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[1.0] Sikorsky S-70 Black Hawk

v1.0.0 / 01 sep 03 / greg goebel / public domain

* The S-70 Black Hawk was a significant step forward in utility helicopter capability for the US Army when it was developed in the mid-1970s. Since that time, it has also proven useful for other roles, such as search and rescue, special operations, medical evacuation, and electronics warfare, and has been acquired by military services around the world.

[1.2] UH-60A / UH-60L
[1.3] BLACK HAWK VARIANTS (1): UH-60Q / ARMY MH-60A, MH-60L, MH-60K


* The Bell UH-1 Huey series of helicopters served the US Army very well in Vietnam, but even as the conflict was heating up in the mid-1960s the Army began to think about a replacement. As the war wound down late in the decade the search for a replacement helicopter came to the top of the queue, and the Army issued a request for industry proposals for the "Utility Tactical Transport Aircraft System (UTTAS)" in January 1972, specifying new levels of performance, survivability, and maintainability.

Boeing Vertol and Sikorsky proposals were selected as finalists in August 1972, with each manufacturer building two ground-test prototypes and three flight-test prototypes, to be put through a thorough evaluation before selection of a winner. Sikorsky preceded prototype construction with a set of five demonstrators, based on modified S-61 and S-65 transport helicopters plus the experimental S-67 gunship, to validate UTTAS technologies.

The first flying Sikorsky UTTAS prototype, with the company designation of "S-70" (later "S-70A") and the service designation of "YUH-60A", performed its initial flight on 17 October 1974. The Boeing Vertol entry, the "YUH-61A", performed its first flight on 29 November 1974. The Army evaluation of the machines began in the spring of 1976 and was very thorough.

Sikorsky particularly impressed the Army when one of the YUH-60A prototypes crash-landed in a heavily wooded area at Fort Campbell, Kentucky. The aircrew was unharmed, and after replacing the rotor blades the helicopter flew itself out and was returned to full service with minimal additional repairs. Sikorsky was judged the winner of the competition on 23 December 1976, with the company awarded an initial production contract for the "UH-60A Black Hawk". The contract specified delivery of three more YUH-60As and 15 initial-production UH-60As. Many more production orders would follow.

Initial flight of a production Black Hawk was on 17 October 1978, four years to the day after the initial prototype flight, and the type entered service with the US Army's 101st Airborne Division in June 1979. Although the Black Hawk's reliability wasn't up to spec initially, the problems were largely overcome. The UH-60A saw initial combat service in the US invasion of the island of Grenada in 1983. One demonstrated its survivability by coming home with a wounded pilot, 45 bullet holes in the airframe, two holes in the main rotor, and one in the tail rotor. UH-60As would also see service in the invasion of Panama, OPERATION JUST CAUSE, in 1989.


[1.2] UH-60A / UH-60L

* The UH-60A is of conventional main-tail rotor configuration and is powered by twin General Electric T700-GE-700 turboshaft engines, providing 1,165 kW (1,560 SHP) each. The engines are rated to operate for a half hour even following complete loss of oil. A Solar T62T-40-1 auxiliary power unit (APU) with 75 kW (100 SHP) is mounted between the engines for starting and ground power. The UH-60A has wheeled, fixed taildragger landing gear featuring heavy-duty shock absorbers to take up the shock of a hard landing. The landing gear can be fitted with additional wide ski-style pads for operations on snow or marshy ground. The fuel tanks are also crash-resistant, and armored as well.

Both the main and tail rotors have four blades. They can resist impacts of 23 millimeter cannon projectiles. Each main rotor blade has titanium spars, glass-fiber skinning, a honeycomb core, and a nickel leading-edge abrasion sheath. The tail rotor is made of graphite-epoxy composite and is canted at an angle of 20 degrees off the vertical. There is a straight horizontal tailplane, or "stabilator", at the base of the tailfin. The main rotor can be manually folded for air transport.

