Polikarpov BDP

The Polikarpov BDP (Bolshoy Dvoynyy Puskovik) was a late‑1930s Soviet twin‑engine bomber prototype conceived by Nikolai Polikarpov’s design bureau as a response to the Air Force’s demand for a high‑speed, medium‑range attack aircraft capable of delivering payloads over front‑line targets. First flown in the spring of 1939, the BDP combined an all‑metal semi‑monocoque fuselage with a low‑wing configuration and featured two Shvetsov M-62 radial engines mounted on the wing undersurface. Retractable main landing gear, slotted flaps, and a streamlined engine cowling reduced drag, allowing a maximum speed of 470 km/h and a service ceiling of 9 500 m—remarkable figures for a bomber of its class at the time. Armament consisted of a ventral bombardier’s compartment with a 500 kg bomb load, plus defensive turrets equipped with 7.62 mm ShKAS machine guns. Although the BDP never entered mass production—its development being overtaken by the more capable Tupolev SB and later the Il‑4—the aircraft provided valuable data on high‑performance twin‑engine layouts, aerodynamic refinements, and structural techniques that informed Soviet bomber design throughout World War II. Its brief career thus marks an important evolutionary step in the USSR’s transition from biplane to modern monoplane combat aircraft.