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Japanese

75 cm Base Range Finder

75 cm Base Range Finder (Japanese)

This instrument is very similar to the 80 cm base range finder, Keuffel and Esser Model 1918. It also resembles the design of the Barr and Stroud instrument. It is, therefore, assumed that it is used much the same as the American 80 cm base, M1914M1 Range Finder. It is a coincidence type range finder with a split field of view, and is used by light field artillery units.

The ocular prism consists of three optical components cemented together resembling the arrangement in the American 1 meter base range finder, M1916. The eyepiece assembly is of the symmetrical type. The halving plate is a thick piece of optical glass with plano parallel surfaces. The measuring wedge and range scale are a single assembly. The latter is illuminated by the light rays entering through the range scale illuminating window, and reflected by a mirror. The objectives, installed as matched pairs are burnished in their cells. The penta prisms and wedge windows resemble those used in American range finders.

An effort has been made, through a bushing in the center of the buffer assemblies, to desiccate the instrument. It is not believed that the eyepiece assemblies can be sufficiently sealed to make this effective.

The tripod is lightly constructed and has no locking device for the legs. The tripod mount permits the range finder to be locked or rotated in azimuth. There is also a leveling device, but no level vial.

SPECIFICATIONS

Base length       75 cm
Magnification12 power
Range100 to 10,000 yds.
Field of viewVertical 2°—horizontal 3°
Weight of range finder9 lbs.
Weight of carrying case6 lbs.

Japanese: p. 180 (March 1, 1945)

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Japanese

40 cm Base Range Finder

40 cm Base Range Finder - WWII, Japanese

This range finder is a superimposed image vertical base instrument designed for use with machine gun and mortar fire. It consists of two major assemblies: the elbow, and the diaspirometer unit and head. The elbow housing is of seamless aluminum, 4 3/4 inches in length. It contains the eye and field lens, an amici prism, a reticle, a penta prism, and the objective lens. The brass diaspirometer unit contains two wedges with connecting gears that govern the aluminum range drum; the extension tube made of seamless aluminum which maintains the base length of the instrument; and the cast aluminum head which houses a penta prism and a weak correction wedge.

The instrument is used in conjunction with a mount and tripod. Because of the short base length, this range finder is not accurate at distant ranges.

SPECIFICATIONS

Power           4 diameters
Field of view (upper field) 11°
      (lower field) 4°
Base length 40 cm
Measuring limits 30 to 1,500 meters

Japanese: p. 179 (March 1, 1945)

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Japanese

Battery Commanders Telescopes

Model 93, 8 x 6° 15′

Model 93 Battery Commanders Telescope
Model 93 Battery Commanders Telescope
This telescope is so constructed that the tubes can be used only in the vertical position. Its primary use is believed to be for observation and correction of artillery fire.

The eyepieces are of the multiple thread focusing type, and the diopter scale is graduated from +2 to -3. The reticle design consists of a vertical and horizontal mil scale graduated in increments of one mil from 0 to 30 on each side of 0. A light receptacle for artificial illumination of the reticle is provided.

The telescope is fitted with an angle of site mechanism. The hinge mechanism of the assembly consists of a simple hinge pin and a fitted yoke. The interpupillary mechanism is locked near the base and between the two tubes.

 
Telescope with Integral Tripod

Battery Commanders Telescope with Integral Tripod
Battery Commanders Telescope with Integral Tripod
The general purpose of this instrument is believed to be the observation and correction of fire, used with either machine guns or artillery. Unlike the instrument above, it employs a scissor movement and may, therefore, be used in either a vertical or horizontal position.

The reticle is the only angle measuring device provided. The limit for horizontal angles is 30 mils to the right and 10 mils to the left of zero. Vertical angles of plus and minus 20 mils can be measured. The 90° prisms are cemented. Minimum and maximum interpupillary distances are 60 mm and 70 mm.

The tripod is simply constructed, light in weight, and sturdy. It comprises an adapter or bracket for the telescope, a tripod head, and three tubular, fixed length legs with small metal shoes.

SPECIFICATIONS

        Model 93       Tel. with Int. Tripod
Power8 diameters8 diameters
Field of view6° 15′6°
Interobjective distance3 3/4 ins. 
Interpupillary setting58 to 70 mm54 to 70 mm
Deviation of light in vertical plane10 ins.9 ins.
Diameter of Exit Pupil.2 ins..15 ins.
Overall length12 3/4 ins.12 ins.
Overall width6 1/4 ins. 
Weight6 lbs., 5 ozs.2 lbs., 2 ozs.
Length of tripod 11 13/16 ins.
Weight of tripod 11 ozs.

