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TianGe laser-guided bomb

At the 2012 Zhuhai Air Show, Harbin in China was built to display the Tian Ge series of laser-guided bombs. The most exciting thing is that the Tian Ge series of laser-guided bombs had no "wind heads", which indicates that it uses a gyro-stabilized seeker, the proportion guided control system, the overall tactical technical indicators have reached or approached the level of the US Paveway-3, thus indicating that China has taken a big step forward in laser guided weapons.

The so-called proportional guidance method is that in the process of the guided weapon flying toward the target, the weapon speed vector rotational angular velocity (the angular velocity of the ballistic inclination in the vertical plane, the angular velocity of the ballistic declination in the horizontal plane) is proportional to the target angular velocity of the target. Thereby, the guidance precision of the system is greatly improved and the trajectory with the falling angle requirement can be realized. In order to cooperate with the new guidance method, the TianGe laser-guided bomb uses a gyro-stabilized seeker, and its seeker includes an optical system, a four-quadrant photodetector, a preamplifier and pre-processing circuit, a frame structure, a servo mechanism, and The angle measuring system and the gyro stability system, the electronic cabin includes an amplifying circuit, a sample and hold circuit, a digital signal processing machine, an interface circuit, a gyro stable driving and a control circuit.

The laser echo signal reflected by the target is collected by the optical system and concentrated on the photosensitive surface of the four-quadrant photodetector. After photoelectric conversion, four channels of electrical signals are obtained. After the four-channel mesh is processed by information, the laser is processed on one hand. The pulse is detected and recognized to form the target capture signal and the gate signal. On the other hand, the four signals of the target are subjected to difference processing, and an angular error signal of the angle between the target line of sight and the optical axis in the pitch and azimuth is obtained. The angular error signal is used to form the driving command in the pitch and azimuth directions on the one hand, so that the seeker tracks the target accordingly, and on the other hand forms a guidance control command to let the weapon fly to the target according to a certain guiding law.

After adopting the new guidance system, the precision of hitting the TianGe laser-guided bomb is greatly improved. Take the 500-kilogram laser-guided bomb as an example. If the ground-attack air attack tactics are used, its accuracy can be improved to about 3 meters. Using airborne air attack methods, the guidance accuracy can reach 5 meters.

Due to the improvement of the performance of the guidance system, the scope of application of the laser guidance system in China has expanded, and the varieties of related systems have also been improved. At the 2012 Zhuhai Air Show, the completed group exhibited 100 kg, 250 kg, 500 kg and 1000 kg class laser-guided bombs of different specifications are equipped with different tactical carriers to combat different targets, such as 100 kg class can be equipped with light attack aircraft, unmanned attack aircraft, perform surgical strikes, and 1000 kg class can be equipped with heavy duty Attack the aircraft and attack the ground or the ground to a solid target.

The large 1000 kg "Tian Ge" series laser-guided bomb is currently the heaviest of its kind in China. Others include 100 kg, 250 kg, and 500 kg series, which can be used for drones and can be used as weapons with trainers and light combat aircraft. system. The front section of the bomb is equipped with a laser guide head, which uses the current international mainstream laser and satellite composite guidance, which can accurately determine the target's position and distance, and guide the bomb to track and strike. For example, despite its heavy weight, the "Tian Ge" 1000 kg laser-guided bomb can easily hit targets 20 kilometers away, and the accuracy error is conservatively estimated to be less than 3 meters.

According to relevant reports, China has begun to adopt the third-generation 612x480 photoelectric pods, and large-area CCD cameras and high-power laser devices have also been successfully developed. These have laid a solid foundation for the development of a new generation of photoelectric aiming pods in China. It provides a prerequisite for increasing the distance of laser guided bombs in China, so we have seen that the TianGe laser-guided bombs at the Zhuhai Air Show have generally increased the launch distance. From the relevant data, the launching distance of the Tian Ge series of laser-guided bombs is generally more than 20 kilometers, and it has the ability to conduct an out-of-zone attack on the new generation of field air defense systems.

The laser-guided bomb increases the throwing distance. In addition to increasing the height of the launch, it also increased the lift-to-drag ratio of the system. However, the shape of the bomb is conical. According to Bernoulli's theorem, the object of this shape has very low lift. The main lift contribution comes from the wing. Lift is directly proportional to the area of the wing, so the best way to increase the lift of the bomb is to increase the area of the wing. From the related pictures, the wing area of the TianGe 500kg laser-guided bomb seems to have increased, which increases the lift of the system and increases the lift-to-drag ratio. However, there is a disadvantage in increasing the area of the wing, which is to increase the system's drag. The speed of the bomb in the air is low, the resistance is mainly induced resistance, the induced resistance is related to the aspect ratio, and the aspect ratio is equal to the square of the wingspan divided by the area of the wing. That is to say, if the bomb wing area does not increase the wingspan, then the aspect ratio will be lowered. The lower the aspect ratio, the greater the induced resistance, which is not conducive to the increase of the lift-to-drag ratio.

The TianGe 250 kg laser-guided bomb took the opposite approach. Its wing area is reduced, so that although the lift is reduced, the aspect ratio is increased, the induced drag is reduced, and the lift is improved. Increase, its delivery distance will not fall, but it can still reach 20 kilometers. Of course, the reduction of the wing area will lead to the reduction of the rudder area, which is not conducive to the control of the bomb and will reduce the maneuverability of the bomb.

