Classification of Mach regimes In 'Aviation'

Flying at high speeds is a dream that millions of people around the world not only is it a thrill to imagine travelling at supersonic speeds or even hypersonic speeds it's also tempting to imagine arriving at your destination faster how fast can you fly exactly here is a look at how the aerospace industry categorizes the speeds of light and the type of aircraft capable of achieving the speech.

Typically we measure the speed of an Aircraft by its Mach number which is velocity related to the speed of sound approximately 770 miles per hour 1239 km per hour at sea level Mach 1 is the speed of sound.

Four general categories define the speed of flight        

- Subsonic

- Transonic

- Supersonic

- Hypersonic

Each is relative to a Mach number

• Subsonic

At this speed and aircraft is travelling slower than the speed of sound less than about Mach 0.8 subsonic aircraft include everything that flies slowly including all general aviation aircraft such as the Cessna 172 ultra lights and even paraglides.

Commercial aircraft such as the Boeing 777 and Airbus 330 and smaller regional jets that have less than 100 seats are subsonic as well most older military jets also fall into the subsonic category examples include the

which was developed in the 1950 and flown by us Air force for 25 years

• Transonic

At this speed and aircraft is approaching the speed of sound but hasn't yet reached and surpassed Mach 1 at some place on the aircraft the speed will exceed Mac 1 while at other it will be less than Mach 1. There are handful of aircraft that fly deep in the Transonic regime including the Cessna citation X and the gulf stream G650.

The line between subsonic and transonic is blurry. There are even transonic flows on both of the subsonic commercial airliner examples mentioned above.

In some cases you can even see the shadow of the shock wave on the upper wing.

• Supersonic

At this speed, the entire aircraft experiencing supersonic airflow and traveling at speeds faster than Mach 1

Generally supersonic speeds range from Mach 1.2 to Mach 5 Boom's Overture will fly comfortably in the supersonic regime at Mach 2.2

Rockets such as the space shuttle fly at supersonic speeds immediately after liftoff and for about 45 seconds until about two minutes after lunch.

During this time, the shuttle accelerates from Mac 1 to Mac 5.

Many types of military aircraft are also capable of supersonic flight.

• Hypersonic

At this speed, an aircraft is travelling faster than Mach 5. Space shuttle which flies at hypersonic speeds in the Earth's upper atmosphere.

The reason for the distinction between supersonic and hypersonic is due to temperature changes.

At speed above Mach 5 most metals will melt or become so soft then they can't be used for any type of structure. As a result hypersonic aircraft must go to extreme measures for heat protection.

While it's challenging to imagine what happens to an aircraft at such temperatures here are two examples.

Aluminum will melt at approximately 1,200°F or 660°C and Steel will melt at approximately 2,500°F or 1,371°C.