*The interobjective distance with the tubes horizontal, and the interpupillary scale set at 64 mm is 21 ins.; with the tubes vertical, and the interpupillary scale set at 64 mm, the interobjective distance is 5 ins.

Japanese: p. 178 (March 1, 1945)

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Japanese

Multiple Power Observation Telescope

Japanese Multiple Power Observation TelescopeThe Japanese multiple power observation telescope has three powers: 33X, 24X, and a third degree of magnification which has not been determined because of the absence of a third eyepiece in the instrument examined. Selection is made by rotating a dome-shaped holder in which the three eyepieces are mounted. This is somewhat similar to the turret head employed in motion picture cameras and to the selective eyepiece head of compound microscopes.

The objective is a compound lens with an air space between the crown and flint components. A modified porro prism is used for the erecting system. The reticle design used with the 24 power eyepiece is a simple cross. The 33 power eyepiece is not equipped with a reticle. No provision is made for an instrument light. An open line sight is provided for quick location of an object in the field of view.

The support which is made largely of machined brass castings has an upper and lower movement. The azimuth scale is graduated from 0 to 360 degrees in 1/2 degree steps; a vernier indicator allows readings of one minute to be made. Leveling is accomplished by adjusting the length of the tripod legs. The elevation arc is graduated in increments of 1/2 degrees to + and -30 degrees from 0. The tripod is of wood with brass fittings.

SPECIFICATIONS

Length of telescopes         24 ins.
Weight of telescopes 12 lbs., 8 ozs.
Height of support 11 1/2 ins.
Distance between trunnions 5 1/4 ins.
Weight of support 13 lbs., 4 ozs.
Length of tripod 38 1/4 ins.
Length of tripod (legs extended) 55 1/2 ins.
Weight of telescope 8 lbs., 8 ozs.

Japanese: p. 177 (March 1, 1945)

Categories
Japanese

Antiaircraft Director, Model 2

This appears to be the latest model of mechanical antiaircraft director made by the Japanese. It has data receivers (selsyns) for azimuth, angle of site, and slant range, probably provided for use with radar equipment. Primary input data may also be obtained by optical tracking by means of telescopes attached to the director and a height finder.

Computation is based on angular rates. The transmitted data is future azimuth, future quadrant elevation, and future fuze. Data is transmitted to each weapon by means of selsyn motors and applied to the weapon by means of a match pointer system resembling that used with the American 90 mm, M1 antiaircraft fire control equipment. It is believed that this instrument is capable of furnishing data for three weapons. It is assumed the azimuth receiver will work with both the 8 cm and the 12 cm Japanese antiaircraft guns.

As compared with th her modern directors, it is felt that this instrument is deficient in both design and construction. An angular rate computer is considered too inaccurate for anything other than small or medium caliber automatic tracer controlled antiaircraft fire. Human error is permitted through the curve-following method of introducing time of flight, superelevation, and converting slant range into altitude. A great deal of backlash exists in various gear trains and in the mechanical linkage of the multipliers.

SPECIFICATIONS

Limits as indicated by drums and dials
   Slant range (dial calibration)       40,000 meters
   Slant range (limit of movement w/ alt. converter) 19,000 meters
   Horizontal range 12,500 meters
   Altitude 9,000 meters
   Quadrant elevation -10° to + 90°
   Fuze 35 seconds
   Dead fuze time 10 seconds
   Wind velocity 20 meters/sec.
   Azimuth No limit
   Angular rate Undetermined
   Electrical data
      Cycles 50 or 60
      Volts 50 or 60
   Weapon with which used 120 mm, 45 cals. A.A. gun and 80 mm, 40 cals. A.A. gun.
Characteristics
   Height 44 1/4 ins.
   Length 34 1/2 ins.
   Date of manufacture Showa 18 (1943)
Weapon data obtained from drums
   Fuze types (120 mm gun) M88 (1928), M89 (1929), M91 (1931)
   Muzzle velocity 825 meters/sec.
   Fuze types (80 mm gun) M89 (1929), 5th year type (1930)
Muzzle velocity 670 meters/sec.

Japanese: p. 176 (March 1, 1945)

Categories
Japanese

Antiaircraft Director

Antiaircraft Director (Japanese, WWII)

This director (possibly referred to by the Japanese as Model 97) is a plan prediction type of computer. It is probably used with the Japanese Model 88 (1928) 75 mm antiaircraft gun.

