It will enable development of hypersonic missiles which can travel at six times the speed of sound. A scramjet engine (supersonic-combustion ramjet) is one which can operate at hypersonic speed. A Hypersonic Vehicle can be an airplane, missile, or spacecraft

India on Friday flight-tested a hypersonic technology demonstration vehicle (HSTDV) from the Abdul Kalam Island off the Odisha coast paving way for development of hypersonic cruise missiles. Developed by the Defence Research and Development Organisation (DRDO), the hypersonic air-breathing scramjet technology was put to test for the second time in the last three years.

Defence sources said though the mission did not meet all parameters, some critical events including auto-ignition of the scramjet, aerodynamic configuration for hypersonic manoeuvres and thermo-structural characterisation of high-temperature materials, were validated.

Mounted on a solid rocket motor, the cruise vehicle was tested to achieve the desired flight path at a velocity of six times the speed of sound (nearly 02 km/second) apart from the separation mechanism at hypersonic velocities. During the first test on June 12, 2019, the cruise vehicle was mounted on an Agni-I solid rocket motor, which took it to an altitude of 30 km, where the aerodynamic heat shields were separated at hypersonic Mach number.

A defence official said, this time, a different flight path was planned for the vehicle and accordingly in mid-air, the scramjet engine was auto-ignited to propel the cruise vehicle at Mach 6. When asked whether the test was successful, he said, “The DRDO is analysing the data generated during the test.”

The one tonne, 5.6 metre long air vehicle features a flattened octagonal cross-section with mid-body stub-wings and raked tail fins and a 3.7-meter rectangular section air intake. The scramjet engine has been integrated in the cruise vehicle under the mid-body, with the aft-body serving as part of the exhaust nozzle. The engine worked at high dynamic pressure and at very high temperature.

Defence sources said the cruise vehicle is being developed as a carrier for hypersonic and long-range cruise missiles. It will also have multiple civilian applications including the launching vehicle of small satellites at low cost.