A U.S. Air Force Sikorsky H-5F lifts off during the Korean War. (U.S. Air Force)
4 August 1950: During the Battle of the Pusan Perimeter, wounded soldiers were evacuated from the battlefield by helicopter for the first time when a Sikorsky H-5F of Detachment F, 3rd Emergency Rescue Squadron,¹ Air Rescue Service, United States Air Force, flew Private 1st Class Claude C. Crest, Jr., U.S. Army, from the Sengdang-ni area to an Army hospital. By the end of combat in 1953, 21,212 soldiers had been medevaced by helicopters.
Only the second military helicopter, the H-5 was frequently flown overloaded and outside of its center of gravity limits. The helicopter was not armed, though the pilot normally carried an M1911 .45-caliber semi-automatic pistol, and the crewman, a .30-caliber M1 Carbine.
Eleven commercial Sikorsky S-51 helicopters had been purchased by the Air Force in 1947 and designated R-5F. This was later changed to H-5F. It was a four-place, single-engine helicopter, operated by one pilot. The cabin was built of aluminum with Plexiglas windows. The fuselage was built of plastic-impregnated plywood, and the tail boom was wood monocoque construction. The main rotor consisted of three fully-articulated blades built of metal spars and plywood ribs, covered with two layers of fabric. (All metal blades soon became available.) The three bladed semi-articulated tail rotor was built of laminated wood. The main rotor turned counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right.) Its normal operating range was 175–195 r.p.m. The tail rotor was mounted on the helicopter’s left side in a pusher configuration. It turned clockwise as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.)
Sikorsky S-51 three-view drawing with dimensions. (Sikorsky Historical Archives)
The helicopter’s fuselage was 41 feet, 1¾ inches (12.541 meters) long. The main rotor had a diameter of 48 feet, 0 inches (14.630 meters) and the tail rotor diameter was 8 feet, 5 inches (2.565 meters),² giving the helicopter an overall length of 57 feet, ½ inch (17.386 meters) with rotors turning. It was 12 feet, 11–3/8 inches (3.947 meters) high. The tricycle landing gear had a wheel base of 10 feet, 1 inch (3.073 and the tread was 12 feet, 0 inches (3.658 meters). The S-51 had an empty weight of 4,050 pounds (1,837 kilograms) and maximum gross weight of 5,300 pounds (2,404 kilograms) below 1,000 feet (305 meters) MSL.³ Fuel capacity was 100 gallons (379 liters).
The H-5F was powered by an air-cooled, supercharged, 986.749-cubic-inch-displacement (16.170 liter) Pratt & Whitney R-985 AN-5 (Wasp Jr. T1B4 ) which was placed in the fuselage behind the crew compartment with the crankshaft vertical. The R-985-AN-5 was a direct-drive, nine-cylinder radial engine with a compression ratio of 6:1. It required 91-octane aviation gasoline and was rated at 450 horsepower at 2,300 r.p.m., Standard Day at Sea Level. The R-985 AN-5 was 48.00 inches (1.219 meters) long, 46.25 inches (1.175 meters) in diameter and weighed 684 pounds (310.3 kilograms) with a magnesium crankcase.
The H-5F had a maximum speed (VNE) of 107 knots (123 miles per hour/198 kilometers per hour). Range was 275 miles (443 kilometers). The service ceiling was 14,800 feet (4,511 meters). The absolute hover ceiling was 3,000 feet (914 meters).
Sikorsky H-5, Korea. (U.S. Air Force)
¹ Reorganized as the 3rd Air Rescue Squadron 10 August 1950.
² An 8 foot, 9 inch (2.667 meter) all-metal two-blade tail rotor assembly became standard with the H-5G, and was available to retrofit earlier helicopters.
³ The maximum gross weight had to be reduced 150 pounds (68 kilograms) for each additional 1,000 feet of altitude.
18 July 1967: For the first time, a U.S. Air Force Sikorsky HH-3E Jolly Green Giant combat search and rescue helicopter refueled in flight from a Lockheed HC-130P Combat King command and control aircraft during an actual rescue mission in Southeast Asia.
A Lockheed HC-130P Combat King refuels a Sikorsky HH-3E Jolly Green Giant, with escorting Douglas A-1E and A-1H Skyraiders, Southeast Asia, 1968. (U.S. Air Force)
British Airways’ Sikorsky S-61N Mark II, G-BEON, at Newquay Cornwall Airport, 21 July 1982. (Carl Ford)
16 July 1983: At 11:10 a.m., a British Airways Sikorsky S-61N-69 Sea King helicopter, c/n 61-770, registration G-BEON, departed Penzance Heliport (PZE) enroute across the Celtic Sea to St. Mary’s Airport, Isles of Scilly. On board were a crew of 3 and 23 passengers. Visibility was poor due to fog. Flying under visual flight rules, the helicopter was at 250 feet (76 meters) while the pilots tried to maintain visual contact with the surface of the calm sea.