As per UTTAS requirements, a Lockheed C-130 transport can carry one Black Hawk, a Lockheed C-141B can carry two, and a Lockheed C-5 can carry six. The C-141B is being replaced by the Boeing C-117. It is unclear how many Black Hawks a C-117 can carry, but it would be hard to believe it could carry any less than three or four.

The UH-60A carries a crew of three, including two pilots and a crew chief / gunner, all sitting on armored seats. 11 troops can be carried normally, though up to 20 can be accommodated in a pinch. There are doors on either side that slide rearwards and have two windows. The UH-60A has a belly sling hook with a capacity of up to 3,630 kilograms (8,000 pounds) and can lift a 105 millimeter artillery piece or a Hummer vehicle.

A machine gun can be pintle-mounted in a slide-open window on each side of the helicopter just behind the cockpit. Positioning the guns in the windows helps reduce clutter in the doorways, reflecting combat experience with the Bell UH-1H when door guns interfered with troops trying to get out of the machine as fast as possible under fire. Initially, M-60D 7.62 millimeter machine guns were mounted, but later were replaced by General Electric M134 7.62 millimeter six-barrelled Gatling-type Miniguns.

The initial prototype differed from production machines in having a fixed swept stabilator, which tended to cause the helicopter to nose up and led to a series of experiments for alternate configurations; a retractable tailwheel; changes in fuselage and engine exhaust configuration; a shorter rotor mast, which led to excessive vibration; and a different window arrangement. The original window scheme included a two-panel side-cockpit window that proved drafty and was replaced by a window with a small slide-open panel, and the original one-piece windows behind the cockpit were replaced with two-piece windows that could be more easily opened. Of course, the prototype was not fitted with full operational kit. Changes were made through the development program that brought successive prototypes by steps to production specification.

   _____________________   _________________   _______________________

   spec                    metric              english
   _____________________   _________________   _______________________

   main rotor diameter     16.36 meters        53 feet 8 inches 
   tail rotor diameter     3.35 meters         11 feet 
   footprint length        19.76 meters        64 feet 10 inches
   fuselage length         15.26 meters        50 feet 1 inch
   height, rotor head      3.76 meters         12 feet 4 inches
   height, tail rotor      5.13 meters         16 feet 10 inches

   empty weight            4,820 kilograms     10,625 pounds
   MTO weight              9,185 kilograms     20,250 pounds

   max speed               295 KPH             185 MPH / 160 KT 
   service ceiling         5,790 meters        19,000 feet
   range, internal fuel    592 KM              368 MI / 319 NMI
   _____________________   _________________   _______________________

Along with export sales of UH-60A variants, detailed in a later section, two UH-60As were obtained by the US Navy Test Pilot's School at Patuxent River, Maryland, and 14 UH-60As were passed on to the US Customs Service for drug enforcement duties. These machines are basically stock UH-60As, though they are fitted with a Nitesun searchlight, and are known informally as "Pot Hawks". They are painted black with dark gold trim.

UH-60As set aside as ground instruction airframes are designated "GUH-60A", and a handful of machines reserved for experimental roles are designated "JUH-60A". One JUH-60A evaluated a "fly by light" fiber-optic-based flight-control system under the "Advanced Digital-Optical Control System (ADOCS)" program, and was of course nicknamed the "Light Hawk".

* A number of improvements have been added to the Black Hawk since its introduction:

It is unclear how widely some of this gear, such as the countermeasures systems or cable cutters or rescue hoist, have been fitted to the Army Black Hawk fleet.

* A total of 974 UH-60As were delivered to 1989, when it was replaced in production by the improved "UH-60L", which has more powerful T700-GE-701C turboshafts, providing 1,417 kW (1,900 SHP) each, and an uprated power transmission capable of handling a total of 2,535 kW (3,400 SHP). All improvements added to the UH-60A during production are standard items on the UH-60L, which also features a modified tail rotor control system. Early production UH-60Ls retained the UH-60A flight control system which limited available power, but this was quickly upgraded to the "Automatic Flight Control System (AFCS)" of the navalized S-70B Seahawk, discussed in the next chapter and permitted full use of the new engines and powertrain.

