Today in WW II: 11 Oct 1939 Letter signed by Albert Einstein is delivered to US President Franklin D. Roosevelt, urging the United States to rapidly develop the atomic bomb before Germany does, the inspiration for the Manhattan Project. More↓
The Bell H-13 Sioux helicopter was acquired by the Army in 1946 as an adaptation of the Bell commercial Model 47. It was the first Army aircraft named for an Indian tribe, a tradition that is still used. The H-13 was the primary helicopter used during the Korean War for all tasks (e.g. wire laying, liaison, reconnaissance and training), but most famously for Medical Evacuation (MedEvac) as portrayed in the TV-series MASH named for Mobile Army Surgical Hospital (MASH) units, the destination of the MedEvac flights in Korea.
While the Army and Air Force designated this helicopter as the H-13, the Navy and Marine Corps, who eventually purchased over 200 of them, knew it as the HTL.
At the beginning of the Korean War, the Army had 56 H-13s in its inventory - the B Models and 4 of the older YH-13As. All models were used widely by the helicopter detachments. In the early 1960s at the beginning of the Vietnam War, the Army had 861 H-13s in its inventory. Although more advanced helicopters were the primary platforms in Vietnam, the H-13E Sioux proved useful as an observation helicopter for the cavalry, infantry and air assault divisions.
The H-13 series featured the Bell-designed short weighted gyro-stabilizer bar at 90° to, and beneath, the main rotor, an innovation that increased stability and safefy of the aircraft. Early models had open cockpits or sheet metal cabins, but the most common model, the H-47G, introduced in 1953, has the familiar full bubble canopy, welded tube lattice tail, and saddle fuel tanks.
One of the most popular light utility helicopters ever built, the H-13 Sioux was produced in 20 different configurations, with model numbers ranging from A to T. (It was also known as YR-13 and OH-13). The commercial equivalent Bell model 47 was used in 40 countries, with production from 1946 to 1976. In the U.S. military, the Bell H-13 Sioux was superceded by the more advanced OH-6A Cayuse light observation helicopter and OH-58 Kiowa in 1968-1969.
Varied with model from Franklin 157hp (H-13B/H-13C) to the Lycoming 305hp in later models of the Bell Model 47J-2. Also XH-13F experimental turbine powered Sioux in 1955.
OH-13H Sioux light observation helicopter.
Bell H-13G Sioux, one of 265 produced for the Army in 1951.
XH-13F experimental turbine powered Sioux in 1955 (Bell Model 201). Powered by a Continental-Turbomeca XT51-T-3 Artouste I 220 hp turboshaft engine, this was Bell Helicopter's first turbine powered aircraft.