Historical Background

Sikorsky Aircraft at the time a Division of United Technologies was no doubt a pioneer in the development of the modern military helicopter. That is something that could not always be said and when the Army released the Request for Proposal (RFP) to the Helicopter Industry for the Utility Tactical Transport Aircraft System (UTTAS) Program in January 1972 no one expected the winner to be Sikorsky. It would be like going to a Vegas roulette table and putting all your money on the Zero hoping the ball does not land on anything Red or Black. In the case of the UTTAS that would be Bell Helicopter and Boeing-Vertol. Why do I say this, well up to this point it had been 15 years since Sikorsky had built a helicopter for the military. Bell Helicopter had flooded the Military with the UH-1 Iroquois and AH-1 Cobra. While the Boeing-Vertol CH-47A Chinook was the military’s medium lift helicopter.

On the other hand, the last Helicopter that Sikorsky had built for the Military was the CH-53 (Sikorsky S-65) which began production in 1964. It also had lost the Advanced Aerial Fire Support System (AAFSS) with its Sikorsky S-66 in November 1965 to the Lockheed YAH-56A Cheyenne. Which would be canceled in 1969 due to technical problems. In May 1971 Sikorsky would take shot number 2 when the Military announced the selection of Boeing-Vertol to perform the first phase of the Heavy Lift Helicopter (HLH) development. Boeing would go on to build the XCH-62 HLH, but like the Cheyenne in 1975 this program would also be cancelled. I guess what was truly shocking was that the Military had already been operating the CH-54A Tarhe (Sikorsky S-64 Sky Crane) in Vietnam with good results.

Utility Tactical Transport Aircraft System (UTTAS)

The Utility Tactical Transport Aircraft System (UTTAS) program was a pivotal U.S. Army initiative launched in the early 1970s to develop a next-generation utility helicopter to replace the aging UH-1 "Huey" series. The UTTAS would be a twin engine helicopter that is expected to replace the UH-1 Iroquois in the Air Assault, Air Cavalry, and Aeromedical Evacuation missions. It was designed to be the Army’s first true squad assault helicopter and was designed to transport troops and equipment into combat, resupply them while in combat, perform aeromedical evacuations, reposition reserves, and other combat support missions.

The major UTTAS program requirements
based on a Performance altitude of 4,000 feet and 95 degrees Fahrenheit (35 degrees Celsius) and included:
  • Carry a basic mission payload of 11 Combat-equipped troops (2640 lbs.), plus 3 crew members.
  • Mission endurance of 2.3 hours with a 20-minute fuel reserve.
  • Mission reliability rate of .98 (probability of completing a mission).
  • Maintain a Cruise Speed of 145 to 175 knots.
  • Achieve a vertical climb rate of 450 to 550 feet per minute.
  • Use no more than 95% intermediate (military) rated power.
  • Achieve a yaw rate of 15 degrees per second while flying 35 knots sideways.
  • Maintenance man-hours per flight-hour of 3.8 hours. (1.0-hour preventive and 2.8 hours fault correction)
  • Must be air-transportable in aircraft like the C-130 and C-141 with minimal disassembly.
  • Must use two General Electric T700-GE-700 engines.

Ultimately three companies (Bell Helicopter, Boeing-Vertol, and Sikorsky) would respond to the Request for Proposal.

Bell Helicopter proposed the Bell Model 240 which was a twin-engine helicopter. It was larger than the UH-1 Huey and included a fail-safe modular transmission, 4 bladed swept tip Main Rotor and 4 bladed Tail Rotor.

Bell Model 240
Magazine Ad for the Bell Model 240 (UTTAS)

Boeing Vertol proposed their model 179 (YUH-61A) which was also a twin-engine Helicopter and consisted of a rigid Main Rotor design, 4 bladed Tail Rotor, and sported a tricycle style landing gear.

Boeing Vertol YUH-61A (UTTAS)
Boeing Vertol YUH-61A 73-21656 in Hovering Flight.

Sikorsky proposed the model S-70 (YUH-60A) which was also a twin-engine Helicopter and consisted of a four bladed fully articulated Main Rotor using elastomeric bearing, a 4 bladed Tail Rotor that was canted 20 degrees, and a dual-stage oleo main and Tail Landing Gear.

Sikorsky YUH-60A Flight of Three
A Flight of three Sikorsky YUH-60A.

In August 1972, the U.S. Army selected Sikorsky and Boeing Vertol as competitors with the requirement to build 3 prototypes each for flight testing, 1 ground test vehicle, and 1 for laboratory structural testing. Sikorsky also made the decision to build a fourth prototype aircraft concurrently with internal funding and was primarily used in-house by Sikorsky for engineering evaluation, materials testing, and systems refinement, and to perform marketing demonstrations. It also served as a risk-reduction platform during the final stages of UH-60A development.

The Fly-off evaluations began in early 1976. Two aircraft from each competitor were sent to Fort Rucker, Alabama, and then Fort Campbell, Kentucky for testing under tactical conditions by US Army pilot. The third prototype from each competitor, which was fully instrumented, began testing at Edwards AFB, California, with the US Army Aviation Engineering Flight Activity carrying out the evaluation as part of the government tests.

On 23 December 1976, Sikorsky YUH-60A was declared the winner of the competition to produce the UH-60A, which would subsequently be named the UH-60A Black Hawk.