INVESTIGATIONS IN GERMANY
TANK ARMAMENT RESEARCH,
MINISTRY OF SUPPLY
SECTION G SIGHTING EQUIPMENT AND METHODS OF FIRE CONTROL
See Section A of this report
Leitz, (Wetzlar), Steinheil Sohne(Munich), Optika Fabrik, Messkirch, and Winkel-Zeiss (Gottingen)
- Gunner's Sight
The latest tank sight in full production was the T.Z.F.12 (a) with dual magnification (x2.5 and XS). A new version, TeZeFel3 was on the way, but this was very similar to the T.Z.F.12 (a), the main difference being that the overall length was shorter.
The increasing thickness of frontal armour, and the un-desirability of piercing large holes through it, had caused later German developments to follow along similar lines to those in England and America. The alternatives of taking the sight through the side or the roof of the turret had been considered. Leitz had produced drawings of a lateral off-set sight passing through the side armour, the optical arrangements of the sight being based on the T.Z.F.12 (a), but without the optical hinge. The sight was laid out in such a way that the eye point was on the trunnion axis of the sight. This project appears to have met with little favour and was dropped.
Requirement was finally crystallised on a monocular periscopic sight (prismatic erection) with no magnification and 6 ma. exit pupil, and it was intended that this sight should be universal for tank, anti-tank and flak guns. The design of Carl Zeiss was accepted, and at the end of the war the sight was actually being produced. Drawings of the sight were obtained from Steinheil Sohne (Munich) and two sights were obtained from Winkel Zeiss (Gottingen). The sight is essentially a central laying sight, range being fed on to the top mirror and the whole sight moving with the gun. The range drum consists of a disc mounted on the back of the sight, and on the circumference of the disc are cut cams for the various types of ammunition. A lever mechanism transmits range from the cam to the spring-loaded top mirror. Up to five range cams can be incorporated on the same disc. A subsidiary optical system utilises a portion of the light from the top mirror, this light passing twice through the range disc and being finally introduced into the eye piece of the sight. This results in a swan area at the top of the field of view being obscured, and in this area is imaged a portion of the range scale engraved below the cam being used. For replacement purposes, the sight can readily be broken between the object glass and the top mirror, the lever arm to the top mirror being in two sections whose faces simply rest on one another. It was intended that the ten power optical system should be universal, but that the periscopic relief from object glass to top mirror and the range disc should be different in the different applications. In the sights removed from Winkel Zeiss, no lead computing mechanism was incorporated. Deflection marks on the fixed graticule were provided for estimation of lead. It is worth noting that Winkel Zeiss have 100 sights partially made, and that they estimate that all these sights could be completed in one month.
Development work had not ceased, however, with the production of these X10 periscopic sights (W.Z.F. series). Leitz were insistent that there was a demand for a periscopic sight with alternative magnifications, preferably X3 and X10, and drawings obtained from the firm seem to bear this out. Another demand was for the incorporation into the optical system of a moving part which could be linked to a gyroscopic control and which could provide a stabilised sight-line (cf. statement by General Guderian, Section A). A sight W.S.F.3 designed by Leitz, but which had not reached the prototype stage, indicates the lines along which the above requirements were to be satisfied. The alternative magnifications were to be provided by means of two erector systems which could be switched in or out of the optical path as in T.Z.F.12 (a). One erector is positioned before and one after the 45deg reflecting surface at the base of the periscopic relief. The arrangements for feeding range on to the top mirror and making the range setting visible at the edge of the field of view are very similar to those used in the (W.Z.F. series of sights. The top mirror is linked to the stabiliser to give a stabilised sight-line. The differential mounting of the top mirror to accommodate both tangent elevation and stabilisation cannot be described in detail here. The sight is connected to the gun through a parallel linkage. Two graticules are positioned in the focal plane of the object glass, one being fixed relative to the sight casing while the other is attached to the axis in the sight controlled by the stabiliser and this graticule therefore remains fixed in space. The relative movement of the two graticules gives a warning to the gunner as to when the gun is about to swing through the sight-line.
- Integrated Fire control Systems
Little information was gathered as to German developments towards an integrated fire control system for direct fire.
- Other optical Equipment
- Bore Sights
The only bore sighting device seen was being made by Leitz. It consisted essentially of a spigot which could be accurately centred in the muzzle, and an elbow telescope mounted on the end of the spigot. The length of the spigot aligned in the bore was roughly 2 ft, and each end was centred by two pairs of expanding shoes. Each pair of shoes was driven outwards by identical cam faces, the pairs of cams being sprung against one another.
- Periscopic Sights
An interesting development was being carried out by Steinheil Sohne (Munich). They had produced a unit power periscope with 90deg apparent (and in this case, real) field. Only spherical lenses were used in the eyepiece. A roofed-pentag was used before the object glass in place of the conventional 45deg reflecting surface, and this together with a 45deg reflecting surface at the base of the periscopic relief gives the required erection. The sight was 'originally developed for the Luftwaffe, but may have applications to tanks as a machine-gun sight. Drawings of the sight were obtained.
- Commanders Observation Instrument
Steinheil Sohne were also developing an observation instrument with a periscopic relief of 54 cm. A double-dove prism was mounted in front of the O.G. to give scanning through l80deg. The first designs were for X1.5 magnification, exit pupil 8 mms, apparent field 75deg, but later design was to take the magnification up to X4. Drawings of the X1.5 instrument were obtained.
A new version of the Commander's observation periscope T.S.R.1. was seen at the Optika Fabrik, Messkirch, the new instrument being designated S.R.4. The periscopic relief could be shortened by removing a central section of the tube 40 cm. long which contained two lenses, The periscope had a rocking top prism which was linked to a drum just above the eye lens, the drum being graduated in mils,
Leitz mentioned that this firm manufactured sighting equipment. It was found that the following equipment was made in the factory or in nearby workshops:-
|Hull gunner's periscope
||31 and 36
|Commander's observation per
|Machine gunner's sight
A graticule for subtense range finding ad been made and fitted into the scissors binoculars.
The firm maintained an optical computation section, but did only very little research and development work,
Rodenstock Optische Werke, Munich Telescope T.Z.F.5
T.Z.F.l2 a (optical parts only)
The firm was concerned solely with production. The instruments made included the following:-
It was stated that Herr Otto (of the firm Alkett of Berlin) designed, for Rheinmetall-Borsig, brackets and other metal parts to receive tank sighting-equipment which was supplied by the optical firms. The firm had no knowledge of proposals or equipment for commanders control of a tank gun. Even the azimuth ring in the commanders cupola had been abandoned in normal tanks.
Krupp, Essen (evacuated to Kettwig)
As with Rheinmetall-Borsig,, the firm of Krupp was only concerned in designing metal brackets etc. to receive the sight equipment,