•Muzzle velocity: 2,890 f/s
•Maximum horizontal range: 19,100 yds
•Maximum vertical range: 41,300 ft
•Maximum effective ceiling: 37,000 ft
•Theoretical rate of fire: 15 rpm
•Practical rate of fire: 8 to 10 rpm
•Weight in action: 11.56 tons
•Elevation: -3° to +87°
•Traverse: 360°
•Length of barrel: 60 cals
•Ammunition—three classes, as follows:
(i) HE with time fuze (weight of projectile, 32 lbs 11 oz)
(ii) HE with percussion fuze (weight of projectile, not known)
(iii) AP with base fuze (weight of projectile, not known)
An automatic fuze-setter is used with the gun, but it is not known whether it operates on the same principles as does the fuze-setter fitted on the 8.8-cm weapon. Details of the loading and firing mechanism are not known, but they are probably substantially the same as for the 8.8-cm gun.
(2) Fire control.—The Kommandogerät No. 40 is employed with this gun for firing at aircraft. A description of the Kommandogerät No. 36, which is used with the 8.8-cm gun, is given in a later portion of this study (see par. 8b (1), below). It is believed that the No. 40 operates on the same principle as the No. 36. In addition, the Kommandohilfsgerät No. 35 (auxiliary predictor) can also be used with this gun. A description of the latter instrument appears elsewhere in this study.
(3) Personnel.—Except for additional men that might be required to handle the heavier ammunition, the personnel comprising the gun detachment is substantially the same as for the 8.8-cm weapon.
k. 127-mm AA Gun
The 12.7-cm Flak 38 (5-inch) is a naval AA weapon. Although this gun is known to be used by the Germans, mainly in a static AA role in Germany, little reliable data is available concerning its characteristics and operation. Its known main characteristics are as follows:
•Muzzle velocity: 2,500 f/s
•Maximum horizontal range: 19,600 yds
•Maximum vertical range: 42,600 ft
•Maximum effective ceiling: 35,000 to 40,000 ft
•Theoretical rate of fire: 12 rpm
•Practical rate of fire: 8 rpm
•Elevation: 0° to 90°
•Traverse: 360°
•Weight of projectile: 55 lbs
•Length of barrel: 50 cals
l. 150-mm AA Gun
The 15-cm Flak 39 (5.91-inch) is used by the Germans in a dual-purpose role, for AA and coast defense. For the most part it is found on fixed mounts in static roles, manned to a large extent by Navy personnel. Little accurate information is available on this gun, but the following limited data will serve to give some indication of its capabilities:4
•Muzzle velocity: 3,450 f/s
•Maximum horizontal range: 34,000 yds
•Maximum vertical range: 66,000 ft
•Maximum effective ceiling: 40,000 to 45,000 ft
•Theoretical rate of fire: 12 rpm
•Practical rate of fire: 6 to 8 rpm
•Weight of projectile: 88.6 lbs
8. Fire Control
a. Solution of the AA Fire-Control Problem
There is no indication that a director of any type is ordinarily used with the light and medium Flak guns, the Germans apparently having decided that the development of the Flak sights already described is more profitable and practicable than the development of directors. For use with heavy guns. the German development of fire-control apparatus is strikingly similar to our own. They have an older, angular-speed director which is used for auxiliary purposes, but the latest and most commonly used instrument operates on the linear-speed method, using present azimuth, present angular height, and present slant range as basic elements.
b. Equipment
(1) Kommandogerät (stereoscopic fire director) (figs. 11 and 12).—(a) Description.—This fire-control instrument combines into one instrument a 4-meter-base Zeiss stereoscopic height- and range-finder, and a director. Two types are known: the No. 36, employed with the 8.8-cm Flak gun, and the No. 40, employed with the 10.5-cm Flak gun. The principles and method of operation of the No. 40 are not known, but they are probably similar to those of the No. 36, details of which follow.
(b) Method of operation.—The stages in the production of the firing data in the No. 36 are as follows:
(1) The height- and range-finder furnishes present azimuth, angle of sight, and slant range to the target, all of which may be termed initial data.