Standard ballistics are obtained from cams; approximations and spot corrections take care of wind effects, muzzle velocity, and air density variations. The director is provided with telescopes, and with electric data receivers for azimuth and angular height, and for altitude or horizontal range.

The director imposes significant limits on altitude and horizontal component rates. The maximum altitude rate is +/- 179 miles per hour. The maximum horizontal component rates are 335 miles per hour. It is not known whether it is Japanese practice to orientate their directors with respect to true North; but if that is the case, targets flying in the cardinal directions with ground speeds in excess of 335 miles per hour would be beyond the capability of this director. Such ground speeds, when aided by wind, may be feasible. It should be noted that the director is capable of handling greater speeds if the target does not fly parallel to one of the principal coordinate axes.

Optical tracking is provided on the director proper. An electrical data transmission system provides for the use of an external tracker such as a radar unit.

SPECIFICATIONS

Time of flight         30 secs. max.
Present altitude         0 to 7,655 yds.
Future altitude         -820 to 8,475 yds.
Present horizontal range         0 to 10,936 yds.
Future horizontal range         0 to 10,936 yds.
N-S and E-W rates         +/- 164 yds./sec.
Altitude rate         +/- 87 yds./sec.
Lateral deection         +/- 800 mils.
Horizontal range prediction         +/- 4,101 yds.
Altitude prediction         +/- 820 yds.

Japanese: p. 175 (March 1, 1945)

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Japanese

150 mm Mortar, Model 97 (1937)

150 mm Mortar, Type 97 (1937)

This mortar, of conventional design, is a smooth bore, muzzle-loading weapon referred to by the Japanese as a medium mortar. Although its tactical use is not fully defined, it is known to have been used in fixed concrete emplacements as a part of the island defense system.

The Model 97 is very heavy and sturdily constructed, weighing 770 pounds complete with sight. The breech cap and stud, with assembled firing mechanism, are screwed on in the normal manner. The firing pin may be adjusted to three different positions by means of a cam lock. When the lock is in the rear center position the firing pin is in a safe position; when the lock is turned to the right, the pin is “Floating,” or, in other words, may be actuated by a sharp blow on the end of the cam shaft. When the firing pin is locked forward, the operation is the same as that of a mortar with a fixed firing pin.

The bipod is of normal construction with but one exception. The elevating screw is actually two concentric screws, comparing very favorably with a single screw in stability and overall length. The traversing screw, buffer mechanism, and collar assembly are of the same design as other Model 97 Japanese mortars. The bipod and cradle may be separated for handling.

The base plate is a heavy ribbed stamping of 0.25 inch metal built up by reinforcing ribs welded to the original stamping. It has the usual ball and socket locking arrangement. The sight is a panoramic elbow telescope of three power and thirteen degree field.

SPECIFICATIONS

Caliber         150 mm (5.906 ins.)
Weight (complete) 770 lbs.
Weight of tube 257 lbs.
Weight of bipod & traversing assembly (total) 174.5 lbs.
Weight of sight & extension 1.5 lb.
Weight of baseplate 337 lbs.
Length of tube 75.37 ins.
Length of tube (internal) 66 ins.
Length of baseplate 47.75 ins.
Width of baseplate 35.5 ins.

Japanese: p. 127 (March 1, 1945)

Categories
Japanese

140 mm Seacoast Gun Type 3

140 mm Seacoast Gun Type 3 -- Japanese, WWII

It is believed that this naval coast defense weapon was designed primarily for use against ships, as the fuzes used with the gun’s ammunition are not sensitive enough to function satisfactorily upon impact with soft ground. This gun uses separate loading ammunition, and has a standard type mushroom head obturator. The breechblock is the horizontal swinging, interrupted screw type, having three threaded segments with two step threads. A hydropneumatic recoil mechanism is located above the barrel.

A naval pedestal type mount is used. Strips of iron fastened to and radiating from the pedestal are buried in the ground to insure stability. The piece is sometimes fitted in a casemate, the front and sides of which are cast in one piece. The top is rolled plate. A mantlet is fitted to the gun on the inside of the casemate. Gun and casemate are rotated manually, as no power system is provided.

No fire control equipment, with the exception of a telescopic sight mount, was recovered with the gun, and it is believed that the piece is fired by direct laying.

