Daily Archives: October 17, 2021

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 project chief test pilot John Dixson made the first flight of the prototype YUH-60A, 73-21650, at the company’s Stratford, Connecticut, facility. This helicopter was the first of three prototypes.

Early flight testing revealed excessive vertical vibrations associated with the main rotor. Extensive engineering and flight testing determined that this was caused by air flow upward through the rotor system and around the transmission and engine cowlings. The purpose of the low-mounted main rotor was to aid in fitting inside transport aircraft with minimal disassembly. It was necessary to increase the height of the mast and reshape the cowlings to achieve an acceptable level of vibration.

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 at roll-out, 28 June 1974, with low main rotor, large-area tail rotor pylon and swept stabilator. (Sikorsky, a 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. The helicopter could be transported by a Lockheed C-130 Hercules.

The three UTTAS prototypes were 63 feet, 6 inches (19.355 meters) long, with rotors turning. The span of the horizontal stabilizer was 15 feet, 0 inches (4.572 meters). The prototypes’ overall height was 16 feet, 10 inches (5.131 meters).

The three Sikorsky YUH-60A UTTAS prototypes. A fourth prototype, an S-70, was built and retained by Sikorsky for internal research and development and demonstrations. (Vertical Flight Society)

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.

The YUH-60A had a four-blade fully-articulated main rotor with elastomeric bearings. It had a diameter of 52 feet, 0 inches (15.850 meters). During flight testing, the diameter was increased to 52 feet, 4 inches (15.951 meters), and finally to 52 feet, 8 inches (16.053 meters). The blades were built with titanium spars and used two different airfoils and a non-linear twist (resulting in a net -16.4°). The outer 20 inches (0.508 meters) were swept aft 20°. These characteristics improved the helicopter’s maximum speed and hover performance. The main rotor turned counterclockwise, as seen from above (the advancing blade is on the right) at 258 r.p.m. The blade tip speed was 728 feet per second (222 meters per second). During flight testing it was decided to change the main transmission gear reduction ratio in order to operate the engines at a slightly increased r.p.m. At the higher r.p.m., the engines produced an additional 50 horsepower, each.

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, a variable-pitch stabilator has replaced the fixed horizontal stabilizer, the engine cowlings have been redesigned, and the crew side window is the two-piece version. (U.S. Army Aviation Museum)

The four-bladed bearingless 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.

Cutaway illustration of the T700-GE-700 turboshaft engine. (Global Security)

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.

Sikorsky YUH-60A prototype, 73-21650, late configuration. (Vertical Flight Society)

While operating with an Army crew on the night of 9 August 1976, YUH-60A 73-21650 developed a significant vibration. An emergency landing was made. Because of darkness and mist, the pilots thought they were landing in a corn field, but it was actually a pine tree plantation. The helicopter’s rotors cut down more than 40 trees with trunk diameters up to 5 inches (12.7 centimeters).

Close inspection by Army and Sikorsky personnel found that the only visible damage was to the four main and four tail-rotor blades other than nicks and dents to the airframe that were of no structural concern. All gearboxes and engines turned freely, and all flight controls responded properly. ¹ The blades were replaced on-site and the helicopter was flown out the following day.

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, Connecticut, 20 February 2008. (Sikorsky, a Lockheed Martin Company)

¹ Black Hawk: The Story of a World Class Helicopter, by Ray D. Leoni, American Institute of Aeronautics and Astronautics, Reston, Virginia, 2007, Chapter 8 at Page 173.

© 2019, Bryan R. Swopes

17 October 1922

A Vought VE-7SF takes off from USS Langley (CV-1). (National Naval Aviation Museum)
A Vought VE-7 takes off from USS Langley (CV-1). (National Naval Aviation Museum)

17 October 1922: Lieutenant Commander Virgil Childers (“Squash”) Griffin, Jr., United States Navy, made the first takeoff from an aircraft carrier of the U. S. Navy when he flew a Chance Vought Corporation VE-7 fighter from the deck of USS Langley (CV-1) while the ship was anchored in the York River along the west side of Chesapeake Bay, Virginia.

