Two prototypes of the five-seat Bell 48 were delivered to the Air Force in May 1948 for testing as the XR-12 (later H-12). The pre-production YH-12B had eight seats; the production H-12 had ten seats.
Use of medical aidmen as flight medics reappeared during the Korean War, with the introduction of the helicopter. Although the Army did not use medical aidmen as flight medics on board helicopters, they were used by the Navy and Marine Corps. This was due to the type of rotary wing aircraft each service was using at the time. The Navy used a two-seater version called the Hiller HTE-1, later redesignated the H-12.
In July 1947, development began on a production prototype called the Hiller 360 or UH-12. This helicopter was developed with three-across seating, a 160 hp vertically mounted Franklin motor, an overhead control stick, and two wooden rotor blades. The prototype, the 360X, first flew on 11 November 1947, and was publicly demonstrated one month later. It was heavily marketed for agricultural use. With a $20,000 price tag, it was far less expensive than any other contemporary helicopter. Three more pre-production aircraft were built to speed civil certification, which was granted in October 1948. By this time, Hiller had moved the company into a permanent headquarters on 61 acres in Palo Alto, California, and completed a $150,000 production factory. An improved version, the UH-12A, received supplemental certification in May 1950. It featured new rotor blades and a 10% grow weight increase. 194 of these early UH-12/As were built.
This type of helicopter saw extensive use in Korea. The onset of the Korean War meant a sudden need by the Army for more helicopters. In September 1950, the Army began testing a UH-12A with enclosed litter carriers and military radios, designated H-23. The Hiller helicopter has been featured on many of television's "MASH" episodes. The Army ordered 105 H-23A Ravens at the end of 1950; in addition, 16 UH-12As had been previously ordered by the Navy as trainers, but when the war broke out, these HTE-1s were converted to Army use.
Early H-23 performance and reliability in Korea were inadequate. The H-23B used a 200 hp Franklin engine, landing skids instead of wheels, and a stronger structure. Flight testing began in September 1951 with first production deliveries two months later. By this time the company officially changed its name to Hiller Helicopters. Gross sales in 1952 reached $14.4M compared to $0.6M in 1949. Civil helicopter production was resumed in June 1952, with the UH-12B (H-23B).
After the cessation of hostilities, improvements in helicopter technology sparked development the aeromedical evacuation doctrine. The UH-12C/H-23C was introduced in 1955 with all metal rotor blades and a goldfish bowl cockpit canopy. A total of 145 were delivered to the Army. An observation version, the OH-23D with a 320 hp Lycoming engine and an uprated gearbox found 483 more orders. The most highly produced version was the UH-12E/OH-23G. A four seat version, the Hiller 12E4/OH-23G, was also built. The Hiller L3 (12E-L) and L4 (12E4-L) used the new high inertia L rotor instead of the Rotormatic paddles used on previous Hiller designs. This L rotor used a Hamilton Standard stability augmentation system and new wide-chord metal rotor blades with high lift and inertia. These blades gave a smoother ride, more solid control feel. All together, more than 2,000 UH-12/H-23 helicopters were produced, including 300 in exports.
Considered the most versatile helicopter in production, the UH-12E provides unparalleled capability including external load work, aerial observation and primary through turbine flight training - all using the same basic airframe. All of this can be done without the need for pilots to meet special FAA training and experience requirements necessary with some other aircraft. Known as flying pick-up trucks, Hiller helicopters are the proven choice for agriculture, forestry and construction. The Hiller UH-12E boasts the highest useful load of any helicopter in its class; 300 pounds more than its closest competitor. Its simple construction adds to its versatility. Hiller is the only light helicopter that can be serviced and maintained without extensive preparation work or removing cowlings. Hiller is also the only manufacturer that publishes full maintenance manuals so components do not have to go back to the factory for overhaul.
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