THE SCIENCE BEHIND STEALTH AIRCRAFT

THE SCIENCE BEHIND STEALTH AIRCRAFT To move deep into enemy territory by air or sea and remain invisible to the enemy eye is an air or navy commander's dream. Probably because of that, govern- ments across the world are spending billions of dollars in developing stealth capabilities for their forces. From the simple camouflage paints of the past to today's hi-tech electronic sensors and radars, stealth technology has come a long way. Stealth, put simply, is nothing but a design technique that reduces the enemy's ability to detect, track attack an aircraft or warship. THE WHAT AND HOW OF STEALTH TECHNOLOGY Stealth can simply be termed a mechanism to evade the enemy's detection systems. The radar system is key to understanding how stealth works. · The coating has microscopic pyramidal structure that maximizes the number of bounces a wave makes within the structure–with each bounce the radio wave loses energy and exits with lower signal strength. Radars send out a burst of radio signals that is reflected back by the object it strikes. The reflected signal is processed to determine the direction, size and position of the target. The more an aircraft reflects radio waves the better it is for detection. Stealth aircraft This is what engineers and scientists working on stealth technology try to dodge. Their main aim is to make the aircraft or warship or submarine invisible to radars. The two most important methods of achieving stealth are reshaping the surface of the aircraft so that it reflects away the signals sent by radars and coating the aircraft with materials that absorb radio signals. Deflection of radio waves Most aircraft are have a slightly rounded body which makes them a very efficient radar reflectors. Stealth aircraft are quite different, with very sharp edges and flat surfaces so that when a radar signal hits them the waves are reflected back at an angle that avoids detection. Normal aircraft Stealth aircraft Radio waves To add to the capability, stealth aircraft surfaces are coated with materials that absorb radar energy so that even if the radar signal is reflected back the 'radar signature' is no more than that of a bird. Radio signals Radar HISTORY OF STEALTH TECHNOLOGY War films are full of scenes where soldiers hide behind bushes while stealing up to an enemy base or where they paint their faces and wear uniform with colours similar to those of their surroundings to avoid detection. The thought behind stealth is centuries old but the usage of fighter jets and, subsequently, submarines prompted governments to look for new-age stealth features. During World War I, both the Germans and the British tried to develop stealth technology for their aircraft but with little success. In Radar following period, armed forces around the continued to work on the ide including attempts during World War II. The real development, however, came in the post-war period, during late 1950s, by the US air force. The US built a high-altitude reconnaissance aircraft. Since then, countries across the world have been trying to develop stealth technology. COUNTERMEASURES & LIMITATIONS The enemy can use multiple simultaneous detection points to detect the aircraft. Stealth aircraft are mostly designed to avoid reflecting a radar signal directly back towards the radar transmitter. If there are several receivers over a wide area, it's more likely that one would pick up the signal. Radar fitted on a stealth fighter to be used for aiming at enemy targets would give away its own position. Also, stealth aircraft can be tracked from high-altitude airborne radars. Stealth technology is expensive and so large-scale production is a problem. Also, the materials used require special and costly maintenance. Some experts believe stealth aircraft are vulnerable to detection by infrared systems, which rely on the natural heating of an aircraft's surface. Not all believe stealth fighter jets make the best fighter jets. Some militaries feel stealth technology affects manoeuvrability as they are less aerodynamic. Stealth technology is also vulnerable to multiple sensors used together, like infrared coupled with a high power radar. WHO HAVE STEALTH FIGHTERS? RUSSIA CHINA The US first got the idea of stealth fighters from a Russian scientist. It is developing the T-50 PAK FA-a fifth-generation stealth fighter prototype being built by Sukhoi, which would succeed its ageing fighter jet fleets. China's J-20 is a fifth-generation stealth fighter prototype which is expected to be fully developed in the next few years. T50 PAK FA J-20 SOUTH KOREA South Korea is working on Kai Kf-X, a fifth-generation multi-role fighter that includes powerful tracking and engagement facilities with inherent stealth features. US KAI Kf-X F-117 B-2 INDIA India and Russia are jointly developing a multi-role fighter aircraft with stealth capabilities. It would have features like stealth, supercruise speed and advanced sensors. India is also working on an Advanced Medium Combat Aircraft (AMCA)-a single-seat, twin-engine fifth-generation stealth multipurpose fighter. It is, however, still in the initial stages of development. India is also developing stealth features for its warships. JAPAN Japan is developing the Sunshin, which would be its first fifth-generation fighter aircraft. It is being manufactured by Mitsubishi Corp. F-22 F-35 Among the pioneers of stealth aircraft, it already has several of them, like the F-117, B-2, F-22 and F-35 Lightning II. It is working on the next generation of stealth fighters. AMCA Sunshin Iran, Turkey and Sweden are also working on stealth aircraft. Graphics by Yatish Asthana/Mint Compiled by Mayank Aggarwal/Mint