USSR Aircraft weapons

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)

NR-23.

The NR-23 is basicly a modified variant of the NS-23. The objetive was to increase the rate of fire.

The engineer Richter ( also quote as Rikhter in some sources) was the responsible behind the mechanical "accelerator" introduced in this cannon. The accelerator is a piece used in automatic armament wich increases the speed of bolt movement. Obviously that also increased the rate of fire wich is about 750-800 rpm.

The NR 23 shot the same cartrigde as the NS 23 and was the armament used in Mig-15, Mig 17. early Mig-19 and also as defensive gun of IL-28 and Antonov An-10.
In the bombers emplacement it have a steel bracing to reduce the aerodinamic flutter.

Its barrel is slightly longer than NS 23 and the counterrecoil spring is cover by cilindrical metal sheet.


2 x NR 23 in pack MiG 17.

Keep up the good work, Charles!

One slight amendment: the MiG-15 used the NS-23. The modified MiG-15bis introduced the NR-23.

Thank you very much Tony, every amendment is welcomed.

Oh, which of the 37mm guns did the Mig 15 use?

The Nudelman N-37.

I will post information about that gun later.

Charles, do you happen to know how much the installation of the NS-37 or NS-45 increased the weight of the YAK-9? I imagine there was some extra bracing as well as the gun + ammunition.

Thanks

red admiral said:

Charles, do you happen to know how much the installation of the NS-37 or NS-45 increased the weight of the YAK-9?

Click to expand...

for some 150 kilograms. That's why the fuselage was bulkheaded and the canopy was moved backwards to maintain an acceptable center-of-gravity value. Yak-9T had some 160 kg of fuel less than its predecessor because of the same reason as well.

More information of the Yak-9k you can found here ( with the help of a good translator )

yak -9

Nudelman N-37.

]

In a similar way as the NS 23 the main objetive requesting the design of the N-37 was to deliver a 37mm explosive shell with higher rate of fire than the earlier large caliber OBK-16 guns.

The principle of automatism was the trusty short recoil with a rotating head to lock the chamber. N-37 shoot from a open bolt, meaning that every time the trigger was depressed the bolt advance over the ammo belt extracting a cartrigde, introducing it on the chamber and firing after the later was closed.

N-37 used a modified 37mm cartrigde with shorter case wich reduced muzzle velocity but decreased recoil and allowed a lesser weight compared with NS 37

First prototype of this gun was ready in april 1944, and it was put inside a Yak-9T with good result. In august of the same year the gun was taking operative state with the harder job beign setting properly the "hardness" of fuzes in HE ammunition ( with the early used 37x195mm amunition sometimes the shell didnt explode hitting soft ground) Following test were airborne inside a MiG-9.

The Mikoyan Gurevich MiG 9 was the first operative Jet aircraft of the VV-S and it was equipped with two RD-20 ( copy of german BMW 003 engines) the N-37 was located between the "lip" dividing the airflow for both engines.



This location had some troubles however. Shooting at high altitude the unburned gunpodwer and combustion gases were sucked in by the Klimov engines causing flameouts.

Modifications were introduced in the shape of a muzzle brake wich provide some dispersion for the gases, this cured the situation in some extent but the maximum altitude in wich the MIG 9 could used its big cannon was limited to 8000 meters. The gun modified in this way was denominated N-37D.

For the new MiG 15 the designers placed the N-37D below the air intake and paired with a couple of NS-23 (NR-23 in Mig-15bis) all togheter in a nose pack wich could be dismounted quickly for resupply of ammunition and maintenance.

N-37D/NR-23 pack in the MIG-15bis.

N-37 (II)

The N-37 had the opportunity to enter quickly into combat due to the Korean conflict of 1950-53.
In there it showed a demolishing power against the formation of USAF bombers and its escort fighters.

