Gribovsky G-25
1930s trainer aircraft prototype by Gribovsky
The Gribovsky G-25 (Russian: Грибовский Г-25) was a Soviet tandem seat biplane basic trainer built in the late 1930s. It was hoped to minimize unit costs by using a modified automobile engine but the G-25 did not reach production.
Design and development
The G-25 was probably Gribovsky's only biplane design, aimed to compete with the Polikarpov U-2 as a basic trainer. Its economic construction was partly based on its use of a Western engine originally designed for automobiles. It was a single bay biplane with large forward stagger. The lower wing was mounted on the lower fuselage longerons with N-form interplane struts between it and the upper wing, which was supported over the fuselage on cabane struts.
The G-25 was initially powered by a British made, 63 kW (85 hp) Pobjoy Niagara II, a small radius seven cylinder radial engine with an off-set, geared down propeller shaft. The 1937 first flight was made with this unit but in 1938 the light, air-cooled radial was replaced by a GAZ-Avia-11, a 6-cylinder water-cooled adapted motor-vehicle engine derived from the Dodge D5; the aircraft was redesignated G25bis. The new engine produced the same power as the Pobjoy but was some 70 kg (154 lb) heavier, lowering performance. Water cooling required a prominent central radiator under the rear of the engine.
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This entry incorporates text from “Gribovsky G-25” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.