A Vought VE-7 taking off from USS Langley, 1922. The second airplane is an Aeromarine. (U.S. Navy)
A Vought VE-7 taking off from USS Langley, 1922. The second airplane is an Aeromarine 39 trainer. (U.S. Navy)

USS Langley was the United States Navy’s first aircraft carrier. The ship was named in honor of an American scientist, Samuel Pierpont Langley. It was a former collier, USS Jupiter (AC-3), which had been converted at the Norfolk Navy Yard, 1921–1922. As an aircraft carrier, Langley had a complement of 468 men, including the air wing. The ship was 542 feet, 2.5 inches (165.27 meters) in length, overall, with a beam of 65 feet, 6 inches (19.96 meters) and draft of 22 feet, 1 inch (6.73 meters). The aircraft carrier had a full load displacement of 15,150 long tons (15,393 Metric tons).

Langley was powered by a General Electric turbo-electric drive, with a total of 6,500 shaft horsepower. She could make 15.5 knots (17.8 miles per hour; 28.7 kilometers per hour). The aircraft carrier had a maximum range of 4,000 miles (6,437 kilometers).

USS Langley (CV-1) with Vought VE-7SF fighters on the flight deck, at anchor off Culebra Island, Puerto Rico, 18 March 1926. In the background are a USS Tennessee-class and two USS New Mexico-class battleships. (U.S. Navy)

In addition to her air group of up to 36 airplanes, Langley was defended by four 5-inch/51-caliber guns (127 mm × 6.477 meters). This gun could fire a 50-pound (22.7 kilogram) shell a distance of 15,850 yards (14, 493 meters) when elevated to 20°. Its maximum rate of fire was 9 rounds per minute.

As the more modern aircraft carriers Lexington and Saratoga came in to service, Langley was once again converted, this time to a sea plane tender, and reclassified as AV-3, 21 April 1937.

USS Langley was badly damaged by Japanese dive bombers during the Battle of the Java Sea, 27 February 1942, having been struck by five bombs. The ship was scuttled approximately 75 miles south of Tjilatjap, Java, to prevent capture, when her escorting destroyers fired two torpedoes into her.

USS Langley (CV-1), 1922. (U.S. Navy)
USS Langley (CV-1), 1922. (U.S. Navy)

The Chance Vought VE-7 was originally ordered as a two-place trainer, but its performance and handling qualities were so good that it was widely used as a fighter. The VE-7SF was a single-place, single-engine biplane built for the U.S. Navy.

The VE-7 was 22 feet 5-3/8 inches (6.842 meters) long, with a wingspan of 34 feet, 4 inches (10.465 meters), and height of 8 feet 7½ inches (2.629 meters). The two-bay wings were separated by a vertical gap of 4 feet, 8 inches (1.422 meters) and the leading edge of the  lower wing was staggered 11 inches (27.9 centimeters) behind that of the upper wing. Both wings had 1.25° dihedral. The upper wing had +1.75° incidence, lower wing had +2.25°. The VE-7 had weighed 1,392 pounds (631 kilograms) empty and had gross weight of 1,937 pounds (879 kilograms)

Vought VE-7SF 2-F-16. (Chance Vought)
Vought VE-7SF 2-F-16. (Chance Vought)

The VE-7 was powered by a water-cooled, normally-aspirated, 716.69-cubic-inch-displacement (11.744 liters) Wright-Hispano E3 Alert single-overhead-camshaft (SOHC) 60° V-8 engine, rated at 215 horsepower at 2,000 r.p.m. The engine drove a two-bladed fixed-pitch wooden propeller with a diameter of 8’8″ (2.642 meters). The Wright E3 weighed 465 pounds (211 kilograms).

