Image of the Sh-37 with 40 rounds magazine, this configuration was used in the experimental attack aircraft Tomashevich Pegas.
Nudelman Suranov NS-37.
After the dismissal and later “liquidation” of Taubin and his design team the VV-S appointed other technicians for the development of new weapons in the OKB-16 armament office.
In may 1941 the army High command submitted a requeriment for a series of large caliber weapons capable to defeat armor as well to be used against bombers.
In July 1941 the engineers team with Viktor Nudelman and Vladimir Suranov as chief designers showed the result of its effort, the gun prototype was firstly named “OKB-16-37” In march 1942 the cannon was first tested in a LaGG-3 and after exhaustive testing ( if something you cant blame the russian is not testing his guns until they feel those are reliable) entered in service with Yak-9ts in march 1943 and april 1943 in the Kalinin Front. More than 8000 Ns-37 were completed by the factory Nº 76 in Ishev.
Description:
The NS-37 is a disintegrable metallic belt feed, full automatic, pneumatically triggered, air cooled cannon, the automatism work with the short recoil and rotating bolt head principle.
After the shot barrel and bolt recoil together 35 mm, then a cam milled in the received open the bolt wich turned 90º to extract the used round. The returing mechanish is actuated by a powerful spring and a hydro-pneumatical cilinder above the bolt s head. The buttplate is equipped with 2 concentrical spring to act as buffer ( the recoil forces in the NS-37 exceed 2800 kg)
The bolt shape and mechanism is very much like the Mauser MG 151.
NS-37, left side view:
Characteristics NS-37
Type of action: Short recoil, belt feed.
Overrall lenght: 3400 mm
Barrel lenght: 2400 mm
Width: 241 mm
Weight unloaded: 161 kg
Rate of fire: 240-260 rpm
Muzzle velocity: 850 to 890 m/s.
In Yak and Lagg fighters:
First batch of LaGG-3s with NS-37 with provition for 30 rounds were delivered on December 1942, and were known also as LaGG-3-37 (series 34, according to other sources); they looked as the well-known series 35, but were distinguishable for the long protruding barrel. The only reconigzable item is the lack of muzzle brake used in Shpitalny guns.
The yak-9T had a NS-37 with 32 round emplaced between its V-12 engine. According to the pilots recollections the aim with this guns was true only in the frist two shots, the following would eventually fly over the target.
Yak-9Ts were mostly used as normal fighter engaging bomber and other fighter despite the potential armor killing capabilities. Other favorite target of russian pilot were german barges and fast attack boats in the Black sea.
The faster Yak-3 was also attempted as big gun fighter but despite the installation of a muzzle brake recoil forces of NS 37 were too much for the light aircraft, only 2 Yak-3T were completed.
Provition for the gun was limited to 25 cartrigdes in the Yak-3T.
Yak-9T
Captured, pictured in the facilities of DVL
Detail of the 37 mm ammo belt next to the 12,7 mm UBS belt.
Yak-3T
LaGG-3-37 (NS gun)
NS-37 in Il-2 Sturmovik.
As the main “strafer” and anti-armor aircraft of the Voyenno-Vozdushnyye Sily the mitic Ilyushin Sturmovik was an obvious choice as NS-37 gun carrier.
The geared final transmition of the Mikulin engine wasnt suitable for gun mounting so the most logic step was emplaced a pair under the wings. The NS Il-2 was tested in late 1942 next to an SFK-37 armed Il-2. The OBK-16 weapon had several advantages over the Shpitalny design like a faster rate of fire, light weitgh and better adaptability of his feed system ( belt feed instead magazine feed)
The Ns-37 was installed in a streamlined bulge under each wing with provition for 45 round per gun.
Performances of the aircraft was indeed affected, the take -off lenght was increased in 10 % and the maximum speed reduced in 25 km/h.
The Il-2m armed in that way was first manufactured as series aircraft in march 1943 and entered in service inmediatly. However as in the case with SFK gun this kind of installation was not completely satisfactory.
Acuraccy & terminal ballistic of NS-37
In early 1943 a series of test in the firing range were carried out to find out the true effect of the NS-37 (that in the paper was very promising) against the Panzer formations.
The armor breaking capabilities of the API ammunition were good enough, for example the sides of the Panzer III and Panzer IV were cleanly penetrated at 400 meters with good fragmentation effect inside the vehicle.
