After US, Russia and European Space Agency, India on Sunday successfully test-fired its futuristic Scramjet Rocket Engine that will help in ISRO’s bid to design air-breathing engines
Mach 6
Speed at which rocket travelled with two Scramjet engines
3,277 kg
Rocket weight at lift-off
5 minutes
Total flight time out of which Scramjet engines worked for 5 seconds

Functioning
Super Sonic Combustion RAM Jet (Scramjet) uses hydrogen as fuel and takes in oxygen from the atmosphere as oxidizer. Usually rockets carry both fuel and oxidiser for combustion. It reduces the weight of the vehicle during lift-off by more than half, enabling it to carry heavier payloads into orbit. It’ll cut the launch cost several-fold.

• Scramjet engines to make rockets launches cheaper.
• Theoretically, technology can help an aircraft reach US in two to three hours.
The successful testing of scramjet, or air breathing engine, by India is a baby step in space transportation and would take more than a decade to have such an engine to power a full-fledged rocket.

The testing of the scramjet engine is part of India’s Make in India programme and Indian Space Research Organisation (ISRO) has developed several technologies like a reusable launch vehicle and others as a part of this scheme.

Benefits of Scramjet Technology
Currently Indian rockets carry a huge quantity of oxygen — say 200 tons in a geosynchronous satellite launch vehicle (GSLV) — which gets burnt during the atmospheric flight phase of the rocket.

The scramjet engine will suck the atmospheric oxygen and use that to burn the fuel. As a result the weight of the rocket will come down drastically which in turn can be used to increase the rocket’s carrying capacity. The cost of rocket will also come down.
The scramjet engine can be used to augment ISRO’s reusable launch vehicle.
With this flight, critical technologies such as ignition of air breathing engines at supersonic speed, holding the flame at supersonic speed, air intake mechanism and fuel injection systems have been successfully demonstrated.

The scramjet engine designed by ISRO uses hydrogen as fuel and the oxygen from the atmospheric air as the oxidiser.

This flight demonstration of a hypersonic combustion ramjet engine using atmospheric oxygen in a portion of its journey is a major step for Isro in its pursuit of a space transportation system.

The experimental mission was the first experiment of Isro’s Dual Mode Ramjet (DMRJ) engine, which uses hydrogen as fuel and air from the atmosphere as the oxidiser, at hypersonic (Mach 5 or more — speeds of five times the speed of sound and more) conditions. The programme, with an ongoing one for developing a re-usable launch vehicle, would position the organisation as a major space fare agency, with the ability to offer low-cost access to space in the long term.

Most of the current launch vehicles are designed for one-time use and are expensive. Further, their efficiency, in terms of payload to lift-off mass, is barely two to four per cent. In current rocket technology, 85 per cent of the lift-off mass is the propellant. And, 70 per cent of the latter is the oxidiser. The next generation of launch vehicles will have to use propulsion systems which can utilise atmospheric air.

The ultimate goal is developing a single stage-to-orbit (SSTO) launch vehicle configuration, to finally make access to space a routine affair.
One of the concepts for air-breathing technology being studied worldwide is a ramjet. This uses the vehicle’s forward motion to compress incoming air for combustion. Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites. Ramjets cannot move an aircraft from a standstill. Such a vehicle still needs an assisted take-off like a rocket assist to accelerate to a speed where it begins to produce thrust.

Another concept is the 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 exhaust gases are then accelerated to hypersonic speeds.

While this is conceptually simple, implementation is limited by extreme technical challenges. When the vehicle is within the atmosphere, fuel must be injected, mixed, ignited, and burned within milliseconds. Worldwide efforts are on to achieve powered flight using scramjet engines.

The third concept is a mix of ramjet and scramjet, 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.