The VE-7 had a maximum speed of 106  miles per hour (171 kilometers per hour) and service ceiling of 15,000 feet (4,572 meters). Its maximum range was 290 miles (467 kilometers).

The fighter was armed with two Vickers .30-caliber (7.62 mm) machine guns, synchronized to fire forward through the propeller arc.

Chance Vought VE-7, 2-F-16, assigned to Fighter Squadron 2 (VF-2) (Chance Vought)
Chance Vought VE-7SF, 2-F-16, assigned to Fighter Squadron 2 (VF-2) (Chance Vought)

Rear Admiral Jackson R. Tate, U.S. Navy (Retired) described the first takeoff:

“We were operating just north of the Tongue of the Shoe, seaward of the main channel from Norfolk, Va. A trough about 6 feet long, set up on sawhorses was rigged at the aft end of the flight deck. When the tail skid of the VE-7 used in the test was placed in the trough, she was in the flight attitude.

“We had no brakes, so the plane was held down on the deck by a wire with a bomb release at the end. This was attached to a ring in the landing gear. ‘Squash’ Griffin climbed in, turned up the Hispano Suiza engine to its full 180 hp and gave the “go” signal. The bomb release was snapped and the Vought rolled down the deck. Almost before it reached the deck-center elevator it was airborne. Thus, the first takeoff from a U.S. carrier.”

United States Navy aircraft carrier USS. George H.W. Bush (CVN-77) (Mass Coomunications Specialist 3rd Class Tony Curtiss, U.S. Navy)
United States Navy nuclear-powered aircraft carrier USS George H. W. Bush (CVN-77). (Mass Communications Specialist 3rd Class Tony Curtis, U.S. Navy)

Virgil Childers Griffin, Jr., was born at Montgomery, Alabama, 18 April 1891. He was the first of three children of Virgil Childers Griffin, secretary of the Railroad Commission of Alabama, and Mary Lee Besson Griffin.

Midshipman Virgil C. Griffin, Jr., U.S.N.A.

Griffin was admitted as a midshipman at the United States Naval Academy, Annapolis, Maryland, 25 June 1908, a member of the Class of 1912. Four years later he graduated. Virgil C. Griffin, Jr., was commissioned an ensign, United States Navy, 8 June 1912, with a date of precedence 28 April 1908.

On 14 July 1912, Ensign Griffin was assigned to the 16,000 ton battleship, USS South Carolina (BB-26). Griffin was promoted to lieutenant (junior grade), 8 June 1915. He remained aboard South Carolina until June 1916.

Lieutenant (j.g.) Griffin applied for flight trainning, and on completion, was designated Naval Aviator # 41.

The United States entered World War I in April 1917. On 8 June 1917, Lieutenant (j.g.) Griffin was one of one hundred Naval Aviators who “arrived safely in France for any duty that may present itself. . . They are the first of the American fighting forces to reach France.” On 8 June 1918, Griffin was promoted to lieutenant (permanent rank). He was in command of the U.S. Navy sea plane base at Saint-Trojan, in southwestern France. Griffin was promoted to the rank of lieutenant commander (temporary), 21 September 1918 (Constructive date of precedence 28 February 1907).

Lieutenant Commander Griffin returned to the United States in 1919. He was assigned to the Department of the Navy, Washington, D.C., first to the Naval Operations Aviation Divivision, and in 1920, Naval Operations Inspection Division. Later in 1920, Griffin was assigned to the Atlantic Fleet Ship Plane Division, Mitchel Field, Mineola, New York.

On 8 December 1920, Lieutenant Commander Griffin married 25-year-old Alabama native Miss Elize Whiting Hall, at Mobile, Alabama.

