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The Mach number is named after the physicist and philosopher Ernst Mach [3] according to a proposal by the aeronautical engineer Jakob Ackeret in 1929. [4] The word Mach is always capitalized since it derives from a proper name, and since the Mach number is a dimensionless quantity rather than a unit of measure, the number comes after the word Mach; the second Mach number is Mach 2 instead of ...
Mach number is more useful, and most high-speed aircraft are limited to a maximum operating Mach number, also known as M MO. For example, if the M MO is Mach 0.83, then at 9,100 m (30,000 ft) where the speed of sound under standard conditions is 1,093 kilometres per hour (590 kn), the true airspeed at M MO is 906 kilometres per hour (489 kn).
In aerodynamics, the critical Mach number (Mcr or M*) of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it. [1] At the lower critical Mach number, airflow around the entire aircraft is subsonic. Supersonic aircraft such as the Concorde and combat ...
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. [1] The exact range of speeds depends on the object's critical Mach number, but transonic flow is seen at flight speeds close to the speed of sound (343 m/s at sea level), typically between Mach 0.8 and 1.2.
Total air temperature is an essential input to an air data computer in order to enable the computation of static air temperature and hence true airspeed. The relationship between static and total air temperatures is given by: where: static air temperature, SAT (kelvins or degrees Rankine) total air temperature, TAT (kelvins or degrees Rankine)
For example, Concorde cruised at 1354 mph, or 7.15 million feet per hour, with its engines giving an SFC of 1.195 lb/(lbf·h) (see below); this means the engines transferred 5.98 million foot pounds per pound of fuel (17.9 MJ/kg), equivalent to an SFC of 0.50 lb/(lbf·h) for a subsonic aircraft flying at 570 mph, which would be better than even ...
So the regime of flight from Mcrit up to Mach 1.3 is called the transonic range. [citation needed] Northrop X-4 Bantam (Mach 0.9) — Supersonic [1.2–5) 921–3,836 mph (1,482–6,173 km/h; 412–1,715 m/s) The supersonic speed range is that range of speeds within which all of the airflow over an aircraft is supersonic (more than Mach 1).
Supercritical airfoils feature four main benefits: they have a higher drag-divergence Mach number, [21] they develop shock waves farther aft than traditional airfoils, [22] they greatly reduce shock-induced boundary layer separation, and their geometry allows more efficient wing design (e.g., a thicker wing and/or reduced wing sweep, each of which may allow a lighter wing).