India successfully tested a hypersonic missile-capable vehicle, which can reportedly move at 6x the speed of sound and is expected to be completely developed in 5 years. So what are hypersonic vehicles? How are they different from supersonic jets?
Crux of the Matter
Where Did The Launch Happen?
Defence Research and Development Organisation (DRDO) launched the HSTDV (Hypersonic Technology Demonstrator Vehicle) at 11:03 am on September 7, 2020, from Dr APJ Abdul Kalam Launch Complex at Wheeler Island, Odisha, India.
The HSTDV is an unmanned scramjet demonstration aircraft for hypersonic speed flight that was atop an Agni-I rocket, a short-range ballistic missile (high trajectory), and took an altitude of 18.6 miles and hypersonic velocity.
These aircrafts have a dual-use technology that helps them in acting as launch vehicles for hypersonic and long-range cruise missiles and for civilian purposes, like the launch of small satellites at low cost.
Subsonic v/s Supersonic
Subsonic planes like commercial planes are designed to fly slower than the speed of sound (below Mach 1, the unit of speed of sound). Supersonic planes like fighter jets break that sound barrier and produce a mini sonic boom or a sonic crack.
What Are Scramjets?
The scramjets or supersonic-combustion ramjets are a variant of jet engines called the “air breathing” engines. They can handle airflows of speeds in multiples of speed of sound, due to their capability of operating at those speeds.
Hypersonic speeds are 5x or more than the speed of sound. The HSTDV could achieve 6x the speed of sound or Mach 6 i.e 7000 kmph or 2kmps.
What’s The Technology Behind It?
Thrust is the force that moves any aircraft through the air and is generated by the propulsion system of the aircraft. Different propulsion systems develop thrust in different ways, but all thrust is generated via Newton’s third law of motion i.e every action there is an equal and opposite reaction.
In any propulsion system, a working fluid is accelerated by the system and the reaction to this acceleration produces a force on the system.
What’s Their Use?
Engineers use a thermodynamic analysis of the scramjet to predict thrust and fuel flow. As the scramjet uses external air for combustion, it is a more efficient way to push hypersonic flights within the atmosphere than a rocket, which must carry all of its oxygen. Even Turbojets get hotter on exceeding Mach 3.0.
Hypersonic Flights In The US
- Aerojet General X-8 (Mach 6)
- NASA X-43 (held fastest speed record for an unmanned vehicle twice in the Guinness Book at Mach 9.6)
- North American X-15 (world record for the highest speed ever recorded by a crewed, powered aircraft at Mach 6.7)
Hypersonic Vehicles Worldwide
- India-Russia’s BrahMos-II (Mach 7)
- Russia’s Avangard (Mach 20 – 27) is one of their 6 new strategic weapons.
- China’s DF-ZF (Mach 10) is a part of their military build-up.
- In April 1961, Russian Major Yuri Gagarin became the first human to travel at hypersonic speed, during the world’s first piloted orbital flight. Soon after, in May 1961, Alan Shepard became the first American and second person to achieve hypersonic flight when his capsule reentered the atmosphere at a speed above Mach 5.
- Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. The Mach number is named after Austrian physicist and philosopher Ernst Mach.
- BrahMos-II is a hypersonic cruise missile currently under joint development by Russia’s NPO Mashinostroyenia and India’s DRDO, which have together formed BrahMos Aerospace Private Limited. The name BrahMos is a portmanteau formed from the names of two rivers, the Brahmaputra of India and the Moskva of Russia.