Nudelman-Suranov NS-45
| Nudelman-Suranov NS-45 | |
|---|---|
 |
|
| Type | |
| Place of origin | USSR |
| Service history | |
| In service | 1944—1947 |
| Used by | USSR |
| Wars | Second World War, Cold War |
| Production history | |
| Produced | 1944-1945 |
| No. built | ~200 |
| Specifications | |
| Weight | 152 kilograms (335 lb) |
| Length | 252 centimetres (8.27 ft) |
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| Shell | 45×185mm |
| Shell weight | 1.065 kg (2.35 lb) |
| Caliber | 45 millimetres (1.8 in) |
| Action | short recoil |
| Rate of fire | 260-280 rpm |
| Muzzle velocity | 780 metres per second (2,600 ft/s) |
| Feed system | belt |
The Nudelman-Suranov NS-45 was an enlarged version of the Soviet Nudelman-Suranov NS-37 aircraft . It was evaluated for service on 44 Yakovlev Yak-9K aircraft during World War II, but proved to stress the airframes too much. The NS-45 was also mounted on the prototype Tupolev Tu-1 night fighter after the end of World War II.
The NS-45 was created as a result of a July 1943 decision of the State Defense Committee to arm Soviet fighters with 45 mm autocannons. As with the 37 mm autocannons already installed in some Soviet and lend-lease single-engine fighters, the intended method of installation of the 45 mm gun was to have its barrel pass through the engine block and the empty propeller shaft, in this case that of the Yak-9. Consequently, the main difficulty in designing the 45 mm autocannon was the limitation imposed by the engine blocks available for this aircraft. Accounting for the diameter of the 45 mm shell, the Yak-9 engine blocks only allowed a wall thickness of 4 mm for the new gun's barrel, which was almost half the thickness of the barrel wall of the NS-37. (Another source gives 55 mm as the diameter of opening in the engine reducer shaft, resulting in a wall thickness of 3.75 mm for the NS-45 barrel relative to 7.1 mm for the NS-37 barrel, both measured at this spot which was approximately 61 cm away from the muzzle.)
The decision of the Defense Committee was followed by a short design competition between Soviet designs bureaus OKB-15 and OKB-16. The former proposed an enlarged version of their unreliable Shpitalny Sh-37; although they made a prototype that passed factory tests in a LaGG-3, their 45 mm gun was not accepted for state trials because of the known issues with the Sh-37 design. OKB-16 presented an enlarged version of their successful NS-37. The recoil force of the NS-45 peaked at seven tons, a force roughly 40% greater than that experienced with the NS-37 (about 5.5 tons). Consequently, the NS-45 was fitted with a muzzle brake—a first in Soviet aircraft-gun design.
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