JAS-39 adopts the central wing layout to obtain the best wing-body fusion effect, which also makes the store get a good ground clearance. Generally speaking, the ground clearance of external stores has always been a difficult problem for small aircraft. Because of the central wing, the main landing gear of JAS-39 aircraft is installed on the fuselage. In addition, in order to obtain the best aerodynamic coupling with the main wing, the front wing should have a certain installation angle. JAS-39 "Gryphon" adopts a chamfered delta wing with a serrated leading edge and a sweepback angle of 45. The high-lift device consists of two groups of leading edge flaps, which are connected with the elevator of the aircraft through a full-authority three-redundancy fly-by-wire flight control system. At high angle of attack, the leading edge flap is deflected downward, which can delay the stall of the wing. When the trailing edge flap deflects downward, it can make the aircraft look up, thus improving the agility of the aircraft. This is different from the traditional aircraft with longitudinal stability. For the aircraft with longitudinal stability, the downward deviation of the trailing edge flap will make the aircraft produce bow moment. The full-motion canard is also a tangent triangle with a leading edge sweepback angle of 43.
one of the advantages of JAS-39 "Gryphon" layout is that direct lift can be generated by deflecting the canard and elevator at the same time. Differential deflection of canard can produce lateral force, and combined with rudder deflection, direct lateral force can be produced without changing the course of the aircraft. This "uncoupled" flight mode is very useful when air-to-air attacks are carried out with guns, or when unguided weapons are dropped on ground targets. In the design process of JAS-39 aircraft, the weight reduction of the aircraft was realized by widely adopting new technologies and advanced computer simulation technologies, in which the amount of composite materials accounted for 25%~3% of the airframe structure. Carbon fiber composites are mainly used for skin and spar, tail wing, elevator, landing gear door and some inspection covers. The skin is not glued to the supporting structure, but installed by countersunk head screws. In order to eliminate the oil leakage of the whole oil tank, sealing materials are used at the contact points. It is estimated that JAS-39 aircraft has about 1, fasteners, and the machined parts account for about 15% of the airframe structure in terms of cost.
according to the manufacturing technology of modern aircraft, the fuselage structure of JAS-39 aircraft is divided into several parts, in which the wing is divided into seven parts and the fuselage is divided into three parts, and the three parts of the fuselage are permanently connected together in the final assembly stage, which can eliminate the weight increase caused by the traditional transitional connection. The middle fuselage is divided into three parts: the gun cabin, the landing gear section and the fuselage installation section. The bending moment of the wing is transmitted to the fuselage through three spaced frames, and there is only an auxiliary installation joint at the root of the leading edge. Considering the long chord length of the root of the delta wing, this design is amazing. The reason is that the main frame is limited by the main landing gear compartment and the engine inspection door. The F44 engine is assembled and disassembled from the lower part of the fuselage, in order to easily replace the engine on a crowded aircraft carrier. This situation forced Saab to design a wing root stiffener with high strength to transfer the bending moment of the wing to the fuselage. JAS-39 has greatly reduced the workload of pilots through careful design of cockpit display and control system, and obviously improved the operational efficiency of aircraft. The core component of the cockpit is the EP-17 display system of Ericsson, which adopts three 12mm×15mm multifunction heads-up displays (HDD) and one Kaiser wide-angle holographic head-up display (HUD). Three monochrome heads-up displays (HDD) are identical and interchangeable. During the flight, the function of the display can be adjusted to meet the needs of different flight stages or combat tasks. The HDD on the left side generally displays flight data, including data on HUD and data on other self-defense equipment and sensors. The middle HDD displays a computer-generated map of the surrounding area, superimposed with tactical information; The HDD on the right shows the target information from radar, forward-looking infrared and weapon sensors.
although p>HDD is based on the existing TV technology, its performance has been greatly improved, and it can provide high-quality and high-definition pictures in poor light conditions. According to the requirements of the Swedish Air Force, color displays may also be used in future aircraft. Using diffraction grating in HDD can obtain high brightness image. The field of vision of HUD is 28× 22, which can provide both computer-generated weapon aiming symbols and video images generated by photoelectric systems (such as forward-looking infrared devices). All the information displayed in the cockpit can be recorded on a standard tape for the pilot to inquire.
