Bombs and Other Ordnance of the VVS in the GPW
Part VI The FAB 2000 & 5000
With the imminent release of some new Pe-8 model
kits, it seemed high time to examine some of the largest munitions in use
with the VVS. The FAB 5000, for example, was carried during the GPW only
by the Pe-8, and this huge bomb might well make for a lovely diorama for
those with an inclination for such things. Therefore, here are the heaviest
of the wartime Soviet ordnance-- the FAB 2000 and FAB 5000.
FAB 2000SV 1936
At the end of 1933, Zavod 67 began the construction of a heavyweight munition specifically designed for use in the new generation of bombers then being mooted across the USSR, such as the slightly later ANT-40 (Tuploev SB). Design and manufacture of the new 2000 kg weapon posed no problems of any note, being quite literally a scaled up version of the current and highly popular FAB 1000SV. The main body of the weapon consisted of a shell of AGP steel, with separate nose and tail sections of low-grade ADP steel bolted in place. The tail section was secured with four slightly off-set bolts, and the fins were spot welded to the unit with braces between them.
Manufacture of the new FAB 2000SV was undertaken only in trivial quantities prior to 1936. Presumably, this was due to a lack of any aircraft designed for the bomb, and not related to any technical properties with the munition. The typical FAB 2000SV weighed 2135 kg, including its explosive filling of 818 kg of amatol. The bomb was normally fused, i.e. with a pocket at the fore and aft end of the main body, and was carried externally, as no current aircraft in the VVS inventory could accommodate the huge weapon in its bay. Somewhat ironically, aircraft like the SB could not carry the FAB2000 in any case, and prior to the introduction of the TB-7 (Pe-8) the main customer for this large weapon was the venerable TB-3.
Given the weight of the munition, two suspension straps were used to carry the bomb. These were mounted centrally, quite close together, and were identical to the same units employed on the FAB 1000 family. In this form the FAB 2000SV was manufactured, virtually without modification, well into the middle of 1943. The illustration above depicts the bomb in a common IMP finish.
FAB 2000SV finished in lacquer No.67
FAB 2000M43 1943
The 2000 kg SV model, though useful, was rather outdated as a modern munition design. This fact was primarily on the minds of the design staff at GSKB-47, who sought to develop a new weapon in this weight category with superior properties. At the forefront of these concerns was the inefficiency of the SV with respect to the weight of the explosive filling vis a vis the over-all weight of the bomb. Indeed, the figure was less than 40%, and the design team set out at once to correct this situation.
The new Model 1943 (M43) bomb featured a six piece main body quite similar to the ShG series of other FAB munitions, but in this case with welded and not riveted construction. APUB steel of various grades was employed throughout, allowing for a thinner and lighter casing on the bomb, while the main body's general length and diameter of 600 mm was retained (indeed, the elongated design rather closely resembled a torpedo). The fins were spot welded to a tail cone unit, this being bolted to the aft section of the bomb. The resulting M43 variant was exceptionally efficient in terms of filling to weight properties, its ratio of 64% putting it fully in the same category as the RAF's 4000 lbs "Cookie" blast bomb, but with superior penetrative capability. The M43 also introduced an improved explosive filling type, this a 50/50 mixture of amatol and TNT (derivative).
The FAB 2000M43 was extremely successful in service use, and manufacture of this munition continued until after the GPW. No notable modifications were introduced on the M43 during this period. Production commenced during the summer of 1943, supplanting the earlier SV model at the same time. The illustration above demonstrates Industrial Blue paint finish.
FAB 2000M43 finished in lacquer No.67
FAB 2000M44 1944
During 1943 there was much discussion within the VVS over the desirability of a semi-armour piercing munition in the 2000 kg category. This need was quicky realized at Kursk (and in the Baltic) when heavily reinforced enemy fortifications were encountered. Therefore, the design staff at GSKB-47 immediately set to work on such a bomb, the Model 1944.
The M44 was somewhat haphazard and complex in appearance, the main body comprising no fewer than 10 pieces. These, as with the M43, were welded, and APUB steel was used throughout. The main body diameter was retained (600 mm), but the fins were now spot welded directly onto the aft section of the bomb, and reinforced with connecting strips at the aft end. The nose of the weapon was appropriately redesigned for the new role with a thickness of 85-130 mm at the tip. This massive armoured nose cone accounted for a great deal of the munition's weight, and the over-all length was thus reduced to just under four meters.
The resulting FAB 2000M44 typically weighed 1926 kg, with an explosive filling of 991 kg of amotol/TNT mix. Dropped from 2000 m, the M44 could smash through 3.5 m of reinforced concrete comfortably, and the resulting detonation of almost 1000 kg of explosive would undermine virtually any structure. Manufacture of the M44 commenced in the late spring of 1944 and continued until well after the GPW without notable modification.
FAB 5000NG 1943
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 laboured exhaustively on heavy bombs for the VVS, even from the late 1930s. Apparently, his work at last found an audience with the government, and on 6 May 1943 the NKO issued instruction No. 0340 to place into manufacture a 5000 kg version of Gelperin's several prototypes.
The large body was comprised of three main sections, these featuring welded construction. High quality AB-1 nickel-steel (as used for amour plate, and such like) 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, but also heavily reinforced with steel rods welded to the the same on the starboard side. Stiffening pieces were additionally bolted to the aft section of the fins. The fuse pockets were entirely typical, despite the great size, and were positioned fore and aft.
To suspend the bomb in the aircraft, and entirely new mounting method was developed. Three (two in the prototypes) threaded inserts were built integral to the main housing, these 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, these 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. However, in all three photographs which I examined showing this weapon in service use, two rather formidable straps were used and the bolt openings covered, and there was no sign of the cable nor its associated mounting hardware. No explanation can be found at present for this observation; perhaps both patterns were manufactured in series?
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 this contribution of designer N. Gelperin (N.G.); the two names should be seen to be interchangeable. 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 [one must think with horrific effect, as well-- 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 famously noted that FAB 5000s were alleged to have been used in the demolition of a fortress at Koningsberg earlier in the year; if true, these must have been prototype weapons, one presumes.