Tag Archives: John Dixson

17 October 1974

First flight, Sikorsky YUH-60A 73-21650 at Stratford, Connecticut, 17 October 1974. (Sikorsky, a Lockheed Martin Company)

17 October 1974: Sikorsky Chief Pilot James R. (Dick) Wright and test pilot John Dixson made the first flight of the prototype YUH-60A, 73-21650, at the company’s Stratford, Connecticut, facility. This was the first of three prototypes.

After eight months of testing, the U.S. Army selected the YUH-60A for production over its competitor, the Boeing Vertol YUH-61A. In keeping with the Army’s tradition of naming helicopters after Native Americans, the new helicopter was named Black Hawk, who was a 17th Century leader of the Sauk (or Sac) people.

Sikorsky YUH-60A 73-21650 in an early configuration, with low rotor, large-area tail rotor pylon and swept stabilator, circa 1974. (Sikorsky, Lockheed Martin Company)

The Sikorsky Model S-70 (YUH-60A) was designed to meet the requirements of the U.S. Army Utility Tactical Transport Aircraft System (UTTAS). It had a 3-man crew and could carry an 11-man rifle squad. It could be transported by a Lockheed C-141 Starlifter.

The YUH-60A had an empty weight of 11,182 pounds (5,072 kilograms) and gross weight of 16,750 pounds (7,598 kilograms). The helicopter had a structural load factor of 3.5 Gs. With 1,829 pounds (830 kilograms) of fuel, it had an endurance of 2 hours, 18 minutes.

Sikorsy YUH-60A 73-21650 (c/n 70-001), right profile. In this photograph, the prototype has been modified closer to teh production variant. The rotor mast is taller, the vertical fin has been decreased in size, the crew side window is the two-piece version. (U.S. Army Aviation Museum)
Sikorsky YUH-60A 73-21650 (c/n 70-001), right profile. In this photograph, the prototype has been modified closer to the production variant. The rotor mast is taller, the vertical fin has been decreased in size, the crew side window is the two-piece version. (U.S. Army Aviation Museum)

The YUH-60A had a four-blade fully-articulated main rotor with a diameter of 53 feet, 8 inches (16.358 meters). The blades had 18° negative twist and turned counterclockwise, as seen from above (the advancing blade is on the right) at 258 r.p.m. The blade tip speed was 725 feet per second (221 meters per second).

The four-bladed tail rotor was positioned on the right side of the tail rotor pylon in a tractor configuration. The tail rotor diameter was 11 feet (3.353 meters), and turned 1,214 r.p.m., rotating clockwise as seen from the helicopter’s left (the advancing was blade below the axis of rotation). The blade tip speed was 699 feet per second (213 meters per second). The tail rotor blades had -18° of twist. Because the Black Hawk’s engines are behind the transmission, the aircraft’s center of gravity (c.g.) is also aft. The tail rotor plane is inclined 20° to the left to provide approximately 400 pounds of lift (1.78 kilonewtons) to offset the rearward c.g.

Power was supplied by two General Electric T700-GE-700 modular turboshaft engines, rated at 1,622 shaft horsepower at 20,900 r.p.m. Np, at Sea Level under standard atmospheric conditions. The T700 has a 5-stage axial-flow, 1-stage centrifugal-flow compressor, with a 2-stage axial-flow gas producer and 2-stage axial-flow power turbine. The T700 is 3 feet, 11 inches (1.194 meters) long, 2 feet, 1 inch (0.635 meters) in diameter and weighs 437 pounds (198 kilograms). The helicopter’s main transmission was designed for 2,828 horsepower. The engines are derated to the transmission limit.

The YUH-60A had a cruise speed of 147 knots (169 miles per hour/272 kilometers per hour) at 4,000 feet (1,219 meters) and 95 °F. (35 °C.). It could climb at 450 feet per minute (2.29 meters per second) at the same altitude and air temperature.

73-21650 crashed into the Housatonic River near the Stratford plant at 9:10 a.m.,  Friday, 19 May 1978, killing all three Sikorsky employees on board, pilots Albert M. King, Jr., John J. Pasquarello, and flight engineer John Marshall.

During routine maintenance an airspeed sensor for the all-flying tailplane had been disconnected. As the Black Hawk transitioned from hover to forward flight, the all-flying tailplane remained in the hover position and forced the helicopter’s nose to pitch down to the point that recovery was impossible.

A Sikorsky YUH-60A and Boeing Vertol YUH-61A hover for the camera. (U.S. Army)
A Sikorsky YUH-60A and Boeing Vertol YUH-61A hover for the camera. (U.S. Army)

The Black Hawk has been in production since 1978. More than 4,000 of the helicopters have been built and the type has been continuously improved. The current production model is the UH-60M.

