Cheaper rockets, a reality with scramjet

The Indian Space Research Organisation (Isro) has achieved an important breakthrough with the development and successful test launch of a supersonic combustion ramjet (scramjet) engine last week. These engines mark a major advance on the existing rocket technology as they will ensure cheaper and more efficient use of rockets in aerospace programmes. Conventional rockets carry fuel and liquid oxygen for propulsion, but a scramjet engine uses oxygen present in the atmosphere to burn the fuel. Over 80% of the weight of a rocket in use now is taken up by the propellant, and much of the weight of the propellant is accounted for by oxygen. Air-breathing scramjet engines will lead to the use of lighter and smaller rockets which can carry much greater payload. Launch vehicles now carry only 2-4% of their lift-off mass into orbit. While the conventional rocket stages are burned up on re-entry into the atmosphere and are thus wasted, scramjet engine technology can lead to development of launch vehicles which can be reused after they are guided back to land on earth. They attain much higher velocity too.

The advantages of the use of such technology are obvious. It will help cut costs in the competitive space launch business by multiples. The Indian space programme is already known for its economy and efficiency and has attracted launch business from other countries. It was only recently that Isro launched 20 satellites at one go. The commercial prospects of the new technology are, therefore, very high. Scramjet engines have use in other areas as well. They may be used in cruise missiles for greater speed and thrust. The use of air-breathing rocket engine technology is envisaged in civil aviation, too. Scramjet-powered aircraft may be developed which will be faster and will make air travel cheaper, as fuel cost is the most important factor in the cost of air travel now. 

The strategic and commercial advantages of the new technology are likely to unfold in the coming years.What has been achieved by the technology demonstration has to be developed further for actual use. But the success is remarkable because the ignition and combustion at such high speed for six seconds is being compared to “lighting a candle in a hurricane condition and sustaining the flame” for that duration. India is the fourth country to test the scramjet technology in flight after the US, Russia and China. Future challenges involve increasing the time of combustion and making the engine work at higher speeds. It may take years for full development of a successful scramjet rocket engine but last Sunday’s success should give Isro the confidence that it can be achieved.