Grokhovskii G-37, ULK

Purpose: ‘Universal flying wing’.

Design Bureau: WS-RKKA Leningrad, Chief Designer Vladimir Rentel.

The numbering of’Grokhovskii’ aircraft is dif­ficult to interpret, and this aircraft preceded the G-31. The concept was that of a versatile aircraft for airborne assault, but it was soon evident that a Universalnoye Letayushchyeye Krylo, universal flying wing, would have wide commercial appeal. Construction was as­signed to Vladimir Rentel, who had the air­craft built in Grebno (rowing) port, Leningrad. It was taken to the airfield where from No­vember 1935 it was tested by VPChkalov, who was impressed. He later flew it to Moscow in 2hrs SOmin (average 250km/h, 155mph, which Shavrov says was ‘almost a record’). The G-37 was used for a long series of tests, including dropping of heavy loads.

The G-37 was a remarkably capable early example of an aeroplane designed to lift a de­tachable payload container (later types in­
cluded the Fi333, Miles M.68 and Fairchild XC-120). To save time the wing was that of an ANT-9 (PS-9), made of Kolchug duralumin with mainly corrugated dural skin, though the ailerons did not project beyond the wing tips. It is possible this wing came from a crashed PS-9 along with the 680hp BMW VI water – cooled V-12 engines, though these were in a different installation. The engine cowls were extended down into large trousers over the main landing gears, which contained the en­gine-cooling radiators. At the rear they extend­ed into tail booms, all these structures being of light alloy. Each boom had a tailwheel, and the twin-finned tail was duralumin with fabric cov­ering. On the centreline the wing was expand­ed into a small nacelle for the pilot and engineer. The underside of the centre wing was provided with attachments for a standard pre-loaded payload container, though no pho­tographs have been found with this in place. The completed G-37 was painted with gay stripes and stylized red stars and slogans.

There seems little doubt that this was an excellent and potentially versatile aircraft, and it is not known why it was never ordered for military or civil use.