Nevertheless due to the little ammunition capacity the burst was of short duration (6.1 seconds) reason why the pilot had to be to be careful with his use, also the cadence was not suitable to fight against a jet fighter in maneuvers of high speed since easily a F-86 could get "in between" the shots .

A thing is certain, the combination of guns of the Soviet fighters gave them enough and superior firepower compared with the sixgun configuration of machine guns of the F-80/84/86, several MiG-15 returned to home with a large number of impacts of caliber 12,7mm in its fuselage whereas the Fighters of the UN could not repeat the feat after being hit powerful Russian guns.

For the heavy fighters Yak-25/27 it was adopted a denominated variant N-37L, this airplane mounted two guns with a belt feed of 100 cartrigdes.

The Yak-27 used a longer barrel variant designated NN-37L, its longer tube increased muzzle velocity to 700 mps.

19,500 units of N-37 were manufactured between 1947 and 1960.


Characteristics:


Calibre: 37 x 155 mm

Automatism operation: Short recoil, rotating bolt, pneumatically charged.

Total lenght: 2455 mm

Barrel lenght: 1380 mm

Max width: 235 mm

Weight: 105 kg.

Rate of fire N-37D: 400-450 rpm

Rate of fire: NN-37L : 550-600 rpm.

Muzzle velocity: 650 to 700 mps.

Manufacturer: Factory Nº 74 Ishev.

Shpitalny Sh-3.

This a rarity, the only information I found about this gun is it used the same ammunition of the NS-23/NR-23 and had a increased rate of fire to 800-900rpm. I cant find a close up photo or squematic of the mechanism but being a Shpitalny design my guessing is it was gas operated.

It was put in a Yak-15 prototipe and in a very interesting pivoting emplacement in the Mig-15Su, experimental variant of 1950. The standard quick-change armament pack housing one 37mm and two 23mm guns was replaced by a fixed installation of two powerful Sh-3 23mm guns, each with 115 rounds.

MiG-15 SU



Each gun was mounted below the fuselage in a streamlined fairing. The barrels projected through a vertical slot so that, mounted on trunnions and driven by an irreversible electric screwjack, it could be elevated to +11° and depressed to -7° (there was no lateral movement). The Ministry order for this conversion was signed on 14th September 1950, and the SU was factory-tested between 2nd January and 27th March 1951.

Official VVS testing followed from 30th June to 10th August 1951. The general opinion was that in tight turning combat the system was useful in bringing the guns to bear, and it also enabled a head-on attack to be made with less risk of collision. The concept seemed to have merit, but it was not adopted for production.

MiG-15 Su profile.

I forgot the post with information about the N-37 ammunition, so :

37x155mm ammunition:

Cartridge cases are brass and filled with 127g of 4/1 FL propellant, they use the same percussion primer as the 45mm antitank rounds use. Maximum armor penetration of the AP shell was 50mm.

20 cartridges of older manufacture were packed in a wooden box and separated by wooden spacers, these boxes weighted 40kg. Later, 10 cartridges were packed in a sealed metal container and 3 of those containers were overpacked in a wooden box weighting 56kg. Cartridge belt links are packed in 400 pieces separately in a wooden box that weighted 60kg.
Ammunition was manufactured by the Czech Republic, Poland and Russia.

OZT: HEI-T 735 670 Conventional HEI-T shell filled with 37g of HEI, self-destruction nose fuzes A-37, A-37U or B-37 fitted
OFZ, HEI 729 670 As above but without tracer and filled with 49g of HEI

BR: APHE 734 670 Base fuzed APHE shell filled with 36,1g of HE, AD-37 base fuze
BZT: AP-T 735 670 Pointed AP shell with ballistic windshield cap (no incendiary!), tracer element is sometimes not fitted
This type is also used as TP-T training round UB-37 TP Airburst 726 670 As HEI shell but with self destruction fuze without impact action, light blue colored fuze tip. For aerial target practice, self destructs between 9 and 12 sek.

