User:Colin Douglas Howell/Large piston helicopters

Single-engined large piston helicopters

Large helicopters powered by a single piston engine. These were usually transports, seating around 12 to 20 passengers (plus a crew of two or three), with a maximum takeoff weight in the range of 13,000 to 17,000 pounds and with engine power of 1,400 to 1,700 horsepower. The engine was always a large air-cooled radial. Helicopters of this sort were also used for other tasks, such as search and rescue, anti-submarine warfare, and ground attack. The most common helicopters in this class were the Mil Mi-4 and the Sikorsky H-34.

(The unusually heavy and powerful tandem-rotor Bell HSL, with a maximum takeoff weight of 26,500 pounds and an engine of 2,100 horsepower, yet dedicated to anti-submarine warfare rather than transport, was rather an outlier in this category and had a very short career.)

These large helicopters first appeared in the early 1950s. Although large helicopters began to use turboshafts rather than piston engines in the later 1950s, the piston-engined Sikorsky H-34 remained in production through the 1960s, and its Soviet counterpart, the Mil Mi-4, through the 1970s.

Piasecki H-21 Workhorse/Shawnee / Model 44

Piasecki CH-21C Shawnee of the U.S. Army circa the 1960s

American 15-to-20-passenger tandem-rotor transport helicopter, used by the U.S. Air Force and Army, among other military and civil operators. Sometimes nicknamed "Flying Banana", a nickname it borrowed from its predecessor, the Piasecki HRP.

• Produced: 1952–1959
• Number built: over 700
• Capacity: 20 passengers (plus 3 crew)
• Gross weight: 15,200 lb (6,895 kg)
• Engine: Wright R-1820-103 Cyclone 9 9-cylinder radial, 1,425 hp (1,063 kW)
• Maximum speed: 127 mph (204 km/h, 110 kn)
• Range: 265 mi (426 km, 230 nmi)
• Service ceiling: 9,450 ft (2,880 m)

Mil Mi-4 "Hound" / Harbin Z-5

Mil Mi-4 formerly used by Czech military

Soviet 16-passenger transport helicopter, used by Soviet and affiliated military and civil operators. Also built in China by Harbin Aircraft Manufacturing as the Z-5. Clearly inspired by the Sikorsky H-19 Chickasaw, but much bigger and more powerful, with a couple of special features of its own: rear clamshell doors with a vehicle loading ramp, and (in military versions) a gondola beneath the nose for a machine gunner.

• Produced: 1953–1979
• Number built: over 4,000 (over 3,400 by Mil, 558 Harbin Z-5)
• Capacity: 16 passengers (plus 2 crew)
• Maximum takeoff weight: 16,645 lb (7,550 kg)
• Engine: Shvetsov ASh-82V 14-cylinder radial, 1,680 hp (1,250 kW)
• Maximum speed: 115 mph (185 km/h, 100 kn)
• Range: 310 mi (500 km, 270 nmi)
• Service ceiling: 18,000 ft (5,500 m)

Sikorsky H-34 Choctaw / HSS-1 Seabat / HUS-1 Seahorse / S-58

Sikorsky CH-34C Choctaw of the U.S. Army circa the 1960s

American 12-to-18-passenger transport, utility, and anti-submarine warfare helicopter, used by the U.S. military and other militaries as well as civil operators. Built under license in France by Sud-Aviation; also built under license in turboshaft form in Britain as the Westland Wessex.

• Produced: 1954-1970
• Number built: 2,108
• Capacity: 18 passengers (plus 2 crew)
• Maximum takeoff weight: 13,300 lb (6,033 kg)
• Engine: Wright R-1820-84 Cyclone 9 9-cylinder radial, 1,525 hp (1,137 kW)
• Maximum speed: 122 mph (196 km/h, 106 kn)
• Range: 190 mi (310 km, 170 nmi)
• Service ceiling: 12,000 ft (3,700 m)

Bell HSL-1

A Bell XHSL-1 prototype being tested by the U.S. Navy circa 1953

American four-seat tandem-rotor anti-submarine warfare helicopter, equipped with sonar and armed with two Mk 43 lightweight anti-submarine torpedoes. Tested in small numbers by the U.S. Navy before being prematurely retired in 1960; most of the examples produced were never used. Heaviest, most powerful helicopter ever to use a single piston engine, and the only tandem-rotor helicopter ever built by Bell.

• Introduced: 1957
• Number built: 53
• Capacity: 4
• Maximum takeoff weight: 26,500 lb (12,020 kg)
• Engine: Pratt & Whitney R-2800-50 Double Wasp 18-cylinder radial, 2,100 hp (1,600 kW)
• Maximum speed: 124 mph (200 km/h, 108 kn)
• Range: 350 mi (560 km, 300 nmi)
• Service ceiling: 14,400 ft (4,400 m)

Twin-engined large piston helicopters

Very large helicopters powered by twin piston engines. Few such helicopters were ever built in quantity; most either never got past the prototype stage or were converted to turboshaft power before reaching production. The only exceptions were the Yakovlev Yak-24 and the Sikorsky H-37 Mojave. These had maximum takeoff weights of around 30,000 to 35,000 pounds, were powered by twin air-cooled radial engines of around 1,500 to 2,000 horsepower, and could seat 26 to 40 passengers or carry several tons of cargo, either internally or externally.

Such extreme piston-engined helicopters were short-lived; by the time they reached service in the middle 1950s, turboshafts were already replacing large piston engines, so these craft were rendered obsolete almost as soon as they were born.

Yakovlev Yak-24 "Horse"

Yakovlev Yak-24U of the Soviet Air Force at Russia's Central Air Force Museum

Soviet 40-passenger twin-engine tandem-rotor transport and heavy-lift helicopter, used by the Soviet Air Force and possibly Aeroflot. The largest ever piston-engined production helicopter. The rear end had a ramp-type door for loading.

• Introduced: 1955
• Number built: 40-100 (sources differ)
• Capacity: 40 passengers (plus 4 crew)
• Maximum takeoff weight: 34,900 lb (15,830 kg)
• Engines: two Shvetsov ASh-82V 14-cylinder radials, 1,700 hp (1,300 kW) each
• Maximum speed: 109 mph (175 km/h, 94 kn)
• Range: 165 mi (265 km, 143 nmi)
• Service ceiling: 8,900 ft (2,700 m)

Sikorsky H-37 Mojave / HR2S-1

Sikorsky HR2S-1 of the U.S. Marines circa 1957

American 26-passenger twin-engine transport and heavy-lift helicopter, used by the U.S. Army and Marines. The largest production helicopter in the West at the time, and the most powerful ever piston-engined production helicopter. The nose had clamshell doors with a ramp for loading. The engines were mounted in external nacelles to free up interior space, and the main landing gear retracted into these nacelles.

• Produced: 1956-1960
• Number built: 154
• Capacity: 26 passengers (plus 3 crew)
• Maximum takeoff weight: 31,000 lb (14,061 kg)
• Engines: two Pratt & Whitney R-2800-54 Double Wasp 18-cylinder radials, 2,100 hp (1,600 kW) each
• Maximum speed: 130 mph (209 km/h, 113 kn)
• Range: 145 mi (233 km, 126 nmi) with maximum payload
• Service ceiling: 8,700 ft (2,650 m)