The most striking feature of the PL-12D and PL-21 is that it is equipped with an aviation ramjet rocket engine, which uses air as an oxidizer, without adding any oxidizer, only needs to carry fuel, which greatly reduces its weight and increases its specific impulse, that is, each kilogram of fuel can produce more propulsion. In principle, ramjet rockets have a much longer flight range than conventional solid-state rockets, in which the proportion of oxidizer is usually greater than that of fuel oil, and the specific impulse of oxidizer is usually smaller, therefore, the specific impulse of solid-state rockets is generally smaller.
But why did the PL-15 and PL-17 not use ramjet rocket engines, but solid-state rocket engines? This is mainly due to the fact that solid-state rocket engines themselves have some advantages, such as the development from a single pulsation engine to a dual-pulsation or multi-pulsation engine, which allows it to be adjusted according to different flight conditions, so as to achieve a longer fuel rate and greater range. In addition to this, there is another way, which is to put it at a higher altitude, with the help of the scarcity of air, reduce air resistance, save fuel, and increase the range. Either way, either way, it can raise the range of solid-state rockets to a new level, and it is not far behind ramjet rocket engines. We can make a comparison of the two reports.
The first article was carried out on the basis of the American AIM-120, which uses a single solid-state propellant, and its flight range is not long, and the maximum effective attack range of the current AIM-120 D is only more than 150 meters. According to the article, if it is at an altitude of 10 km, then the maximum distance is 145 km. If it is at a lower altitude, then the distance will be much shorter.
However, replacing the AIM-120's engine with two pulses, and with an interval of 30 seconds between each two launches, was able to launch the AIM-120 at a distance of 182 km. This is much better than a single pulse, but it is still far from the PL-15, which can be launched from more than 300 kilometers. To achieve this distance, it is necessary to use a high-throw trajectory that allows it to move at high speed in the air, reduce air resistance, and increase the attack range.
The second is an air-to-air missile similar to the PL-15, which has a length of four meters and a diameter of 203 mm, also uses a solid-state propellant with a double pulse, and uses a high-throw trajectory that allows it to attack at an altitude of thirty or forty kilometers. In this way, its attack range will be greatly increased, and when its second wave propulsion power reaches 100%, its effective range will only be 180 km, which is comparable to the AIM-120. However, if you can adjust the propulsion of Wave 2, for example, to 167%, then the power range of the missile can reach more than 400 kilometers. This is due to the fact that as the speed of the vehicle decreases, the amount of propulsion required decreases, which reduces fuel consumption and thus extends the range.
In addition to this, it also boasts extremely high speeds, flying at more than 1,300 meters per second in most cases, or close to Mach 4. In addition, there is one thing mentioned in this report, and that is to start with 1A high-speed flight of Mach 2, with a load of 6 g, during the flight, at a distance of 320 km, during the flight, the missile will be at a distance of 320 km, and in the course of this it will have a range of 320 km. It is considered an effective range of 320 km. If you fly head-on, the attack range is even greater.
On ramjet engines, you can't use high-throw ballistics, which is a technique that has to draw in air, and once you get to a high altitude, the air in the air becomes very bad, which leads to a lack of power in the engine, which leads to a lack of power in the engine. In addition, for an air-to-air missile, it is impossible to use a very complex air intake. Thus, despite the fact that the air-to-air missile with a ramjet rocket engine has a stronger specific impulse, it cannot fly at high altitudes, and in real combat, the real effective distance of the European "Meteorite" missile is only 150 meters. This is also the main reason why PL-12D, PL-21 and other equipment use ramjet rocket engines.
So, what is the effective distance of the PL-15 from the PL-17 missile? We can deduce something from their size and their parameters. The PL-15 has a length of 4 meters and a diameter of 203 mm, which is very similar to the results in the second article, so we speculate that the effective attack range of the PL-15 is also more than 400 kilometers, and in frontal combat, its effective range can even reach more than 500 kilometers. The length of the PL-17 reached 58 m, the caliber reached 300 mm, which was much more than the PL-15, so we assume that the PL-17 also had a much higher firing range than the PL-15, probably between 600-700 km. This distance is enough to pose a great threat to a wide range of enemies such as AWACS aircraft, tankers, transport aircraft, etc., because their radar reflection range is too wide, and it is difficult for our radar to detect and lock on. In addition, the PL-15 and PL-17 are very likely to be data links in two directions, which can receive our intelligence from our early warning aircraft and satellites, so as to achieve the two guidance modes of A and B, and increase the hit rate.
However, the PL-15 and PL-17 air-to-air missiles have certain problems due to their large size, such as they cannot fit into the internal magazine of the stealth fighter, but must be hung outside, which causes certain restrictions on stealth ability and maneuverability. Therefore, PL-15 and PL-17 are non-stealth fighters, which may be more suitable for non-stealth fighters such as J-16 and J-11, which have a higher load capacity and higher load capacity, and can carry multiple PL-15 and PL-17 to achieve ultra-long-range attacks. Stealth fighters like the J-20 and J-31 will require smaller long-range air-to-air missiles, such as the PL-15E, which have a length of 365 meters, caliber 180 mm, can fit into the internal magazine of the J-20, its effective range is 200-300 km, and the power is also considerable.
The PL-15 and PL-17 air-to-air missiles are new advances in the development of domestic air-to-air missile technology, using solid rocket engines, double-pulse technology, high-throw trajectory, adjustable thrust and other technologies to make them have ultra-long distances, can effectively kill the enemy's large-sized targets, and enhance our army's air supremacy. PL-12D, PL-21 and other models of air-to-air missiles are the earliest test models in China, using ram propellants, although in principle has a certain superiority, but in practical application there are many limitations, in terms of distance is not outstanding, so it is gradually eliminated. At the same time, it also shows that in the process of developing China's air-to-air missiles, it has been carrying out independent research and development, which has laid a solid foundation for the development of our army.