UH-60 Black Hawk

The UH-60 Black Hawk is a four-bladed, twin-engine, medium-lift utility helicopter manufactured by Sikorsky Aircraft. Sikorsky submitted the S-70 design for the United States Army's Utility Tactical Transport Aircraft System (UTTAS) competition in 1972. The Army designated the prototype as the YUH-60A and selected the Black Hawk as the winner of the program in 1976, after a fly-off competition with the Boeing Vertol YUH-61. The UH-60A entered service with the Army in 1979, to replace the UH-1 Iroquois as the Army's tactical transport helicopter.

Development
In the late 1960s, the United States Army began forming requirements in for its Utility Tactical Transport Aircraft System (UTTAS) helicopter to replace the UH-1 Iroquois based on experience in Vietnam. The Army also initiated the development of a new turbine engine for its helicopters that would become the General Electric T700. The Army required significant performance, survivability and reliability improvements from both UTTAS aircraft and powerplant.[1] The Army released its UTTAS requests for proposals (RFP) in January 1972.[2] Four prototypes were constructed, the first (YUH-60A) flying in October 1974, and evaluated against a rival Boeing-Vertol design, the YUH-61A. Prior to delivery of the prototypes to the US Army, a preliminary evaluation was conducted in November 1975 to ensure the aircraft could be operated safely during all testing.[3] Three of the prototypes were delivered to the Army in March 1976, and one was kept by Sikorsky for internal research. The Black Hawk was selected for production in December 1976. Deliveries of the UH-60A to the US Army began in October 1978 and the helicopter entered service in June 1979.[4]

UH-60 Black Hawks equipped with M60 machine guns near An Najaf, Iraq in May 2005.
In the late 1980s, the model was upgraded to the UH-60L (first production aircraft 89-26179) which featured more power and lift with the upgrade to the -701C model of the GE engine.
The current production model (UH-60M) will extend the service life of the UH-60 design well into the 2020s, features still more power and lift and state of the art electronic instrumentation, flight controls and aircraft navigation control.

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Design
The Black Hawk helicopter series can perform a wide array of missions, including the tactical transport of troops, electronic warfare, and aeromedical evacuation. A VIP version known as the VH-60N is used to transport important government officials (e.g., Congress, Executive departments) with the helicopter's call sign of "Marine One" when transporting the President of the United States.[5] In air assault operations it can move a squad of 11 combat troops with equipment or reposition the 105 mm M102 howitzer with thirty rounds of 105 mm ammunition, and a four-man crew in a single lift. Alternatively, it can carry 2,600 lb (1,170 kg) of cargo or sling load 9,000 lb (4,050 kg) of cargo.[6] The Black Hawk is equipped with advanced avionics and electronics for increased survivability and capability, such as the Global Positioning System.
The UH-60 can be equipped with stub wings at top of fuselage to carry fuel tanks or possibly armament. The initial stub wing system is called external stores support system (ESSS). It has two pylons on each wing to carry two 230 US gal (870 L) and two 450 US gal (1,700 L) tanks in total. The ESSS can also carry 10,000 lb (4,500 kg) of armament such as rockets, missile and gun pods. The ESSS entered service in 1986. However it was found that with four fuel tanks it would obstruct the firing field of the door guns. To alleviate the issue, the external tank system (ETS) with unswept stub wings to carry two fuel tanks was developed.[7]
The unit cost varies with the version due to the varying specifications, equipment and quantities. For example, the unit cost of the Army's UH-60L Black Hawk is $5.9 million while the unit cost of the Air Force MH-60G Pave Hawk is $10.2 million.[8]