(2) The rate of change, obtained by continuously feeding this data into the predictor, provides the horizontal ground speed and the course angle of the target, which may be termed intermediate data.
Figure 11.—Kommandogerät in traveling position.
(Note that the range-finder is carried separately.)
(3) The combination of initial and intermediate data provides the vertical and lateral defection and range correction to determine the future position. From this combination, the gun data is obtained by mechanical computation within the predictor.
(c) Transmission of data to guns.—The gun data thus obtained (in terms of firing azimuth, quadrant elevation, and fuze) are normally transmitted electrically to the guns, in the following manner: each of the three receiver dials at the gun (i.e., for firing azimuth, quadrant elevation, and fuze) is provided with three mechanical pointers pivoted at the center of the dial. There are three concentric circles on the dial, each with 10 holes numbered from 0 to 9, each hole being fitted with an electric bulb. The outer circle represents units; the center, tens; and the inner, hundreds. The appropriate bulbs light up in accordance with the data transmitted from the Kommandogerät. The actual value of the reading is different for each dial, the unit (i.e., on the outer circle) in each instance having the following values:
•Azimuth receiver : 0.36°
•Elevation receiver : 0.10°
•Fuze receiver : 0.5 (of the German system of fuze range)5
Figure 12.—Kommandogerät ready for use.
These figures provide a measure of the limits of accuracy obtained in transmission. The two gun-layers and the fuze-setter bring their mechanical data pointers into coincidence (covering the illuminated bulbs with the transparent celluloid ends of the pointers) by manually actuating azimuth and elevation handwheels on the guns, and the fuze-setting handwheel on the machine fuze-setter.
(2) Kommandohilfsgerät (auxiliary fire director).—This instrument is used for auxiliary purposes, and operates on the principle of calculation of the rates of change of angular velocity. A separate 4-meter-base stereoscopic height- and range-finder provides the present slant range to the target, and this data is passed orally to the director. By following the target continuously for azimuth and elevation, and by setting in range continuously, the rates of change of azimuth, elevation, and slant range are obtained. These, multiplied by time of flight, give the lateral and vertical deflections and a correction for range. These corrections, applied to the present data, provide future data which are corrected for abnormal ballistic conditions, dead time, and drift, and which are then passed to the guns as gun azimuth, quadrant elevation, and fuze. Data in this case are transmitted to the guns by telephone, no electrical transmission being provided.
(3) Telescopic sight for 88-mm gun.—The 8.8-cm gun is fitted with a telescopic sight primarily for the engagement of ground targets; the latest type is the telescopic sight 20-E (ZF 20-E). It weighs about 10 pounds and is a monocular type with a magnification of four and a field view of 17.5 degrees. The reticle is made with two cross lines interrupted at the center to form a laying mark, an arrangement which is usual in German instruments. There is a range drum graduated in hundreds from 0 to 9,400 meters, and a super-elevation drum with graduations of 1/16 of a degree, from 0° to 12°. There are also lateral- and vertical-deflection drums.
For AT use, the lateral- and vertical-deflection drums are set to zero. Range is set on the range drum, thereby automatically applying
the necessary super-elevation. Corrections from observation of fire are applied to deflection drums as required.
An older type of instrument, the 2F 20, may be fitted. This has the same particulars, but no range drum; superelevation must be found from a range table and applied.
(4) Radio-location equipment.—It is known that German radio-location equipment for fire-control data is being produced on a high priority, and there is no doubt that this will constitute a most important line of future development. This activity is taking place parallel to the development of radio-detection equipment for warning against hostile aircraft. Aerial observers flying over gun positions in Germany and the gun-defended portions of occupied European countries have reported seeing instruments, identified as German radio-location instruments, in close proximity to gun positions. This would indicate that these radio-location instruments are being used with gun batteries, probably as a means of furnishing early basic data to the directors. Another possible use of these instruments is to furnish early information for calculation of data for barrage and deterrent fire.
