Bell H-13 Sioux

Bell Helicopter

Industry	Aerospace, defense
Founded	1935
Founder	Lawrence Dale Bell
Headquarters	Fort Worth, Texas , United States
Products	Helicopters, military aircraft

This article is about the military variants of Bell 47 models. For the civilian variants, see Bell 47.

The Bell H-13 Sioux is a light, single-engine helicopter from the United States, produced by Bell Helicopter primarily for military applications. The British military operated license-built versions manufactured by Westland Aircraft, known as the Sioux AH.1 and HT.2. Notably, it was the first helicopter to receive certification for civilian use.

Development

In 1947, the United States Army Air Forces—which later became the United States Air Force—placed an order for the upgraded (Bell Model 47A). The majority of these were marked as YR-13, with three adapted for winter conditions designated YR-13A. The United States Army officially procured Bell 47 helicopters in 1948 under the designation H-13, which subsequently earned the nickname Sioux.

Between 1947 and 1958, the United States Navy acquired several Bell 47s under the designation HTL-1. The United States Coast Guard tested this model and purchased two HTL-1s to support various operations in New York Harbor. The U.S. Navy’s most prevalent Bell 47 variant was the HTL-4, which featured a tail boom without fabric covering. In 1952, the Coast Guard obtained three HTL-5 models—similar to the HTL-4 but powered by Franklin O-335-5 engines—and operated them until 1960. Later, in 1959, two Bell Model 47G helicopters were acquired by the Coast Guard and designated as HUL-1G.

During the Korean War, the H-13 was among the main helicopters utilized by the U.S. Army, with the H-13D variant being especially common. It fulfilled multiple roles such as observation, reconnaissance, and medical evacuation missions. Its medevac function earned it the nickname "Angel of Mercy." In the early stages of the Vietnam War, it served as an observation helicopter before being replaced in 1966 by the Hughes OH-6 Cayuse.

The British Army ordered the Bell 47 under specification H.240, designating it as Sioux and producing it under license through Westland Helicopters. Due to licensing restrictions imposed by an agreement with Sikorsky Aircraft, which barred Westland from manufacturing a rival U.S. design directly, Westland obtained production rights via a license from Agusta, who had previously secured rights from Bell. The initial contract covered 200 helicopters; Agusta constructed the first 50 units at Gallarate, Italy, followed by Westland producing 150 at Yeovil. The maiden flight of Westland's Sioux occurred on March 9, 1965.

Design

The Sioux is a three-seat helicopter featuring a single engine and a single main rotor, primarily used for observation and fundamental training purposes. The Bell 47G model was introduced in 1953 and is easily identified by its distinctive full bubble canopy—a term coined by its designer, Arthur M. Young. This canopy was created by heating a large Plexiglas sheet and shaping it over a plywood mold using air pressure, resulting in a form resembling a soap bubble. The helicopter also includes an exposed welded-tube tail boom, saddle-mounted fuel tanks, and skid-type landing gear. In the UH-13J variant, which derives from the Bell 47J, the design incorporates a metal-covered tail boom and fuselage along with an enclosed cockpit and cabin.

Many military versions of the H-13 were outfitted with medical evacuation panniers attached to each skid, equipped with acrylic glass shields to protect patients from wind exposure.

A significant advancement in the Sioux's development was Bell’s integration of a short, weighted gyro-stabilizer bar positioned beneath and perpendicular to the main rotor. This bar featured streamlined counterweights at both ends and was connected to detect the rotor’s plane, maintaining it in a horizontal position. Functioning as a hinged flywheel linked to the cyclic pitch control, this stabilizer utilized gyroscopic inertia to keep the rotor blades aligned independently of fuselage motion caused by crosswinds. Additionally, it provided sufficient inertia during flight to ensure autorotation capability if the engine failed.

The 47G model was powered by a single 260 horsepower Lycoming VO-435 piston engine. Fuel supply came from two externally mounted high-positioned tanks. The Sioux employed a two-bladed main rotor complemented by short inertial stabilizing minor blades.

Military

File:Bell 47 (H-13G) medevac inflight bw.jpg

An H-13 equipped with medical evacuation panniers

YR-13

A total of 28 Bell 47A helicopters were acquired by the United States Army Air Forces for testing purposes. These YR-13s were powered by a 175 hp (130 kW) Franklin O-335-1 piston engine. Out of these, 10 units were transferred to the U.S. Navy and designated as HTL-1, with two subsequently handed over to the U.S. Coast Guard.

YR-13A

Three YR-13 helicopters modified for cold-weather operations in Alaska. In 1948, they were redesignated as YH-13A.

