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AIM-9 Sidewinder

The AIM-9 Sidewinder is a supersonic, heat-seeking, air-to-air missile carried by fighter aircraft. It has a high-explosive warhead and an active infrared guidance system. The Sidewinder was developed by the US Navy for fleet air defense and was adapted by the U.S. Air Force for fighter aircraft use. Early versions of the missile were extensively used in the Southeast Asian conflict.

The AIM-9 has a cylindrical body with a roll-stabilizing rear wing/rolleron assembly. Also, it has detachable, double-delta control surfaces behind the nose that improve the missile's maneuverability. Both rollerons and control surfaces are in a cross-like arrangement. The missile's main components are an infrared homing guidance section, an active optical target detector, a high-explosive warhead, and a rocket motor.

The infrared guidance head enables the missile to home on target aircraft engine exhaust. An infrared unit costs less than other types of guidance systems, and can be used in day/night and electronic countermeasures conditions. The infrared seeker also permits the pilot to launch the missile, then leave the area or take evasive action while the missile guides itself to the target. In September 1958 Chinese Nationalist F-86s fired the first Sidewinder air-to-air missiles to down 11 communist Chinese MiG-17s over the Formosa Straits. Until that time, aircraft defensive means where primarily limited to pilots and tail gunners firing small caliber ammunition in dog-fight situations.

On September 24, 1958, the PLA air force fighter units rose from the airfields for another combat mission toward Taiwan. The second crisis of the Taiwan Straits was in full swing, and air skirmishes over neutral waters became almost regular. In these battles, MiG-17, which were in service with the People's Republic of China, actively demonstrated their superiority over the older F-86 of the Taiwan Air Force: at a greater speed, the PLA machines could dictate the distance and choose the moment to attack, and the greater range of the 37-millimeter guns H -37D compared with the 12.7-mm machine guns "Sabres" allowed the Communists not to be substituted for retaliatory strikes. As a result, the airs of the air duels were usually favorable for the PLA.

But this time something went wrong. The fighters that rose from the airfields of mainland China returned in disorder, fairly battered, bearing losses. The pilots reported that the blame for everything was the use by pilots of Taiwan of a fundamentally new weapon - guided Air-to-air missiles. Nobody yet knew that on that day the history of one of the most famous types of guided weapons began. Emerged in the 1950s, this missile is still in armament, and even with the most advanced and technologically advanced powers.

Sidewinder started in 1950, at the Naval Ordnance Test Station of the US Navy. As part of the initiative project, the engineers of the Center developed a project of a very simple and cheap infrared homing head, suitable for installation on aircraft missiles. In fact, the US Navy already had one missile program - developed since 1947 AAM-N-2 "Sparrow". But the rocket, eventually adopted for service in 1956 as "Sparrow I", was in general quite a clumsy, forced decision that had little in common with the subsequent family of AIM-7 Sparrow III missiles.

The progenitor of the "Sparrow" family had a "beam-riding" method - that is, the rocket moved toward the target in a straight line, drawn by a rotating radar beam. For stable guidance, it was required that the pilot of the carrier aircraft constantly keep the target in sight all the time the missile was flying. The range of application was small (since the expansion of the radar beam led to a decrease in accuracy), and in addition, the system could not be used at all at low altitudes, since the reflection of the rotating beam from the surface of the earth or water completely knocked the missile to confusion.

As a result, already in 1950 it became clear that "Sparrow-I" would be no more than a temporary solution. She was replaced by a "Sparrow-II" missile, with active radar guidance, but there were already many technical problems. Therefore, when the engineers of the Center suggested that the Navy command create a very simple and cheap air-to-air missile by installing an infrared homing head developed by them in an initiative order for a conventional FFAR (also known as Mighty Mouse) airborne missile, the admirals agreed without hesitation.

The first "Sidewinder" was born exclusively as a combination of temporary solutions and "cheap" technologies. In fact, it was still the same FFAR, which was installed by the IR GOS and an autopilot connected to the steering planes. The infrared head, developed by NOTS engineers, was the main "highlight" of the project: American designers used the innovative solution for those times, making a conical scan with a rotating mirror that cast reflected IR rays onto the stationary photocell placed in front of it.

Although for the US and in general the world rocket industry such a design of the GOS was a novelty, for the first time the idea of ??a rotating mirror with a stationary thermoelement was created by the Japanese, who developed in 1944-1945 a self-guided infrared bomb "Ke-Go". By using the concept of a rotating mirror and a fixed photoelement based on lead sulphide, NOTS designers succeeded in achieving a very high cheapness and compactness of the sensor head.

The guidance was not on the current position of the target, but the displacement of this position in the interval between the scans (if it did not exceed 5 degrees, the autopilot did not respond). Due to this, the rocket did not "chase" the target, but followed the interception point ahead of time.

To stabilize the missile, the engineers of NOTS proposed (for the first time in the world) a very simple and easy solution both in terms of implementation and in terms of weight - the Rollerons. Mounted on stabilizers, the rollers were unwound by the oncoming airflow, and created a gyroscopic effect, preventing (purely physically) tipping or rotating the rocket. The installation of roller skaters made it possible to avoid the need to equip the rocket with a complex mechanical autopilot and significantly save weight.

The result was a very cheap and light (the weight of the first models was less than 70 kg) aircraft homing missile, for the first time in the history of air-to-air missiles, fully implementing the principle of "shot-and-forget." The shell that captured the target did not need any control from the side of the carrier aircraft. On the rocket was mounted 4,5-kilogram warhead, powered by a double (infrared / shock) fuse. The range was about 4.5 km.

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Page last modified: 01-07-2021 17:59:56 ZULU