Type 96 25mm L / 60 cannon
| Type 96 25mm L / 60 cannon | |
|---|---|
|
|
|
| General Information | |
| Military designation: | 九六 式 二 十五 粍 高 角 機 銃 |
| Manufacturer country: |
 Japan
|
| Developer / Manufacturer: | Yokosuka marine workshops |
| Development year: | 1935 |
| Production time: | 1936 to 1945 |
| Number of pieces: | 33,000 |
| Weapon Category: | Anti-aircraft gun |
| Team: | 3 for single mount 7 for twin mount 9 for triple mount |
| Technical specifications | |
| Pipe length: | 1.5 m |
| Caliber : |
25 mm |
| Caliber length : | L / 60 |
| Number of trains : | 12 |
| Twist : | clockwise |
| Weight ready for use: | Single carriage 785 kg Triple carriage: 2200 kg |
| Cadence : | actual 110 rounds / min |
| Elevation range: | −10 ° to +80 degrees |
| Side straightening area: | 360 ° |
| Furnishing | |
| Ammunition supply: | Box magazine with 15 rounds |
The 25 mm L / 60 cannon type 96 ( Japanese 九六 二 十五 粍 高 角 機 銃 ) was a machine gun that was used by the Imperial Japanese Navy as an anti-aircraft gun during World War II . The designation Type 96 indicates the year of the first development, the year Kōki 2596 or 1936 according to the Gregorian calendar.
history
After various problems with the water-cooled 40 mm Vickers anti-aircraft gun introduced in 1925 became known, the Japanese Navy decided in 1935 to replace it with a weapon based on the French Hotchkiss 25 mm anti-aircraft gun .
After studies on the weapon in France, some samples with changes according to Japanese requirements were ordered from Hotchkiss. The weapon now achieved a theoretical rate of fire of 180 to 200 rounds per minute with a 250 g bullet.
The Japanese made further changes and exchanged the flash hider for a model that was based on a development by Rheinmetall and, to a lesser extent, also took on the function of a muzzle brake . Manufacturing was also simplified by using castings in areas where previously forged parts had been used.
Mass production of the weapon began after the tests in 1936 and the Type 96 automatic cannon was gradually introduced on all warships of the Imperial Japanese Navy as the standard weapon for close-range air defense. The weapon was mounted individually, in groups of two or three on mounts.
Models
The development process continued and produced several variants for different purposes:
The models 1, 2 and 3 differed by different types of mounts and were intended for ships and land bases. The Model 4, on the other hand, was developed for arming Japanese submarines and had a high-quality barrel that was better protected against corrosion from salt water. Three variants of this model 4 were developed, which differed in the different versions of the mount, which was either permanently installed, could be lowered manually into the submarine or could be retracted electrically into the hull.
The model 5 had a modified gearbox for the mount, the models 6 and 7 were single mounts that rested on an axle with two wheels so that they could be carried by ground troops. Model 10 was a version for arming torpedo boats with a single mount that had a modified mechanism for pivoting in the horizontal.
By the end of the Second World War, around 33,000 type 96 automatic cannons and 20,000 mounts in single, twin and triple designs were produced. Most of it was used on warships. As a permanently installed version for the defense of land bases, 2,500 weapons were produced. As mobile systems for land use, only 100 weapons were built on twin and single mounts.
The largest number of Type 96 automatic cannons ever mounted on a ship was reached in 1945 when the battleship Yamato was equipped with 152 units in 50 triple and two single mounts and the Shinano aircraft carrier even received 155 Type 96.
technology
weapon
The weapon was an air-cooled gas pressure loader that fired 25 mm projectiles at a theoretical rate of 220 rounds per minute at a muzzle velocity of 900 meters per second.
The rifled barrel was 1.50 m long and weighed 43 kg. It was clockwise with twelve 0.25 mm deep pulls. The barrel was screwed to the weapon and had to be replaced after about 6000 shots, because it was then so worn that the range and accuracy decreased rapidly. The change took about five minutes.
The gas pressure used to power the cartridge reloading mechanism could be adjusted to vary the number of shells fired per minute. The theoretical rate of fire reached 200, 220 or 250 rounds per minute. The standard setting was 220. Due to the constant reloading of the magazines, only around 110 rounds per minute were actually achieved.
The recoil that occurred when the projectiles were fired was intercepted below the weapon by two hydraulic cylinders , each of which had a diameter of 6.7 cm and was around 43 cm long.
The ammunition was supplied from around 7 kg steel magazines with 15 cartridges each, which were inserted vertically into the weapon above the breech. Empty shell cases were ejected from the bottom of the gun.
