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Hypersonic Technology

  • 18 Oct 2021
  • 7 min read

Why in News

Recently, it has been reported that China tested a nuclear-capable hypersonic glide vehicle that circled the globe before speeding towards its target.

  • Several countries, including the US, Russia and China, are developing hypersonic missiles which travel at a speed five times that of sound.
  • Though slower than ballistic missiles, they are harder to intercept and can be manoeuvred.

Key Points

  • Implications for India:
    • Hypersonic technology developments, in the backdrop of growing US-China rivalry and a year-long standoff with Indian forces in eastern Ladakh, is certainly a threat for India's space assets along with the surface assets.
    • The offence system operating at these speeds would mean a requirement to develop defence systems at these speeds.
  • Hypersonic Speed and Technology:
    • About:
      • Hypersonic speeds are 5 or more times the Mach or speed of sound.
      • Mach Number: It describes an aircraft’s speed compared with the speed of sound in air, with Mach 1 equating to the speed of sound i.e. 343 metre per second.
    • Types (2):
      • Hypersonic cruise missiles: These are the ones that use rocket or jet propellant through their flight and are regarded as being just faster versions of existing cruise missiles.
      • Hypersonic Glide Vehicle (HGV): These missiles first go up into the atmosphere on a conventional rocket before being launched towards their target.
    • Technology Used: Most hypersonic vehicles primarily use the scramjet technology, which is a type of Air Breathing propulsion System.
      • This is extremely complex technology, which also needs to be able to handle high temperatures, making the hypersonic systems extremely costly.

Ballistic Missile vs Cruise Missile

Ballistic Missile

Cruise Missile

  • Travel in projectile motion and trajectory depends on gravity, air resistance and Coriolis Force.
  • Comparatively follows a straight trajectory of motion.
  • Leave the earth’s atmosphere and re enter it.
  • The flight path is within the earth’s atmosphere.
  • Long-range missiles (300 km to 12,000 km)
  • Short range missiles (range upto 1000 km)
  • E.g. Prithvi I, Prithvi II, Agni I, Agni II and Dhanush missiles.
  • E.g. BrahMos missiles

Classification of Missiles Based on Speed

Speed Range

Mach Number

Velocity in m/s

Subsonic

< 0.8

< 274

Transonic

0.8–1.2

274–412

Supersonic

1.2–5

412–1715

Hypersonic

5–10

1715–3430

High-hypersonic

10–25

3430–8507

  • Development of Hypersonic Technology in India:
    • India, too, is working on hypersonic technologies.
      • As far as space assets are concerned, India has already proved its capabilities through the test of ASAT under Mission Shakti.
    • Hypersonic technology has been developed and tested by both DRDO and ISRO.
    • Recently, DRDO has successfully flight-tested the Hypersonic Technology Demonstrator Vehicle (HSTDV), with a capability to travel at 6 times the speed of sound.
    • Also, a Hypersonic Wind Tunnel (HWT) test facility of the DRDO was inaugurated in Hyderabad. It is a pressure vacuum-driven, enclosed free jet facility that simulates Mach 5 to 12.

Air Breathing Propulsion System

  • About: These systems use atmospheric oxygen, which is available up to about 50 km of earth’s surface to burn the fuel stored on-board thereby making the system much lighter, more efficient and cost effective.
  • Examples of Air Breathing Propulsion System include the Ramjet, Scramjet, Dual Mode Ramjet (DMRJ).
  • Ramjet:
    • A ramjet is a form of air breathing jet engine that uses the vehicle's forward motion to compress incoming air for combustion without an axial compressor.
    • Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites.
    • Ramjets cannot produce thrust at zero airspeed; they cannot move an aircraft from a standstill.
    • A ramjet-powered vehicle, therefore, requires an assisted take-off, like a rocket assist, to accelerate it to a speed where it begins to produce thrust.
    • The ramjet works best at supersonic speeds and as the speed enters the hypersonic range, its efficiency starts to drop.
  • Scramjet:
    • A scramjet engine is an improvement over the ramjet engine as it operates at hypersonic speeds and allows supersonic combustion, which gives it its name — supersonic combustion ramjet, or scramjet.
    • 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,
      • A diverging nozzle where the heated air is accelerated to produce thrust. The exhaust gases are accelerated to hypersonic speeds using a divergent nozzle.
    • The speed at which the vehicle moves through the atmosphere causes the air to compress within the inlet. As such, no moving parts are needed in a scramjet, which reduces the weight and the number of failure points in the engine.
  • Dual Mode Ramjet (DMRJ):
    • The third concept is a mix of ramjet and scramjet, which is called DMRJ.
    • There is a need for an engine which can operate at both supersonic and hypersonic speeds.
    • A DMRJ is an engine design where a ramjet transforms into a scramjet over Mach 4-8 range, which means, it can operate in both the subsonic and supersonic combustor mode.

Source: IE

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