User:MinorProphet/Draft subpages/WW2 German heavy FlaK fire directors



The de:Kommandohilfsgerät 35, Kommandogerät 36, and de:Kommandogerät 40 are analog fire control computers used by the German armed forces during WW2 to direct their heavy 88 mm, 105 mm, and 128 mm anti-aircraft (FlaK) guns.

The Kommandohilfsgerät 35 uses an angular speed method to arrive at a computed firing solution. The Kommandogeräte 36 and 40 operated on the linear speed method, using present azimuth, present angular height, and present slant range as basic inputs; the firing solutions were sent electrically to each individual gun in a battery of four.

Outline of anti-aircraft fire control
Ha, maths and diagrams...!

How far away is it? How high above the horizontal is it? How fast is it travelling? How far ahead do we have to shoot (lead) for the shell to arrive at the target's future position? If we shoot a shell now, how long is it going to take before it hits the target? (flight time)?

Director (military) has a decent explanation of what the director does - but can't find a theoretical explanation of the mathematics involved.

Well, has exactly this, with diagram, but in tech German. Needs translating...

Overview
There were three models of fire directors of increasing complexity, used to control an emplaced battery of (generally) four FlaK guns:
 * Kommandohilfsgerät 35 (abbreviated in German as Kdo.Hi.Ger. 35)
 * Kommandogerät 36 (abbreviated in German as Kdo.Ger. 36)
 * Kommandogerät 40 (abbreviated in German as Kdo.Ger. 40)

They were all used in conjunction with the Em 4m R(H) 34 or 36 (Entfernungsmesser Raumbild (Höhe)) (Stereoscopic 4 meter rangefinder Model 1934 or 36): this was mounted on a separate tripod for use with the simpler Kdo.Hi.Ger. 35, and integrated into the Kdo.Ger. 36 and 40.

For all the predictors, the following data about the target from the rangefinder is continuously input by hand:{TME p. 128}
 * (a) Present angular height
 * (b) Present azimuth
 * (c) Present slant range

The fire director computes and outputs the following:{TME p. 128}
 * (a) Quadrant elevation
 * (b) Future azimuth
 * (c) Time of flight of projectile, expressed in fuze units

With the Kdo.Hi.Ger. 35 these values are telephoned to the guns, and simultaneously sent electrically from the Kdo.Ger. 36 & 40 directors via a switchboard through electric cables to each gun in the four-gun battery. Each gun has two identical dials for setting elevation and azimuth on the right-hand side, each controlled by a handwheel, and an electrically operated fuze-setting mechanism on the left-hand side. The firing solution values can be optionally sent by telephone from the Kdo.Ger. 36 & 40, by three extra crew members.

Kommandohilfsgerät 35
Personnel layout with separate 4 meter rangefinder,

Crew of 9, with 4 for the rangefinder, plus an officer.

The Kommandohilfsgerät 35 is an earlier angular speed director which was used for auxiliary purposes with telephone communication only from controller to guns.{TME p. 138}

The handwheels have a flywheel within the case to give a steady rate of change. Push buttons operate a brake for quick stopping, and a clutch allows swift traverse or elevation. {TME p. 138}

Transported on special trailer 53 Sonderanhänger (1 achs.) (Sd. Ah. 53)

Kommandogerät 36 - electrical operation
Layout of personnel:

The trailer-transportable Kommandogerät 36, with a crew of 11, was used in the field with the 8.8 cm Flak.

Hogg somewhere shows that the great majority of Flak 88s were intended for fixed installations, and only around 30%? were used as mobile flak or anti-tank guns. Also used on flak trains. The fire directors were never used with 88s in the anti-tank role.


 * So: Most pics tend to show the 35, 36 and 40 predictors in dug-in positions. I need to find out exactly how the heavy flak batteries were used, eg in User:MinorProphet/Draft subpages/Panzer Artillery Regiments.
 * They may not have been. I came across a passage somewhere find ref, fool! (maybe in one of those post-war monographs (USAF Historical Studies) by pardoned German generals...) that only 2 cm and 3.7 cm light Fla were transferred to the Army during 1942–1943, and that the 8.8 cm heavy Flak was always under Luftwaffe control.


 * Is it the case that the Kommandogerät 40 (with a crew of 5) was used for fixed installations of 8.8 cm, AND 10.5 cm and 12.8 cm guns?

As with all the fire predictors, Present angular height, Present azimuth and Present slant range are continuously input; and quadrant elevation, future azimuth and projectile flight time (as fuze settings) are computed and output. These three values are simultaneously sent electrically from the Kdo.Ger. 36 director via a switchboard through electric cables to indicator dials on each gun in the four-gun battery.

Transported on the Sonderanhänger 101 (Sd. Ah. 101) and later the Sonderanhänger 104 (Sd. Ah. 104)

A few KG 36 and 40s were mounted on de:VOMAG 6-wheeled trucks, to accompany similarly-mounted 8.8 cm flak guns. Pics: Selbstfahrlafette auf Fahrgestell VOMAG 7 OR 660 mit 8,8 cm Flak

Azimuth and elevation dials
Ǖbertragungsgerät 30 - As fitted to the Flak 18 and 36. Jentz calls it a Lampenempfänger (light signal receiver).

