Indian Missile Program Updates

Hypersonic Technology Demonstrator Vehicle (HSTDV)


From UPSC perspective, the following things are important :

Prelims level : Ramjet, Scramjet

Mains level : Indian missile program

The DRDO has successfully demonstrated the hypersonic air-breathing scramjet technology with the flight test of the Hypersonic Technology Demonstration Vehicle (HSTDV).

Take note of close dissimilarities between Ramjet and Scramjet engines.


  • HSTDV is an unmanned scramjet vehicle with a capability to travel at six times the speed of sound.
  • The scramjets are a variant of a category of jet engines called the air-breathing engines.
  • The ability of engines to handle airflows of speeds in multiples of the speed of sound gives it a capability of operating at those speeds.
  • Hypersonic speeds are those which are five times or more than the speed of sound.
  • The unit tested by the DRDO can achieve upto six times the speed of sound or Mach 6, which is well over 7000 km per hour or around two km per second.

Its development

  • The DRDO started on the development of the engine in the early 2010s.
  • The ISRO has also worked on the development of the technology and has successfully tested a system in 2016. DRDO too has conducted a test of this system in June 2019.
  • The special project of the DRDO consisted of contributions from its multiple facilities including the Pune headquartered Armament and Combat Engineering Cluster.

Back2Basics: Ramjet V. Scramjet

  • A ramjet is a form of air-breathing jet engine that uses the vehicle’s forward motion to compress incoming air for combustion without a rotating compressor.
  • Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites.
  • 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.
  • Ramjets work most efficiently at supersonic speeds around Mach 3 (three times the speed of sound) and can operate up to speeds of Mach 6.
  • However, the ramjet efficiency starts to drop when the vehicle reaches hypersonic speeds.
  • A scramjet engine is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion. Thus it is known as Supersonic Combustion Ramjet or Scramjet.

Get an IAS/IPS ranker as your 1: 1 personal mentor for UPSC 2024

Attend Now

Notify of
Inline Feedbacks
View all comments


Join us across Social Media platforms.

💥Mentorship New Batch Launch
💥Mentorship New Batch Launch