SPECIFICATIONS

Caliber         140 mm (5.5 ins.)
Weight (firing position)
Length (overall) 23 ft., 8 ins.
Length (firing position)
Height (firing position)
Width (overall)
Length of tube 22 ft., 10 1/2 ins.
Length of rifling 19 ft., 3 1/2 ins.
No. of grooves 42
Width of grooves
Depth of grooves 0.051 in.
Width of lands
Muzzle velocity (shell) 850 meters (2,789 ft.) per sec.
from range disc on gun
Max. range (horizontal) 17,000 meters (18,598 yds.)
from range disc on gun
Rate of fire
Traverse 360°
Elevation 30°
Depression -7°
Length of recoil
Ammunition
Wt. of projectile (H.E.) Common         83.8 lbs.

Japanese: p. 114.6 (August 1, 1945)

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Japanese

120 mm, 45 Caliber, Naval Dual Purpose Gun, Type 10

120 mm, 45 Caliber, Naval Dual Purpose Gun, Type 10 (Japanese WWII)

The Japanese Type 10 dual purpose gun has a 45-caliber barrel of monobloc construction with uniform right hand rifling. A long, narrow rectangular projection on the bottom of the barrel slides in a groove in the sleeve type cradle, preventing the barrel from rotating. The bearing surface for recoil being the machined barrel surface. The cradle is mounted on a pedestal mount which permits a traverse of 360 degrees.

The elevating handwheel is on the right side of the mount, while the traversing handwheel is on the left. An auxiliary handwheel on the left side permits the piece to be elevated and traversed by the gunner. To compensate for muzzle preponderance, a spring pusher type equilibrator is used. The gun is well balanced, and exceptionally easy to elevate. The recoil mechanism is a hydrospring type, the two outside cylinders housing the counterrecoil springs, and the center cylinder the hydraulic mechanism. A semiautomatic horizontal sliding breechblock is used.

The mount is of riveted construction.

SPECIFICATIONS

Caliber       120 mm (4.7 ins.)
Weight (firing position) 6,500 lbs.
Length (gun and mount) 19 ft., 6 1/2 ins.
Length (firing position)
Height (gun and mount) 7 ft., 8 1/2 ins.
Height (firing position)
Width (gun and mount) 7 ft., 1 in.
Length of tube 17 ft., 1 1/2 ins.
Length of rifling 14 ft., 9 1/2 ins.
Length, of chamber 29.5 ins.
No. of lands 34
Width of grooves 1/4 in.
De-th of grooves .050 in.
Width of lands 1/8 in.
Muzzle velocity (shell) 2,700 f/s
Max. range (horizontal) 17,000 yds.
Max. range (vertical) 32,800 ft. (fuze)
Rate of fire 10-12 rds.
Traverse 360°
Elevation 75°
Depression 10°
Length of recoil 19.3 ins.
Ammunition H.E. shrapnel; H.E. phosphorus
Wt. of projectile 45.75 lbs.

Japanese: p. 114.5 (August 1, 1945)

Categories
Japanese

120 mm, 45 Caliber, 11 Year Type Gun

Japanese 120mm 45 Caliber 11 Year Type Gun

This gun is a naval coast defense weapon manufactured at Sasebo Arsenal. It uses semi-fixed ammunition. The barrel is of built-up construction with uniform right hand twist rifling. A manually operated, horizontal sliding block breech mechanism is used. It is unusual in that the block does not pass all the way across the rectangular breech ring. The rear of the breech ring is cut in a keyhole shape. The operator of the elevation handwheel may fire the gun by means of a lever mechanism, or it may be fired by a lanyard attached to the right side of the breechblock.

The recoil system comprises three cylinders, two located above and one below the barrel.

The mount consists of a rectangular upper carriage which is mounted on a pedestal normally embedded in a solid foundation. A traversing scale is located on the pedestal. The traversing handwheel is in a horizontal position with the vertical shaft engaging a series of gears in the base mount. Platforms attached to the upper pedestal are provided for the gun layers and move in traverse with the gun.

Fire control equipment is of the usual Japanese naval coast defense gun type.

SPECIFICATIONS

Caliber      120 mm (4.72 ins.)
Weight (traveling position)
Weight (firing position)
Length of gun (overall)18 ft., 3 1/4 ins.
Length of tube 17 ft., 3 3/4 ins.
Height of gun 6 ft., 11 ins.
Height (firing position)
Width (overall)
Length of rifling 14 ft., 8 1/2 ins.
No. of lands34
Width of grooves
Depth of grooves
Width of lands
Muzzle velocity (H.E. shell)2,700 f/s
Max. range (horizontal)
Max. range (vertical)
Rate of fire
Traverse360°
Elevation50°
Depression10°
Length of recoil
AmmunitionH.E.
Wt. of projectile (H.E.)44.75 lbs.

Japanese: p. 114.4 (August 1, 1945)