Disintegrating Rotating Bands for German Shells, WWII Tactical and Technical Trends, No. 42, January 13, 1944 (Lone Sentry)

The Germans have produced another rather striking innovation for higher velocity ammunition, in keeping with their hollow-charge projectiles, the Gerlich taper-bored gun and the ammunition for it. This is a streamlined shell with guide and rotating bands both designed to fall to pieces and release themselves from the shell while in flight with the object of perfecting the air-form to decrease resistance. At present these shells are known to be of 105-mm (4.13 in) and 150-mm (5.90) caliber, HE (see accompanying sketches).

a. General Description

In addition to being similar in general design, both projectiles are HE and are fitted with nose-percussion fuze type AZ-23v, the detonator being similar to those for the usual type of German HE shell. Beneath the fuze is a booster located by a booster holder. In the case of the 105-mm shell, it is type gr. Zdlg. C/98 Np, and for the 150-mm shell it is type Zdlg. 36. Beneath the booster is a smoke pellet. Both projectiles are painted yellow.

[Disintegrating Rotating Bands for German Shells]

b. Disintegrating Bands

A detachable guide band forms the bourrelet of the projectile. This band has three cuts extending almost completely through the band and spaced 120° apart. The complete band, which is a push fit on the shoulder, is held in position by three ball bearings. These are seated in three cavities spaced equally around the periphery of the shoulder of the shell and project into cylindrical drillings through each segment of the guide band. The drillings are threaded towards the outer circumference, and the ball bearings after insertion, are finally located by screws which seat the outer surface of the bearings. After insertion of the balls and the positioning of the three screws, the guide band is firmly attached to the shell body. If the three cuts in the guide band were completed, each segment, together with its retaining ball, would be free to fall away from the shell body.

The rotating band holder is located at the base of the shell, which is keyed to receive it. The holder itself is in three detached segments held in position only by the soft iron rotating band. Movement is prevented by three cylindrical pieces fitting into cavities located in the shell body and the driving-band holder. There are also three cylindrical pins between the segments.

[Base of 105-mm HE Shell]

c. Functioning

It is believed that after leaving the gun the guide band and the rotating band holder are each split into three separate segments which, together with the ball bearings, pins and cylindrical pieces retaining them, are flung off. The remaining projectile is then of much better aero-dynamic shape than is possible with a conventional projectile.

d. Characteristics

The following are the general characteristics of these projectiles:

105-mm

Weight of projectile 10.5 kg (23.1 lb)

Weight of bursting charge 0.5 kg TNT

Stencillings on body 14
764
R8 (smoke pellet type)
Hi 9.8.42 Ma

150-mm

Weight of projectile 28.7 kg (63.14 lb)

Weight of bursting charge 3.4 kg TNT

Stencillings on body 14
186
R9 (smoke pellet type)
Hi 9.8.42 Ma
Z 3033

It is worth noting that the usual weight for the 105-mm shell is about 33 pounds, and the weights of the ordinary 150-mm projectiles, 88 and 95 pounds. By lightening the projectile and eliminating the bands, a substantial increase in velocity and range is probably attained.

e. Packing

The 105-mm projectile is packed in a wooden crate. The 150-mm projectile may be packed in a wooden crate or a wicker basket.

It is not known with which equipment these projectiles are intended to be used. Neither cartridge cases nor charges have as yet been identified. It should be noted that the disintegration of the guide band and rotating band holder is likely to cause some danger in an area forward of the muzzle.