Great Circle route from Penzance Heliport, Cornwall, to St. Mary’s Airport, Iles of Scilly, 33 nautical miles (37 statute miles/60 kilometers) away. (Great Circle Mapper)
Because of the limited visual cues, the crew did not recognize that they were in a slight descent. At approximately 11:35 a.m., the Sikorsky slammed into the ocean at cruise speed. It sank almost immediately. Only six persons survived, including the pilots, Dominic Lawlor and Neil Charleton. The helicopter sank to the sea bed 200 feet (61 meters) below. It was later recovered by the salvage vessel RMAS Seaforth Clansman, along with the bodies of 17 victims.
The wreck of British Airways S-61N Sea King G-BEON on board RMAS Seaforth Clansman. Isles of Scilly, 1983. (Andrew Besley/cornishmemory.com)
The official investigation determined that the cause of the accident was pilot error by their failure to recognize and correct the unintentional descent while attempting to fly in conditions not suitable for visual flight. This was the worst helicopter accident in terms of fatalities up to that time.
The Sikorsky S-61N is a civil variant of the United States Navy HSS-2 Sea King. The first S-61N, s/n 61143, first flew 7 August 1962. It is a large twin-engine helicopter with a single main rotor/tail rotor configuration. The S-61N fuselage is 4 feet, 2 inches (1.270 meters) longer than that of the HSS-2. The S-61N is 72 feet, 7 inches (22.123 meters) long and 16 feet, 10 inches (5.131 meters) high, with rotors turning.
The main rotor has five blades and a diameter of 62 feet (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The tail rotor also has five blades and a diameter of 10 feet, 4 inches (3.149 meters). They each have a chord of 7–11/32 inches (0.187 meters). At 100% r.p.m., the main rotor turns 203 r.p.m. and the tail rotor, 1,244 r.p.m. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right side.) The tail rotor turns clockwise, as seen from the left side. (The advancing blade is below.)
G-BEON was powered by two General Electric CT58-140-1 turboshaft engines, each of which had maximum power rating of 1,400 shaft horsepower for takeoff and 1,500 SHP for 2½ minutes. The main transmission was rated for 2,300 horsepower, maximum.
The S-61 has a cruise speed of 166 miles per hour (267 kilometers per hour). The service ceiling is 12,500 feet (3,810 meters). The maximum takeoff weight is 20,500 pounds (9,298.6 kilograms).
Between 1958 and 1980, Sikorsky built 794 S-61 series helicopters. 123 were S-61Ns.
President Eisenhower fastens his seat belt aboard H-13J-BF Sioux 57-2729, on the White House lawn, 12 July 1957. (U.S. Air Force)Dwight David Eisenhower, 34th President of the United States
12 July 1957: President Dwight D. Eisenhower was the first United States president to fly in a helicopter when a U.S. Air Force H-13J-BF Sioux, serial number 57-2729 (c/n 1576), flown by Major Joseph E. Barrett, USAF, departed the White House lawn for Camp David, the presidential retreat in the Catoctin Mountains of Maryland. Also on board was a U.S. Secret Service special agent. A second H-13J, 57-2728 (c/n 1575), followed, carrying President Eisenhower’s personal physician and a second Secret Service agent.
The helicopter was intended to rapidly move the president from the White House to Andrews Air Force Base where his Lockheed VC-121E Constellation, Columbine III, would be standing by, or to other secure facilities in case of an emergency.
Major Barrett had been selected because of his extensive experience as a combat pilot. During World War II, he had flown the B-17 Flying Fortress four-engine heavy bomber. During the Korean War, Barrett had carried out a helicopter rescue 70 miles (113 kilometers) behind enemy lines, for which he was awarded the Silver Star.
Bell H-13J 57-2729, flown by Major Joseph E. Barrett, with President Eisenhower and a Secret Service agent, departs the White House, 2:08 p.m., 12 July 1957. (The White House)
The two helicopters were manufactured by the Bell Helicopter Company at Fort Worth, Texas, and delivered to the Air Force at Wright-Patterson Air Force Base on 29 March 1957. The presidential H-13Js were nearly identical to the commercial Bell Model 47J Ranger. The H-13J differed from the civil Model 47J by the substitution of main rotor blades of all-metal construction in place of the standard laminated wood blades.
