4.5-generation fighter aircraft as fourth-generation jet fighters that have been upgraded with AESA radar, high-capacity data-link, enhanced avionics, and "the ability to deploy current and reasonably foreseeable advanced armaments". Contemporary examples of 4.5-generation fighters are the Sukhoi Su-30SM/Su-34/Su-35, the J-15B/J-16 claimed to have AESA, the Chengdu J-10C, the Mikoyan MiG-35, the Eurofighter Typhoon, the Dassault Rafale, the Saab JAS 39 Gripen, the Boeing F/A-18E/F Super Hornet, the Lockheed Martin F-16E/F/V Block 70/72, McDonnell Douglas F-15E/EX Strike Eagle/Eagle II, HAL Tejas MK1A, JF-17 block III and the Mitsubishi F-2. Characteristics Performance Whereas the premier third-generation jet fighters (e.g., the F-4 and MiG-23) were designed as interceptors with only a secondary emphasis on maneuverability, interception has been relegated to a secondary role in the fourth generation, with a renewed emphasis on close-range dogfighting and maneuverability. While the trade-offs involved in combat aircraft design are again shifting towards beyond visual range (BVR) engagement, the management of the advancing environment of numerous information flows in the modern battlespace, and low-observability, arguably at the expense of maneuvering ability in close combat, the application of thrust vectoring provides a way to maintain it, especially at low speed. Key advances contributing to enhanced maneuverability in the fourth generation include high engine thrust, powerful control surfaces, and relaxed static stability (RSS), this last enabled via "fly-by-wire" computer-controlled stability augmentation. Air combat manoeuvring also involves a great deal of energy management to maintain speed and altitude under rapidly changing flight conditions. Fly-by-wire Early fourth-generation fighters like the F-15 Eagle and F-14 Tomcat retained electromechanical flight hydraulics. One of the innovations on fourth-generation jet fighters is FBW, while generation 4.5 introduced AESA radar. The General Dynamics YF-16, eventually developed into the F-16 Fighting Falcon, was the world's first aircraft intentionally designed to be slightly aerodynamically unstable. This technique, called RSS, was incorporated to further enhance the aircraft's performance. Most aircraft are designed with positive static stability, which induces an aircraft to return to its original attitude following a disturbance. However, positive static stability, the tendency to remain in its current attitude, opposes the pilot's efforts to maneuver. An aircraft with negative static stability, though, in the absence of control input, will readily deviate from level and controlled flight. An unstable aircraft can therefore be made more maneuverable. Such a 4th generation aircraft requires a computerised FBW flight control system (FLCS) to maintain its desired flight path. Some late derivatives of