Sikorsky is a Lockheed Martin Company.

A Sikorsky UH-60M Black Hawk in flight. (Sikorsky, a Lockheed Martin Company)
Sikorsky's UH-60M Black Hawk for the U.S. Army, seen here in the Military Hangar at Sikorsky Aircraft in Stratford, Conn. Feb. 20, 2008.
Sikorsky’s UH-60M Black Hawk for the U.S. Army, seen here in the Military Hangar at Sikorsky Aircraft in Stratford, Conn. Feb. 20, 2008. (Sikorsky, a Lockheed Martin Company)

© 2018, Bryan R. Swopes

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13 March 1977

The number 2 Sikorsky S-76 makes teh type's first flight, 13 March 1977. (Sikorsky Historical Archives)
The number 2 Sikorsky S-76 prototype, s/n 76002, makes the type’s first flight, 13 March 1977. (Sikorsky Historical Archives)

13 March 1977: The Sikorsky S-76A Spirit prototype made its first flight at the company’s Development Flight Center, West Palm Beach, Florida (06FA). This was the number two aircraft, serial number 76002, registered N762SA. Sikorky’s chief pilot, John Dixson, and S-76 program test pilot Nicholas D. Lappos were in the cockpit.

Test pilot Nick Lappos is congratulated following teh first flight of the Sikorsky S-76, 13 March 1977. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Test pilot Nick Lappos is congratulated following the first flight of the Sikorsky S-76, 13 March 1977. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

The Sikorsky S-76A is a twin-engine medium helicopter designed to carry up to 12 passengers 400 nautical miles (460.3 statute miles, 740.8 kilometers) for the offshore oil industry. It is flown by two pilots and is certified for instrument flight. The helicopter can be configured to carry up to thirteen passengers.

The S-76 is used as a passenger transport, executive or VIP aircraft, and in law enforcement, search and rescue or military service. It is also widely used as a medical transport.

In 1979, Sikorsky proposed the new helicopter for consideration as the U.S. Coast Guard Short Range Recovery Helicopter, along with competitors Aérospatiale and Bell Helicopter. The S-76 was considered to be the most suitable of the three but the company withdrew before any contract was awarded. The Aérospatiale SA-365 Dauphin variant was finally selected and became the MH-65 Dolphin.

Air Logistics accepted the first Sikorsky S-76A production helicopter 27 February 1979. (Sikorsky, a Lockheed Martin Company)
Air Logistics accepted the first Sikorsky S-76A production helicopter 27 February 1979. (Sikorsky, a Lockheed Martin Company)

The S-76A has an overall length of 52 feet, 6 inches (16.002 meters) with rotors turning, and overall height of 14 feet, 6 inches (4.420 meters). The S-76A had an empty weight of 7,132 pounds (3,235 kilograms) and a maximum gross weight of 10,500 pounds (4,763 kilograms).

The four bladed, fully-articulated main rotor has a diameter of 44 feet, 0 inches (13.411 meters). The main rotor hub is constructed of forged aluminum and uses elastomeric bearings to allow for blade flapping and lead-lag. The blades are made of composite materials formed around a hollow titanium spar. The blade tips are swept to reduce the formation of blade tip vortices. Each blade is 19 feet, 11¾ inches long. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the right.) At 107% NR, the maximum speed with power on, the rotor turns 313 r.p.m.

A four-bladed tail rotor with a diameter of 8 feet, 0 inches (2.438 meters) is mounted on the left side of a pylon in a pusher configuration. The tail rotor turns clockwise as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.)

A Sikorsky S-76A in flight over the City of new York. (Sikorsky, a Lockheed Martin Company)
A Sikorsky S-76A in flight over the City of New York. (Sikorsky, a Lockheed Martin Company)

The S-76A was originally powered by two Allison 250-C30 turboshaft engines mounted side-by-side, behind the main transmission. The engines were rated at 557 shaft horsepower (maximum continuous power). 100% torque is 564 foot-pounds. Later production models have used Turbomeca and Pratt & Whitney Canada engines.

The S-76A has a cruise speed and maximum speed (VNE) of 155 knots (178 miles per hour, 287 kilometers per hour). (The helicopter’s cruise speed is the same as its maximum.) The service ceiling is 15,000 feet (4,572 meters). The maximum altitude for takeoff and landing is 6,900 feet (2,103 meters).

The Sikorsky S-76 remains in production, with more than 1,100 helicopters built. There were 307 S-76A and S-76A+ variants produced, followed by the S-76B, S-76C, -C+ and -C++. The current production model is the S-76D.

Sikorsky S-76D N7621Y, c/n 761021. (Sikorsky, a Lockheed Martin Company)

© 2017, Bryan R. Swopes

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