One of the I-153 (alias I-15ter) prototypes photographed during thу winter of 1938-9. This M-25V-powered aircraft was a production prototype, and the radio masts on the starboard wing leading edge and tailfin, and bomb shakles beneath the interplane struts, are noteworthy.
Many readers will be surprised to learn that Russian ram-jet flight tests commenced as early as 1940. Photo: A Polikarpov-designed I-153 fighter with an M-62R radial of 850 h.p. and an experimental Merkulov ramjet under each wing. Between 10 and 15 per cent gains in operational speeds were achieved. The I-153 used to test Merkulov's DM-4 ramjets during August-October 1940.
An M-62-powered I-153 that had crash-landed at its base after combat during the opening phase of Operation "Barbarossa" (small-calibre bullet holes can be seen immediatelly aft of the engine cowling and in the lower wing/fuselage fillet) and was subsequently found by German forces when the airfield was overrun.