In 1923, Lieutenant Commander Griffin returned to sea duty aboard USS Langley. he was next stationed at NAS Pensacola, Florida, 1924–1925. He served aboard USS Lexington (CV-2), 1926–1927. In 1929, Griffin returned to Langley, before being assigned Scoutig Squadron TWO (VS-2B) aboard USS Saratoga, flying the Vought O2U-2 Corsair.

On 29 December 1931, Griffin was promoted to commander. He was stationed at NAS Pearl Harbor, Territory of Hawaii, in 1932.

Commander Griffin once again returned to Langley, as the aircraft carrier’s executive officer, 1933–1934.

In 1937, Commander Griffin was commanding officer, NAS Anacostia, Washington D.C. He had additional duties in the Navy’s Bureau of Aeronautics.

In 1938 and 1939, Commander Griffin was chief of staff and aide to the Commander, Carrier Division TWO (ComCarDiv 2), aboard USS Yorktown.

Consolidated PBY-3 of Patrol Wing FIVE, circa 1939. (U.S. Navy)

Later in 1939, Commander Griffin was assigned as commanding officer Patrol Wing FIVE. The wing included patrol squadrons VP-51, VP-52, VP-53 VP-54, and the airplane tenders USS Gannet (AVP-8), USS Thrush (AVP-3), USS Owl (AM-2) and USS Patoka (AV-6).

Griffin was promoted to the rank captain, 1 November 1939. On 1 May 1940, Captain Griffin was placed in command of NAS Isle Grande, San Juan, Puerto Rico.

Captain Virgil C. Griffin, Jr., U.S. Navy, with Mrs. Ernest Hemingway (née Martha Ellis Gelhorn), circa 1942. (National Museum of the United States Navy) 80-G-13028a

Captain Virgil Childers Griffin, Jr., retired from the United States Navy, 1 January 1947. He died at San Diego, California, 27 March 1957, at the age of 66 years. He was buried at the Fort Rosecrans National Cemetery.

© 2018, Bryan R. Swopes

17 October 1913

Zeppelin L2 LZ 18 (© Ullstein Bild)
Zeppelin L2 (LZ 18). The smoke is coming from the forward engine car. (© Ullstein Bild)

17 October 1913: On the morning of a scheduled test flight at Flugplatz Johannisthal-Adlershof, an airfield south east of Berlin, Germany, Marine-Luftschiffes L2, the second rigid airship built for the Kaiserliche Marine (Imperial German Navy) by Luftschiffbau Zeppelin at Friedrichshafen, was delayed by problems with the engines. The morning sun heated the hydrogen contained in the airship’s gas bags, causing the gas to expand and increasing the airship’s buoyancy.

L2 New York Times 18 October 1913
L2 at altitude. This photograph was published in the New York Times, 18 October 1913. (George Grantham Bain Collection, Library of Congress)

Once released, L2 rapidly rose to approximately 2,000 feet (610 meters). The hydrogen expanded even more due to the decreasing atmospheric pressure. To prevent the gas bags from rupturing, the crew vented hydrogen through relief valves located along the bottom of the hull.

L2 leaves a trail of smoke as it crashes to the ground, 17 October 1913. (Zeppelin-Luftschiffe.com)

In this early design, the builders had placed the relief valves too close to the engine cars. Hydrogen was sucked into the engines’ intakes and detonated. L2 caught fire and a series of explosions took place as it fell to the ground.

All 28 persons on board were either killed immediately, or died of their injuries shortly thereafter.

At the time of the accident, L2 had made ten flights, for a total of 34 hours, 16 minutes.

The flight crew of Marine-Luftschiffes L2 (via LZDEAM.NET)
The flight crew of Marine-Luftschiffes L2

A contemporary news article described the accident:


The Wreck of the Zeppelin.

