The Defence Research and Development Organisation (DRDO) has successfully completed the initial test of the indigenously developed Hypersonic Technology Demonstrator Vehicle (HSTDV), along with other technologies. The HSTDV project under DRDO’s supervision is designed to cater to both military and civilian applications and is set to mark a significant leap in India’s defense capabilities.
Hypersonic Technology Demonstrator Vehicle: Overview
The Hypersonic Technology Demonstrator Vehicle (HTDV) is an unmanned scramjet demonstration aircraft, conceived and developed for hypersonic speed flight. Boasting a cruising speed of 6 Mach, it can scale up to an altitude of 32.5 kilometres within just 20 seconds. The dual-purpose technology offers a low-cost solution for launching satellites and is potentially utilizable for future long-range cruise missiles like Brahmos 2. The development process receives international assistance from countries such as Israel, UK and Russia.
Scramjet Engine Technology Demonstrator
Satellites, as of now, are propelled into orbit by multi-staged satellite launch vehicles, which are non-reusable (expendable). These vehicles carry an oxidiser along with fuel for combustion, thereby producing thrust. Approximately 70% of propellant in today’s launch vehicles is made up of oxidiser. The launch vehicles designed for one-time use have low efficiency as they can ferry only 2-4% of their lift-off mass to orbit. The high expense of these vehicles has triggered a global effort to lower the launch cost, making the next-generation launch vehicles adapt propulsion systems that utilize atmospheric oxygen during their atmospheric flight, significantly reducing the total propellant required.
Air-Breathing Engines: Ramjet, Scramjet and Dual Mode Ramjet (DMRJ)
Air-breathing engines are being developed by various space agencies worldwide and can essentially be categorised into three types: Ramjet, Scramjet and Dual Mode Ramjet (DMRJ). A Ramjet engine uses the vehicle’s forward motion to compress incoming air for combustion without a rotating compressor.
However, Ramjets work most efficiently at supersonic speeds around Mach 3 and can operate up to speeds of Mach 6. When the vehicle reaches hypersonic speeds, the ramjet efficiency starts to decrease. Contrarily, a scramjet engine is an improvement over the ramjet engine as it operates efficiently at hypersonic speeds and allows supersonic combustion, hence named Supersonic Combustion Ramjet, or Scramjet.
Comparison of Different Air-Breathing Engines
| Type | Efficient Operation Speed | Additional Characteristics |
|---|---|---|
| Ramjet | Mach 3 to Mach 6 | Requires assisted take-off like a rocket assist |
| Scramjet | Hypersonic Speeds | Allows supersonic combustion |
| Dual Mode Ramjet (DMRJ) | Mach 4-8 range | Can efficiently operate both in subsonic and supersonic combustor modes |
Dual Mode Ramjet (DMRJ): An Advanced Jet Engine
Lastly, the Dual Mode Ramjet (DMRJ) is a type of jet engine where a ramjet transforms into scramjet over Mach 4-8 range. Effectively, this means it can effectively operate both in subsonic and supersonic combustor modes.
