(1) Description.—The Germans now use one standard machine gun to fill all roles; namely, the air-cooled 7.92-mm (.31-inch) MG 34. This is considered a light machine gun when used with its light bipod, and a heavy machine gun when used with the heavy tripod mount. It is fitted in special single and dual mounts for AA purposes, and is also found in armored cars, carriers, and tanks. It fires all the types of 7.92-mm (.31-inch) ammunition which the German rifles and aircraft machine guns use. But lately there has been a marked emphasis on the use of armor-piercing ammunition in all 7.92-mm weapons. Belt feed is normally employed for the machine gun, but it is quite common for two or more 50-round belts to be joined end to end, thus reducing the delays involved in the changing of belts. A special belt drum, holding one 50-round belt compactly coiled within it, may be fitted on the left of the gun when the weapon is used as a light machine gun or for AA purposes. The gun weighs 15 1/2 pounds without the mount. The barrel is changed after each 250 rounds of continuous fire.

(2) Use in AA Role.—On the AA amount, this machine gun is used organically by all branches of the German Army for local protection against low-flying aircraft. It supplements the fire furnished by rifles. Strictly speaking, this weapon is not classed as a Flak weapon, the 20-mm cannon usually being considered the smallest caliber in the Flak class.

b. 20-mm AA/AT Gun (Models 30 and 38) (figs. 3 and 4)

(1) Description.—The 2-cm[2] Flak 30 (.79-inch)[3] was introduced into the German Navy in 1930 and into the German Air Force in 1935. It has been the main armament of light AA units, and can be used in an antitank role. The gun is fed by a flat box-magazine containing 20 rounds, and is recoil-operated. It has a detachable barrel, and is provided with automatic and single-shot mechanisms. The trigger mechanism is pedal-operated. The gun may be mounted on road or railway vehicles.

Figure 3.—2-cm (20-mm) AA/AT gun 30 in action.

Figure 4.—2-cm (20-mm) AA/AT gun 38 in action on self-propelled mount.

It is normally transported on a single-axle trailer. This trailer may be drawn by motor transport or by horse, and is easily manhandled. The gun and its mount may also be split into loads for transport in particularly difficult country. The gun is normally fired with its mount on the ground and with the trailer removed. It can, however, be fired from the trailer in an emergency (i.e., on the march), rough traverse being obtained by pushing the trailer around.

A later version of the model 30 is contained in the 2-cm Flak 38, which does not differ materially from the earlier version apart from having higher theoretical and practical rates of fire. Particulars pertaining to the 2-cm Flak 38 are as follows:

Normally the penetration performance with AP is 45 mm (1.77 inches) of armor at 100 yards.

(2) Sights.—The two alternative sights normally used with the 2–cm Flak 30 are the Flakvisier 35 and the Linealvisier 21, both of which are also used with the 2-cm Flak 38. A newer sight, known as the Flakvisier 38, has been developed for use with the 2-cm Flak 38.

It should be noted that all these sights are dependent on some separate continuous and accurate means of providing range. For this purpose, each gun detachment includes a range-taker who is equipped with a portable 1-meter-base stereoscopic range-finder.

In addition, a simple telescopic sight may be used with either the 2-cm Flak 30 or the 2-cm Flak 38.

(a) Flakvisier (AA Sight) 35.[4]—This is a reflecting-mirror sight with a computor mechanism operating on the course-and-speed principle. If the target is kept in the center of the sight, and the appropriate settings for slant range, speed, and course and angle of dive or climb are set in, then the bore of the gun is in correct alignment to pass the shell through the future position of the target. The setting for course is by means of a pointer in the horizontal plane which is kept parallel to the estimated course of the aircraft. The setting for angle of dive or climb is by means of a pointer set in the vertical plane.

(b) Flakvisier (AA Sight) 38.—Information about the Flakvisier 38 is at present very incomplete, but what is known shows that it represents a departure from the course-and-speed principle on which the Flakvisier 35 functions. This sight can be used both against air targets, and against moving and fixed land and sea targets.

The Flakvisier 38 is an electric automatic sight. The layer keeps a cross on his object glass coincident with the target, thus obtaining angle of sight and azimuth. Range, either estimated or called out by the range-taker, is set by the range-setter.

The sighting arrangement consists of illuminated cross wires automatically controlled in terms of super-elevation and deflections. The elevating and traversing gears are coupled to elevating and traversing tachometer-dynamos in such a way that the voltages generated by them vary with the speeds of laying.

