The Bell Model 47 appeared in 1946 and became the classic light utility helicopter design of the early Cold War years serving military and civilian markets alike.
Authored By: Staff Writer | Last Edited:
Credit: Image from the Public Domain.
While the helicopter received some attention during World War 2 (1939-1945), it was not until the Korean War that its practical battlefield value was put to the test. One of the most famous designs to emerge from the fighting was the utilitarian Bell Model 47 which headed the opening credits of the M.A.S.H. television series in popular culture (though in its militarized H-13 Sioux form). In reality, the Model 47 proved the consumate workhorse used in a myriad of roles including medical transport and observation. With some 5,600 produced from the span of 1946 into 1974, the Model 47 can still be found in airspaces of today. The Bell Model 47 has been used by the nations of the United States, Australia, Austria, Brazil, Canada, India, Italy, New Zealand, Peru, South Africa and the United Kingdom with many on public display as showpieces. The formal military variant is the Bell H-13 Sioux detailed elsewhere on this site.
Arthur M. Young served as an engineer at Bell Helicopters with a prior history designing and developing helicopter prototypes. With Bell behind him, his prototypes were realized into physical forms and eventually produced the Model 30 of 1943. Three of the type were eventually built and served in an experimental role. A single Franklin 6V4 piston engine developed 160 horsepower to drive the two-blade main rotor and two-blade tail rotor. Its fuselage was akin to a teardrop shape with a single-seat, open-air cockpit at the front, the engine at midships and a tapered empennage housing a drive shaft to the tail rotor. The tail rotor served as a counter-torque mechanism to the pull of the main rotor blades. The three-legged undercarriage was wheeled though fixed in place.
From this design was born the famous Model 47 which improved on several facets of the original. Seating was increased to two and power was derived from either a Franklin- or Lycoming-branded engine, now increased in output power to as much as 300 horsepower. Bell sold the United States Army on the design and the type was adopted for service in 1946 - too late to see operational service in World War 2 which officially ended in September of the previous year. The Bell design also became the first helicopter to be cleared for civilian use on March 8th, 1946. The US Army designated the militarized form as the H-13 "Sioux" and the type was featured heavily in the Korean War (1950-1953) to follow. The Model 47 was also a civilian marketplace stalwart where it's simple construction and contained flight characteristics ensured it a lengthy reach as a multi-role utility mount. The Model 47 was even attributed with several air records including a 1949 claim of reaching 18,550 feet for a helicopter, a 1950 feat seeing a Model 47 pass over the Alps and a 1952 world distance of 1,217 miles from Hurst, Texas to Buffalo, New York - the first for a piston-powered helicopter design.
Of course it became the Korean War that granted the Model 47/H-13 its classic appearance including the bubble canopy and skeletal tail section. The type was used in the MEDEVAC role and as an airborne observation platform.
Preproduction versions carried the simple Model 47 designation and these were powered by the Franklin engine of 178 horsepower. The Model 47A introduced the Franklin O-355-1 piston engine. The Model 47B was outfitted with the same engine while the similar Model 47B-3 was an agricultural platform with open-air cockpit. Then came the Model 47C and it was the Model 47D that introduced the classic bubble canopy design. The Model 47D-1 appeared in 1949 and revealed the classic skeletal tail structure common to many Model 47 pictures. It supported seating for three. The Model 47E introduced the Franklin 6V4-200-C32 powerplant with 200 horsepower output. Then came the Model 47F and the Model 47G which utilized a three-seating arrangement and "saddle bag" fuel stores. The Model 47G-2 introduced a Lycoming VO-435 series engine while the 47G-2A utilized a slightly different VO-435 installation. The Model 47G-2A-1 increased cabin space, featured additional fuel storage volume and brought about use of an all-new rotor blade design. The Model 47G-3 was outfitted with a supercharged Franklin 6VS-335-A series engine while the Model 47G-3B made use of a turbocharged Lycoming TVO-435 engine. The Modle 47G-4 was powered by a Lycoming VO-540 engine and the follow-up Model 47G-5 was a three-seat model. The Model 47H-1 introduced a completely enclosed cabin structure which encompassed the fuselage as well. The Model 47J Ranger was a four-seat model with a Lycoming VO-435 series engine. The Model 47K served as a military trainer for the Model 47J and featured seating for two.
Bell was granted foreign license production with the governments of Italy, Japan and the United Kingdom. Agusta produced the aircraft in Italy while Japanese manufacture was through Kawasaki Heavy Industries (as the KH-4). British mounts were produced by Westland Aircraft.
Many Model 47s are no longer in direct military service but survive through various civilian endeavors - primarily in the tourism industry. Nevertheless, they remain a classic, highly recognizable design.
Status Active, Limited Service
[ 5,600 Units ] : Bell Helicopters - USA
Australia; Austria; Brazil; Canada; India; Italy; Japan; Peru; New Zealand; South Africa; United Kingdom; United States
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