Initial flight of the UH-60L was on 22 March 1988, with service deliveries beginning in October 1989. By the beginning of 2002, the US Army had 539 UH-60Ls in service.

It is very difficult to tell a UH-60L from a UH-60A, since many UH-60As have been upgraded with features fitted standard to UH-60Ls, such as cable cutters and defensive countermeasures. In fact, it was the increasing weight penalty imposed by these features that drove the introduction of the UH-60L.

UH-60Ls were available to fly alongside UH-60As during the Gulf War in 1991, with the Army deploying about 400 Black Hawks of various types to support the conflict. They were fitted with protective covers and other items to protect them from desert sand, and priority was given to implementing upgrades such as long-range fuel tanks and improved avionics.

On 24 February 1991, the first day of the ground war, Black Hawks were the primary element of the biggest single helicopter airlift in history to that time, with a total of over 300 machines participating in an assault on a site in the Iraqi desert codenamed "Landing Zone (LZ) Cobra". Six Black Hawks were lost during the conflict, two of them due to combat action and the other four due to accidents.

Black Hawks have of course participated in other US Army interventions since them, including the infamous Somalia intervention. On 3 October two Black Hawks were shot down during a botched raid and the crew of one slaughtered and dragged through the streets, the whole ugly incident becoming the basis for a well-known movie titled BLACK HAWK DOWN. Black Hawks served, with considerably more distinction, in the US intervention in Afghanistan in 2001 and the invasion of Iraq in 2003.


[1.3] BLACK HAWK VARIANTS (1): UH-60Q / ARMY MH-60A, MH-60L, MH-60K

* The Army obtained a specialized medevac version of the Black Hawk, the "UH-60Q", to replace UH-60A/L machines configured for the medevac role. Like the UH-60A/L medevac machines, the UH-60Q has accommodations for litters and medical attendants, but the arrangements are much more optimal and a more extensive suite of emergency medical gear can be accommodated. The UH-60Q also features a "forward looking infrared (FLIR)" video camera in the nose for night / bad weather flying, plus an external rescue hoist. The the UH-60A/L medevac machines had the old swing-out hoist, which apparently had a substantially smaller lift capacity.

More recently the Army has been upgrading UH-60Qs to "HH-60L" configuration. The exact details of the upgrade are unclear, but it at least involves improved avionics.

* The Army decided to convert 30 UH-60As to a special operations version, known as the "MH-60A", which featured:

As many of its features were tacked on in an improvised fashion, the UH-60A was also called the "Velcro Hawk". These machines were eventually passed on to the Army National Guard, to be replaced in regular Army service by UH-60Ls brought up to a similar "MH-60L Velcro Hawk" configuration. Some UH-60Ls were fitted with external stores on ETS or ESSS stub wings, including a 30 millimeter Chain Gun and unguided rocket pods, and referred by the name of "MH-60L Direct Action Penetrator (DAP)".

* The MH-60As and MH-60Ls were only interim machines, filling the gap until a much more optimized special operations "MH-60K" Black Hawk could be obtained.

The MH-60K is basically a superset of the MH-60L Velcro Hawk, with such features as the inflight refueling probe, HIRSS exhaust shields, disco light IR jammer, chaff-flare dispensers, and NVG-compatible cockpit. It adds a number of significant improvements, however:

A pintle mount for a 12.7 millimeter machine gun was provided in each door. It is unclear if the window Minigun mounts were retained. The 12.7 millimeter machine guns have a much lower rate of fire than the Miniguns but greater range and hitting power. The MH-60K has been qualified for improved armament, including Stinger air-to-air missiles (AAMs) and Hellfire anti-armor missiles, mounted on upswept ESSS pylons. Apparently the FLIR turret was later fitted with a laser target designator to support Hellfire. Such external stores can come in handy when delivering and then supporting special operations teams in the field.