It only inconvenience was the numbers were not completely satisfactory as far as precision goes. Nevertheless it must be pointed that this inaccuracy was due factors non related directly to the design of the weapon but to the power of its cartridge and the types of assemblies and sights.
The Yakovlev and Lavochkin fighter were really light aircrafts compared with "western " designs and is already remarkable that the russian could put a gun of this heavy caliber in it design… not to mention made them work with acceptable a reliability.
In the Ilyushin strafer the problem was worst. Despite the high numbers of tanks claimed as destroyed with this weapon system the same VV-S reckoned its deffects. Compared with the german counterpart, the Ju-87G, the russian aircraft lacked the sofisticated hydro-pneunatic dampening rail used in the german 3,7 Flak 18 gun. Also the all metal, high G designed wings in the Stuka were by far more robust than the sturmovik ones.
In order to prove the aim with the 2 types of assemblies (engine and wing) firing to captured panzers took place from distance of 400 and 300 meters to the one of recovery (this is the minimal distance in which the airplane rises pulling up in order not to hit the ground)
Using a quite conventional tactic to attack in a shallow dive the following results were obtained:
LaGG-3: 5 impacts of an average of 35 shots fired.
Il-2M with NS-37: 3 impacts of average 50-60 shot projectiles.
The low percentage of impacts was caused by:
A) The strong recoil of the weapon curved the wings of the Il-2 distorting its flight path and increasing the dispersion of the burst.
B) The need to set the convergence of the weapons and to harmonizing its sequence of shot.
C) Lack of suitable sights, in fact majority of the Il-2 of the period had not a reflecting sight but a “ring and bead” device, completely inadequate for the shot at medium/long distance.
The airplane saw a limited use in Battle de Kursk . Later was diverted to the Air fleet of the Black Sea. Strafing fast attack boats and transport vessels were by far more easy than hit tank sized targets.
Penetration in gun cover Panzer III ( 35 mm).
Penetration in side armor Pz III ( 30 mm)
Two close impacts of high explosive shells caused the armor breackage in this Pz II ausf F ( 18 mm)
The VVS acknowledged the good typical characteristics of the weapon but it was really disappointed with the performance on his main attack airplane, to the contrary the production of single-engine fighters with heavy arms continued until the end of the war with more of of 3000 Yak-9T/K constructed.
In order to increase the antitank power of the Sturmovik several types of rockets and specialized bombs with shaped charge explosives like the PTAB were introduced.
Firing with HE shells to german bombers was also tested, the results were very good in that aspect, a single shot was enough to ensure destruction of a Ju-87 sized target. Two shots were enough against medium bombers like the Ju-88 and He-111.
A single shot of HE ammo caused the complete destruction of rear fuselage in this Ju-87D.
37x195 mm ammunition.
The powerful cartrigdes used in the NS 37 were a long streamlined beltless botlenecked design.
The two basic types of projectiles were:
OFZ, High Explosive Incendiary, weight 735 grams, muzzle speed 890 mps.
BT, Armor piercing with tracer, 753 grams. Ballistic cap, without any kind of incendiary or explosive filling. Muzzle velocity 870 m/s.
Penetration 48 mm high strenght steel at 300 meters ( 20 º angle)
Nudelman Suranov NS 45.
The introduction by the german army of a completely new generation of heavily armored vehicles in 1943 like the Pz V Panther, Ferdinad and Brummbär caused serious concerns among the VVS high command.
There were fears that the standar barrel armament would not be powerful enough to fend off this menace.
In order to cope with this the gifted technicians of the OKB-16 were again put in charge of the development of the heavy caliber weapon, this time the cannon would be able to shoot the 45 mm round of the infantry M1932 AT gun. The NS 45 was (unsurprisingly) a scaled up variant of the NS 37.
In december 1943 the first prototype was ready for testing. The static shooting quickly demonstrated the power of the new gun…in both ends. A maximum recoil force of 3900 kg with a duration of 0.03 secs was noted.
Such figures recomended the installation of a muzzle brake wich teorically reduced 50 % of the backwards energy ( in practice wasnt in that way)
The gun is short recoil operated and belt feed, weights unloaded 153 kg and the rate of fire is 250 rpm.
Muzzle velocity about 700-710 m/s.