HTL-2

The U.S. Navy’s equivalent to the commercial Model 47D, with 12 units manufactured.

HTL-3

Corresponding to the commercial Model 47E for the U.S. Navy, powered by a 200 hp (149 kW) Franklin 6V4-200-C32 engine. Nine produced.

H-13B

Ordered in 1948 by the U.S. Army with a total of 65 aircraft. All these Army models later adopted the Sioux name.

YH-13C

A single H-13B converted into an engineering test platform featuring skid landing gear and an exposed tailboom.

H-13C

Sixteen H-13B units modified in 1952 to accommodate external stretchers, equipped with skid landing gear and an open tail boom similar to YH-13C.

H-13D

Two-seat Army variant based on the commercial Model 47D-1, fitted with skid landing gear, stretcher mounts, and powered by a Franklin O-335-5 engine. A total of 87 were built.

OH-13E

An evolution of the H-13D featuring three seats and dual controls, with production reaching 490 units.

XH-13F/Bell 201

A modified Bell 47G powered by a Continental XT51-T-3 (Turbomeca Artouste) turboshaft engine. This marked Bell's first helicopter equipped with a turbine engine.

OH-13G

A three-seat model derived from the commercial Model 47-G that introduced a small tailboom elevator. Delivered in quantities of 265 to the U.S. Army.

OH-13H/UH-13H

Based on Model 47G-2 and powered by a 250 hp (186 kW) Lycoming VO-435 engine. At least 453 units were procured by the U.S. Army. The U.S. Air Force operated UH-13Hs.

UH-13J

Two Bell 47J Ranger variants (Bell 47J-1) acquired by the U.S. Air Force for VIP transport duties related to the President of the United States. Initially designated as H-13J.

OH-13K

Two H-13Hs modified with larger diameter rotors and powered by a 225 hp (168 kW) Franklin 6VS-335 engine for evaluation purposes.

TH-13L

Originally referred to as Navy HTL-4.

HTL-5

Powered by a Franklin O-335-5 engine.

TH-13M

Featured a small movable tail elevator and was initially designated Navy HTL-6.

HH-13Q

Initially designated as HUL-1G, this model served in search and rescue missions for the U.S. Coast Guard.

UH-13R

Equipped with an Allison YT63-A-3 turboshaft engine and originally designated as Navy HUL-1M.

OH-13S

A three-seat observation helicopter based on Model 47G-3B designed to replace OH-13H variants. The U.S. Army received 265 units.

TH-13T

A two-seat instrument trainer version for the U.S. Army based on Model 47G-3B-1, powered by a 270 hp (201 kW) Lycoming TVO-435-D1B engine. Total production was 411 units.

Sioux AH.1

A general-purpose helicopter utilized by the British Army, with production consisting of 50 units built by Agusta (Agusta-Bell 47G-3B1) and another 250 constructed by Westland (Westland–Agusta-Bell 47G–3B1). Additionally, a limited number served within 3 Commando Brigade Air Squadron of the Royal Marines.

Sioux HT.2

A training helicopter employed by the Royal Air Force, with Westland manufacturing fifteen units.

H.7

(Thai: ฮ.๗) The designation used by Royal Thai Armed Forces for their OH-13H helicopters.

Civil

Texas Helicopter M74 Wasp

The Texas Helicopter Corporation developed a single-seat agricultural variant of the OH-13E helicopter, equipped with a 200 hp (150 kW) Lycoming TVO-435-A1E engine. This model received certification in 1976.

Texas Helicopter M74A

This single-seat agricultural conversion by Texas Helicopter Corporation is based on the OH-13H helicopter and powered by a Lycoming TVO-435 engine delivering 240 hp (180 kW) for a duration of 2 minutes. It was certified in 1977.

Texas Helicopter M79S Wasp II

Featuring tandem seating and stub wing fuel tanks, this agricultural conversion from Texas Helicopter Corporation is powered by a Lycoming TVO-435 engine rated at 270 hp (200 kW) for up to 5 minutes.

Texas Helicopter M79T Jet Wasp II

The Texas Helicopter Corporation modified Bell 47G helicopters for agricultural purposes, installing 420 hp (310 kW) Soloy-Allison 250-C20S engines.

Operators

File:Australian Army A1 Bell 47G Sioux - A1-398.jpg

Bell 47G Sioux (A1-398) of the Australian Army, utilized for training at RAAF Base Wagga.

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An OH-13 displayed at the Pakistan Army Museum.

