Comment: A 767 is rated at 0.8 Mach.

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A 767 is rated at 0.8 Mach.

A 767 is rated at 0.8 Mach. At sea level, 59 degrees (Mach standard air) Mach is 761 MPH. 0.8 standard air Mach is 608 MPH. The 767 airframe is rated at 0.86 Mach (654 MPH at sea level, 59 degree air temp.), and its engines are capable of exceeding its airframe Mach rating.

Turbine Aircraft engines will stall out at Mach, unless they are designed to exceed such. In order to exceed Mach an engine inlet must be variable, such as the Concord. These aircraft have what is known as a "CD" duct, convergent-divergent duct, that maintains airflow into the inlet when the sonic boom, reversing airflow, is encountered. It is found that many parts of the aircraft exceed Mach before the entire aircraft reaches such. Engine fan blades is one example of this, and a commercial aircraft engine will stall out before the whole aircraft reaches Mach speeds, UNLESS is is designed with CD ducted inlets, such as the Concord is.

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