ELSEWHERE in this issue we comment upon the terrible catastrophe which befell the German Navy’s new Zeppelin L2, on Friday last week, just outside the Johannisthal aerodrome, near Berlin. From the following official account it appears that the airship was making a trial voyage:—

“She started this morning for a high flight, with twenty-eight persons on board. After three minutes she had attained a height of two hundred metres (over 600 feet) when flames burst forth between the fore engine-car and the envelope. In two or three seconds the whole ship was on fire and an explosion occurred. At the same time the airship fell slowly head downwards, until she was forty metres (130 feet) from the earth. Here a second explosion took place, presumably of benzine. When the vessel struck the earth a third explosion occurred, and the framework collapsed. A company of pioneers and guide-rope men hastened to the scene, and doctors were immediately in attendance. Two of the crew were picked up outside the ship still alive, but they died shortly afterwards. Lieut. Bleuel, who was severely injured, was taken to hospital. The remaining 25 of the crew had been killed during the fall of the airship or by the impact with the earth. The cause of the disaster appears to have been, so far as is at present known, an outbreak of fire in or over the fore engine-car.”

The commanding officer was Lieut. Freyer, and he was assisted by Lieuts. A. Trenck, Hansmann, and Busch, with thirteen warrant and petty officers. There were also on board as representing the German Navy, Commander Behnisch, Naval Construtors Neumann, and Pretzker, and three secretaries, named Lehmann, Priess, and Eisele. The Zeppelin Co. were represented by Capt. Glund and three mechanics, and Lieut. Baron von Bleuel was a passenger. The last mentioned was the only one rescued alive, and he died from his injuries a few hours later.

One of the first messages of sympathy was addressed by President Poincare’ to the German Emperor.

Extraordinary scenes, showing the way in which the calamity was regarded in Germany, were witnessed at the funeral service of 23 of the victims, held on Tuesday at the Garrison Church. Upon each of the coffins Prince Adalbert placed a wreath from the German Emperor and Empress, who with the Crown Prince and princess, and Princes Eitel Friedrich, Adalbert, August Wilhelm,  Oscar and Joachim attended in person, while the Government was represented by the Chancellor, Admiral Tirpitz, the Chief of the General Staff, Field Marshall von Moltke, and many other officers. Count Zeppelin was also present.

FLIGHT, First Aero Weekly in the World. No. 252. (No. 43, Vol. V.), 25 October 1913 at Page 1179

Wreckage of the L2 at Flugplatz Johannisthal-Adlershof, Germany, 17 October 1913. (Photo Gebr. Haeckel, Berlin # 3227/2)
Wreckage of the L2 at Flugplatz Johannisthal-Adlershof, Germany, 17 October 1913. (Gebrüder Haeckel, Berlin  3227/2)

The Marine-Luftschiffes L2 had been designated LZ 18 by the builders. Both identifications are commonly used (sometimes, L.II). Technical data for L2 is limited and contradictory. One source describes it as having a length of 158 meters (518 feet, 4½ inches), with a diameter of 16.6 meters (54 feet, 5½ inches). Another states 492 feet.

Eighteen hydrogen-filled gas bags were placed inside the rigid framework and covered with an aerodynamic envelope. The airship had a volume of 27,000 cubic meters (953,496 cubic feet), and a lift capacity of 11.1 tons (24,471 pounds).

Four water-cooled, normally-aspirated, 22.921 liter (1,398.725 cubic inches) Maybach C-X six-cylinder inline engines were carried in two cars beneath the hull. They produced 207 horsepower at 1,250 r.p.m., burning bensin (gasoline). Each engine drove a four-blade propeller through a drive shaft and gear arrangement. These engines weighed 414 kilograms (913 pounds), each.

L2 had a maximum speed of approximately 60 miles per hour (97 kilometers per hour). At reduced speed, L2 had a 70 hour radius of action.

The Kaiser and Imperial princes lead the funeral procession.
The Imperial Princes lead the funeral procession. Left to right, Prince Oskar, Prince August Wilhelm, Prince Adalbert, Crown Prince Wilhelm, Prince Eitel Friederich, Prince Joachim.

© 2016, Bryan R. Swopes