Mikoyan MiG-29 with a USAF F-16 Fighting Falcon
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, 4th generation aircraft try to reach an equilibrium, with most designs, such as the
F-14 and the
F-15, being able to execute
beyond visual range (BVR) interceptions while remaining highly maneuverable in case the platform and the pilot find themselves in a close range
dogfight. While the trade-offs involved in combat aircraft design are again shifting towards 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. on a mission near Iraq in 2003
Fly-by-wire inverted above an
F-14 shown here is an example of fly-by-wire control. Fly-by-wire is a term used to describe the computerized automation of flight control surfaces. Early fourth-generation fighters like the F-15 Eagle and F-14 Tomcat retained electromechanical flight hydraulics. Later fourth-generation fighters would make extensive use of fly-by-wire technology. 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 relaxed static stability (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 computerized FBW
flight control system (FLCS) to maintain its desired flight path. Some late derivatives of the early types, such as the F-15SA Strike Eagle for Saudi Arabia, have included upgrading to FBW.
Thrust vectoring engine view
Thrust vectoring was originally introduced in the
Hawker Siddeley Harrier for vertical takeoff and landing, and pilots soon developed the technique of "viffing", or vectoring in forward flight, to enhance manoeuvrability. The first fixed-wing type to display enhanced manoeuvrability in this way was the
Sukhoi Su-27, the first aircraft to publicly display thrust vectoring in pitch. Combined with a thrust-to-weight ratio above unity, this enabled it to maintain near-zero airspeed at high angles of attack without stalling, and perform novel aerobatics such as
Pugachev's Cobra. The
three-dimensional TVC nozzles of the
Sukhoi Su-30MKI are mounted 32° outward to the longitudinal engine axis (i.e. in the horizontal plane) and can be deflected ±15° in the vertical plane. This produces a
corkscrew effect, further enhancing the turning capability of the aircraft. The MiG-35 with its RD-33OVT engines with the vectored thrust nozzles allows it to be the first twin-engined aircraft with vectoring nozzles that can move in two directions (that is, 3D TVC). Other existing thrust-vectoring aircraft, like the
F-22, have nozzles that vector in one direction. The technology has been fitted to the
Sukhoi Su-47 Berkut and later derivatives. The U.S. explored fitting the technology to the
F-16 and the
F-15, but did not introduce it until the fifth generation arrived.
Supercruise , which features
supercruise Supercruise is the ability of a jet aircraft to cruise at supersonic speeds without using an
afterburner. Maintaining supersonic speed without afterburner use saves large quantities of fuel, greatly increasing range and endurance, but the engine power available is limited and drag rises sharply in the transonic region, so drag-creating equipment such as external stores and their attachment points must be minimised, preferably with the use of internal storage. The
Eurofighter Typhoon can cruise around Mach 1.2 without afterburner; its maximum level speed without reheat is Mach 1.5. An
EF T1 DA (Development Aircraft trainer version) demonstrated supercruise (1.21 M) with 2 SRAAM, 4 MRAAM and drop tank (plus 1-tonne flight-test equipment, plus 700 kg more weight for the trainer version) during the Singapore evaluation.
Avionics cockpit
Avionics can often be swapped out as new technologies become available; they are often upgraded over the lifetime of an aircraft. For example, the F-15C Eagle, first produced in 1978, has received upgrades in 2007 such as AESA radar and
joint helmet-mounted cueing system, and is scheduled to receive a 2040C upgrade to keep it in service until 2040.
active electronically scanned array radar The primary sensor for all modern fighters is radar. The U.S. fielded its first modified F-15Cs equipped with
AN/APG-63(V)2 AESA radars, which have no moving parts and are capable of projecting a much tighter beam and quicker scans. Later on, it was introduced to the
F/A-18E/F Super Hornet and the block 60 (export) F-16 also, and will be used for future American fighters. France introduced its first indigenous AESA radar, the
RBE2-AESA built by Thales in February 2012 for use on the Rafale. The RBE2-AESA can also be retrofitted on the Mirage 2000. A European consortium GTDAR is developing an AESA
Euroradar CAPTOR radar for future use on the Typhoon. For the next-generation F-22 and F-35, the U.S. will use
low probability of intercept capacity. This will spread the energy of a radar pulse over several frequencies, so as not to trip the
radar warning receivers that all aircraft carry. /
laser rangefinder device. In response to the increasing American emphasis on radar-evading stealth designs, Russia turned to alternate sensors, with emphasis on Infrared Search and Track (IRST) sensors, first introduced on the American
F-101 Voodoo and
F-102 Delta Dagger fighters in the 1960s, for detection and tracking of airborne targets. These measure IR radiation from targets. As a passive sensor, it has limited range, and contains no inherent data about position and direction of targets—these must be inferred from the images captured. To offset this, IRST systems can incorporate a
laser rangefinder in order to provide full
fire-control solutions for cannon fire or for launching missiles. Using this method, German
MiG-29 using helmet-displayed IRST systems were able to acquire a
missile lock with greater efficiency than USAF
F-16 in wargame exercises. IRST sensors have now become standard on Russian aircraft. A computing feature of significant tactical importance is the datalink. All modern European and American aircraft are capable of sharing targeting data with allied fighters and AWACS planes (see
JTIDS). The Russian
MiG-31 interceptor also has some datalink capability. The sharing of targeting and sensor data allows pilots to put radiating, highly visible sensors further from enemy forces, while using those data to vector silent fighters toward the enemy.
Stealth uses jet
intakes that conceal the front of the jet engine (a strong radar target) from radar. Many important radar targets, such as the wing, canard, and fin leading edges, are highly swept to reflect radar energy well away from the front sector. While the basic principles of shaping aircraft to avoid radar detection were known since the 1960s, the advent of
radar-absorbent materials allowed aircraft of drastically reduced
radar cross-section to become practicable. During the 1970s, early stealth technology led to the faceted airframe of the
Lockheed F-117 Nighthawk ground-attack aircraft. The faceting reflected radar beams highly directionally, leading to brief "twinkles", which detector systems of the day typically registered as noise, but even with digital FBW stability and control enhancement, the aerodynamic performance penalties were severe and the F-117 found use principally in the night ground-attack role. Stealth technologies also seek to decrease the
infrared signature, visual signature, and
acoustic signature of the aircraft. In the modern-day, the
KF-21 Boramae, though not considered a
5th-gen fighter, has much more significant
stealth than other 4th gen fighters. ==4.5 generation==