Mounts
Twin and triplet mounts were controlled by two shooters. The first rifleman sat on the left side of the mount, two pedals were mounted in front of him, with which he could fire the guns on the mount. With the twin mount, one pedal for each automatic cannon, with the triple mount, one pedal for the two outer weapons and one for the middle one. With his hands he operated a crank with which he adjusted the straightening angle of the Type 96 automatic cannons. He was able to raise the carriage up to + 80 °.
The second rifleman sat on the right and swiveled the gun carriage to the right or left using a wheel. A complete turn of this handwheel moved the mount 5 ° to the left or right. The mounts could be rotated through 360 ° repeatedly, the only exception being the rotating mechanism on the model 2 mounts, which blocked after a 720 ° rotation. In an emergency, Rifleman 1 was also able to control the swivel mechanism, a wheel was attached to the left side of the mount.
The swiveling and straightening mechanism of the heavy twin and triple mounts could be moved manually using a series of gear wheels or two small electric motors . The motors were installed under the seats of the two shooters, each had an output of 0.735 kW (1 hp) at 220 volts and 3.6 amps .
The twin mount was the first to be developed, the triple mount followed in 1941 and the single mount finally in 1943.
team
With single mounts, three soldiers were needed to operate the weapon:
- a shooter for aiming and firing the gun
- a loader for changing the magazines
- a gun leader
Seven soldiers were required for twin mounts:
- a shooter for the direction of altitude and firing the gun
- a shooter for the lateral direction of the weapon
- four loaders (two per automatic cannon)
- a gun leader
With triplet mounts, the number of soldiers increased by only two loaders for the additional automatic cannon to nine men compared to the twin mounts.
Sight and fire control
Function of the visor
If the weapon was used alone and without a fire control system, a sighting device had to be used. It was attached to the carriage and mounted on the left in front of the seat of the first rifleman. In order to aim in such a way that a fast aircraft could also be hit, an open sight with a large ring sight was used for air defense. The ring sight was installed in front of both seats and both sights were coupled to ensure that both soldiers were pursuing the same target through their sights. The second shooter on the right side of the mount followed the target through his sight and swiveled the weapon so that it was always aimed at the target in the firing position. The first gunner on the left adjusted the elevation angle using his hand crank and fired the weapon.
Structure of the visor
In order to be able to fight fast planes, one had to hold up far . That is why the visor had several rings that, viewed from the outside in, stood for ever decreasing target speeds. The outer ring was connected to the middle ring by twelve steel pins, so that twelve fields were formed for different approach angles. The middle ring was connected to the inner ring by four steel pins, while in the inner ring a vertical pin and a horizontal pin formed a crosshair, in the middle of which was another ring.
The ring sight was usually made of metal, but there was also a version made of a glass plate with etched ring markings. An optical aiming aid similar to a telescopic sight also existed.
Fire control for a gun carriage
Experience has shown that the shooters found it difficult to estimate the course, speed and altitude of an aircraft, so the Imperial Navy used a simple mechanical computer on which these values could be set so that the weapon automatically followed these settings via its two electric motors. The system was identical to the control system of the French Hotchkiss machine gun. This calculating machine had been developed by Navy Lieutenant Yves Le Prieur in 1916, but in the pattern used by the Japanese Navy was no longer able to track the fast planes of World War II. Nevertheless, the Le Prieur device was still used in the Pacific War on mounts that were not connected to an external fire control device.
Fire control for several mounts
In order to increase the likelihood of being shot down, the fire of as many mounts as possible had to be combined with their Type 96 anti-aircraft guns on one target. At the same time, it was important that the guns fired at particularly dangerous targets, such as enemy bombs and torpedo planes approaching and not distributing the ammunition to harmless targets, such as planes returning.
Either the Type 95 or the Type 4 Model 3 fire control device were used on warships and on land. The fire control officer had an observation telescope for this purpose, which was installed at a point with as good an overview as possible, with which he selected and followed a target. He estimated the target's speed and then selected the lead angle accordingly . The mechanical computer allowed him to aim and pursue targets up to a speed of 600 km / h. For faster targets, the guide data had to be estimated using three ring markings that were etched into the observation telescope for 700, 800 and 900 km / h. The Type 95 device now transferred the alignment of this telescope via cables inside the ship to the two electric motors in up to three 25 mm mounts and aligned them accordingly.
