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Gribovski G-14
Gribovski G-14 during competitions in Koktebel.
The Gribovski G-14 (Russian: Грибовский Г-14) glider was designed as a two-seater training glider for performing stunts and towed flight. The main objective of its builder when designing this glider was focused on obtaining a simple and cheap model in its production and operation, capable of meeting all the demands of piloting training.
The Gribovski G-14 was designed as a low-wing braced monoplane with wheeled undercarriage. The large wing had a straight leading edge and an inverted trailing edge and was designed with an R-II wing profile. Two parallel struts attached the two-spar wing structure to the top of the fuselage. The wing trailing edge featured large ailerons measuring 1.74 square meters in area.
The landing gear had a conventional composition with two simple 400x150 mm wheels carefully fitted with “pants” and fixed to the wing intrados. The wide span between the two wheels allowed the necessary stability during drag training flights over the ground.
The wide fuselage, covered with plywood, could be used to transport loads and equipment in drag mode, so the structure was reinforced. The cockpits, located in tandem, had a double control system. The Gribovski G-14 was designed for training in night flights, for which it was equipped with the necessary equipment and navigation lights.
The first G-14, built in the workshops of the Zhukovski Military Aeronautical Academy and
nicknamed “Komsomol of the VVA”.
The G-14 prototype was built in parallel by two institutions. A first copy was built in the workshops of the Zhukovski Military Aeronautical Academy and another in Factory No.1 “Aviajim”.
The later fate of the G-14 built at the Academy and nicknamed "Komsomol of the VVA" is unknown. The prototype manufactured in the “Aviajim” factory was towed by air in order to participate in the X National Sailing Competitions held in Koktebel in 1934.
The pilots did not value the G-14 positively. The increased weight of the construction and problems in fixing the wing to the fuselage were highlighted as deficient. The positive aspects were the ample capacity of the fuselage, the good structural resistance and the wide span between the main landers.
The positive qualities of the G-14 glider made it an ideal candidate for conducting a series of experiments, so several specimens were built and configured under the purpose of the tests.
The prototype was specially modified at the “Aviajim” Glider Factory in May 1935 to carry out long-distance flight tests based on the refueling of the tug aircraft from the glider itself.
The first fuel transfer test from the glider to the tow plane was carried out on May 24, 1935 while flying at an altitude of 1,200 meters. From the G-14 piloted by Kuzmín 150 kg of fuel were transferred to the Polikarpov R-5 tug piloted by IS Baranov.
On the basis of these tests it was decided to build a specialized variant of the “flying tanker” known as the G-14 TsL-2A. The need to install fuel tanks in the structure increased the flying weight of this version to 780 kg, forcing measures to ensure the necessary structural strength.
The fuel was placed in five aluminum tanks, four in the wing roots (two on each side) and another in the fuselage, located in the position of the rear cockpit, near the center of gravity of the glider. In total the "flying tanker" could carry 500 liters of fuel. A system of pipes and valves ensured the connection of the fuel system with the connecting hook of the tow rope. The cable in this case was in the form of a hose through which the fuel was transferred and in its center was located a cable intended to withstand the drag loads.
In the autumn of 1935 a Polikarpov P-5L piloted by IS Baranov, towing a G-14 TsL-2A glider piloted by KM Vienslav, made a non-stop flight between Moscow and Koktebel, with refuelling in the air. This flight covered a distance of 1524 km, which was also a glider tow record.
As a continuation of the high-altitude trawl experiments, originally tested on the Gribovski G-9, engineer A. Ya. Scherbakov proposed to use a tandem drag method, of which each glider would fly higher than the previous one. To test this system, two more examples of the G-14 were built on the “Aviajim”.
During testing A. Ya. Scherbakov used two gliders, a G-9 and a G-14. As a tug aircraft, a Túpolev TB-1 was used, to which the G-14 was attached and, in turn, the Gribovski G-9.
The Gribovski G-14 was suitably modified for this flight. The forward cabin was closed and covered, opening to the rear. A reel with a 2 mm cable was located in the rear cabin. In order to guarantee the safe extension of this cable, a pipe was fixed to the right side of the fuselage, which ended on the empennage.
Several flights were executed with this chain. At the beginning of April 1936, the results obtained were established: with the Túpolev TB-1 flying at an altitude of 5000 meters, the G-14 had managed to reach 6000 meters and the G-9 7000 meters.
Subsequent flights were cancelled because flights at this point without sealed cabins were quite uncomfortable for the glider pilots.
From a suggestion by A. Ya. Scherbakov fitted one of the G-14s with a sealed cockpit that made it possible to lighten the pilot's work in the cold, rarefied atmosphere. This cockpit was designed in the form of a kind of stretch calico cocoon preserving the shape of the seated pilot and covered at the top by a metal dome with transparent windows. The instrument panel was located outside the cockpit.
The G-14 thus became the first Soviet fixed-wing aircraft to use a sealed cabin.
G-14 - Two-seater training glider from 1934. Two copies built.
G-14 TsL-2A or G-14 "tanker" - Tanker version built and tested in 1935.
G-14 Ts "Tsepochni" - Experimental version built with the aim of testing Scherbakov's idea of flying a “chain” of towed gliders, each one flying at a higher level than its predecessor. It was tested in flight 1936 - 1937, using a Tupolev TB-1 for towing a G-14 and G-9 .
G-14 GK - 1936 experimental version conceived for high altitude operations with pressurized cabin designed by Scherbakov .
G-14 MP - Single-seater motor glider project from 1936 .
G-14 RP - Single-seater glider project with Dushkin RDA-1-150 reactive power plant,
Wingspan: 15.00 m
Wing area: 18.00 m²
Length: 7.80 m
Height: 1.35 m
Empty weight: 261 kg
Wing loading: 23.4 kg / m²
Surface of the horizontal planes: 3.0 m²
Empennage surface: 1.38 m²
Spoiler area: 1.74 m²
Glide ratio: 15
Optimal speed: 63 km / h
Minimum descent speed: 1.06 m / s
Accommodation: 2

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