India could develop hypersonic cruise missiles powered by air-breathing scramjet engines in about four years, a top government officer said on condition of anonymity

India on Monday took the first steps towards developing a new class of ultra-modern weapons that can travel six times faster than the speed of sound (Mach 6) and penetrate any missile defence, with the Defence Research and Development Organisation (DRDO) carrying out a successful flight test of the hypersonic technology demonstrator vehicle (HSTDV) for the first time from a launch facility off the Odisha coast.

Only the United States, Russia and China have developed technologies to field fast-manoeuvring hypersonic missiles that fly at lower altitudes and are extremely hard to track and intercept. Mach 6 translates into a speed of 7,408 kmph.

India could develop hypersonic cruise missiles powered by air-breathing scramjet engines in about four years, a top government officer said on condition of anonymity.

“The DRDO has successfully demonstrated the hypersonic air-breathing scramjet technology with the flight test of HSTDV at 1103 hours from Dr APJ Abdul Kalam launch complex at Wheeler Island off the coast of Odisha on Monday,” the defence ministry statement said.

An improvement over the ramjet technology, the scramjet engine operates efficiently at hypersonic speeds and allows supersonic combustion. Hypersonic missiles travel at speeds in excess of Mach 5.

Experts say that such vehicles are launched on rockets before they detach and move towards their target in the upper atmosphere. They can be steered to add unpredictability in an attack and because they follow a flat and low trajectory, it is hard to detect them early with radar.

“Congratulations to DRDO India for successful flight of the Hypersonic Test Demonstration Vehicle today. The scramjet engine developed by our scientists helped the flight achieve a speed 6 times the speed of sound! Very few countries have such capability today,” Prime Minister Narendra Modi tweeted.

The hypersonic cruise vehicle was launched using a proven solid rocket motor that took it to an altitude of 30km, where the aerodynamic heat shields were separated at a hypersonic Mach number, the statement said.

“The cruise vehicle separated from the launch vehicle and the air intake opened as planned. The hypersonic combustion sustained and the cruise vehicle continued on its desired flight path at a velocity of six times the speed of sound or nearly 2 km/second for more than 20 seconds,” the statement said. The first test of the HSTDV in June 2019 failed to meet mission parameters.

Developing hypersonic missiles will require the cruise vehicle to travel at speeds above Mach 6 for a few hundred seconds for the weapon to strike its target, said a second official, requesting anonymity.

“Critical events like fuel injection and auto ignition of scramjet demonstrated technological maturity. The scramjet engine performed in a textbook manner,” the statement said.

The parameters of launch and cruise vehicle, including the scramjet engine, were monitored by multiple tracking radars, electro-optical systems and telemetry stations, with the engine working efficiently at high dynamic pressure and very high temperature, it added.

A warship was deployed in the Bay of Bengal to monitor the performance during the cruise phase of the hypersonic vehicle. All the performance parameters indicated a “resounding success” of the mission, the statement said.

“This marks a technological breakthrough for the country. The successful mission will enable us to develop many more critical technologies and pave the way for hypersonic vehicle development,” said DRDO chief G Satheesh Reddy.

The flight test has proven a raft of critical technologies including aerodynamic configuration for hypersonic manoeuvres, use of scramjet propulsion for ignition and sustained combustion at hypersonic flow, thermo-structural characterisation of high temperature materials and separation mechanism at hypersonic velocities, the defence ministry said.

With hypersonic vehicles being key to defeating missile defences, the successful flight of the technology demonstrator vehicle is an important milestone, said Air Vice Marshal Manmohan Bahadur (Retd), additional director general, Centre for Air Power Studies.

“This has been some time in the making and the challenge now is to make a time-bound transition to the prototype testing phase. China is quite ahead in hypersonic tech and India cannot afford to lag behind,” Bahadur said.

The dual-use hypersonic technology has non-military applications too – it can be used for launching satellites and developing commercial planes, experts said.

Defence minister Rajnath, who spoke with scientists associated with the critical project, congratulated the DRDO on the “landmark achievement” towards realising Prime Minister Narendra Modi’s vision of “Atmanirbhar Bharat”.

“The DRDO has today successfully flight tested the Hypersonic Technology Demonstrator Vehicle using the indigenously developed scramjet propulsion system. With this success, all critical technologies are now established to progress to the next phase,” the defence minister wrote on Twitter.

Reddy congratulated the scientists, researchers and other personnel associated with the mission for their “resolute and unwavering efforts” towards strengthening the country’s defence capabilities.