Installation on Yak fighters.
The first aircraft to use this weapon was the Yak-9K, installation of this massive weapon inside the small fighter wasnt free of troubles. Nose of the aircraft had to to be enlarged 25 centimeters. The bore of the proppeller hub in the Klimov VK-105PF has to be increased in 20 mm, that left a very thin space in the cilinders inner walls.
It also affected the flying characteristics of the otherwise nimble fighter, for example the rate of climb slowed down in 20 %. The maximum speed was reduced to 560 km/h. Shooting the NS 45 was no recomended below 360 km/h and it was stricltly forbidden below 300 km/h because the risk of stalling the aircraft. Maneouvrability was hampered too.
Despite the troubles the VVS considered the YAK-9K a “tactical fighter” wich would be used mostly against tanks, locomotives and boats so the lack of performance wasnt really important. Fighter cover of standar armed Yaks were provided for the “Ks” everytime possible. Yak-9k entered in service in march 1944 armed with the NS 45 with 29 rounds belt and one UBS with 200 rounds belt.
Installation on Yak fighters ( part II)
The usual manner of attack against ground targets was the conventional shallow dive tactic, with angles not exceeding 20º and at speed over 500 km/h. Within this parameter the NS 45 gave relative good results, its only inconvenience was the short burst, because the gun was restricted to 2 shot or even single ones per each pass ( wich clearly denied the advantages of a fully automatic weapon)… longer burst would cause the shot flew over the target.
In mid and late 1944 another problem was experienced in Yak-9k units. The continued use of the gun caused the Klimov engine to suffer oil and water leaks. The reason behind that was discovered as the vibration caused by the gun wich made cracks on the alluminun alloy cilinders banks. Those craks pronlonganted affecting the oil pipeline and coolants tanks causing engine overheating and general failure.
Heavy recoil !!! fracture of Klimov VK-105 engine bank caused by the backward force of the NS 45.
Inconveniences like that caused that the production of the K variant was deleted, with only 60 aircraft delivered.
The gun needed a bigger and heavier platform.
NS 45 in attackers.
In erly 1944 the NS 45 was also proposed as the armament of heavy “shturmoviks”. One was the long range, heavily armed Sukhoi Su-8.
Sukhoi’s Su-8 emerged as the most powerful, most heavily armed, and best protected attack aircraft of the war. The designers set out to build the smallest airframe that could carry the requisite fuel and two of the most powerful engines available, Shvetsov ASh-71F 18-cylinder air-cooled radials each offering 2100 hp.
Sukhoi Su-8
The narrow forward fuselage housed the pilot, a large fuel tank, and the radio operator/air gunner in a fully structural armored shell up to 15-mm thick. Extensive bullet-proof glazing in the canopy and lower nose gave the pilot a good view for this type of aircraft.
Twin fins and rudders provided redundancy in the event of damage and gave the air gunner a better field of fire above and to the rear.
Defensive armament consisted of a 12.7-mm Beresin machine gun flexibly mounted in the rear cockpit (or in a small power-driven turret, according to some sources) and a 7.62-mm ShKAS machine gun firing from a ventral position.
This aircraft carried no more and no less than 4 x NS 45 in a belly pod, each gun with 50 rounds, also it had 10 machineguns in wings (shkas) and a heavy armor for pilot and gunner.
Squematic showing underbelly emplacement in Su-8
The Su-8 was a very promising aircraft but also very expensive. No wonder why the VVS prefered the Il-10 instead.
A Tupolev Tu-2 was tested with twin NS-35 inslallation angled donwards in the bomb bay, This variant named properly Tu-2SH did make it into production.
Also a special Il-2M3 with all metal wing was equipped with twin wing pods for the Ns-45, each gun had provition for 40 rounds. Problems with recoil forces ( again) and the end of the war stopped more development of this variant.
45x185mm amunition:
It was obtained modifiying the NS 37 ammo case to accept the 45 mm antitank round.
Weight of the projectile 1150 grams (HE) and 1300 grams ( armor piercing) muzzle velocity 710-720 m/s.
AP shell could penetrate 58 mm of rolled homogeneous armor at 300 m in a 20º angle. ( data from Yak-9k attacking in a dive at 480 km/s)
Sorry I have no info to add PK (if I may call you that). Just wanted you to know that I find your posts most interesting. (you’ve been the only one posting on here recently).
