Petlyakov Pe - 8 The Petlyakov Pe - 8 was a Soviet heavy bomber designed before World War II , and the only four - engine bomber the USSR built during the war . Produced in limited numbers , it was used to bomb Berlin in August 1941 . It was also used for so - called " morale raids " designed to raise the spirit of the Soviet people by exposing Axis vulnerabilities . Its primary mission , however , was to attack German airfields , rail yards and other rear - area facilities at night , although one was used to fly the People ' s Commissar of Foreign Affairs ( Foreign Minister ) Vyacheslav Molotov from Moscow to the United States in 1942 . Originally designated the TB - 7 , the aircraft was renamed the Pe - 8 after its primary designer , Vladimir Petlyakov , who died in a plane crash in 1942 . Supply problems complicated the aircraft ' s production and the Pe - 8s also had engine problems . As Soviet morale boosters , they were also high - value target s for the Luftwaffe ' s fighter pilots . The loss rate of these aircraft , whether from mechanical failure , friendly fire , or combat , doubled between 1942 and 1944 . By the end of the war , most of the surviving aircraft had been withdrawn from combat units . After the war , some were modified as transports for important officials , and a few others were used in various Soviet testing programs . Some supported the Soviet Arctic operations until the late 1950s . Design and development . Development of the Pe - 8 began in July 1934 , when the Soviet Air Forces ( VVS ) issued requirements for an aircraft to replace the obsolete and cumbersome Tupolev TB - 3 heavy bomber . These requirements specified a bomber that could carry of bombs at a speed greater than at an altitude of , figures that were twice the range , speed and service ceiling of the TB - 3 . The task was assigned to the Tupolev Design Bureau ( OKB ) where Andrei Tupolev handed the work to a team led by Vladimir Petlyakov and the project received the internal bureau designation of ANT - 42 . The resulting aircraft , a four - engined , mid - wing cantilever monoplane , was initially designated as the TB - 7 ( , " Tyazholy Bombardirovschik " — Heavy Bomber ) by the VVS and owed more to the streamlined design of the Tupolev SB than to the block - like design of the TB - 3 . The bomber was built mainly of duralumin , with two steel spars in the wings , although the ailerons were fabric - covered . The pear - shaped monocoque fuselage required the pilots to sit in tandem , offset to the left . In the prototype , space for a fifth engine , an auxiliary Klimov M - 100 , was reserved inside the fuselage , in a fairing above the wing spars and behind the pilots . It was intended to drive a supercharger that supplied pressurized air to the Mikulin AM - 34 FRN engines , with the installation designated ATsN - 2 ( ) . Subsequent models omitted the internal engine , and provided seating for a flight engineer and radio operator , behind and below the pilots . The bombardier sat in the nose and manned a turret armed with a ShVAK cannon that covered a 120° cone ahead . A prominent chin gondola , nicknamed the ' beard ' , protruded beneath the nose . The dorsal gunner sat at the rear of the ATsN fairing with a sliding hood covering a ShKAS machine gun and another ShKAS mounted in a ventral hatch . The tail gunner had a powered turret with a ShVAK and , most unusually , there were manually operated ShVAK cannon mounted at the rear of each inner engine nacelle . Crewmen had access to these positions through the wing or by a trapdoor in the upper wing surface . The large internal bomb bay racks held up to of bombs ; external racks held a single FAB - 500 bomb under each wing . The maiden flight of the unarmed prototype , piloted by M . M . Gromov and without the ATsN installation , occurred at Khodynka Aerodrome on 27 December 1936 . After successful initial trials , the ATsN system was installed for the State acceptance trials in August 1937 and the AM - 34RNB engines were fitted during the tests . Gromov reported that the rudder was ineffective and that the outer engines overheated . Subsequent wind tunnel testing identified a problem with the aerodynamics of the radiators and nacelles . To solve this problem , the outer engines ' radiators were moved into deep ducts under the inner nacelles and the rudder was