From 30mm to 40mm

Aditional info on NS 45.

Interestingly enough there was also a Yak-3 variant wich used the 45mm gun, the Yak-3K, the russian source 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.

In the next post I will give a review of the Kurchesvskiy guns and the aircraft armed with those, most of them for experimental purposes.

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.

Images of the Tupolez ANT-23 designated I-12 "Baumanski Komsomoletz" by the VV-s, It was armed with 2 APK-4.

Of unconventional design, it employed a tandem fore-and-aft engine arrangement and twin tailbooms embodying recoilless 76mm Kurchevski APK-4 weapons as integral, but non-load-carrying, structural components, the gun gases being discharged from their tails. First flown in late December 1931. Flight testing continued and it was found the aircraft was overweight and suffered substantially higher drag than had been calculated. On a May 19, 1932 gun test-flight, the port gun exploded, damaging the tail boom which collapsed on touchdown. The plane was repaired and a system to eject the rear propeller to give pilot a safe way to get out was installed. However the project was discontinued in early 1933

The Grigorovich I-z.

Information about the little fighter wich is mostly related with the APK-4 gun, extracted from "Soviet X Planes" and , by the way APK was for Avtomateshko Pushka Kurchevski, meaning Kurchevski automatic cannon.

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By the end of the 1920s design bureaux were receiving contracts for experimental fighters designed to be armed with such weapons. In late 1929 Grigorovich was sent to Central Construction Bureau 7, which was really Hangar 7 at Factory 39, an OGPU secure prison for designers. Here he led the design of the Z, a secret monoplane to be armed with two 76.2mm (Sin) APK-4 guns. To speed construction the powerplant group and forward
fuselage of the first prototype were the same as those of the Polikarpov I-5, which was also built in Hangar 7.

The complete aircraft, called I-Z (Fighter Z) was flown by Benedikt
Bukhgol'ts in (it is believed) early May 1931. It was inspected by Stalin, Voroshilov, Molotov and others on 6th July 1931. Subsequently a small series of 21 production I-Z fighters were produced at GAZ No 39. These were still regarded as experimental. In February/March 1933 aircraft No 39009 was placed on a high platform and used for firing trials, and in September 1933 No 39010 underwent NIl-WS testing. Two of these aircraft were later used in Zveno trials, as described under Vakhmistrov. In 1934-35 Factory No 135 at
Kharkov built a further 72, with modifications, designated IP-1. These saw only limited use, partly because of difficult spin recovery, but were not considered as experimental.

At this time monoplanes were still structurally difficult, and the wing, though of torch-welded stainless (Enerzh-6) lattice construction, still needed underwing bracing to the fixed landing gears. Apart from the semimonocoque rear fuselage, the covering of the whole airframe was fabric. The prototype hada Bristol Jupiter, in a helmeted cowling, while the first production batch had the same 480hp engine built under licence as the M-22
and cowled in a Townend ring. The second batch, from Kharkov, had the 700hp M-25 (Wright Cyclone). The main landing gears variously had spatted wheels, plain wheels or skis.



The guns were suspended from both main spars outboard of the struts (just inboard on the first prototype), and were fed at a slow rate from a seven-round magazine in the wing. A PV-1 machine gun was fitted to
right of centre ahead of the windscreen to assist aiming using the optical sight. The tailplane was mounted high to avoid the rear
blast from the APK-4s.

APK-11 of 45 mm

An attemp to improve the reliability and rate of fire. The caliber of the APK-4 was reduced to 45mm and the magazine was increased to 10 rounds. The only know aircraft that was armed with this gun in the experimental Tupolev ANT-46, a heavy fighter variant of the SB-2.

In the ANT-46 one AKP-11 was imbeded in each wing , aditional armament consisted in 2 ShKas. A single prototytipe was manufactured in 1936 with no further development on this variant.

Other view of the ANT-46 ,the rear nozzles in the pair of APK-11s.