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• Argentine Army
• Argentine Navy
• Argentine Naval Prefecture

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• Australian Army

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• Austrian Air Force

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• Brazilian Air Force

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• Royal Canadian Navy
  • VX-10 Squadron

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• Chilean Navy

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• Colombian Air Force

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• Air Defense Force

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• Ecuadorian Air Force

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• French Air Force
• National Gendarmerie

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• Bundesgrenzschutz
• German Army
• German Air Force

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An H-13 operated by the Maltese Air Wing

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• Hellenic Air Force

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• Honduran Air Force

 Iceland

• Icelandic Coast Guard

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• Indonesian Air Force

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• Indian Air Force

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• Italian Air Force
• Italian Army
• Italian Navy

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• Jamaica Defence Force

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• Japan Ground Self Defence Force
• Japan Maritime Self Defence Force

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• Royal Malaysian Air Force

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• Maltese Air Wing

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• Mexican Air Force
• Mexican Navy

File:RNZAF Sioux 2009.jpg

A Royal New Zealand Air Force Sioux helicopter in 2009

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• Royal New Zealand Air Force

 Norway

• Royal Norwegian Air Force

 Paraguay

• Paraguayan Air Force

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• Pakistan Army Aviation Corps

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• Peruvian Air Force
• Peruvian Navy

Philippines

• Philippine Air Force

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• Senegalese Air Force

Template:Country data South Vietnam

• Operated by the South Vietnam Air Force since April 1956.
  • 1st Helicopter Squadron
  • 2nd Helicopter Squadron

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• Operated by the People's Republic of Yemen Air Force

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• Spanish Air Force
• Spanish Army
• Spanish Navy

Template:Flagicon image Sri Lanka

• Sri Lanka Air Force
  • No.5 Squadron

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• Republic of China Army

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• Royal Thai Air Force

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• Turkish Air Force

File:XT131 RIAT Bthebest.JPG

Agusta Sioux AH.1 from the British Historic Army Aircraft Flight.

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• British Army's Army Air Corps

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• United States Air Force
• United States Army
• United States Navy
• United States Coast Guard

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• Uruguayan Air Force
• Uruguayan Naval Aviation

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• Venezuelan Air Force

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• Zambian Air Force

Canada

• RCN 1387 – HTL-6 exhibited as a static display at the Canada Aviation and Space Museum located in Ottawa, Ontario.

Germany

• 58-5348 – OH-13H presented on static exhibition at the Hubschraubermuseum Bückeburg in Bückeburg, Lower Saxony.
• XT548 – Sioux AH.1 displayed statically at the Flugausstellung Hermeskeil museum in Hermeskeil, Rhineland-Palatinate.

New Zealand

• H-13 Sioux (Bell 47-G3) with registration NZ3705 Sioux showcased at the Royal New Zealand Air Force Museum in Wigram. The helicopter is featured in its RNZAF paint scheme as it appeared when retired in 2012.

Pakistan

• OH-13 exhibited as a static piece at the Pakistan Army Museum in Rawalpindi, Punjab.

South Africa

• XT562 – Bell 47 displayed statically at the Port Elizabeth Branch of the South African Air Force Museum situated in Port Elizabeth, Eastern Cape.

South Korea

File:H-13 Sioux.jpg

An H-13 displayed at the War Memorial of Korea in Seoul.

• H-13 shown as a static exhibit at the War Memorial of Korea in Seoul.

Spain

• OH-13H on display as a static exhibit within the Aeronautical Laboratory of the School of Industrial and Aeronautical Engineering at the Polytechnic University of Catalonia in Terrassa, Barcelona.

Taiwan

• 1101 – OH-13H exhibited at the Republic of China Air Force Academy's subsidiary, the Aviation Education Exhibition Hall.

• 2110 – OH-13H presented at Longtan Sports Park located in Taoyuan City, Taiwan.

Thailand

• 56-2182/H7-9/15 – OH-13H showcased at the Royal Thai Air Force Museum in Bangkok, Thailand.

United Kingdom

Operational

• XT131 (G-CICN) - Sioux AH.1 maintained in flying condition by the Historic Army Aircraft Flight stationed at AAC Middle Wallop.

Exhibited

• XT148 – Sioux AH.1 currently undergoing restoration at the North East Land, Sea and Air Museums in Sunderland, Tyne and Wear.

• XT190 – Sioux AH.1 displayed statically at The Helicopter Museum in Weston-super-Mare, Somerset.

• XT200 – Sioux AH.1 on static exhibition at the Newark Air Museum situated in Newark, Nottinghamshire.

United States

File:BellH13PuebloMuseum.jpg

An H-13 featuring a M*A*S*H-themed paint scheme exhibited at the Pueblo Museum.

