Tuesday, June 24, 2008

Northrop QM-74 Chukar series

Like the Ryan Firebee the Northrop Chukar is a long-serving UAV which entered service in the 1960s and continues in service and development to the current day. The Chukar is a target drone but saw combat service as a decoy drone later in it's career.

BQM-74F launch (c) Northrop Grumman

The Chukar is a small (just over 3.5m long and with a wingspan of 1.69m) zero-length launched UAV sent into the air using JATO rockets from a ground or ship based launcher and can also, with the Chukar III, be launched from an aircraft such as a Hercules if fitted with an air launch kit. At the end of it's mission or if there is a loss of contact the Chukar deploys a parachute for recovery. A floatation kit can also be fitted. The Chukar is intended to provide for a realistic target for gunnery or missile training.

There have several major versions of the Chukar :

MQM-74A Chukar I
Development began of the Chukar in the early 1960s for the US Navy and it went into production in 1968. Powered by a Williams WR24-6 turbojet and launchable with the assistance of JATO rockets from ship or ground the Chukar I entered service with the US Navy, Royal Navy and Italian Navy.

2300 Chukar Is were built by 1973 when production switched to the Chukar II. The Chukar I platform was also developed into the NV-128 surveillance drone but did not enter service and XBQM-108A experimental UAV (using the engine and guidance system from a Harpoon missile) to research "tailsitter" VTOL.

The Chukar I had a maximum level speed of 489mph / 787km/h and a service ceiling of 40,000ft / 12, 200m. Range (at 20,000ft was 273 miles / 439 km).

The Chukar was guided by radio control with automatic stabilisation using gyros and altitude sensors when the target was out of range. The Chukar was fitted with equipment to augment it's radar reflection and also had infrared flares and visual aids such as flashes to aid visual identification.

MQM-74A being prepared for launch

MQM-74C Chukar II
Fitted with a more powerful Williams WR24-7 turbojet the Chukar II had a higher performance. Speed was increased to 593mph / 954 km/h. Range was also increased. The Chukar II was fitted with an autopilot system for guidance. It replaced the Chukar I in production in the early 1970s.

MQM-74C Chukar II launch

BQM-74C Chukar III
The Chukar III was a further developed target drone from 1978 with a computerised A/A37G-13 flight control system to allow more complicated pre-programmed flight operations, including the ability to be air launched, and powered by a Williams WR24-7A. Over 1,600 Chukar IIIs have been built to date.

In the mid 1980s the engine was changed to a more powerful J400-WR-404 and has improved guidance and flight control systems to allow it to simulate an anti-ship cruise missile. Using a radar altimeter it can fly as low as 3m. The target augmentation equipment has also been upgraded.

This is the latest version now in development by Northrop Grumman. Guidance will be GPS/IMU with speed further increased to Mach 0.92 at sea level. The target will also be capable of 8G turns. The BQM-74F can have 6 missions with up to 70 waypoints pre-programmed and the mission can be selected either before or after launch. Northrop say this makes the BQM-74F "the foremost cruise missile replicator available".

The Chukar goes to war

In the 1991 Gulf War Chukar IIIs were used as decoy drones in the second wave of attacks. 37 were launched and began to orbit Baghdad. As the Iraqi radar stations illuminated the Chukars this allowed anti-radiar missiles to strike the radar stations. The decoys were operated by a special team of specialists set up purely for this operation, the team was disbanded after the war. The Chukars were fitted with radar reflectors to mimic the signature of strike fighters. The decoys helped reduce allied aircraft losses from the high number feared to the low number that was suffered in the end.