Yakovlev Yak-14

Yak-14

Manufacturer: Yakovlev
First flight: 1948
Introduced: 1950
Status: Retired
Primary users: USSR Czechoslovakia
Number built: 413

The Yakovlev Yak-14 (NATO reporting name: "Mare", Russian: Як-14) was the largest assault glider ever to enter service with the Soviet Air Force. It was introduced in 1949, at a time when other air forces were abandoning the glider concept. In 1950 a Yak-14 became the first glider to fly over the North Pole.

Development

During World War II, the Soviet Union operated only light gliders like the Gribovski G-11, Antonov A-7 and Kolesnikov-Tsybin KC-20 which were unable to transport vehicles, light tanks or artillery. Only after the war were Soviet designers ordered to develop medium gliders capable of carrying heavy or bulky loads. Work started during 1948, at the Yakovlev bureau, to produce a transport and assault glider for Airbourne Troops (VDV - Vozdushnodesantnyye Voyska). The Yak-14 was a surprising development for the Yakolev Design Bureau, being developed in 1948 at a time when the bureau was already overloaded with projects, and despite the fact that the design bureaus of Antonov Grokhovskii and Tsybin already had considerable experience designing gliders while Yakolev did not. It also came at a time when most Western air forces had already abandoned the concept of heavy assault gliders. Despite this, Yakolev began work on the project in early 1948, giving it a high priority. The design called for a glider capable of transporting a payload of 3,500 kg (7,716 lb), and capable of handling large loads including the 76.2mm gun with a GAZ-67 truck and crew of seven, a 57mm anti-aircraft with truck and crew, an ASU-57 self-propelled gun and crew, or thirty-five fully equipped troops. The tug aircraft was to be a Ilyushin Il-12 or Tupolev Tu-2 as the Li-2 was found to have insufficient power. Responsibility for the design was given to chief engineers Ye G Adler and L L Selyakov.

While some Yak-14s were constructed at Chkalovsk, the majority were produced at factory No. 412 located at Rostov-on-Don. Total production was 413 series gliders.

Testing

The prototype was completed in June 1948 and tested at Medvyezhe Ozero, near Omsk. The principal test pilot was Peskov of the VDV assault air-landing unit. In December 1948 a VDV evaluation unit was formed under Col. V YeGolofastov.

The testing of the Yak-14 was not free from trouble. On one memorable occasion the glider crew noticed that the tug aircraft's starboard engine was on fire. While the glider swerved from side to side to avoid the flames they watched with shock as the tug crew feathered the wrong engine. the flight was over rugged terrain so an emergency landing was out of the question. Eventually the tug crew corrected their mistake and the two aircraft continued for another 80 km (50 miles) in a controlled decent before making a safe landing.

Because Aerofloat had priority for all new Il-12 deliveries some tests were performed using a pair of Li-2s, in a manner similar to the German's use of two Me-110s to tow the Me-321. Another problem was the Soviet's lack of Nylon for tow ropes. Eventually a substitute material called Kapron was used in its place. Once production of the Il-12 had reached sufficient levels Ilyushin was able to design two specialized glider tug versions known as the Il-12D and Il-12TB.

Design

The design of the Yak-14 was similar to that of the British WWII era General Aircraft Hamilcar assault glider, though somewhat smaller, and with half the Hamilcar's payload capacity. The fuselage was based on a welded truss of KhroManSil steel, covered mainly with fabric. The central fuselage had six bulkheads and a re-enforced floor designed for heavy vehicles. The cargo area measured 8m (26 ft 3in) long, and 23.40 cm (92 1/8in) wide, with headroom varying from 22.50 cm to 21.60 cm (85.0 in). Like the earlier Me-321 and Hamilcar, the front of the glider opened to allow easy loading and unloading of vehicles, though unlike the earlier designs, the nose of the Yak-14 pivoted to the right, creating an 83.0 cm by 148.0 cm (32 5/8 X 58 1/4in) opening. The rear of the aircraft could also be opened, with the entire tail section pivoting to the left. When closed they could be quickly locked in place with bolts, and the rear hatch featured a novel connector which automatically reconnect the flying controls leading to the tail. Each side of the fuselage had three rectangular windows containing firing ports. For loading and unloading vehicles ramps were incorporated that could be clipped into place. For troop carrying these ramps could be converted into benches, in addition to other benches permanently fixed on the aircraft's inner walls. Like the Hamilcar, the cockpit was positioned above the cargo area, but on the Yak-14 it was offset to the left. It was accessed by external bent-tube steps which ran up the left side of the fuselage. The cockpit had a very well-equipped instrument panel, and contained side-by-side dual controls which hung from the roof. This diverted the control cables above the cargo hold to maximize cargo space. The instrument panel also featured an innovative oscilloscope which, with the aid of a small transmitter located in the tow aircraft, showed the relative position of the tug when flying in clouds or at night. An RSI-6 radio was also standard.

The Yak-14 featured a tricycle undercarriage incorporating a castoring nose wheel. The undercarriage was supported by air-oil shock struts which could be lowered on landing, allowing the glider to rest on a pair of rubber-sprung, pine/ash skids. An air bottle, also used to pressurize the flaps and wheel brakes, could be used to repressurize the shocks, raising the glider and allowing it to be towed out again.

Operational history

Towed by Ilyushin Il-12D assault transports, the Yak-14 was used by airbourne units for military and civilian missions all over the USSR, and three were delivered to Czechoslovakia in the early 1950s which used them under the designation NK-14.

In March 1954 four Yak-14s were used to transport equipment, including a dozer, to Arctic survey station SP-4(Severnnyy Polyus - north pole), floating on an ice floe. The gliders flew from Tula on March 10, with several stops at Omsk, Krasnoyarsk and the Schmidt Cape, on Sakhalin island in the Far East, before reaching SP-4 in early April during a heavy freeze.

Soviet Air Force transport gliders were gradually withdrawn from service with the arrival of turbo-prop transports like the Antonov An-24 and Antonov An-12, which entered service in the late 1950s.

North Pole

In 1950 a single Yak-14 made worldwide headlines when it became the first glider to fly over the North pole. The tow aircraft was an Il-12.

Variants

Yak-14 Basic production variant. Yak-14M Increased payload version built from 1951. NK-14 (Nakladni kluzak - cargo glider) Yak-14s delivered to Czechoslovakia

Operators

Czechoslovakia

Czechoslovakian Air Force

Soviet Union

Soviet Air Force

Specifications (Yak-14)

General characteristics

Length: 18.44 m (60 ft 6 in)
Wingspan: 26.17 m (85 ft 10 1/4 in)
Height: ()
Wing area: 83.35 m² (897 ft²)
Empty weight: 3,082 kg (6,794.5 lb)
Loaded weight: 6,750 kg (14,881 lb)

Performance

Maximum speed: 300 km/h (186 mph)
Cruise speed: 145 km/h (90 mph)

Comparable aircraft

General Aircraft Hamilcar
Me-321
Airspeed Horsa
WACO CG-4
Gotha Go 242

Yak-14 at Ugolok Neba (Russian)

Bibliography

Gunston, Bill. Yakovlev Aircraft since 1924. London, UK: Putnam Aeronautical Books, 1997. ISBN 1-55750-978-6.

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Source: WikiPedia