According to reports, only the United States and Russia have similar facilities. In general, Mach 5 is considered the differentiating threshold between supersonic and hypersonic wind tunnels. In September this year, the DRDO made a huge technological breakthrough when it successfully tested its hypersonic technology demonstrator vehicle (HSTDV)

Defence Minister Rajnath Singh, on Saturday, inaugurated the Defence Research and Development Organisation's (DRDO) state-of-the-art Hypersonic Wind Tunnel (HWT) test facility placing India in a select group of nations with the technology. 

According to reports, only the United States and Russia have similar facilities. The indigenously-developed facility has the capability to simulate hypersonic airflow and will prove crucial in India's quest to develop futuristic aerospace and defence technologies. 

How Does A Wind Tunnel Work?

Simply put, a wind tunnel enables one to carry out testing of aerospace technologies without actually having to test them in real-life environments. The practice of understanding how airflow affects the performance of a cruise missile, a rocket or an airplane is known as aerodynamics. A wind tunnel then, essentially works off a simple idea – if one cannot collect air flow data when a projectile in this the sky, why not have the airflow past the stationary projectile while it's on the ground?

In a rudimentary sense, a wind tunnel is just a large pipe that wraps around in a circle with a fan located in its centre. When the fan is turned on, air is blown through the pipe. However, in order to control the speed of airflow, the pipe is made narrower and wider at different sections. The narrower the pipe, the faster the air must flow to move through it. 

In general, Mach 5 is considered the differentiating threshold between supersonic and hypersonic wind tunnels. However, there exist hypersonic wind tunnels capable of simulating airflow at much greater speeds up to Mach 11.

'A New Class of Military Threat''

In light of the concerted focus on hypersonic technology by militaries across the world, a hypersonic wind tunnel is critical to configuring how a projectile could withstand immense temperatures and air-flow mid-flight. In September this year, the DRDO made a huge technological breakthrough when it successfully tested its hypersonic technology demonstrator vehicle (HSTDV) powered by a scramjet engine. 

Although not a weapon itself, the successful test flight of the HSTDV was a significant milestone in the nation's quest to develop hypersonic and long-range cruise missiles. The scramjet engine - an upgrade on the ramjet engine - enables supersonic combustion, allowing it to operate efficiently at speeds much greater than Mach 3 (supersonic speeds). The HSTDV can achieve cruise speeds of up to Mach 6 and rise to an altitude of 32.5km in just 20 seconds. 

The American think-tank, RAND Corp, has called hypersonic missiles “a new class of military threat.” Capable of reaching speeds in excess of 5,000 km per hour while retaining manoeuvrability, hypersonic missiles can effectively penetrate missile defence systems and drastically reduce the time an adversary has to respond to an attack. 

However, the technology has several civilian applications as well. It is believed that the development of the scramjet engine will allow India to launch small satellites into orbit at low cost. Currently, India has to rely extensively on the facilities of other nations in this regard.