India became the fourth country after the United States, Russia and China to develop and successfully test hypersonic technology . This indigenous technology will pave the way towards development of missiles travelling at six times the speed of sound (Mach 6). It successfully flight tested the Hypersonic Technology Demonstrator Vehicle using the indigenously developed scramjet propulsion system.

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Hypersonic vehicles fly faster than five times the speed of sound and can enable a new class of flight vehicles that enable faster access to space, rapid military response at long range, and faster means of commercial air travel.

Traditionally, rocket boosters have been used for hypersonic vehicles. Air-breathing engines have several advantages over rockets. Because the air-breathing hypersonic engine uses oxygen from the atmosphere, it eliminates the need to carry oxygen aboard the aircraft, thereby reducing significant vehicle weight.

Two propulsion systems specific to hypersonic flights include ramjet and scramjet

Scramjet engines uses hydrogen as fuel and the oxygen from the atmospheric air as the oxidiser. Conventional rockets carry fuel and liquid oxygen for propulsion, but a scramjet engine uses oxygen present in the atmosphere to burn the fuel. Air-breathing scramjet engines will lead to the use of lighter and smaller rockets which can carry much greater payload.

While the conventional rocket stages are burned up on re-entry into the atmosphere and are thus wasted, scramjet engine technology can lead to development of launch vehicles which can be reused after they are guided back to land on earth. They attain much higher velocity too.

Scramjet engines have use in other areas as well. They may be used in cruise missiles for greater speed and thrust. The use of air-breathing rocket engine technology is envisaged in civil aviation, too. Scramjet-powered aircraft may be developed which will be faster and will make air travel cheaper, as fuel cost is the most important factor in the cost of air travel now.

HYPERSONIC :
Hypersonic flight is one of the four speeds of flight. They are called the regimes of flight. The regimes of flight are subsonic, transonic, supersonic and hypersonic.
Vehicles that fly at hypersonic speeds are flying at six times the speed of sound. The speed of sound is about 768 miles per hour (1,236 kilometers per hour) at sea level. These speeds are referred to by Mach numbers. The Mach number is the ratio of the speed of the aircraft to the speed of sound. Flight that is faster than Mach 6 is hypersonic. Hypersonic includes speeds up to six times faster than the speed of sound, or Mach 6.