ISRO’s supersonic combustion ramjet engine

The test launch of ISRO’s supersonic combustion ramjet engine — or scramjet for short — is a tiny but very important step which will give the Indian aerospace industry a competitive edge in the future. Conventional rockets carry fuel and liquid oxygen, which make up about three quarters of launch weight. A large proportion of that is liquid oxygen. If the engine breathed atmosphere oxygen instead of carrying lox, the payload capacity of the vehicle would increase dramatically. Besides, while conventional rocket stages are consumables, jettisoned after use to burn up on re-entry, air-breathing engines can be designed to be reusable, gliding or parachuting back to earth when expended.

Traditionally the province of government programmes to secure strategic advantage and national prestige, space is turning into a business, a competitive space. The Indian space programme has earned the world’s admiration on precisely this count, encashing imagination and technical ingenuity to slash costs and increase competitiveness in the launch vehicle market. Reusable vehicles with big payloads will cut launch costs and widen margins. In defence, the next generation of cruise missiles is likely to be powered by scramjets that reach hypersonic speeds. However, civil aviation could commercialise air-breathing rocket engine technology even earlier than the space industry. It has a greater incentive and a bigger market. Intercontinental flights which use scramjets to reach hypersonic speeds at the edge of space would cut travel time by a factor in the range of a fifth to an eighth. Long-haul international flights would take no longer than domestic flights do now.
India is now one of only four countries to work on scramjets. ISRO has gained early mover advantage in a technology that is expected to be deployed rapidly in several sectors of aerospace. In terms of strategic and business advantage, the benefits will be enormous.