9. Searchlights
a. Heavy Searchlights
(1) Equipment.—(a) General.—The equipment used with a heavy searchlight consists of four main units: a sound locator, the searchlight, an optical director, and the generator. Beyond the introduction of remote control, little is known of recent developments in German searchlight equipment. Some searchlights of 200-cm, or larger, diameter have been developed, and the sound locator has possibly been improved by the introduction of some form of electrical amplification. The standard heavy searchlight, however, is the 150-cm (60–inch) size. Information from radio-location equipment is almost certainly passed to the searchlights, but the extent and method of its application are unknown.
(b) The ring-trumpet sound locator derives its name from the construction of the four trumpets or horns as a single unit of ring shape. Ordinary stethoscopic listening by two listeners, one for azimuth and one for elevation, is employed. The base length is 135 cm (53.1 inches), giving a theoretical accuracy of about one-half degree. In average weather conditions, the range is about 6,600 yards. The trumpets can be moved through 360° in azimuth and from 0° to 108° in elevation. The "lag calculator" is in the base of the sound locator. Estimated target and sound speeds (the latter based on weather conditions) are set into the lag calculator, which continuously reconstructs the triangle formed by the line of sound reception, the line of sight (present position), and the target course. The azimuth and elevation of the line of sight are shown electrically both at the sound locator and at the searchlight. The sound locator and the searchlight are connected by a cable.
(c) The 150-cm (60-inch) searchlight (fig. 13) has a glass parabolic reflector of 150-cm diameter. The focal length is 650 mm. The high-current-density arc lamp is self-regulating and is fitted in an inverted position in the projector barrel. The light is of 990 million candle power and has a range in favorable weather of 8,800 yards at a height of 13,000 to 16,500 feet. The current consumption is 200 amperes at 77 volts. The projector can be moved in azimuth through 360°, and in elevation from -12° through the vertical to -12° on the other side. The movement of the projector in azimuth is by means of a control arm, which is normally manipulated by hand; its movement in elevation is by means of either of two handwheels, one on the control arm and one on the opposite side of the projector. Electrical receivers for azimuth and elevation show the azimuth and elevation of the line of sight calculated by the sound locator. The beam is exposed and covered by a shutter of Venetian-blind type. More recent models are believed to be equipped with azimuth and elevation driving-motors which can be operated by automatic remote control from the sound locator or from the optical director; the exposing and covering of the beam on these models is controlled from the optical director. It is understood that the driving motors have three or four speeds, 1 degree and/or 1.5, 4, and 16 degrees per second.
Figure 13.—150-cm (60-inch) standard searchlight.
(The elevation receiver is on the side of the drum near the extended hand control, and the azimuth receiver is in the rear.)
(d) The optical director consists of a pair of night glasses of ample magnification mounted on a tripod. The director is fitted with an overhead, open sight and with scales showing the azimuth and elevation to which the night glasses are pointing. When employed with remote-control equipment, it is believed that the optical director is located 30 to 45 yards from the searchlight, thus becoming in effect a control station.
(e) The searchlight generator is driven by an 8-cylinder internal-combustion engine which develops 51 horsepower at 1,500 revolutions per minute. The 24-kilowatt generator gives a direct current of 200 amperes at 110 volts at 1,500 revolutions per minute. The cable to the searchlight projector is 220 yards long.
(2) Mobility.—The sound locator, searchlight, and generator are each mounted on a detachable four-wheeled trailer of standard pattern, towed by a truck. Each section or unit therefore requires three trucks for transportation purposes.