The gun's traversing gear is coupled to a tachometer-dynamo, which produces electric voltage varying directly with the rate of traverse. The terminals are connected to a moving coil meter which measures the strength of the electric current. A variable resistance depending on range setting is introduced, so that the current is regulated both by the tachometer-dynamo and by the strength of the range resistance. With short ranges the corresponding resistance is low and the deflection large; with long ranges, the deflection is small and the resistance high. The resultant lateral deflection is transmitted to the layer's vertical cross wire, which moves in the direction opposite to the course of the aircraft.

Vertical deflection is obtained by multiplying the rate of change of the angle of sight by the time of flight of the shell. Rate of change is measured by the rate of elevation or depression of the gun, whereas time of flight is taken as a measure of the range set. Superelevation in terms of range is added to the vertical deflection to give the appropriate quadrant elevation. The resultant value is automatically applied to the layer's horizontal cross wire.

(c) Linealviser (Linear Sight) 21[3] (figs. 5 and 6).—This is a form of direct AA sight, giving course, speed, and range adjustment. It consists of a horizontal bar which is graduated from 0 to 1,600 meters. Range is set by turning a cylindrical hand nut on the runner of a cartwheel-type foresight, thus increasing the "lead" as the range is increased.

The ring foresight is rotatable, thus enabling course of the target to be set. A bar showing speed from 11 to 150 meters per second is mounted moveably on the foresight. This speed bar can also be adjusted to the angle of dive or climb. The backsight consists of an aperture set between two layers of nonsplintering glass inclined at 45 degrees to the horizontal bar.

Both the Flakvisier 35 and the Flakvisier 38 must be removed before the Linealvisier 21 can be mounted.

(d) Telescopic sight. —A simple telescopic sight (with a magnification of eight) may also be employed for the engagement of armored vehicles and ground targets.

(3) 1-meter-base range-finder[6] (fig. 7).—The 1-meter (39.37-inch)-base range-finder is employed by light AA detachments manning the 2-cm Flak 30 and 38 and the 3.7-cm Flak 36. Magnification is sixfold, and the range is from 800 to 26,200 feet. This instrument is normally used strapped to the range-taker's shoulders, but there is also provision for a small tripod.

Figure 5.—Sketch of Linealvisier 21. 1. Bracket. 2. Suspension claws.       3. Clamping screw. 4. Slit guide. 5. Backsight bracket. 6. Backsight. 7. Slide. 8. Ring foresight.     9. Range knob. 10. Driving disk. 11. Backsight retaining springs. 12. Rule. 13. Aiming line. 14. Setting handle. 15. Speed scale.

The instrument is manufactured by Carl Zeiss of Jena. It is of the standard stereoscopic pattern, estimation of distance being by means of two reticles, one in each eyepiece, which when "fused" stereoscopically appear superimposed upon the image in depth. The instrument is difficult to handle, and considerable practice is necessary before an operator can obtain satisfactory results. The operator is required to produce accurate results at slant ranges up to 4,000 meters (4,400 yards)

Figure 6.—Sighting the target with Linealvisier 21.

(4) Personnel. The gun detachment consists of seven men as follows:

Figure 7.—1-meter-base range-finder in use with 3.7-cm (37-mm) AA/AT gun.

c. 20-mm Four-Barreled AA/AT Gun (Quadruple Mount)[7] (Fig. 8)

(1) Description.—The 2-cm Flakvierling 38 consists of four 2-cm Flak 38 guns. It may be employed either against aerial or ground targets. It is normally transported on a special trailer, but may also be mounted on half-track vehicles or railway mounts.

There is also a static version for use on Flak towers, in coast defenses, etc. In the trailer version, the gun is normally fired with its mount on the ground and with the trailer removed. It can, however, be fired front the trailer in an emergency (i.e., on the march). A traverse of only about 10 degrees at top elevation is possible in this position. Two foot-levers operate the trigger mechanism. Each foot-lever actuates the triggers of two diametrically opposite guns (i.e., the top left and the bottom right, and the top right and bottom left). This arrangement provides uninterrupted, continuous fire. While two guns are firing, the magazines of the other two can be changed. When both firing levers are operated, all four guns fire simultaneously. Furthermore, should there be a stoppage on one or more guns, the remaining guns can continue to fire. Provision is made for single-shot or continuous fire on each weapon. A shield may be fitted to the carriage. This weapon fires the same ammunition as does the 2-cm Flak 38 described above.