File:Bell OH-13D Sioux RSideFront CFM 7Oct2011 (15138580578).jpg

OH-13 displayed at the Cavanaugh Flight Museum

Operational Aircraft

OH-13H

• 58-1528 – Currently operated by Ocean Air Inc., located in Eugene, Oregon.

TH-13T

• 65-8040 – Housed at the Cavanaugh Flight Museum in Addison, Texas, this unit is painted to resemble an H-13D. It was removed from public view when the museum closed indefinitely on January 1, 2024, and is planned for relocation to North Texas Regional Airport in Denison, Texas.

Static Exhibits

H-13B

• 48-0796 – Displayed at the South Carolina Military Museum in Columbia, South Carolina. This aircraft represents the initial H-13B model, bearing serial number 101, and was manufactured in mid-July 1948.

H-13D

• 48-0845 – Preserved at the United States Army Aviation Museum in Enterprise, Alabama.

OH-13D

• 51-2456 – Exhibited at the United States Army Medical Department Museum situated at Fort Sam Houston, San Antonio, Texas.

OH-13E

• 51-13934 – Part of the collection at the Evergreen Aviation & Space Museum in McMinnville, Oregon.
• 51-14010 – Located at the U.S. Army Transportation Museum within Joint Base Langley–Eustis, near Newport News, Virginia.
• 51-14062 or 51-14077 – Preserved at the Aviation Hall of Fame and Museum of New Jersey in Teterboro, New Jersey.
• 51-14175 – On display at the Yanks Air Museum in Chino, California.
• 51-14193 – Exhibited within the United States Army Aviation Museum in Enterprise, Alabama.
• 51-14218 – Also part of the collection at the United States Army Aviation Museum in Enterprise, Alabama.

OH-13G

• 52-7833 – Displayed at the Wings of Freedom Aviation Museum located in Horsham, Pennsylvania.

H-13H

• 58-1520 – Exhibited by the South Dakota Air and Space Museum in Box Elder, South Dakota.

OH-13H

• 59-4949 – Utilized as a training airframe at Portland Community College, situated in Portland, Oregon.

UH-13H

• 56-2217 – On display at the Castle Air Museum in Atwater, California.

OH-13S

• 63-9085 – Exhibited at the Texas Air & Space Museum in Amarillo, Texas. It features a "M*A*S*H" paint scheme and is on loan from Amarillo College.
• 64-15338 – Preserved by the Flying Leatherneck Aviation Museum in San Diego, California.
• 64-15393 – Part of the collection at the Intrepid Sea, Air & Space Museum in New York, New York.

TH-13T

• 67-15963 – Displayed with a "M*A*S*H" paint scheme at the Pueblo Weisbrod Aircraft Museum, located in Pueblo, Colorado.
• 67-17053 – Exhibited at the Hill Aerospace Museum in Ogden, Utah.

HTL-2

• 122952 – On exhibit at the Pima Air & Space Museum, based in Tucson, Arizona.

HTL-4

• 128911 – Part of the collection at the National Museum of Naval Aviation, located in Pensacola, Florida.

HTL-6

• 142377 – Also held by the National Museum of Naval Aviation, Pensacola.
• 142394 – Preserved by the Flying Leatherneck Aviation Museum, San Diego.

HTL-7

• 145842 – Displayed within the collection of the Pima Air & Space Museum, Tucson.

Unspecified Model

• An airworthy XH-13F is maintained by the Fantasy of Flight facility in Polk City, Florida.
• The U.S. Veterans Memorial Museum in Huntsville, Alabama features an H-13D on public display.

Specifications (Sioux AH.1)

Bell YR-13 three-view line illustration

Three-view line drawing of the Bell YR-13

Bell H-13G Sioux three-view line illustration

Three-view line drawing of the Bell H-13G Sioux

Popular culture

The H-13 helicopter has been prominently featured in numerous film and television productions, often playing significant roles. Notably, it is closely linked with the M*A*S*H television show (1972–1983) as well as the 1970 film adaptation. The helicopter is prominently displayed in the opening credits and is central to the series finale, which remains the highest-rated single episode ever broadcast in the United States. The popularity of the series greatly contributed to the H-13 becoming widely recognized as the iconic helicopter associated with the Korean War. Additionally, the H-13 was a key feature in the Whirlybirds television series that aired from 1957 to 1959.

Notes

Bibliography

• United States, Headquarters Department of the Army, Army Concept Team in Vietnam. Final Report of Essential Load of Scout Helicopters. Saigon, Vietnam: Army Concept Team in Vietnam, 1966.

External links

• Bell 47.net
• Bell 47 Project: University of Toronto (archived January 30, 2009)
• Specifications for Model 47G from The International Directory of Civil Aircraft by Gerard Frawley