In order to further reduce the pilot's workload, Gryphon aircraft adopts a manual throttle control stick, and all the control buttons of radar and weapons are placed on the throttle-stick. Saab company studied both the center and side steering column, and finally chose the center small steering column. This kind of steering column can be operated by right hand or left hand when necessary. In the avionics system of Gryphon, there are more than 4 D8 computers of Ericsson, which are connected together by a redundant MIL-STD-1553B data bus: one bus is used for basic data and flight data of the aircraft, one bus is used for cockpit display and radar, and one bus is used for tactical and weapon information. Subsequent batches of aircraft and export-oriented aircraft have five data buses. Using five data buses can keep the "load" of each data bus at a low level. JAS-39 was designed as an air superiority fighter, but it was used as an attack aircraft when it first entered service. When carrying out the ground attack mission, the Gryphon aircraft can carry a variety of weapons, mainly Hughes' AGM-65a/B' cub' (Rb75) air-to-ground missiles and DWS-39 small bomb scatterers outside the defense zone. The "Young Livestock" missile is a TV-guided missile that has been tested in actual combat. It has a range of about 3km and carries a warhead of 57kg, which is used to attack tanks and other armored targets. DWS39 is unpowered, and its range depends on the launching conditions. Before launching, the target data is transmitted to the weapon, and the weapon is guided and controlled by the inertial navigation system. Submunitions can be 24 anti-runway bombs, 96 cluster bombs, 12 anti-tank mines, 54 SB44 bomblets or 1,848 M42GP bomblets. Unguided weapons include 8kg M5 bomb, 6kg M6 bomb and ARAK7 rocket.
when carrying out anti-ship mission, the main weapon of Gryphon aircraft is Saab Rbs-15F anti-ship missile. The missile carries a 2kg semi-armor-piercing blasting warhead with a range of 9km, with inertial guidance in the middle section and active radar guidance in the beam section. For self-defense, Gryphon aircraft is equipped with electronic countermeasures equipment, including radar warning receiver and electronic warfare system. The electronic warfare system consists of chaff/tracer scatterer, towed radar decoy and jammer installed in the pylon under the wing. When performing reconnaissance tasks, all sensors and photographic equipment are installed by plug-ins.
Sweden had hoped to develop the successor of Rb71 over-the-horizon missile, but after several years' work, it finally decided to adopt Hughes' AIM-12 medium-range air-to-air missile AMRAAM. It is important that the Swedish Air Force is allowed to conduct flight tests of missiles. Since the Swedish Air Force has only ordered 1 AIM-12 missiles, the Gryphon aircraft may also use Meteor air-to-air missiles. The export type of Gryphon aircraft may also use Meteor missile, because Meteor missile and AIM-12 missile are interchangeable, and only a few software changes are needed. Both missiles have the ability to distinguish different targets, using data link and inertial guidance, so as to remain stealth for as long as possible after launch. The data link is used to update the information about the target, which can be provided by this aircraft or other aircraft (such as other Gryphon aircraft or S1B early warning aircraft). Gryphon aircraft can carry AIM-9L and AIM-9J rattlesnake missiles during short-range attacks. A 27mm Bk27 "Mao Se" machine gun is installed in the fairing at the lower left of the belly. The avionics of JAS-39 aircraft were designed and manufactured by Ericsson, and then integrated by Saab. Compared with the avionics of Saab-37 "Lei", it has been greatly improved. The PS-5 radar of Ericsson/GMAv is adopted, and its data processing capacity is three times that of the PS-46/A radar of Lei aircraft, but its volume is only 6% and its weight is only 5%. PS-5A is a multi-mode pulse Doppler radar, which adopts slot waveguide planar array antenna and liquid-cooled traveling wave tube transmitter. By using complex and changeable waveforms and high, medium and low pulse repetition frequency, various working modes required by various tasks are realized. In order to improve the resolution and realize the detection of long-distance targets, frequency modulation pulse compression is used.
The working mode of radar is controlled by software, which mainly includes the following contents: air-to-air: long-range search and tracking; Multi-target tracking while searching; Short-range wide-angle search and tracking; Automatic control of air guns and missiles. Air-to-air: search and tracking; Tracking ground and sea targets while scanning; High resolution drawing; Air-to-air ranging Adopting all programmable signal and data processors, it has good electronic anti-interference ability and flexibility to adapt to future development. The flexible waveform of PS-5A avoids the inaccuracy of radar ranging and optimizes the performance in each working mode. There are few sidelobes when the planar antenna array scans, which reduces the sensitivity to interference and improves the efficiency of radar. Radar can also meet the data transmission requirements of guided medium-range air-to-air missiles (such as AMRAAM advanced medium-range air-to-air missiles and Meteor missiles). Because of its modular design and built-in self-detection function, radar has good applicability and low maintenance cost. It adopts a new type of active phased array technology, in which more than 1, transmitting/receiving units are used. In order to expand the azimuth of radar, the antenna is installed on a movable chassis, which can obviously increase the scanning range of radar. This design method is unique in phased array radar. Using AESA technology to improve the target detection and tracking performance of radar.
The Swedish Air Force has been using the Tactical Instrument Landing System (TILS), which is not only outdated, but also expensive to use, and is not suitable for scattered wartime airports. Therefore, it is necessary to develop a system, which relies entirely on airborne sensors and airborne equipment, and can guide aircraft to any airport and ensure safe landing in all-time and all-weather conditions. The new system adopts two new technologies for Gryphon aircraft, namely the new integrated navigation system (NINS) and the new integrated landing system (NILS). In addition, NINS can also use the information of traditional navigation equipment, such as ranging device (DME), VHF omni-directional beacon (VOR) and TACAN, if the pilot needs it.