Incidentally, in principle Hellfire can be carried on a standard UH-60A/L with ESSS and some sources mention this as a possible configuration, but a standard Black Hawk doesn't have a Hellfire sighting system and would have to rely on another platform to target the missiles. Unguided 70 millimeter rocket pods would only require a fixed gunsight, but the Black Hawk isn't a gunship and is not as a rule used as an offensive weapon. Of course, when shooting is going on any available weapon may end up being thrown into the fight, but it seems unlikely that "plain vanilla" UH-60A/Ls are often fitted with external offensive armament, and in fact it's hard to find any pictures of them configured with such stores. Minelaying pods are of course a practical option.

The first MH-60K performed its initial flight on 10 August 1990, with the first of an initial production batch of machines performing its first flight on 26 February 1992. While the service careers of special operations machines tend to be kept quiet, MH-60Ks undoubtedly played significant roles in the Afghan intervention and the invasion of Iraq.



* In February 1981, the US Army performed the first flight of a UH-60A modified as the "YEH-60B Stand Off Target Acquisition System (SOTAS)" for battlefield surveillance. This machine featured extended main landing gear that straddled a long rectangular box antenna for the Motorola SOTAS radar system. In operation, the main gear retracted upward and the antenna rotated to scan the battlefield area.

The Army decided to collaborate with the US Air Force on the much more capable E-8 Joint Stars battlefield surveillance system, based on the Boeing 707 airliner, and so the SOTAS program was cancelled in September 1981.

* The Army converted a number of UH-60As to the "EH-60C" configuration, which was fitted with the "Quick Fix IIB" electronic warfare system to locate, monitor, and jam adversary communications. Originally, the Army had tried to fit the Quick Fix system to the Bell UH-1H Huey, but it was simply too much for the old UH-1H to carry.

A "YEH-60A" prototype performed its first flight on 24 September 1981. Following "production" conversions were originally designated "EH-60A" but this was then changed to EH-60C. Tracor Systems performed 66 EH-60C conversions up to 1988. The Army originally planned to obtain 130 EH-60Cs but ran out of money.

The EH-60C could be recognised by the two large dipole antennas along each side of the tailboom, and a long whip antenna that could be pivoted down from the belly in flight. The EH-60C carried two operators along with pilot and copilot, and features a datalink system to download intelligence data to ground stations or other platforms.

In the late 1990s, about seven EH-60Cs were upgraded to "EH-60L Advanced Quick Fix" configuration, with the airframes brought up to UH-60L specification (with the more powerful engines and more rugged transmission) and improvements in avionics. However, the program stalled and it appears that nothing more was done with it the EH-60L, and the EH-60Cs were retired.

* Nine UH-60As were modified as VIP transports and supplied in 1998 to the US Marine Corps' HMX-1 based out of Quantico, Virginia. These machines featured the Seahawk AFCS; a communications operator's position to support an extensive secure communications suite; a weather radar mounted in a small radome under the nose; improved avionics hardened against an electromagnetic pulse; HIRSS exhaust shields; a countermeasures suite; and a soundproofed luxury VIP cabin.

They were originally given the designation of "VH-60A", which was changed to "VH-60N" in 1989. The VH-60Ns are used to support the US President and his staff, and are known as "Presidential Hawks". Their callsign is "Marine One". At last notice, they were painted in shiny white and dark forest green colors. It appears these are the only Black Hawks in formal USMC service.



* The US Air Force is also an S-70 user, employing the type for the combat search and rescue (CSAR) and special operations roles. The path the USAF took to get that capability is an interesting story.

In the early 1980s, the Air Force wanted to find a replacement for the Sikorsky S-61R / HH-3E "Jolly Green Giant" and Bell HH-1 Hueys then in service in the USAF SAR role. The S-70 looked like the right tool for the job, resulting in a series of programs that had an odd tendency to go down dead ends:

* A number of other UH-60As and UH-60Ls may have been brought up to something resembling the Credible Hawk configuration, but if so it was strictly as a temporary measure, since the Credible Hawks were to be brought up to "MH-60G Pave Hawk" configuration in a two-phase program.