On warships in particular, there was also the problem of limiting the straightening angle. Riflemen or fire control officers who were focused on a specific aerial target could accidentally direct fire against the superstructure of their own ship if they were not careful. For this reason, in the type 95 and type 5 control devices, limiting screws were built into the slewing mechanism, which did not allow slewing beyond a certain point. In the case of mounts that fought targets without a fire control device via the sight, the gun leader had to order the shooter to stop fire in good time.
ammunition
The ammunition for the Type 96 automatic cannon consisted of a brass case with a 102 g propellant charge and the projectile. The case and bullet weighed around 660 g when ready for use.
The vast majority of the bullets produced for the Type 96 automatic cannon belonged to two models:
HE shells:
- HE grenade , 200 g
- HE grenade with tracer , 118 g
- Explosive grenade with tracer and fragmentation charge, 118 g
The HE shells were fired with an impact fuse , which detonated the explosive in the grenade when it hit an obstacle. In the version with tracer, when the projectile was fired, the burning drift landing in the case ignited a 9.2 g charge in the bottom of the grenade made of a mixture of barium peroxide , magnesium and sodium nitrate , in which a reaction took place, so that during the flight a bright point was visible on the grenade. In the case of the dismantling charge, only a small hole was drilled between the compartment with the tracer charge and the compartment with the explosive charge, so that the burning tracer charge jumped into the explosive charge at the end of its burning time and exploded or "dismantled" the grenade.
Explosive Grenade:
- Explosive incendiary bullet , 203 g
The floor contained a TNT - aluminum mixture and white phosphorus in the ratio 1: 2. After the TNT charge was ignited, the phosphorus was distributed burning with the fragments of the projectile body and burned down at a temperature of up to 1,300 ° C.
In addition, a US report from 1953 reported a bullet classified as armor piercing with a tracer, which had no detonator and was filled with diatomite . However, the analysis of the projectile showed that it was made of a significantly softer steel than other armor-piercing projectiles, so that no statement can be made about its effectiveness. Another report gives the penetration rate with 25 mm steel at 450 m / s impact speed.
rating
Japanese calculations determined the average amount of ammunition that one had to fire in order to shoot down an aircraft at a certain distance and altitude with a certain type of anti-aircraft weapon.
This value was given for the 25 mm automatic cannon type 96 with 1,500 rounds for a target that flew no more than 2,000 meters away at an altitude of less than 1,000 meters. Although the range of the weapon was greater, shooting at targets more than 2,000 meters away has been described as completely ineffective. The reason given is the fire control system, which was not able to coordinate the fire of several Type 96 anti-aircraft guns over long distances with their larger lead angles. Shelling aircraft that did not fly a straight and therefore predictable course is described as ineffective even at short distances.
One of the reasons was considered to be the weak electric motors for the automatic straightening, which could not turn the mounts fast enough to follow a fast aircraft as it flies by. Furthermore, the weapon generated strong vibrations during continuous fire , which impaired accuracy.
Another problem was the ammunition supply from the 15-round magazines. She slowed the possible rate of fire by about half. The additional soldiers who were needed for reloading had to be accommodated and taken care of on ships and they moved unprotected on deck during an air attack, so that particularly among the air defense crews on large ships, heavy losses could arise in such attacks.
To make matters worse, the Imperial Japanese Navy suffered from a lack of ammunition after the battles for Bougainville and in some battles only ten rounds per gun were allowed to be fired at each attacking aircraft.
Even when hits were hit on enemy aircraft, the destructive power of the projectiles was often insufficient to cause serious damage. For example, of 144 American aircraft shot down during the Battle of Midway, only about five were lost to anti-aircraft fire.
Evidence and references
Remarks
- ↑ The American report O-47 shows in its general overview on p. 12 an angle of + 85 ° for all mounts, but expressly mentions only + 80 ° in the detailed individual reports for the twin and triple mounts.
- ↑ "Steel" does not mean " armored steel" here , but simply steel with a high yield point
- ↑ Compare in particular Musashi and Yamato
Individual evidence
- ↑ USNTMJ O-47, p. 43
- ↑ USNTMJ O-47 pp. 1 and 13
- ↑ USNTMJ O-30 p. 52
- ↑ Japanese Explosive Ordnance, p. 449
- ↑ USNTMJ, O-19, p. 58
- ↑ USNTMJ O-47 p. 1
- ↑ USNTMJ O-44 pp. 7 and following
- ^ Marc Stille: Midway 1942: Turning Point in the Pacific. Osprey, 2010, ISBN 978-1-84603-501-2 , p. 21.
literature
- REPORTS OF THE US NAVAL TECHNICAL MISSION TO JAPAN 1945-1946, O-47, Japanese Naval Guns and Mounts Article 2 AA-Machine Guns and Mounts, 1946
- Japanese Explosive Ordnance (Army Ammunition - Navy Ammunition), United States Government Printing Office , 1953
