The Petlyakov Pe-8 – Soviet Heavy Bomber

Soviet Flag

The Petlyakov Pe-8 was conceived from a requirement to replace the Soviet Union’s ageing fleet of Tupolev TB-1 (ANT-4) and Tupolev TB-3 (ANT-6) bombers, which had become obsolete at the outbreak of World War II in 1939. The Pe-8 was the only four-engined heavy bomber in the Soviet fleet during the war, with the exception of the Petlyakov Pe-8, the Soviet Air Force (Russian: Военно-воздушные силы, tr. Voyenno-Vozdushnye Sily, literally “Military Air Forces”) favoured twin-engined medium bombers as the Luftwaffe had done for the duration of WWII.

Design and development of the Pe-8 began with its first flight on the 27th of December 1936. The aircraft remained in service until 1944. Deliveries to the Soviet Long-Distance Bomb Group Regiment (Russian: Avia Polk Dahl’nevo Deystviya—APDD) began in 1940. Although the Pe-8 was built in limited numbers (only 93 were constructed), it was used in “morale raids” to boost Soviet spirits in the early campaigns of Operation Barbarossa, the German invasion of the Soviet Union, which began on the 22nd of June 1941. The Petlyakov Pe-8 conducted its first bombing attack on Berlin in August of the same year.

ANT-42 the first prototype.
ANT-42 the first prototype.

 

In addition to attacking Berlin, German airfields, Railway yards and factories, one example of the Pe-8 was used to fly the People’s Commissar of Foreign Affairs (Foreign Minister) Vyacheslav Molotov from Moscow to the United States in 1942.

The Petlyakov Pe-8 was originally designated as the ‘Tupolev TB-7’ it was re-named as the Petlyakov Pe-8 after its Chief Designer Vladimir Petlyakov was killed in a plane crash in 1942. The Pe-8 experienced a high loss rate during the war. This was largely due to the aircraft being perceived as a high-value target by Luftwaffe pilots. The loss rate of these aircraft, whether from mechanical failure, friendly fire, or combat, doubled between 1942 and 1944.

Because of this and the Soviet armed Forces gaining ascendency over the Luftwaffe and Wehrmacht, the type was withdrawn from service in 1944. The Petlyakov ended its career as a V.I.P. transport, test aircraft and a few supported the Soviet Arctic operations until the late 1950s.

From the 19th May till 12th June 1942, this aircraft flew to USA with V.M.Molotov aboard.
From the 19th May till 12th June 1942, this aircraft flew to USA with V.M.Molotov aboard.

Design and Development

The development of the Petlyakov Pe-8 began in 1934 when it was recognised that the ageing and obsolete Tupolev TB-3 (ANT-6) bombers would need to be replaced by a modern design with a greater range and bomb carrying capacity. These requirements specified a bomber that could carry 2,000 kg (4,400 lb) of bombs 4,500 km (2,800 mi) at a speed greater than 440 km/h (270 mph) at an altitude of 10,000 metres (32,808 ft), figures that were twice the range, speed and service ceiling of the TB-3.

The Tupolev Design Bureau (OKB) led by Andrei Tupolev was given the task of developing the new bomber. 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 (Russian: Тяжёлый Бомбардировщик, 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.

Tupolev TB-3.
Tupolev 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 (Russian: Agregat tsentral’novo nadduva—Central Supercharging Unit). 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 20-millimeter (0.79 in) 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 7.62-millimeter (0.300 in) 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 4,000 kg (8,800 lb) of bombs; external racks held a single 500-kilogram (1,100 lb) FAB-500 bomb under each wing. A single FAB 5000Kg bomb could be carried in a modified bomb-bay.

Pe-8 turret detail
Pe-8 turret detail
Pe-8 tail turret detail
Pe-8 tail turret detail

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.

Petlyakov Pe-8 in flight

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 100 mm (3.9 in); 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 5,000-kilogram (11,000 lb) 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 12.7-millimeter (0.50 in) Berezin UBT 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, particularly with the engines, 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.

A Pe-8 fitted with AM-35A Engines.
A Pe-8 fitted with AM-35A Engines.

In 1940, six aircraft without engines were fitted with Mikulin AM-35A engines, while VVS officials evaluated both the Charomskiy ACh-30 and Charomskiy M-40 aircraft Diesel engines. At least nine Pe-8s were fitted with Diesel engines in 1941, but neither the ACh-30 nor the M-40 was 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. The Tupolev TB-7 was re-designated as the Pe-8 after Petlyakov was killed in a Pe-2 crash on 12 January 1942.