The following additional characteristics pertain to the four-barreled mount:

(2) Sights.—The equipmient is provided with the Flatvisier 40 (or, where not available, Linealvisier 21—see b (2) (c), above), and a telescopic sight for the engagement of ground targets (see b (2) (d), above). The Flakvisier 40 operates on the same principle as the Flakvisier 38, described in b (2) (b), above. Apparently, Flakvisier 35 may also be used on the 2-cm Flakvierling 38.

d. 37-mm AA/AT Gun (figs. 7 and 9)

(1) Description.—The 3.7-cm (1.45-inch) Flak 36 is the smallest caliber of medium Flak artillery. This gun is mounted on a two-wheeled trailer, detached when the gun is in the firing position, but the gun can be fired from the trailer in an emergency. This method can be adopted both in an AT and an AA role on the march; movement in azimuth is, however, very limited under these conditions, and the crew may have to move the gun and trailer bodily to enable the target to be engaged,

Figure 8.—2-cm (20-mm) Flakvierling 38 on fixed support, showing ammunition feed.

Figure 9.—Demonstration class inspecting 3.7-cm (37-mm) AA/AT gun. (The German instructor is pointing to the feed mechanism.)

When on the trailer, the gun is towed behind motor transportation in which the personnel and stores are also carried. This gun also is found on self-propelled half-track vehicles and on railway mounts. Other characteristics of this gun are as follows:

(2) Sights.—The Flakvisier 33 is normally used for AA fire with this Weapon. This sight is believed to be similar in principle to the Flakvisier 35 used with the 2-cm Flak 30, described above. Observation by tracer is used with this sight for close targets where the angular velocity is high; in such cases, only the course is set into the sight.

(3) Personnel.—The gun detachment consists of 12 men as follows:

e. 40-mm AA Gun

Although used by the Germans, the 4-cm (1.57-inch) Flak 36 iS not encountered very often in German AA units. The few guns known to be in the hands of the Germans are believed to have been taken for the most part from the Polish Army after the Polish Campaign. The 4-cm Flak 36 is a Bofors gun, having characteristics similar to the weapon used by the British except for some few variations in performance characteristics. A few characteristics of this gun are as follows:

f. 47-mm AA Gun

The 4.7-cm Flak 37 has in the past been used to some extent by the Germans as a medium AA/AT gun, but there are indications that the Germans are not entirely satisfied with its performance, and that no attempt will be made to produce this gun any large quantity, This weapon is a Czech model, having originally been produced at the Skoda works and adopted for use by the Czechoslovakian Army, The gun is tractor-drawn, but it is also found on some self-propelled mounts. A few of the characteristics are as follows:

g. 50-mm AA AT Gun

The 5-cm Flak 41 (1.97-inch) has only recently been brought into service. Its introduction indicates a considered need for a medium gun with a higher ceiling and greater destructive power than the standard medium 3.7-cm. No detailed or accurate information is available about its performance, but it is claimed by the Germans to fire both HE and AP ammunition and to be provided with a new Flak sight 41, which, according to a sketchy German report, is operated by one man and is a completely automatic clockwork-sight. Also according to the report, range is introduced and angular velocities are calculated in such a way that superelevation and vertical and lateral deflections are automatically applied.

This reported new gun should not be confused with the 5-cm Pak[8] 41, which is purely an AT weapon,

h. 75-mm AA Gun

The 7.5-cm Flak L/60 is a 1938 model, and is only slightly modified from the 7.5-cm Flak L/59, which is a 1934 model. The 7.5-cm Flak L/60 is carried on a trailer mount and is ordinarily tractor-drawn, Some versions of this gun may also be found on self-propelled mounts, and in fixed AA installations. The weapon is not used to any great extent, however, since the 88-mm gun has become the standard German gun of this class, just as the U.S. 90-mm AA gun is superseding the U.S. 3-inch AA gun. Some of the characteristics of the 7.5-cm Flak L/60 are as follows:

i. 88-mm Dual-Purpose Gun (figs. 10 and 16)

(1) Development.—The German 8.8-cm gun was introduced in 1934 as the standard mobile AA gun. It was then known as the 8.8-cm Flak 18. In 1936, during the Spanish War, it proved a very effective weapon against tanks, which were at that time relatively lightly armored. In order to develop still further this dual-purpose employment, the Germans produced armor-piercing ammunition for the weapon, a telescopic sight suitable for the engagement of ground targets, and a more mobile carriage; an HE shell with a percussion fuse was also produced so that the weapon could, when necessary, be employed in a field-artillery role.

The improved equipment was ready in time for the Battle of France, when it proved itself capable of dealing with the heavier French tanks, against which the then standard AT gun, the 3.7-cm (1.45-in) Pak, was relatively ineffective. The next step was to provide the gun with a new carriage, from which the gun could engage tanks without being taken off its wheels, and to fit a shield. Still more recently, a self-propelled mount has been reported: and while there is no precise information as to its design, it appears that from this mount the gun can readily take on ground, but not air, targets.