Capable of carrying a pilot and up to three passengers, the Ranger was constructed with an enclosed cabin built on a tubular steel framework with all-metal semi-monocoque tail boom. The main rotor diameter was 37 feet, 2.00 inches (11.328 meters) and tail rotor diameter was 5 feet, 10.13 inches (1.781 meters), which gave the helicopter an overall length of 43 feet, 3¾ inches (13.185 meters) with rotors turning. The height (to the top of the centrifugal flapping restraints) was 9 feet, 8 inches (2.946 meters). The helicopter had a maximum gross weight of 2,800 pounds (1,270 kilograms).
The main rotor, in common to all American-designed helicopters, rotates counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right.) The anti-torque (tail) rotor is mounted to the right side of an angled tail boom extension, in a tractor configuration, and rotates counter-clockwise as seen from the helicopter’s left. (The advancing blade is above the axis of rotation.)
The main rotor is a two-bladed, under-slung, semi-rigid assembly that would be a characteristic of helicopters built by Bell for decades. The main rotor system incorporates a stabilizer bar, positioned below and at right angles to the main rotor blades. Teardrop-shaped weights are placed at each end of the bar, on 100-inch (2.540 meters) centers. The outside diameter of the stabilizer bar is 8 feet, 6.781 inches (2.611 meters). (A similar system is used on the larger Bell 204/205/212 helicopters.)
The H-13J was powered by an air-cooled, normally-aspirated 433.972-cubic-inch-displacement (7.112 liter) AVCO Lycoming VO-435-A1B (O-435-21) vertically-opposed 6-cylinder direct-drive engine. The VO-435 had a compression ration of 7.3:1. It was rated at 220 horsepower at 3,200 r.p.m., maximum continuous power, and 260 horsepower at 3,200 r.p.m. for takeoff. The VO-435-A1B weighed 393.00 pounds (178.262 kilograms).
Engine torque is sent through a centrifugal clutch to a 9:1 gear-reduction transmission, which drives the main rotor through a two-stage planetary gear system. The transmission also drives the tail rotor drive shaft, and through a vee-belt/pulley system, a large fan to provide cooling air for the engine.
One of the two presidential Bell H-13J Sioux helicopters hovers over the White House lawn. (U.S. Air Force)
Fuel was carried in two gravity-feed tanks, mounted above and on each side of the engine. The total fuel capacity was 34.0 gallons (128.7 liters)
Cruise speed for the H-13J was 87–98 miles per hour (140–158 kilometers per hour), depending on gross weight, and its maximum speed was 105 miles per hour (169 kilometers per hour). The helicopter had a hover ceiling in ground effect (HIGE) of 8,100 feet (2,469 meters). The service ceiling was 15,000 feet (4,572 meters).
Both H-13J Sioux served as presidential aircraft until 1962. They were redesignated UH-13J and continued in use for VIP transportation until 1967.
Bell UH-13J-BF Sioux 57-2729 is in the collection of the Smithsonian Institution National Museum National Air and Space Museum, Steven V. Udvar-Hazy Center, while its sister ship, 57-2728, is at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio, along with Columbine III.
The first presidential helicopter, USAF H-13J-BF Sioux 57-2729, on display at the Steven V. Udvar-Hazy Center, Smithsonian Institution National Air and Space Museum. (NASM)
New York Airways’ Sikorsky S-55A, N405A, at the East River heliport in the early 1950s. (This aircraft was destroyed following a tail rotor pylon attachment failure at Sarawak, Malaysia, 2 April 1964.)
8 July 1953: America’s first helicopter airline, New York Airways, began scheduled passenger service, operating flights between the three area airports—La Guardia, Idlewild and Newark. There were 16 flights per day at 90-minute intervals.
The first aircraft used was the Sikorsky S-55, a commercial variant of the military H-19 Chickasaw. It carried 8 passengers and a cargo of U.S. Mail. The mail contract actually was the source of 75% of NYA’s revenue.
As its popularity increased, New York Airways shifted to larger helicopters when they became available, adding three Sikorsky S-58s in 1956. In 1958, the fleet was changed to the Vertol V-44 tandem-rotor helicopter, a commercial model of the Piasecki H-21 Shawnee. In 1962 the turbine-powered Boeing Vertol BV 107-II replaced the earlier helicopters. NYA’s final aircraft was the twin-turbine Sikorsky S-61.
On 16 May 1977, the landing gear of a S-61L failed while on the roof top heliport of the Pan Am building in Manhattan. The helicopter rolled over and spinning rotor blades killed four waiting passengers. Broken blades then fell to the street, fifty-nine stories below, killing a pedestrian and injuring several others.
With its reputation severely damaged and fuel prices escalating, New York Airways filed for bankruptcy in 1979. It’s surviving helicopters are operated today by Columbia Helicopters, Inc., Aurora, Oregon.