Pe-8 with M-40 Engines
Pe-8 with M-40 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 (Russian: Osobovo Naznacheniya—Special Mission) 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 1,200 kilograms (2,646 lb. Sources disagree if the armament, either partly or entirely, was removed.

Pe-8 M-40 with M-40 deisel engines 1941.
Pe-8 M-40 with M-40 deisel engines 1941.

When Operation Barbarossa began on 22 June 1941, only the 2nd Squadron of the 14th Heavy Bomber Regiment (Russian: Tyazholy Bombardirovochnyy Avia Polk—TBAP), 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-2s 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, CombrigMikhail Vodopianov, to which both regiments belonged, was attacked mistakenly by Polikarpov I-16s 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 and Danzig as well as German-occupied cities in the Soviet Union. The regiment was re-designated as the 746th Separate Long-Range Aviation Regiment (Russian: Otdel’nyy Avia Polk Dahl’nevo Deystviya—OAPDD) 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 sorties and dropped 606 tonnes (596 long tons; 668 short tons) 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.

Pe-8 AM-35A with 3-tone camouflage.
Pe-8 AM-35A with 3-tone camouflage.

The 890th Long-Range Aviation Regiment (Russian: Avia Polk Dahl’nevo Deystviya—APDD) 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 (Russian: Dal’nebombardirovochnaya Aviatsionnaya Diviziya—DBAD), 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 606 tonnes (596 long tons; 668 short tons) 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 nightfighters 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 system. 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 enemy aircraft. 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.

Junkers 88C-6 Nightfighter NJG 5
Junkers 88C-6 Nightfighter NJG 5

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 Helsinki, Tallinn and Pskov. In February 1944, 3 raids were undertaken by the Pe-8 over the city of Helsinki. The raid of 06/02/1944 was the largest, comprising 24 Pe-8 bombers from the 45th Division of the Long-Distance Bomb Group Regiment (APDD). During the second raid on the 07/02/1944,two super-heavy 5.4 tonne FAB-5000 bombs were dropped on Helsinki, one destroyed the cable works, and the other struck the railway works.

University of Helsinki main building after the third 1944 raid.
University of Helsinki main building after the third 1944 raid.

The FAB-5000 Bomb

FAB-5000 Bomb 1943
FAB-5000 Bomb 1943

The FAB-5000 5 tonne bomb was the culmination of a series of munitions developed by Zavod 67 in 1933. A requirement was tendered by the Soviet experimental design bureau (OKB) for a 2000kg+ weapon that could be carried by the Tupolev ANT-40. Manufacture of the new FAB 2000SV began in 1936, the munition was technically sound, however, construction was slow and insignificant quantities of the bomb were produced.

The FAB 2000SV weighed 2135 kg, including its explosive filling of 818 kg of amatol. The weapon was carried externally on the TB-3, as there were no aircraft in the VVS inventory that could carry a 2000kg payload internally until the introduction of the Petlyakov Pe-8.

The FAB 2000SV was manufactured, virtually without modification, well into the middle of 1943. Several variants were produced, including; the FAB 2000 M43, the FAB 2000 M44, the FAB 2000 NG 1943 and the FAB 5000kg bomb.

It was unusual in Soviet bomb design during the GPW for a single engineer to have a major role in the development of a series manufactured munition, but with the VVS’ titanic 5000 kg weapon, this was apparently the case. At the NKB’s Design Bureau 35, Head Engineer N. Gelperin worked extensively on heavy bombs for the VVS from the late 1930s. On the 6th of May 1943 the NKO issued instruction No. 0340 to manufacture a 5000 kg version of one of Gelperin’s several prototypes.

The large body was comprised of three main sections, of welded construction. High quality AB-1 nickel was employed for the main body and nose section, while the tail cone could utilize AB-1 or APUB. The large fins were spot welded to the tail cone unit, supported by heavily reinforced steel rods welded on the starboard side. The aft section of the fins were additionally reinforced with steel plates. The fuse pockets were positioned fore and aft.

To suspend the bomb in the aircraft, an entirely new mounting method was developed. Three (two in the prototypes) threaded inserts were built, which were integral to the main housing. These were designed to accept a 16 mm bolt with a simple mounting lug at the top end. A length of heavy gauge steel cable was affixed to each side of the bomb, which was designed to help the armourers when lifting the munition into place. This arrangement is detailed in the factory drawings which were supplied in Pir’ev and Raznichenko’s official VVS bomb history, along with a note that provision was made to alternately utilize bomb straps to store the FAB 5000.