enlarged and redesigned with a smooth skin . Construction of a second prototype began in April 1936 , incorporating lessons from the first aircraft and feedback from the VVS . Designers widened the fuselage by ; the ' beard ' was also widened and the tail section was modified to lessen resistance and improve rudder function . A reconfigured control system included an autopilot and the engineers redesigned portions of the electrical system . The engines were changed to the more powerful AM - 34FRNVs and a redesigned undercarriage was fitted to the airframe . Two additional fuel tanks increased the craft ' s range . The defensive and offensive armament was revised , and the bomber ' s weaponry expanded to twin ShKAS guns in the nose , nacelle and tail turrets and a dorsal turret with a ShVAK ; this design eliminated the ventral gun . The bomb bay was modified to allow for a single FAB - 5000 bomb to be carried and provisions were added to carry VAP - 500 or VAP - 1000 poison gas dispensers under the wings . The arrests of both Tupolev and Petlyakov in October 1937 , during the Great Purge , disrupted the program and the second prototype did not make its first flight until 26 July 1938 . Although this prototype served as the basis for the series aircraft , further modifications were made to the armament . New weaponry included a retractable ShVAK in the MV - 6 dorsal turret , another ShVAK in a KEB tail turret and a Berezin UB T machine gun in each ShU barbette in each inner engine nacelle . Another fuel tank further increased the range , and the ' beard ' was removed entirely , replaced by a more streamlined nose . Authorization for production was slow for several reasons , including the Great Purge , but also due to the scarcity of resources , and a shortage of workers . Although production facilities in the Kazan Factory No . 124 were ready as early as 1937 , the order to begin was not given until 1939 . Manufacture and supply problems . Engine supply problems complicated the construction of the aircraft . Production of the ATsN superchargers could not be organized in any systematic way and only the first four Pe - 8s were equipped with them . Factory No . 124 shut down its Pe - 8 production line at the beginning of 1940 while alternative engines were evaluated . Somewhere in the massive Soviet chain of command , the decision was made to proceed without the superchargers . The unavailability of the Klimov M - 100 engine of the ATsN - 2 installation required a design change , although this modification allowed a commander and radio operator to be carried in its place . Then , to compound the problem further , the production of AM - 34FRNV engines ended in the second half of 1939 . Only two or four Pe - 8s were equipped with them . Eighteen of the aircraft produced by the end of 1940 were fitted with AM - 35A engines . In 1940 , six aircraft without engines were fitted with Mikulin AM - 35 A engines , while VVS officials evaluated both the Charomskiy ACh - 30 and Charomskiy M - 40 aircraft Diesel engine s . At least nine Pe - 8s were fitted with Diesel engines in 1941 , but neither the ACh - 30 nor the M - 40 were entirely satisfactory , despite greatly increasing the range of the aircraft . All surviving Pe - 8s were re - engined with AM - 35As by the end of 1941 . Production continued slowly at Factory No . 124 ; most of the factory ' s resources were devoted to the higher - priority Petlyakov Pe - 2 , a successful light bomber . At this time , most of these aircraft , re - designated as the Pe - 8 after Petlyakov was killed in a Pe - 2 crash on 12 January 1942 , were built with out - of - production AM - 35A engines . The 1 , 380 - kW ( 1 , 850 - hp ) Shvetsov ASh - 82 radial engine was proposed as a replacement to alleviate the shortage of engines and this modification went into production in late 1942 . The exhaust arrangements of the ASh - 82 were not compatible with the gun turrets in the rear of the engine nacelles and the guns were removed , reducing the aircraft ' s defensive capability . At the end of 1943 , the nose turret was deleted in favor of a manually operated ShKAS machine gun in a more streamlined nose . This version of the aircraft proved to have much the same range as the diesel - engined versions , but reliability was greatly improved . Production of the Pe - 8s totaled 93 . The last