(2) Description.—(a) General.—For all practical purposes, the operating characteristics of the 18, 36, and 38 models of this weapon are the same. The main characteristics of the 8.8-cm Flak 18 are as follows:

(b) Gun data (8.8-cm Flak 18).—The gnu consists of a jacket, a sleeve, a removable tube in three sections, and a breech ring. The three-section tube is held in place by the breech ring in the rear and by a locking collar in the front, both of which are secured to the sleeve. The sleeve is secured to the jacket by a locking ring at the breech end. One of the joints in the three-section liner is the chamber of the gun and is therefore sealed by the shell case, but the other occurs at about one-third of the distance to the muzzle.

The breech mechanism is of the horizontal sliding-wedge type, semiautomatic, and self-cocking. As the gun recoils, the mechanism opens, ejects the empty case, and at the same time, compresses the striker and breechblock operating springs. Loading is by automatic rammer used in conjunction with a loading tray.

Figure 10.—8.8-cm (88-mm) dual-purpose gun in action.

Firing is by percussion. The withdrawal of the loading tray will operate the firing mechanism unless set to "Hand." The breechblock may be opened and closed by hand if desired. The mechanism must be hand-operated for loading the first round. Safety arrangements are incorporated in the mechanism to prevent firing until the breech is in the closed position.

(c) Mount data.—The mount has a platform which rests squarely on the ground when the gun is in the firing position. The platform has four legs, with jacks at the outer ends of each for approximate leveling. In the traveling position, the two side legs fold upward. The pedestal is secured to the platform and supports the body through a gimbal ring and body pivot housing. The body, which contains the azimuth and elevation gears, supports the cradle on its trunnions and rotates in the housing for azimuth traverse. Accurate cross-leveling is accomplished by rocking the body pivot housing in the gimbal ring by means of cross-leveling handwheels on the platform. A 5-degree movement is possible by this means.

The gun slides on the cradle, to which it is connected through the recoil mechanism. The recoil system incorporates a hydraulic buffer below the barrel, and a hydro-pneumatic recuperator above. Both cylinders are secured to the cradle, and the pistons are connected to the breech ring. The buffer contains 18.8 pints of buffer fluid. The recuperator contains about 4 1/2 gallons of fluid and an approximately equal volume of air at 39 atmospheres. Length of recoil is variable, being about 1,050 mm at 0 degrees quadrant elevation, and 700 mm at 85 degrees quadrant elevation. The automatic rammer operates with the return cylinder, loading tray, and actuating mechanism. The internal construction of the return cylinder resembles that of the recuperator on a smaller scale.

A hand-operated fuze-setter with two openings is fitted to the left side of the body.

To put the gun in traveling position, the side legs are folded upward and secured. A limber and carriage are attached to the platform, which is raised by winches and secured. Some modifications of this gun are capable of being fired from the traveling position at ground targets, and there is also a model on a self-propelled mount.

(3) Ammunition.—The three types of ammunition used with this weapon are as follows:

Penetration of the AP projectile against homogeneous armor plate is approximately as follows:

(4) Fire control.—The gun may be laid on the target by three methods:

(a) Indirect laying, by matching the pointers of the data receivers, which are controlled by the director (Kommandogerät No. 36, described in par. 8 b (1), below).

(b) Direct laying, by means of the Flak ZF 20–E telescopic sight. Vertical and lateral deflections are applied to the telescope, and the man at the azimuth handwheel puts the cross hairs on the target. The gun is elevated by the man on the elevation handwheel, who follows an indicating arm which moves with the sight.

(c) The dial sight may be used for laying the gun in azimuth, while the quadrant elevation is set in by the elevation man as ordered.

(5) Mobility.—This gun is normally towed by two types of half-track vehicles. These vehicles, which are respectively of 140 and 185 horsepower and weigh 11 1/2 and 14 1/2 tons loaded, carry the gun crew, as well as a supply of ammunition in lockers at the rear of the vehicle. The exact amount of ammunition carried is not known, but seems to be at least about 35 rounds.

(6) Personnel.—(a) For action against aircraft.—The gun detachment consists of a detachment commander and nine men, with duties for antiaircraft action as follows:

(b) For action against ground targets.—For the engagement of ground targets, the duties of this gun detachment are as follows:

j. 105-mm AA Gun

(1) Description.—The 10.5-cm Flak 38 (4.14-inch) is being encountered in increasing numbers. Although the 8.8-cm gun, because of its success and in particular its value as a dual-purpose weapon, is likely to remain the main armament of heavy Flak, it is known that the 10.5-cm gun ranks high on German priorities for war production. The possibility that this larger weapon may be developed as an AA/AT gun must, therefore, be reckoned with. It is noteworthy that a new tractor-drawn mobile version was produced some time ago, although it is reported that the mount proved unsatisfactory.

Some of the main characteristics of this weapon are as follows:

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:

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:[9]