Tag Archive for '20mm'

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20 mm Aircraft Cannon Ho 5 (Browning Principle)

20 mm Aircraft Cannon Ho 5 (Browning Principle)

This weapon, an improvement on the 12.7 mm Japanese copy of the U.S. Cal. .50 aircraft machine gun, is a recoil-operated, disintegrating metallic link belt-fed, air-cooled, aircraft machine cannon. It is mounted as a fixed weapon and as such it is fired electrically by remote control.

The recoil mechanism consists of a metal cylinder into which is fitted a coil spring. Through the center of this extends a 5/16-inch rod which screws into a brass bushing. The rod extends through the spring follower which rests on the coil spring and is secured by two lock nuts. Buffering action takes place in the recoil direction only. There is no quick change barrel. Because of the weight of the bolt and the heavy recoil spring, a booster is used, this being found in the flash hider.

The gun has a high cyclic rate of fire, muzzle velocities of 2,304 f/s (A.P.), 2,430 f/s (H.E.), and a penetration performance of 7/8-inch homogenous plate at 20° at 200 yards; 1/2-inch at 20° at 580 yards. The maximum weight lifting capacity of the belt is 62 pounds.

The disassembly of the weapon is the same as the Browning Cal. .30 and Cal. .50 machine guns with a few minor exceptions. The Japanese weapon has no back plate latch. The back plate is held in place by two pins, one at the top, and one at the bottom.

SPECIFICATIONS

Caliber         20 mm (0.79 in.)
Weight w/accessories 104 11/16 lbs.
Weight w/o accessories 86 3/4 lbs.
Length (overall) 63 3/4 ins.
Sight radius
Principle of operation Recoil with muzzle cup
Feeding device Metal link belt type
Capacity of feeding device 100 rounds
Cooling system Air
Ammunition types A.P., H.E., Incendiary
Cyclic rate 950 r.p.m.
Type of sight Reflector
Weight of barrel 12 1/8 lbs.
Length of barrel 35.4 ins.
Length of rifling 31.5 ins.
Rifling
   Twist R.H.
   Form
   No. of grooves 8
   Depth of grooves
   Width of grooves
Chamber pressure
Muzzle velocity (A.P. Shot) 2,304 f/s
         (H.E. Shell) 2,430 f/s
Effective range 600 yds.

Japanese: p. 252 (June 1, 1945)

20 mm Aircraft Automatic Cannon, Model 99 Mk 1 Flexible

20 mm Aircraft Automatic Cannon, Model 99 Mk 1 Flexible

This weapon is an air-cooled, blowback-operated, Oerlikon type machine cannon. It operates on the same basic principle as all Oerlikon cannons of this type. The Japanese gun is a close copy of the Swiss gun, in that it is designed for full automatic fire only. The gun is manufactured in Japan on Swiss machinery. The above illustration shows the flexible version.

A significant feature is that the parts which are subjected to little wear, such as the grips, mounts, gunners’ shoulder rest, and other exterior parts are generally made of light weight metal.

This weapon is almost identical with other Model 99 (1939), 20 mm aircraft cannon reported to be used in the majority of Japanese planes, both as fixed guns in fighter craft, and as flexible guns in bombing planes. The weapon is fed from a drum type magazine. It is cocked or charged by manual means, and has no semiautomatic charger or rounds counter. The cocking handle is rotated to draw the recoiling parts to the rear and cock the gun for the first shot, the gun firing from an open bolt. Cocking operations for succeeding shots are performed by the blowback operation of the gun itself.

SPECIFICATIONS

Caliber         20 mm—0.87 ins.
Weight (without magazine) 62 lbs.
Weight of 60 rd. magaine (empty) 20 lbs.
Length (overall) 55 ins.
Length of barrel 30 ins.
No. of grooves 9; Uniform right hand twist
Width of grooves
Depth of grooves 0.022 in.
Width of lands
Muzzle velocity (shell) 1,930 f/s.
Cyclic rate 510 r.p.m.
Traverse Flexible aircraft
Length of recoil
Turns of cocking handle required to cock piece 11 1/2 ins.
Ammunition HE; HE with tracer; HE with self-destroying tracer; HE-I; AP; AP tracer; AP-HEI; Long burning tracer; Practice
Wt. of HE projectile 4.50 ozs.
Type of feed 60 rd. drum

Japanese: p. 251 (June 1, 1945)

Pz. Kpfw. IV für 2 cm Flakvierling 38: Antiaircraft Gun on Medium Tank Chassis

Pz. Kpfw. IV für 2 cm Flakvierling 38: Antiaircraft Gun on Medium Tank Chassis

This equipment consists of the four-barrelled 2 cm (.79 in.) antiaircraft gun mounted on the Pz. Kpfw. IV chassis. The gun has been mounted in an open topped, nine-sided turret. Elevation is from 10° to 90° and traverse is 360°.

The gun is the normal 2 cm Flakvierling 38 with the triangular base removed. Two guns are mounted on either side of the cradle. The guns are fired by a set of foot pedals; each pedal operates the trigger mechanism of the two diametrically opposite guns. The weapon is traversed and elevated manually by the gunner who also aims and fires it.

The 2 cm Flakvierling 38 is supported by two four-inch I-beams which are located 15 inches below the normal tank turret ring. The I-beams are in the center below the turret opening and extend across the width of the tank chassis.

There is no traversing rack on the turret ring. A rod from the gun upper carriage supports the gunner’s seat and is fastened by a U-bolt to the turret to form a connection between the gun mount and the turret armor. At the front of each side of the upper carriage is a collapsible rod which also can be fastened to the turret armor. In this manner, the gun mount and turret traverse together.

The turret is 43 inches high, 6 feet, 6 inches wide, and 8 feet long. The armor plate is 15 mm thick. Each side of the turret is composed of two plates of equal dimensions welded together. The top plates are sloped at an angle of approximately 30 degrees and the bottom plates are undercut at the same angle.

SPECIFICATIONS

Weight       26 tons (estimated)
Length 19 ft., 4 ins.
Width 9 ft., 8 ins.
Height 9 ft.
Ground clearance 15 ins.
Tread centers 7 ft., 10 7/8 ins.
Ground contact 11 ft., 6 ins.
Width of track 15 ins.
Pitch of track 4 3/4 ins.
Track links 98
Fording depth 3 ft.
Theoretical radius of action:
   Roads 130 miles
   Cross country 80 miles
Speed:
   Roads 25 m.p.h.
   Cross country 15 m.p.h.
Armor:
   Front plate of superstructure 85 mm at 10° to vertical
   Sides of superstructure 30 mm
Armament 2 cm Flakvierling 38
Ammunition H.E. Shell, tracer; H.E.-Incendiary; A.P. shell, tracer.
Rounds 16 clips in turret (20 rds in each); 15 boxes in tank.
Engine Maybach HL 120 TRM, 320 hp.
Transmission Synchromesh—6 speeds forward, 1 reverse
Steering Epicylic, clutch brake
Crew 5

German: p. 34.1 (August 1, 1945)