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17th of October 1974

Updated: Oct 17, 2021

It was on this day in aviation history in 1974 that the YUH-60A helicopter made its first flight.

The YUH-60A prototype during its maiden flight at Stratford Connecticut. Please note the short rotor mast on this prototype.


It was the first of three prototypes that Sikorsky Chief Pilot J.R. Wright and Project Chief Testpilot J, Dixson lifted flew this day. Although after the first flight it was reported the aircraft behaved perfectly, there were excessive vibrations observed during the early test flights. which were attributed to the main rotor. Further flight testing and engineering research revealed the vibrations were caused by an upward airflow around the rotor head, transmission and engine cowlings. This led to the redesign of the rotor mast (lengthened) and the engine cowlings. These design changes fixed the vibration issue.

A UH-60 helicopter with the redesigned rotor mast. Please note the difference with the first picture in the blog.

With the vibration issue sorted out, testing continued and after 8 months of testing the US Army selected the YUH-60A for production. In keeping with the tradition of naming their helicopter types after Native Americans, the YUH-60 was named after the 17th Century leader of the Sauk tribe, Black Hawk.

The design of the YU-60A (Internally with Sikorsky known as the Model S-70) was based on the requirements of the US Army. It was flown by a minimum of a three-man crew and could carry 11 soldiers. Depending on its role and/or mission the crew compliment will vary. It was designed to fit in a Lockheed C-130 Hercules transport aircraft for transportation over larger distances than the aircraft own range, More than 4000 UH-60 have been built since 1978 in many variants. The aircraft is used in many roles from troop carrier and medivac aircraft to police helicopter and a firefighting role. Some specifications for the UH-60L Black Hawk Variant:

Crew

- minimum 3

Powerplant - General Electric T700-GE-701C Turboshaft engines - 1890 shp Performance - Max Cruise Speed at 4,000 ft with a temperature of 95°F; 152 knots - Max Cruise Speed at 2,000 ft with a temperature of 70°F; 159 knots

- Safe Limited Speed (SLS); 155 knots - Vmo 193 knots Vertical rate of Climb at 95% MRP - at 4,000 ft with a temperature of 95°F; 1,550 ft per minute

- at 2,000 ft with a temperature of 70°F 2,750 ft per minute - SLS > 3,000 ft per minute Service Ceiling - on a ISA day 19,1510 ft Weight - Empty 11,516 Lbs - Mission gross weight - 17,432 Lbs - Maximum gross weight - 22,000 Lbs - Maximum gross weight (ferry) - 24,500 Lbs Length - 64 ft 10 in

Height

- 16 ft 10 in

Rotor - Diameter 53 ft 8 in

- Four titanium and fibreglass blades


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