The "Phase Two" update (the Credible Hawk being "Phase One") included fitting the machines with a Bendix-King 1400C navigation radar in a radome on the left side of the nose; AN/ASN-137 Doppler radar; a GPS-INS set; a moving-map display; secure communications; and defensive countermeasures, including a disco-light IR jammer, AN/ALE-40 chaff-flare dispensers, and an AN/APR-39A(V)1 threat warning system.

The "Phase Three" update was to include an AN/AAQ-16 FLIR imager; a partial glass cockpit, with twin flat-panel displays and a head-up display (HUD); display; a door mount on each side for a 12.7 millimeter machine gun, along with the gun mount in each window; IR lights for night refueling; and ring-laser gyro inertial navigation system.

However, to no surprise given the zigzag evolution of this branch of the Black Hawk family, it didn't precisely work out that way. Only 16 of the total of 98 MH-60Gs received the Phase 3 gear. These Pave Hawks were assigned the special operations role, while the other 82, with the Phase Two equipment fit, were assigned the CSAR role in October 1991 and redesignated "HH-60G".



* In the late 1990s the Army initiated a program with Sikorsky to update about 1,217 UH-60A and UH-60L Black Hawks to the new "UH-60M" standard by 2020, renewing the aircraft for decades more service. Initial flight of the first of four UH-60M prototype was in 2000. The four prototypes represented distinct different production paths:

The main elements of the UH-60M update include:

Avionics improvements include a dual-redundant MIL-STD 1553B data bus; an improved data modem to link the aircraft into a "tactical Internet"; a "glass cockpit" with color multifunction displays; a digital map system; a cockpit voice and flight data recorder, obtained as a commercial off-the-shelf system; a GPS-INS set; a computer mission-planning system to allow mission plans to be created on ground-based PCs and downloaded into the aircraft; updated radio systems; and a new AFCS.

Structural improvements include fit of new beams, similar to those now used in US Navy Seahawks, in the transmission area to increase airframe life; strengthening of the aircraft skin around the gunner's window, and fitting a new window design; strengthening of the skin around the cargo doors; and a general service life assessment, in which the airframe is cleaned and inspected, with replacement of corroded or damaged areas.

UH-60As will require more refit than UH-60Ls. The UH-60L already has an improved and ruggedized gearbox plus T700-GE-701C engines. These will be added to all UH-60As being upgraded to UH-60M standards. About 193 UH-60As have received an interim upgrade, being fitted with a UH-60L tail assembly to keep them flying until they can be modernized to UH-60M specification.

About half the UH-60As lack ESSS hardpoints, and these will also be added in the upgrade program. A new ruggedized 872 liter (230 US gallon) external tank is being designed as part of the upgrade.

Other new UH-60M features include additional avionics maintenance access doors and an improved infrared protection system. The upgrade program will also include updating 66 retired EH-60C Quick Fix machines to the UH-60M standard.

* In early 2003, the Army took delivery of the first "Army Airborne Command & Control System (A2C2S)", a flying command post based on the UH-60L. The A2C2S is fitted with five tactical workstations and communications to support commanders at the battalion level and higher. The system will be able to obtain intelligence information over datalinks from unmanned aircraft and other platforms, assimilate it, and pass commands to tactical elements in action. The A2C2S is not intended to operate as a "flying command post" as such. The helicopter platform is simply intended to fly from one location to another, with command post operations conducted on the ground.

The Army plans to obtain a total of 121 A2C2S machines, with formal operational introduction in 2004. Work on a "Block 2" A2C2S will begin in 2005. The improved system will be based on the UH-60M, and will hopefully feature the new "Joint Tactical Radio System (JTRS)", which will integrate many of the communications functions on the current A2C2S. Additional A2C2S systems may be obtained given the new US national emphasis on "homeland security".