(3) Personnel.—The individual searchlight section is composed of 14 individuals with duties as follows:
•Section Commander
•No. 1 : Searchlight layer for elevation
•No. 2 : Searchlight controller and layer for azimuth
•No. 3 : Lamp attendant
•No. 4 : Optical director spotter
•No. 5 : Generator attendant
•No. 6 : Engine attendant
•No. 7 : Lag-calculator operator
•No. 8 : Azimuth listener
•No. 9 : Elevation listener
•No. 10 : Sound locator spotter
•3 truck drivers
(4) Communications.—Field telephones are the normal means of communication, each battery having three telephone-erection parties, with sufficient equipment to connect the searchlight sections to platoon headquarters, which, in turn, are connected to battery headquarters. Communications with battalion headquarters are also normally by telephone. Each battery has one small truck equipped with voice radio for communication with the battalion, and two details with pack voice-radio for use within the battery as required.
b. Light Searchlights
(1) Equipment.—(a) General.—The equipment consists of a 60-cm (23.50-inch) searchlight and a generator. This highly mobile and easily handled equipment, designed for use without a sound locator against low-flying targets, appears to have given satisfaction in the limited role for which it was intended. There are no indications that any changes in the design are contemplated.
(b) The 60-cm (23.58-inch) searchlight has a glass parabolic reflector of 60-cm diameter. The focal length is 250 mm. The high-current-density arc lamp is self-regulating and is fitted in an inverted position in the projector barrel. The light is of 135 million candle power and has a range (in focus) in favorable weather of 5,700 yards at a height of 5,000 feet; with dispersed beam the range is 3,500 yards. The current consumption is 90 amperes at 60 volts. The projector is moved in azimuth and elevation by handwheels operated by the searchlight controller, who is seated behind the projector barrel. The beam is exposed and covered by a shutter of Venetian-blind type.
(c) An 8-kilowatt searchlight generator gives the required current at 85 volts. It is connected to the searchlight by a cable 110 yards long.
(2) Mobility.—The projector is mounted on a detachable two-wheeled trailer, towed by a truck. The same truck carries the generator, which can either be operated in the body of the truck or be unloaded on the ground.
(3) Personnel.—The individual searchlight section is composed of five individuals with duties as follows:
•Section Commander
•No. 1 : Searchlight controller
•No. 2 : Lamp attendant
•No. 3 : Generator attendant
•Truck driver
No. 1 lays the searchlight as ordered, and puts the light into action with a dispersed beam. The section commander gives directional orders and
orders a search, if required. The search is carried out in S-shape light-tracks across the target course. If No. 1 gets on target, No. 2 puts the beam in focus. No. 1 shuts off the beam on the section commander's orders.
(4) Communications.—Since light searchlights normally operate directly with light-gun platoons, the light-searchlight section from the communication point of view is normally serviced by the light Flak battery or platoon with which the light-searchlight section is operating.
10. Barrage Balloons
a. General
Although no extensive use of barrage balloons was contemplated by the Germans before the beginning of World War II, subsequent developments proved that barrage balloons have a definite psychological value as well as a practical value, and experiments conducted prior to the outbreak of the war were very soon put into practical use over strategic manufacturing centers in western Germany.
As in the U.S. Army and in the British Isles, the main purpose of the German barrage balloon is to hold a steel cable suspended vertically in the air. Thus, below the operating height of the balloon, this cable obstacle presents both a physical and mental hazard to enemy pilots attempting to enter that space. It is of course axiomatic that the type of balloon used for this purpose will be strong enough to suspend the cable, and that the balloon is designed in accordance with sound aeronautical principles (i.e., in terms of streamlining, capacity to resist wind stress, etc.). The extent of engineering developments of the German barrage balloon since the beginning of World War II is not definitely known, but it is believed that any changes effected consist only of minor modifications of the types in existence at the beginning of the war.
b. Description (fig. 14)
At the beginning of World War II, there were two general types of barrage balloons in existence in Germany. Both types were egg-shaped and had four fins at the tail end: a top fin, two side fins, and a bottom fin. The top fin and two side fins were inflated with air. The bottom fin was called the steering sack and had an opening at both ends. When the balloon was up, air entered the bottom opening of the fin and made its exit through the top opening. The fins (and especially the bottom fin) served to keep the balloon in proper position with respect to the wind and air currents. When inflated, the shape of the balloon could be likened to a short fat cigar, with a tail like a Japanese goldfish. Rubber cords were fastened tightly around the outside of the inflated balloon to assist in keeping its shape and strength.
German Artillery in Combat Page 6