FAB-5000 Bomb with mounting straps.
FAB-5000 Bomb with mounting straps.

Series production of the FAB 5000 began during the summer of 1943. The munition’s official designation appeared to be “FAB 5000”, but Pir’ev and Raznichenko also described that in period documentation the nomenclature “FAB 5000NG” was common, this acknowledging the contribution of designer N. Gelperin (N.G.). This mighty weapon was used for the first time in regular service during the Orel-Belgorod counter-offensive operations following Kursk, mainly against troop and vehicle concentrations. The calculated zone of lethality for a non-armoured target in proximity to a ‘normally fused’ FAB 5000 blast was given as 428 meters. However, it was also noted that FAB 5000s were used in the demolition of a fortress at Koningsberg earlier in the year. As mentioned earlier, two super-heavy 5.4 tonne FAB-5000 bombs were dropped on Helsinki, one destroyed the cable works, and the other struck the railway works.

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-LeaseB-25 Mitchells 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.

The contribution that the Petlyakov Pe-8 made during World War II cannot be underestimated. During 1941, when it seemed that the Nazi war machine was unstoppable, the bombing raids that this aircraft made on Berlin proved to the Germans that the Allies and especially the Soviet people were still in the fight. In a very real sense, the Pe-8 represented hope to an occupied Europe.

 

In my next article I shall be reviewing the Zvezda 1:72 scale Petlyakov Pe-8.

Zvedza Pe-8 Box-Top

Special thanks go to Massimo Tessitori at the VVS Research Page for his article: TB-7/Pe-8 AM-35 during the war: http://mig3.sovietwarplanes.com/pe-8/pe-8evolution/pe8am35duringthewar.htm

Bibliography

  • Bergstrom, Christer (2007). Kursk—The Air Battle: July 1943. Hersham, Surrey: Classic Publications. ISBN 1-90322-388-1.
  • Gordon, Yefim (2008). Soviet Airpower in World War 2. Hinckley, England: Midland Publishing. ISBN 978-1-85780-304-4.
  • Gordon, Yefim; Rigamant, Vladimir (2005). OKB Tupolev: A History of the Design Bureau and its Aircraft. Hinckley, England: Midland Publishing. ISBN 1-85780-214-4.  Cite uses deprecated parameters (help)
  • Gunston, Bill (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey. ISBN 1-85532-405-9.
  • Gunston, Bill (1995). Tupolev Aircraft since 1922. Annapolis, MD: Naval Institute Press. ISBN 1-55750-882-8.
  • “Pe-8: Last of a Generation”. Air International (Bromley, UK: Fine Scroll) 19 (2): 76–83, 101. August 1980. ISSN 0306-5634.
  • Pe-8 on www.airpages.ru

 

 

 

 

 

3 thoughts on “The Petlyakov Pe-8 – Soviet Heavy Bomber”

  1. I thought I would have a gander on the site and found this gem of an article. Superb work here Richard. Fascinating and factual reading.

    The pilots sitting in tandem reminds me of the prototype B-52; in perception rather than configuration. The 5th engine concept is a fascinating one but I can see why the designers omitted it. Would have been a mechanical headache for the engineers.

    Diesel aeroengines!!!

    For me personally the aircraft’s combat career mirrors the Italian Piaggio P.108B in many resepects. That too ended its days as a VIP transport.

    FAB5000. I worked it out and 5,000kg is just over 11,000lbs making it only fractionally smaller than the British Tallboy bombs however the Tallboy warhead comprised just over half the weight of the total weapon. That means the FAB5000 was more powerful (warhead-wise) than the Tallboy which gives the aircraft a powerful punch. That being said the Tallboy was probably the smarter weapon being a true Earthquake bomb which causes much wider devastation. I would be interested in reading a direct comparison of both weapons.

    1. The Pe-8 was certainly an extraordinary aircraft, and very big with a crew of eleven; Length: 23.2 m (76 ft ¼ in); Wingspan: 39.13 m (128 ft 4 in); Height: 6.20 m (20 ft 4 in); Wing area: 188.66 m² (2,030.7 ft²). At a time when the US was still exercising neutrality (albeit supplying us), and the strategic bombing offensive against Germany would not begin in earnest until 1942, Pe-8s were the only heavy bombers taking the war to Berlin. The FAB 5000 is certainly an impressive weapon, I’d like to see how it compares to the Tallboy, but I suspect, as you point out that the Tallboy being an ‘earthquake’ weapon was technologically superior. Thanks for your input Tony.

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