Thank you. Is a detailed and complete topic as you might see.
if I may call you that
Panzer sounds better. 
Nudelman Suranov NS-23.
1944 design. In order to replace the VYa 23 gun in the new generation of fighters and shturmoviks, the main objetive in the NS 23 was to increase the rate of fire and to made a gun compatible with synchronization devices.
Nudelman & Suranov adapted their short recoil operation to the new shorter cartrigde giving a increased ciclic rate of fire between 600-650 rpm.
A total control of the firing pin during automatism allowed the cannon to be coupled with interruption gears in single engine fighters.
Its only disandvantage was the reduce muzzle velocity compared with the earlier 23 mm model, however as the NS 23 was not proposed as anti-armor weapon this was felt irrelevant by the VVS. ( as I said before the antitank work was taken in late war by specialized bombs and rockets)
NS 23 compared with the shorter Shvak.
4 x NS 23 in wings, Ilyushin Il-10
The NS 23 was adapted by several late war and post war aircraft such as: MiG-9, Yakovlev Yak-7U, Yak-9U, Yak-15, Yak-17, and Yak-23 Il-10, Il-18, Il-20 ( fixed) Lavochkin La-9 and La-11 ( synchro) and defensive in Ilyushin Il-22.
The manufacturing of NS 23 ended in 1950.
Il-22 rear emplacement.
NS-23 characteristics:
Action: short recoil rotating bolt head. Counterrecoil by helicoidal spring and Hydropneumatic cilinder.
Charging: pneumatical
Lenght: 2230 mm
Weight: 37 kg
Rate of fire: 600-650 ( 500 rpm in La-9 and La-11)
Muzzle velocity: 685-710 m/s
3 x NS 23 in the nose (lavochkin La-9)
[b][u]Aditional info on NS 45.
[/u][/b]Interestingly enough there was also a Yak-3 variant wich used the 45mm gun, the Yak-3K, the russian sourse in very laconic about its destiny “…was not in series production”.
Probably suffered the same structural and recoil troubles of its NS 45 armed bigger brother.
Recoiless cannons.
There was several entusiast of the recoiless gun in the USSR as early as 1918. The major exponent in the period of time we are interested was L.V Kurchesvskiy, engineer who designed several types with calibres varying between 45 up to 152mm
The principle was invented by the Colonel Davies of the US navy in 1916. Using the actioan and reaction principle the gun need to launch a counterweigh with the same mass and speed to eliminate the recoil.
The RG weapons had the advantage to use a large caliber tube thus a large caliber shell wich could be fired from a relatively small aircraft.
It disavantage is that even today is difficult to obtain a reliable working automatic mechanism.
APK-4 in caliber 76 mm.
This was originally designed in 1929 but manufacturing of the weapon did not commenced until 1931. it was a very sophisticated and ambitious recoiless cannon. The gun was a repeater actuated by compressed air wich moved the magazine and dropped a reload into the chamber. Total capacity were one shot ready to fire plus 6 reloads.
The ammunition was comprised of a semicombustible cloth case with a counterweight in the base. Propellant weight was 600 grams. Projectile weight was 4,1 kg, muzzle speed 350 m/s.
Teorically the counterecoil effect was achieved by launching part of the cloth case along its counterweight. However in static and dinamic test part of the cloth was stuck in the chamber or the ejection nozzles so the gun wasnt entirely recoiless. Further development created the variants APK-4bis and APK-4m, wich tried to solve reliability problems, however those affected the APK guns during its entire career, the main source being the repeating mechanism. A variant with a 20 round drum magazine was projected in 1933 but never constructed.
Manufacturing of the variants APK-4, APK-4bis and APK-4m ended in 1935 and APK-4m with some 110 guns completed. It was tested in the Tupolev ANT-23 and Grigorovich I-Zs.
The Yak-9B light bomber dropping the PTAB.
Very damned interesting series of threads, Panzerknacker, this and the German aircraft armaments one.
I have thoroughly enjoyed both. It is a pity most of My collection of relevant books was lost.
Technical question though: The ShVak cannon in 20 mm, with the penetration power of the 37mm incorporating the sub-calibre slug. Was that cannon ever actually used in an aircraft? Only sources I have seen are unconfirmed.
Regards, Uyraell.