Pe - 8s were completed in 1944 as Pe - 8ONs ( ) with Charomskiy ACh - 30B engines and a fillet at the base of the vertical stabilizer . These were special VIP transports with a seating capacity of twelve and a cargo capacity of . Sources disagree if the armament , either partly or entirely , was removed . Wartime operational history . When Operation Barbarossa began on 22 June 1941 , only the 2nd Squadron of the 14th Heavy Bomber Regiment ( ) , based at Boryspil was equipped with Pe - 8s , but was not ready for combat . Two of its nine Pe - 8s were destroyed by German air strikes shortly after the war began , before the Pe - 8s were withdrawn out of reach in Kazan . Stalin ordered that the squadron be reformed into a regiment , and that it strike targets deep inside German territory . Theoretically , this tactic would boost Soviet morale by demonstrating the vulnerability of the enemy . The squadron was re - designated on 29 June as the 412th TBAP and began training for long - range missions . On or about 27 July it was again renamed , this time as the 432nd TBAP . On the evening of 10 August , eight M - 40 - engined Pe - 8s of the 432nd TBAP , accompanied by Yermolaev Yer - 2 s of the 420th Long - Range Bomber Aviation Regiment ( DBAP ) , attempted to bomb Berlin from Pushkino Airfield near Leningrad . One heavily loaded Pe - 8 crashed immediately upon take off , after it lost an engine . Only four managed to reach Berlin , or its outskirts , and of those , only two returned to their base . The others landed elsewhere or crash - landed in Finland and Estonia . The aircraft of the commander of the 81st Long - Range Bomber Division , Combrig Mikhail Vodopianov , to which both regiments belonged , was attacked mistakenly by Polikarpov I - 16 s from Soviet Naval Aviation over the Baltic Sea and lost an engine ; later , before he could reach Berlin , German flak punctured a fuel tank . He crash - landed his aircraft in southern Estonia . Five more Pe - 8s were lost during the operation , largely due to the unreliability of the M - 40s . Seven Pe - 8s were lost during the month of August alone , rendering the regiment ineffective . During this period , the surviving aircraft were re - equipped with AM - 35As , which gave them a shorter range , but a more reliable engine . By 1 October 1941 , the regiment mustered fourteen Pe - 8s after having been replenished by new aircraft from the factory . It spent the rest of the year conducting night raids on Berlin , Königsberg , Danzig and as well as German - occupied cities in the Soviet Union . The regiment was re - designated as the 746th Separate Long - Range Aviation Regiment ( ) on 3 December . No aircraft were reported on hand two days later after this designation , but eleven were on strength on 18 March 1942 . During the winter of 1941 – 42 , the regiment was assigned the destruction of a railroad bridge over the Volga River , near Kalinin . In April 1942 , one aircraft flew diplomatic personnel and mail on a non - stop flight from Moscow to Great Britain . This was a test run for a flight carrying Soviet Foreign Minister Molotov and his delegation from Moscow to London and then to Washington , D . C . and back , for negotiations to open a second front against Nazi Germany ( 19 May – 13 June 1942 ) . The flight crossed German - controlled airspace on the return trip without incident . From August 1941 to May 1942 , the regiment flew 226 sortie s and dropped of bombs . In the course of these missions , they lost 14 bombers , five in combat , and the rest from engine malfunction . The regiment received 17 Pe - 8s as replacements . Sixteen aircraft were on hand on 1 May 1942 , but the number had only increased to seventeen two months later ; the regiment was losing aircraft almost as fast as they were being replaced . The 890th Long - Range Aviation Regiment ( ) was formed on 15 June 1942 and both regiments were used to bomb German - held transportation centers of , among others , Orel , Bryansk , Kursk and Poltava . The pace of activity increased and the regiments flew as many missions in August as they had in the first ten months of the war . By the eve of the Soviet counterattack at Stalingrad , Operation Uranus , on 8 November the regiments had fourteen Pe - 8s on hand . Under the command of the 45th Long - Range Bomber Aviation Division ( ) , they did not