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"German Mobile Auxiliary Director" from Tactical and Technical Trends

The following U.S. military report on the German antiaircraft auxiliary director was originally published in Tactical and Technical Trends, No. 14, Dec. 17, 1942.

[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


The mobility and tactical efficiency of heavy antiaircraft units are, at least to some extent, limited by their elaborate fire-control equipment. The Germans have designed an auxiliary director (reported to be the Kommandohilfsgerät 35) as an alternative to the standard director (Kommandogerät 36) for occasions when the latter is out of action or otherwise not available. The auxiliary director is also reported to be used for fire control against ground targets (see Tactical and Technical Trends, No. 6, p. 8).

The auxiliary director weighs about 400 pounds and does not need any electrical equipment. Heights or ranges are obtained from a separate 13-foot stereoscopic height- and rangefinder, and passed orally to the director. In the standard director, the rangefinder is incorporated. This simplification has, of course, only been introduced at the expense of accuracy in the data provided.

The director works on simple angular rates ignoring the meaning factor. By following the target continuously in line and elevation, and by setting in range (or height) continuously, deflections in terms of rate of change are multiplied by present time of flight. It is claimed that these approximations counterbalance each other, since with an approaching target, rates of change of bearing and angle of sight will be too small, while time of flight will be too great, thus giving a close approximation. At the crossing point, when the error is greatest, it is considered that errors so caused will be within the 50 percent zone of fire.

The fuze setting is obtained from the rate of change and the present range. The data are corrected for abnormal ballistic conditions, dead time, and drift and transmitted by telephone to the guns. The dead time allowed is 3 seconds. No allowance is made for wind and displacement.

The setting-in of range is interesting, in that a target not flying at a constant height can be engaged. Height, not range, is set in when the target is flying at a constant height.

A crew of four are employed on the rangefinder, and distribution of duties on the director is as follows:

No.  5 Layer for azimuth
No.  6 Layer for elevation
No.  7 Range setter
No.  8 Lateral rate-setter
No.  9 Vertical rate-setter
No. 10 Range rate-setter
No. 11 Reader of azimuth to guns
No. 12 Reader of elevation to guns
No. 13 Reader of fuze setting to guns

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