تحويل سرعة الصوت إلى ماخ: الطيران العسكري والتجاري والهندسة الفضائية

Mach number is defined as the ratio of an object's speed to the speed of sound in the surrounding medium at that location. Mach 1.0 means traveling at exactly the speed of sound; Mach 2.0 means traveling at twice the speed of sound. The speed of sound at sea level in standard conditions (15°C) is 661.47 knots (340.29 m/s). However, the speed of sound decreases with altitude because temperature decreases. At 35,000 feet where commercial aircraft cruise (-56.5°C), the speed of sound is only 573 knots. Therefore, an aircraft maintaining Mach 0.85 at sea level travels at 562 knots, but the same Mach 0.85 at 35,000 feet equals only 487 knots true airspeed—demonstrating why Mach number is more useful than true airspeed for describing aerodynamic behavior.

Mach number directly correlates with aerodynamic behavior and structural stresses experienced by aircraft. Aerodynamic phenomena like shock wave formation, compressibility effects, and shock-boundary layer interactions depend on Mach number, not absolute airspeed. An aircraft at Mach 0.95 experiences transonic aerodynamic effects regardless of whether it's flying at sea level or 35,000 feet. Additionally, aircraft structural limits are defined in Mach terms because the dynamic pressure and thermal effects depend on the relationship between airspeed and the speed of sound. For example, the Concorde had a maximum operating speed of Mach 2.04, not a fixed airspeed, because the aerodynamic heating and structural stresses were Mach-dependent. Using Mach numbers allows engineers to design aircraft that operate safely across multiple altitudes and temperature conditions.