* The Army and Sikorsky are also in discussion over a follow-on to the UH-60M, known as the "Future Utility Rotorcraft (FUR)", previously the "UH-60X". This machine would use the rotor system, controls, and drive train from the Sikorsky S-92; a tail plug extension to deal with the wider rotor; new, more powerful engines; and larger internal fuel tanks. Other features being considered are a health-and-usage diagnostic system, though this may be fitted to the UH-60M; active vibration control; and a 4,535-kilogram (10,000 pound) capacity external load hook.



* To no surprise, the Black Hawk has been extensively exported. The biggest foreign user is South Korea, with 100 "UH-60Ps" in service, very similar to the UH-60L. The first was delivered from Sikorsky in late 1990, with the next 19 assembled by Korean Air from knockdown kits, and the rest built in Korea.

* Mitsubishi in Japan has license-built the UH-60L in a SAR version designated the "UH-60J" to replace the Kawasaki-Vertol KV-107 Sea Knight in Japanese service. The UH-60J variant features external fuel tanks on upswept ESSS mounts, external rescue winch, Japanese-built radar and a FLIR turret in the nose, and bubble side windows for observers.

Sikorsky delivered the first two pattern examples, which has the company designation of "S-70A-12", with the next two supplied as kits for assembly by Mitsubishi. All following production is built by Mitsubishi, with the T700 engines license-built in Japan by Ishikawajima-Harima. The first Mitsubishi-built machine delivered in early 1991 and the type becoming operational in 1992.

Total orders included 30 UH-60Js for the Japanese Air Self-Defense Force (JASDF) and 20 for the Japanese Maritime Self-Defense Force (JMSDF), for a total of 50. JASDF machines are fitted with T700-IHI-701A engines and have four litters, while JMSDF machines are fitted with marinized T700-IHI-401C engines and have 11 litters. 11 litters sounds a bit crowded, but 11 is the number of crew in a JMSDF P-3C Orion patrol aircraft and the JMSDF UH-60Js were configured accordingly. JASDF SH-60Js are painted in high-visibility yellow-and-white colors, while JMSDF SH-60Js are painted in bright red-and-white colors.

In 1995, the Japanese Ground Self-Defense Force (JGSDF) ordered a utility variant of the UH-60L from Mitsubishi, designated the "UH-60JA". It features a UH-60L airframe but improved avionics, including FLIR, color weather radar, GPS navigation receiver, and an NVG-compatible cockpit. The first evaluation machine was delivered in 1997. The JGSDF plans to obtain 70 UH-60JAs, though the number of actual deliveries and current status of this effort are unclear.

* Australia obtained a single "S-70A-9" Black Hawk, leading to production of 38 more locally by Hawker de Havilland. These machines were originally assigned to the Royal Australian Air Force, but later reassigned to the Australian Army. They are basically UH-60Ls with HIRSS exhausts, cable cutters, the Seahawk AFCS and folding stabilator, an external rescue hoist, and some Australian-specified avionics.

* Israel received ten US Army surplus Black Hawks in July 1994, free of charge. The Israeli Air Force later purchased 24 new-build UH-60Ls, with deliveries in 2002.

* Saudi Arabia has obtained 21 "Desert Hawks", including 12 "S-70A-1" machines configured as utility transports, one S-70A-1 configured as a VIP transport, and 8 "S-70A-1L" medevac machines. The utility transports can be fitted with French GIAT 20 millimeter cannon on pintle mounts, while the medevac machines have an external hoist, provision for six litter, and a searchlight.

* Other nations have obtained the Black Hawk in small quantities:

* Sikorsky sells an "S-70C" version of the Black Hawk that is supposed to be for civil operators, but that description partly appears to be a "cover" for selling Black Hawks to nations where providing something that was clearly identified as a "weapon" was troublesome. S-70C users include:


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