AIM-9 Sidewinder AAM
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Right: The upcoming AIM-9X Sidewinder (Hughes Missiles photo).
| Contractor: | Raytheon Co.; Ford Aerospace & Communications Corp; Loral |
| Power Plant: | Thiokol Hercules Bermite Mk 36 Mod 71 single-stage rocket |
| Length: | 9ft 5in (2.87m) |
| Body diameter: | 5in (13cm) |
| Finspan: | 24.8in (63cm) |
| Flight speed: | Mach 2.5 |
| Guidance: | Solid-state infrared (IR) |
| Warhead: | 20.8lb (9.4kg) |
| Launch weight: | 191 lbs (86.7kg) |
| Range: | 11nm (13mi; 20km) |
| Unit cost: | $41,300 U.S. |
BACKGROUND
The AIM-9 (AIM stands for Air-Intercept Missile) Sidewinder is without a doubt the most widely used and most successful air-to-air missile (AAM) the world has ever seen. The idea for it came about in 1949 when the U.S. Navy needed an AAM to defend its fleets and fight future air battles. At the time, radar-guided missiles were being developped, but radar technology back then was still too new and unreliable to fit into a reasonably-sized missile body. So a scientist working for the Navy produced an infrared, or IR, guided missile, which was mounted into a 5in-diameter body, and did not require expensive and bulky fire-control radars, allowing them to be installed to many existing airframes. The Sidewinder's first flight took place in September 1953, and service entry occured in 1956 with the AIM-9B. The Sidewinder got its name from the fact that in early tests, the IR seeker was in a fixed mounting slightly off the missile's centerline, so when the missile spun in flight the target appeared to move, from the missile's point of view, causing it to constantly issue course "corrections" to keep the target centered. This probelem was later solved in later models.
The AIM-9 consists of four sections: The Guidance/Control Section (GCS), the warhead, the fuse, and the rocket motor. The WGU-4A/B GCS includes an IR seeker cooled before launch by a cryogenic Argon/Nitrogen gas in order for the seeker to be more IR-sensitive. This requirement sometimes has drawbacks because the seeker head cannot always be cooled for the entire duration of the launch platform's longer missions. The WDU-17 annular blast-fragmentation (ABF) warhead weighs 20.8lbs (9.4kg). Of that weight, 7.9lbs (3.6kg) of it consists of the high-explosive (HE), while the rest of the weight consists of the preformed metal rods surrounding the explosve. These rods are blown outward by the HE's detonation towards the target, and are designed to destroy the target by either penetrating its fuel tanks, or by, shall we say "severly increasing the target's surface area". The DSU-15/B proximity fuse is controlled by the target detector, ot TD, which sends out pulsed IR beams through IR-transparent windows. When the IR reflected of the target reaches a certain point, the missile determines it's within lethal range and detonates the warhead. The Hercules Bermite Mk-36 Mod 71 solid fuel rocket motor propels the AIM-9 at a speed of approximately Mach 2.5 for a maximum flight time of around 60 seconds. At the rear of the missile are 4 fixed guidance fins (maneovering is controlled through the 4 movable forward fins). On the rear tips of these fixed fins are "rollerons". These are small wheels that are spun by the air rushing by in flight, causing a gyroscopic effect that helps stabilize the missile in flight.
There have been many versions of the AIM-9 over the years. The AIM-9A was mainly used for test. The AIM-9B, the first production version, was a rear-aspect-only missile with limited range. Another drawback, due to the AIM-9B's
relatively poor IR-discrimmination capabilities, was that if the target was within a 20o angle from the Sun, from the Sidewinder's viewpoint, the AIM-9B would most often go for that star. The AIM-9J,
a combination of the earlier AIM-9B and E, had better maneovering capabilities and delivered higher performance. Deliveries of this version began in 1977. The AIM-9L included a more powerful motor and an improved optical fuze. Deliveries began
in 1976. The AIM-9P has a greater range, solid-state electronics (better suited for carrier landings and extreme weather conditions), and increased reliability and maintainability standards. Deliveries began in 1978. The AIM-9P-1 had an optical TD instead of
an IR fuze, the AIM-9P-2 had a reduced-smoke motor, and the AIM-9P-3 combined both of these improvements. The latest version of the Sidewinder, the AIM-9M is currently the only model in service. It has the all-aspect features of the AIM-9L, but better all-round performance.
The "Mike", as it is commonly referred to, entered operational service in 1983 and is compatible with pretty much all current tactical aircraft that have an air-to-air capability. The AIM-9M also scans for targets in the UV portion of the electromagnetic spectrum, increasing
target detection and track capabilty. The AIM-9M-9 has better capability against IR countermeasures such as flares and jamming. An older,
but not terribly successful version of the Sidewinder, the AIM-9C was quickly withdrawn from service many years ago, but many have been pulled from storage, and given new electronics to serve in the anti-radiation missile (ARM) role, under the designation AGM-122 Sidearm.
The AIM-9 production figures are remarkable: over 110,000 units have been produced for 27 countries excluding the U.S. Also, when several AIM-9's fell into Soviet hands in the 1950's and 60's, the USSR quickly produced an exact copy, under the designation R-13/AA-12. Just how effective
the Sidewinder is has been proven again and again in history. One of the first Sidewinder engagements took place in 1958 when the Taiwanese Air Force, flying U.S.-built F-86 Sabres, downed 14 Chinese MiGs with AIM-9's in a single battle. More recently, over a 10-year period from 1981 to 1991,
the AIM-9L/M in U.S. service has been fired in combat 22 times. 16 hits were recorded, resulting in 13 kills. In the 1982 Falklans War, Royal Navy Sea Harriers downed 25 Argentinian planes with the AIM-9, and recently the Saudi Arabian Air Force has scored 2 Sidewinder kills, the
Pakistani Air Force has scored 16 Sidewinder kills, and several more have been achieved by the Israeli Air Force.
As for the AIM-9's future, a new project called the AIM-9X is underway, and this will incorporate Imaging-Infrared (IIR) technology which includes software that can actually distinguish one airplane's IR signature from another's and ID the airplane. The AIM-9X will also likely incorporate a
helmet-mounted sight (HMS), allowing quicker (2 to 4 seconds faster) AIM-9 launches, and also the ability to acquire targets as much as 60 degrees off the launch platform's nose. A Honeywell HMS demonstrated target aquisition and interception capabilty 67 degrees off an F-16's nose in a series
of February 1994 tests. The AIM-9X, in a system known as Box Office, will incorporate 4 thrust-vectoring paddles around the exhaust area,
allowing 60-G turns by the missile. Another project underway for the AIM-9X is a "smart" warhead, which will be designed to attack a target's specific systems such as the engines. This is neccesary because the Sidewinder's relaitvely small warhead was designed to destroy early Soviet jets by
causing a catastrophic fire or explosion in its fuel tanks, because early Russian jets did not incorporate self-sealing fuel tanks, and later Russian an European planes now do. The AIM-9X is still in a very prelimiary stage, and companies likely interested in becoming the prime contractors include
Raytheon, Lockheed Martin, Hughes, and Loral. Development is scheduled to be completed in 2002.