participate in the Stalingrad air attacks . In 1943 , from the division ' s primary airfield at Kratovo , southeast of Moscow , the regiments bombed transportation centers , airfields and troop concentrations . The railroad yard at Gomel was a favorite target and the regiment dropped approximately of bombs there between February and September 1943 . It is not clear if these sorties were made by Pe - 8s alone or in combination with other aircraft . In addition , the regiment dropped the first FAB - 5000 bomb on Königsberg in April 1943 , continuing the pin - prick attacks against targets deep in the German rear . In May 1943 , efforts shifted to disrupt the German concentration of forces for the Battle of Kursk . In one sortie , the 109 bombers of the 45th DBAD struck the rail junction at Orsha during the evening of 4 May , most of which were not Pe - 8s ; the German High Command reported the destruction of 300 rail wagons and three ammunition trains . By 1 July , the regiment had 18 Pe - 8s for deployment during the early phase of the Battle of Kursk . The long - range aviation units continued to attack targets in the German rear areas at night , supporting the Soviet ground offensive in the Orel Bulge , called Operation Kutuzov , that began on 12 July . The Germans had transferred the nightfighter s of the Fourth Group of Nightfighter Wing 5 ( IV . / Nachtjagdgeschwader 5 ) , flying a mix of Junkers Ju 88 and Dornier Do 217 aircraft , to counter the Soviet raids near the Orel area . Initially , the night fighters were ineffective against the Soviet raids , until the deployment of their ground radar " eyes " . Once the Germans had use of their radar , after the night of 17 – 18 July , Soviet losses skyrocketed . Although the Germans flew only fourteen sorties that night , they claimed eight kills . On the night of 20 – 21 July , Captain ( Hauptmann ) Heinrich Prinz zu Sayn - Wittgenstein , commander of IV . / NJG 5 , shot down three himself . The exhaust plume of the ASh - 82 engine may have been a contributing factor ; the engines lacked flame dampening exhausts , making their plume visible from a distance . Despite its losses , the 746th was re - designated as the 25th Long - Range Guards Aviation Regiment ( GAPDD ) on 18 September 1943 in recognition of its achievements . Removal from combat . The loss of Pe - 8s to all causes — mechanical , combat , friendly fire — had steadily increased from one aircraft per 103 flights in 1942 to one per 46 sorties in 1944 . Despite the losses , production kept pace with need . The number of aircraft belonging to the 45th DBAD continued to rise ; 20 were on hand on 1 January 1944 and 30 on 1 June . The Pe - 8s flew 276 sorties in 1944 against such targets as Helsinki , Tallinn and Pskov . Aviation historian Yefim Gordon maintains that the Pe - 8 flew its last mission on the night of 1 – 2 August 1944 , but the Statistical Digest of the VVS contradicts this claim , showing 31 Pe - 8s assigned to 45th DBAD on 1 January 1945 and 32 on hand on 10 May 1945 . However , during this period the 45th DBAD only had three regiments , none of which used the Pe - 8 as their primary aircraft , so while the 45th DBAD may have had Pe - 8s , these may not have been in use as the primary combat aircraft . The 890th began to fly Lend - Lease B - 25 Mitchell s in the spring of 1944 and was itself re - designated as the 890th Bomber Aviation Regiment on 26 December 1944 . The 362nd APDD was formed in early 1944 with four Pe - 8s received from the other two regiments , but these were returned in the spring of 1944 , when the regiment began to convert to the Lend - Lease Mitchells . Post - war use . After the war , the Pe - 8 was used extensively as a testbed for trials involving Soviet derivatives of the German V - 1 flying bomb and it was designated as the Pe - 8LL for prototype piston engine trials . It was also used as a mother ship for the experimental rocket - engined Bisnovat 5 in 1948 – 49 . Aeroflot received several of the surviving Pe - 8s for polar exploration . Their military equipment removed , they had additional fuel tanks installed , were painted orange , and had their engines upgraded to either ASh - 82FN s or Shvetsov ASh - 73 s . One landed at the North Pole in 1954 and others helped to monitor the drift ice stations NP - 2 , NP - 3 and NP - 4 during the late 1950s .