The most obvious wing to increase the launch distance is the long-shaped wing, which can increase the lift and reduce the induced drag, thus obtaining a better lift-to-drag ratio. However, the bomb was mounted on the plane and limited by the space on which the aircraft was mounted. The size of the wing, especially the wingspan, should not be too large, so the shrinkable wing design was used on the TianGe 100kg laser-guided bomb. A telescopic long-shaped wing is embedded in the main wing. When the aircraft is mounted, the long-shaped wing is included in the main wing. After the launch, the long-shaped wing is extended to increase the wingspan. This can increase the aspect ratio, reduce the induced drag, and increase the distance of the shot. According to Zhuhai Air Show, Tian Ge's 100-kilogram laser-guided bomb can reach a distance of 30 kilometers. The effect of this is quite obvious.

However, there are limitations to this approach, that is, the length of the wing is still limited, so that the aspect ratio of the wing cannot be increased too much, and the lift-to-drag ratio of the whole missile is directly related to the aspect ratio. According to domestic and foreign experience, when the aspect ratio is increased from 2 to 10, the full-bomb lift-resistance ratio can be increased by 3 times, and the range can be increased by about 3 times. The effect is still very obvious, so a new generation of laser-guided bombs such as the Paveway adopts long-range gliding.

The wing is used to increase its launch distance, and the built-up group also exhibited a 250 kg gliding extended range laser-guided bomb, which has a distance of 80 kilometers. The gliding extended range laser-guided bomb should be the same as the Paveway-4, using GPS/INS and laser guided dual-mode guidance. The laser is transported close to the atmosphere. This is because the dust, smoke and the like in the atmosphere absorb the energy of the laser. This is also a big disadvantage of the laser. The laser guided weapon is generally closer. As mentioned earlier, even the third-generation photoelectric pods are difficult to reach more than 50 kilometers at an altitude of 10,000 meters, so the 250 kg gliding extended-range laser-guided bombs can hardly reach 80 kilometers by laser guidance alone. Distance should be the same as Paveway-4, using GPS / INS and laser guided dual-mode guidance.

Relevant units in China have exhibited Thunder-type GPS/INS and laser-guided dual-mode guided bombs at the Zhuhai Air Show, marking that China has mastered this technology, so the company’s 250-kilogram gliding extended-range laser-guided bomb uses this technology. With this dual-mode guidance system, the company's 250-kilogram gliding extended range guided bombs have greater operational range and flexibility. For example, after the bomb is released, the pilot can select the guidance system according to the battlefield situation. If the smoke on the battlefield is large and the performance of the laser guidance system is degraded, then the guidance system can be selected, or the target can be used to extend the range. Mode to combat long-range targets; if high-precision targets are needed to reduce additional damage, then laser guidance mode is selected to improve the accuracy of the strike. This flexibility is clearly unmatched by ordinary GPS/INS guided bombs or laser-guided bombs.

It should be pointed out that the advancement of the guidance system has also increased the distance of the bomb. From the related pictures and information, the Tiange series laser-guided bomb adopts the extended range design, which means that it increases the delivery distance and thus improves the carrier. Survival on the battlefield. We know that the early field air defense systems such as small and medium caliber anti-aircraft guns and portable air defense missiles have relatively close range.

The Russian ZSU-23 four-tube 23mm self-propelled anti-aircraft gun has a range of about 4 kilometers on the air target. According to China's army, it conducted an assessment to improve the survivability of the aircraft on the battlefield. The early field air defense systems such as small and medium caliber anti-aircraft guns and portable air defense missiles are relatively close. The Russian ZSU-23 four-tube 23mm self-propelled anti-aircraft gun has a range of about 4 kilometers for the air target. The assessment, if the attack aircraft is striking at 800 meters per hour at a height of 1000 meters, the ZSU-23 shoots with a long shot (4x25 points), even if the caliber is 2 km, its hit probability drops to 20%, even 35mm high-altitude guns can only maintain a good probability of hitting around 4 kilometers, and the first generation of portable air defense missiles have limited range due to low sensitivity and weak anti-interference ability of infrared devices.

Portable air defense missiles such as the early SA-7 are only about 4 kilometers away from the jet intercept. Even some large air defense systems, such as the wasp self-defense system, launch 9K33 air defense missiles. At that time, the range was only 8 kilometers, so the early laser-guided bombs were placed at a distance of about 10 kilometers to achieve an off-site strike against ground targets.

In the 21st century, the range of the field air defense system has been greatly developed. Even with the light air defense system, its range has made great progress. The "Tunguska" artillery combined air defense system launched the 9M311 missile, and the range has reached 8,000. Meters, while the latest 5726 missile has a range of 20 kilometers, so that the ground field air defense system can already attack the laser-guided bomb before it is loaded, while the combat aircraft is mounting the laser-guided bomb. Due to the increase in weight and resistance, poor maneuverability and low survivability, a new generation of laser-guided bombs needs to be deployed farther to improve the viability of the aircraft.

For air-to-ground weapons such as unpowered bombs, the launch distance is equal to the height-to-elevation ratio. According to the experience of several US local wars in the 1990s, combat aircraft are at a height of 6,000 meters and 20 kilometers away. Throwing laser-guided bombs can guarantee their own safety, but the higher the height, the farther the distance is, and the target recognition ability will also increase. This has led to the generation of new-generation photoelectric aiming pods in the United States and Europe to support the launch of laser-guided bombs. Including the United States ATFLIR photoelectric pods, Sniper photoelectric pods and France's Damocles photoelectric pods.