Important Facts For Prelims
Air Breathing Engines
- 10 Dec 2022
- 3 min read
Why in News?
Recently, the Indian Space Research Organisation (ISRO) has successfully conducted the hot test of Scramjet Engine, a type of Air Breathing Engine.
- India is the fourth country to demonstrate the flight testing of a Scramjet Engine.
What are Air Breathing Engines?
- About:
- An air-breathing engine is an engine that takes in air from its surroundings in order to burn fuel.
- All practical air breathing engines are internal combustion engines that directly heat the air by burning fuel, with the resultant hot gases used for propulsion via a propulsive nozzle.
- A continuous stream of air flows through the air-breathing engine. The air is compressed, mixed with fuel, ignited and expelled as the exhaust gas.
- Thrust produced by a typical air-breathing engine is about eight times greater than its weight.
- The thrust results from the expulsion of the working gases from the exhaust nozzle.
- Types:
- 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 a rotating compressor.
- Ramjets work most efficiently at supersonic speeds but they are not efficient at hypersonic speeds.
- Scramjet: A scramjet engine is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion.
- Dual Mode Ramjet (DMRJ): A dual mode ramjet (DMRJ) is a type of jet engine where a ramjet transforms into a scramjet over Mach 4-8 range, which means it can efficiently operate both in subsonic and supersonic combustion modes.
- 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 a rotating compressor.
| 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 |
- Significance:
- Air Breathing Engine provides a technological key for low-cost space transportation system.
- The technology is an important step towards developing reusable launch vehicles.
- Basically, of the total launch vehicle mass, 86% is propellant mass in the launch vehicle. Out of that propellant, 70% is oxidiser.
- These engines can reduce nearly 70% of the propellent carried in the vehicles as these systems use atmospheric oxygen, which is available up to a height of 50km from the earth’s surface.
