Conference Brochure for the Symposium on Applied Aerodynamics and Design of Aerospace Vehicles (SAROD) that is being organized biennially to share the experiences of specialists involved in a major aerospace vehicle design programme that is being pursued in India as well as abroad showcased the final configuration of the Hypersonic Technology Demonstration Vehicle (HSTDV).

Hypersonic air-breathing scramjet technology developed by the DRDO was first tested in 2020 using a proven solid rocket motor, which took it to an altitude of 30 kilometers (km), where the aerodynamic heat shields were separated at hypersonic Mach number.

DRDO is planning to test another round of HSTDV without the headshields this time. The program is called Technological demonstrator and the Production weaponised variant of the HSTDV will be one that is seen in the above image.

DRDO plans to have a workable production-ready HSTDV ready to commence user trials from 2024-25 onwards.

Hypersonic Technology Demonstrator Vehicle (HSTDV) – An Overview

The HSTDV is an unmanned scramjet demonstration aircraft for hypersonic speed flight. It is being developed as a carrier vehicle for hypersonic and long-range cruise missiles, and will have multiple civilian applications including the launching of small satellites at low cost. The HSTDV program is being run by the Defence Research and Development Organisation.

Hypersonic Technology Demonstrator Vehicle (HSTDV) – Successful Test by DRDO

1. HSTDV was tested at APJ Abdul Kalam testing range (Wheeler Island) in Odisha’s Balasore.
2. India is only the fourth country in the world after the US, Russia and China to develop and test the technology that will pave the way for missiles that will travel at six times the speed of sound.
3. The launch was done using Agni missile booster.
4. The Agni solid rocket booster launched the cruise vehicle to an altitude of 30 Km, at this altitude the aerodynamic heat shields were separated at hypersonic speed. In the next step, there was separation of launch vehicle and cruise vehicle.
5. Hypersonic combustion sustained and the cruise vehicle continued on its desired flight path at a velocity of six times the speed of sound (Mach 6), which is nearly 2 km, for more than 20 seconds.
6. Ethylene was the fuel used by the scramjet combustor.

Hypersonic Technology Demonstrator Vehicle (HSTDV) – Monitoring of the Successful test

The successful test of HSTDV was monitored using the following

1. Ship deployed in the Bay of Bengal to monitor the performance during the cruise phase of hypersonic vehicle. 
2. Electro-optical systems
3. Multiple tracking radars 
4. Electro-optical systems

Hypersonic Technology Demonstrator Vehicle (HSTDV) – Critical Technologies Tested Successfully

India joined an elite club of 3 other nations to have successfully tested HSTDV. The reason is due to the advancements that need to be made in developing critical technologies. The following critical technologies were successfully tested

1. Thermo-structural characterisation of high temperature materials
2. Separation mechanism at hypersonic velocities
3. Sustained combustion at Hypersonic flow
4. Use of scramjet propulsion for ignition
5. Aerodynamic configuration for hypersonic manoeuvers
6. Importantly, the air-intake of the HSTDV opened as planned once it left the launch vehicle.

Hypersonic Technology Demonstrator Vehicle (HSTDV) –  Advantages of successful test by DRDO

1. With this successful test of HSTDV mission, the Defence Research and Development Organisation (DRDO), said it has demonstrated capabilities for highly complex technology that will serve as the building block for NextGen Hypersonic vehicles and cruise missiles.
2. It can be used for launching satellites at low cost.
3. This test augurs well for the development of air-breathing in technologies in India.

Scramjet Engines

1. A scramjet (supersonic-combustion ramjet) is a ramjet engine in which the airflow through the engine remains supersonic, or greater than the speed of sound. Scramjet powered vehicles are envisioned to operate at speeds up to at least Mach 15.
2. Scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine
3. Scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion.
4. The scramjet is composed of three basic components: a converging inlet, where incoming air is compressed; a combustor, where gaseous fuel is burned with atmospheric oxygen to produce heat; and a diverging nozzle, where the heated air is accelerated to produce thrust. Unlike a typical jet engine, such as a turbojet or turbofan engine, a scramjet does not use rotating, fan-like components to compress the air; rather, the achievable speed of the aircraft moving through the atmosphere causes the air to compress within the inlet. As such, no moving parts are needed in a scramjet

Ramjet Engines

1. A ramjet, is a form of airbreathing jet engine that uses the engine’s forward motion to compress incoming air without an axial compressor or a centrifugal compressor.
2. A ramjet-powered vehicle, requires an assisted take-off like a rocket assist to accelerate it to a speed where it begins to produce thrust.
3. Ramjets work most efficiently at supersonic speeds around Mach 3 (2,300 mph; 3,700 km/h). This type of engine can operate up to speeds of Mach 6 (4,600 mph; 7,400 km/h).

Speed – Different Classification

While referring to missile technology or space technology, one would often come across different types of speed namely subsonic speed, supersonic speed and hypersonic speed.

The below table gives simple difference between the above 3 mentioned speeds in terms of mach number and kilometer/hour (Km/hr)

Speed Classification	Mach Number	Km/hr
Subsonic speed	< 0.8	< 980
Supersonic speed	1.2 – 5.0	1,470 – 6,126
Hypersonic speed	5.0 – 10.0	6,126 – 12,251

Frequently Asked Question – Hypersonic Technology Demonstrator Vehicle (HSTDV)

Q.1. What is hypersonic test demonstrator vehicle?

Ans. The HSTDV is an unmanned scramjet demonstration aircraft for hypersonic speed flight. It is being developed as a carrier vehicle for hypersonic and long-range cruise missiles, and will have multiple civilian applications including the launching of small satellites at low cost.

Q.2. What is technology demonstrator?

Ans. A technology demonstration or demonstrator model, informally known as a tech demo, is a prototype, rough example or an otherwise incomplete version of a conceivable product or future system, put together as proof of concept with the primary purpose of showcasing the possible applications, feasibility, performance and method of an idea for a new technology.

Q.3. Which country has become the recipient of hypersonic technology?

Ans. India has successfully test-fired Hypersonic Technology Demonstrator Vehicle (HSTDV), making it only the fourth country in the world after the US, China and Russia to develop and test the technology that will pave the way for missiles that will travel at six times the speed of sound.

Q.4. Is India working on hypersonic missile?

Ans. India is involved in developing a hypersonic cruise missile in cooperation with Russia. The system, known as the Brahmos II, is based on a supersonic cruise missile.

Q 5. Which country has fastest hypersonic missile?

Ans. Russia has the fastest hypersonic missile.