Mach number:-
Mach number (Ma or M) is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure. It is commonly used to represent the speed of an object when it is traveling close to or above the speed of sound.
where
is the Mach number
V is the relative velocity of the source to the medium and
a is the speed of sound in the medium
Mach number is named after:-
The Mach number is named after Austrian physicist and philosopher Ernst Mach, a designation proposed by aeronautical engineer Jakob Ackeret. Because the Mach number is often viewed as a dimensionless quantity rather than a unit of measure, with Mach, the number comes after the unit; the second Mach number is "Mach 2" instead of "2 Mach" (or Machs). This is somewhat reminiscent of the early modern ocean sounding unit "mark" (a synonym for fathom), which was also unit-first, and may have influenced the use of the term Mach. In the decade preceding faster-than-sound human flight, aeronautical engineers referred to the speed of sound as Mach's number, never "Mach 1."
In French, the Mach number is sometimes called the "nombre de Sarrau" ("Sarrau number") after Émile Sarrau, researching on explosions in the 1870s and 1880s.
Overview on mach number:-
Since the speed of sound increases as the temperature increases, the actual speed of an object traveling at Mach 1 will depend on the fluid temperature around it. Mach number is useful because the fluid behaves in a similar way at the same Mach number. So, an aircraft traveling at Mach 1 at 20°C or 68°F will experience shock waves in much the same manner as when it is traveling at Mach 1 at 11,000 m (36,000 ft) at -50°C or -58F, even though it is traveling at only 86% of its speed at higher temperature like 20°C or 68°F.
High-speed flow around objects:-
Flight can be roughly classified in six categories:-
they are:-
subsonic- >1.0 x mach number
transonic- 0.8-1.2 x times the mach number
sonic- 1.0 x mach number
supersonic- 1.2-5.0 x mach number
hypersonic- 5.0-10.0 x mach number
high-hypersonic- > 10.0 x times of mach number
mach planes are classified basing on the so called mach number
they are named as mach-1,mach-2,mach-3,mach-4,mach-5, and so on
the latest mach plane is a mach 9.8 whose velocity is 3 334.842 m / s
here is the mach 9.8 flight, it is a unmanned air vehicle
this is the fastest plane ever beyond limit
it goes to a maximum altitude of
110,000 feet.
it is automatic. Thanks to NASA, for this fastest mach plane ever
Critical mach number:-
In aerodynamics, the critical Mach number (Mcr) of an aircraft is the lowest Mach number at which the airflow over any part of the aircraft reaches the speed of sound.
For all aircraft in flight, the airflow around the aircraft is not exactly the same as the airspeed of the aircraft due to the airflow speeding up and slowing down to travel around the aircraft structure. At the Critical Mach number, local airflow in some areas near the airframe reaches the speed of sound, even though the aircraft itself has an airspeed lower than Mach 1.0. This creates a weak shock wave. At speeds faster than the Critical Mach number:
drag coefficient increases suddenly, causing dramatically increased drag
in aircraft not designed for transonic or supersonic speeds, changes to the airflow over the flight control surfaces lead to deterioration in control of the aircraft.
basically i love aeronautics that is why i posted this...........
to all lovers of aeronautics........
