The Yakovlev Yak-24 is a Soviet twin-engine, tandem rotor, transport helicopter developed by Yakovlev in the 1950s. The Yak-24 saw limited use in the Soviet Air Force, and the exact number produced and duration of service are unknown due to inconsistencies in data.
Design and development
In September 1951, following a meeting of Joseph Stalin with senior aircraft designers the Soviet Union issued two design specifications for helicopters, with the intent of rapidly accelerating Soviet helicopter development. The requirement for a medium-sized helicopter which could transport 12 people was issued to the MilDesign Bureau, which would result in the Mil Mi-4, while the requirement for a larger helicopter capable of transporting 24 people was given to the Yakovlev Design Bureau under Alexander Yakovlev. Prototypes of both types had to be flying within a year - 'unlimited support' was to be provided for these two programmes by the nationalresearch institutes. Yakovlev made two prototypes for flight testing, and two more for static and dynamic ground tests. The first prototype was flown on 3 July 1952. It was powered with two 1,268 kW Shvetsov ASh-82V radial engines and was built in a tandem rotor layout, which was not typical for Soviet helicopters, which soon brought it the nickname Letayushchiy Vagon – 'the Flying Railroad Car'. The engines and transmission system were identical to the already-proven single-engine Mil Mi-4, but the Yak-24 proved to be less successful. Its engines were linked together so each could drive one or both rotors, but such an arrangement caused strong vibrations in the airframe. After the problems were partially solved, the new helicopter was ordered for production by the Soviet Air Force, which began in 1955 at Factory No. 272 in Leningrad. In July 1955, the Yak-24 was first presented to the public in Tushino, and on 17 December 1955 it set two new worldpayload records, lifting a 2,000 kg load to 5,082 m and 4,000 kg to 2,902 m. The initial variant was the Yak-24 – Army transport helicopter, that could carry up to 30 airborne troops, 18 stretchers or 3,000 kg of cargo. From 1958, the improved model Yak-24U was produced, with all-metal rotors of larger diameter and an all-metal fuselage. It could carry 40 soldiers or 3,500 kg of cargo, including two GAZ-69 jeeps or anti-tank guns. A civilian variant for 30 passengers was the Yak-24A, produced from 1960 in small numbers for Aeroflot. It was also used as a flying crane, lifting an external load of 5,000 kg. There were two proposed models: the Yak-24K nine-seat VIP salon with a shorter fuselage and the civilian Yak-24P for 39 passengers with stronger 2,013 kW turboshaft engines, but neither reached production. Data on the Yak-24 is inconsistent and sometimes contradictory, the exact number of helicopters produced is unknown, with estimates ranging from 40 to 100 units depending on the source of the data. All sources agree that production of the Yak-24 was curtailed due to technical problems, and the need for a heavy transport helicopter was fulfilled by the successful Mil Mi-6, becoming its de facto replacement. According to some sources, the passenger Yak-24A for Aeroflot was not actually produced. The exact date of the Yak-24's decommissioning from the Soviet Air Force, and possibly Aeroflot, is unknown. A surviving Yak-24 is preserved at the Central Air Force Museum in Monino, Russia.
