CHAPARRAL Air Defence System

The US Light Antiaircraft Development Program that began in 1952 consisted of three sub-programs: the improved RADUSTER
system for interim use, followed by the advanced 37mm VIGILANTE
system, and finally, the futuristic self-propelled MAULER guided missile system, which was to be  ultimate solution to the low-altitude forward area air defence problem for US Army.

All three programs failed to fructify and reach maturity; while the RADUSTER was abandoned in 1958, VIGILANTE was stopped in 1963 and the MAULER in 1965.

Though the REDEYE program as still progressing well, it was yet to be operationalised and to fill the void created by the cancellation of the MAULER, US Department of the Army decided to adopt a forward area air defence plan based on a combination of the self-propelled HAWK Battalions and composite missile and gun battalions consisting of the CHAPARRAL and VULCAN, together with a Forward Area Alerting Radar to provide early warning and target identification information.

It was originally planned to  provide a quick-fix, interim CHAPARRAL- FAAR capability by January 1968 and was to be a simple assemblage of off-the-shelf hardware.  The system was intended for deployment to Europe only, and was to remain in the field some 2 to 4 years, until the MAULER became available. What ultimately was fielded was far removed from the original concept. Notwithstanding the shortcomings, CHAPARRAL, based on the Raytheon AIM-9 Sidewinder short-range air-to-air missile,  was the only truly mobile weapon of this class ever fielded by the US military (as the Avenger, LAV-AD, and Linebacker vehicles can only fight in a stationary position).

The  CHAPARRAL system comprises of four basic components; the MIM-72 Chaparral missile, the M54 launcher, and the M730 vehicle that carries them, which was derived from the M548. Collectively, these are also referred to as the M48 fire unit. The first Chaparral battalion was fielded in 1969 and were gradually transferred to the US Army National Guard in the late 1980s, and finally retired by the US Army entirely by 1998, though the system remains in service with several other nations including Egypt.

Technical Description

The first model of the missile, the MIM-72A, was directly derived from the AIM-9D Sidewinder. Its only significant structural differences from the AIM-9D are that only two of the fins on the MIM-72A have rollerons, while the other two are non-moving. The seeker head of the MIM-72A is derived from that of the FIM-43 Redeye MANPADS missile, and as a result, it is highly susceptible to flares, infrared jamming, and sun glare.

The MIM-72A is propelled by a Mk.50 solid-fuel rocket motor, and has a top speed of Mach 1.5, a ceiling of 3 000 m, and a maximum range of 9 000 m. Its warhead is a Mk.48 11kg continuous rod munition. Its minimum effective altitude and range are 25 m and 500 m, respectively.

The newer MIM-72G has  the M121 smokeless motor first introduced in the E model, and the new M817 directional doppler fuse and M250 blast fragmentation warhead as also the RSS (Rosette Scan Seeker) seeker head derived from that of the FIM-92B Stinger. The RSS seeker head substantially improved the Chaparral’s guidance and sensitivity, allowing for head-on engagements, and also giving this missile significant resistance against flares and infrared jamming systems.

General characteristics (MIM-72A)

Length: 2.90 metres 

Wingspan: 63.0 centimetres 

Diameter: 127 millimetres 

Launch weight: 86 kilograms 

Speed: Mach 1.5

Range: 500 to 9,000 metres 

Altitude: 25 to 4,000 metres 

Guidance: Passive infra-red tail chase only.

Motor : MK 50 solid-fuel rocket motor (12.2 kN) for 4.7 s

Warhead: 12.2 kilograms MK 48 Continuous-rod warhead.

The launch vehicle for the Chaparral is the M730-based M48 with mobility virtually equal to the M113 and M548 series vehicles including air transportability in a C-130H Hercules, and airdrop capability.

The M54 launcher can traverse 360 degrees in 6 seconds, and can elevate to 90 degrees, or depress to -9 degrees. It is stabilized in 2 planes, allowing the M48 to launch while on the move.

The MIM-72 Chaparral missiles are loaded onto the four launch rails manually, as this munition is light enough for two men to carry with their bare hands. Protective covers on both ends of the missile are removed and the fins manually installed prior to launch. Protective shutters are closed over the windscreen of the M48 fire unit prior to launch as well, due to the possibility of the Chaparral missile’s backblast shattering unprotected glass.

The M48 vehicle lacks either search or targeting radar, and relies on a separate radar set for long-range detection and tracking of aerial targets. It does however possess an IFF system.

Performance

It is not clear if  the Chaparral has ever been used in combat, though the US military has never launched one in anger. 

Given the performance of the Vietnam War-era Sidewinder missiles, it is generally assessed to demonstrate a pK Ratio of at least 25% though it is doubtful if it can ever be achieved in combat. It also needs to be remembered that most guided missiles have pK Ratios of between 0.5% and 10% only.

Upgrades

As one of the handful of countries still operating the CHAPARRAL system, Egypt is set to upgrade it under a $17 million contract with the United States’ ProjectXYZ. The system modifications work will be carried out  in Cairo, Egypt and is expected to be completed 30 December 2020. It will include CHAPARRAL equipment, tools, materials and test equipment along with personnel to perform system integration and checkout; technical support, training, program management, and documentation support.