On the Flak 18 and 35 guns the dials have three concentric rings of 10-volt electric bulbs, and each ring has a pointer with a translucent index. The pointers are geared together in the ratio of 1:10:100. Turning the handwheel moves the pointers and the relevant elevation or traverse mechanism, and when one of the indexes covers a bulb, it goes out. This happens for each ring in turn as the operator continues to turn the handwheel; and when all the bulbs are out on all three dials, the gun is correctly aimed at the target.{TME pp 138-40}

Pic, a bit out of focus, with the dial covers on These dials were also fitted to 150 cm searchlights.

Hogg says that the Ǖbertragungsgerät 30 was not completely satisfactory and was replaced in 1939 with the Ǖbertragungsgerät 37, a system based on Selsyn (a brand) synchronous motors. This was fitted to the Flak 37. Jentz calls this the Folgeziegeempfänger (directional indicator with dials).

The receiver dials on the the Flak 37 were provided with two sets of pointers, one electrically controlled from the director, the other mechanically linked to the gun. The gunlayers then matched the position of the predictor-operated pointers to lay the gun correctly (often termed 'follow-the-pointer'). This was easier to operate and maintain, gave finer control and smoother following of the data. These dials were also fitted to 200 cm searchlights

Pic, apparently with two dials IWM Duxford

Much better pic, 88mm Flak 36 Walk Around Page 1, Prime Portal

Fuze setting mechanism
When operated electrically from the Kdo.Ger. 36 director, the fuze setter uses a dial with three rings of lights similar to the azimuth and elevation dials. A small handwheel turns the pointers to black out the lights. The operator then turns a crank connected to a flywheel which powers the fuze-cutting ring. A round is thrust downwards into a large cup which grips the fuze: a toothed clutch rotates an adjusting pin which sets the clockwork timer correctly on the fuze. A lever releases the round which is then pushed into the gun breech by the loader (a specific member of the gun crew) for firing. There are two cups, allowing two fuzes to be set simultaneously. A bell just above the fuze setter indicates that the gun is on target.{TME p. 144} It rings for 3 seconds (Ladeverzugzeit, loading time) during which time the fuze setting cannot be changed any more, and the round must be loaded into the breech and fired.

Kommandogerät 36 (and 40?) - telephone operation
The firing solutions of the KG 36 can also be sent to the guns by telephone, in which case 3 more operators are needed. Instead of the bulbs in the dials being lit, the relevant degrees of elevation and azimuth, and the fuze setting numbers are individually telephoned to the gun personnel.

Other rangefinders


When the heavy flak were guns used as ground artillery, especially as anti-tank guns, the fire directors were not needed and often the dials for traverse, elevation and fuze-setting were removed (eg in the North African campaign). (Hogg early on?) For direct fire, the monocular Flakzielfernrohr 20 (or 20 E, with range drum) telescopic sight was mounted on the right-hand side of the gun, geared to the elevation quadrant.{TME pp. 109, 113} Hand-held rangefinders were often used in conjunction.

The EM 34 'coincidence-type' 0.7 m monocular range finder was used by German machine gun, mortar and some artillery units during the Second World War. It was designed by Carl Zeiss AG and manufactured by Emil Busch A-G, de:Rathenower Optische Werke

The range finder is fitted internally with a series of prisms, beam splitters and mirrors, which divide the viewed image into two halves. When focussed into one image, the range finder provides a calculated distance or altitude to the target. In low light conditions a battery-operated internal lighting system could be used.

A stereoscopic rangefinder such as the Em. 1m R36 Entfernungsmesser (1 metre rangefinder Raumbild [Model] 36 [1936]), could also be used to estimate the distance to the target.


 * German 88-mm Antiaircraft Gun Material Technical Manual. War Department.

SIGHTING AND FIRE CONTROL EQUIPMENT]
 * Re-typed with a different format: TM E9-369A: German 88-mm Antiaircraft Gun Materiel: CHAPTER 4

Para 83. RANGE FINDER MODEL 34.

There was also a 0.9 m rangefinder. See pic And also a 2-meter one.

Misc. info re flak guns
The KG 36 and 40 were used on Flak towers to direct the 10.5 cm FlaK 38 and 39. The KG 40 was used for the 105mm and the single and twin 128mm FlaK 40 on the Humboldthain Flak tower.

Development and production history
In 1927, "The first operational fire director (Kommandogerät P 27) entered active service with the army's anti-aircraft forces at Königsberg, the anti-aircraft site that the Inter-Allied Military Control Commission allowed the Reichswehr to maintain after World War I. Live fire field tests conducted against targets towed by aircraft in 1928 led to the subsequent order for ten of the P 27 fire directors.[60] [60]= Koch, Flak, p. 16