This a self-propelled base venting rocket projectile filled with a mixture of petrol and oil. The ventures are inclined to the axis of the projectile causing rotation and stability in flight. It is fired electrically from either a six-barrel two-wheel mobile projector (28/32 Nebelwerfer 41) or from its own transporting crate which serves as a projector. In the latter case, four crates are laid on simple wooden ramp (schweres Wurfgerät 40) or a metal ramp (schweres Wurfgerät 41) or six crates are mounted on an armoure personnel carrier (Schwerer Wurfrahmen HO).

The overall length of the complete round is 4 feet 2 inches and its total weight 174 lb. External markings in the round are shown in Fig. 21. Rounds suitable for hot climates are also stencilled "Tp".

Shell filled petrol/oil mixture.

Bursting charge of penthrite wax.

Incendiary igniter.

Fuze Wgr.Z. 50+.

Gaine gr.Zdlg. C/98 Np.

Tail unit with propellant charge and ignition system.

Electric ignition fuze.

12 fuzes Wgr.Z. 50+ each in a separate plastic container.

15 gaines packed 5 in a plastic container.

16 single electric ignition fuzes and 4 quadruple fuzes, in a cardboard box.

The overall length of the shell is 31.6 inches and its diameter 12.8 inches. The empty body weighs 13 lb. 12 1/2 oz. and is of thin sheet steel 0.07 inches thick; it is welded circumferentially at about its centre. Two cirrcumferential ribs are also formed in the body, and one below the head and the other above the streamlined base. The head is shaped to a low crh and prepared to receive a plastic adapter which incorporates a gaine container. Near the nose is a charging hole closed by a plug. The base is streamlined and terminates in a short cylindrical tube which is screwthreaded internally to receive the tail tube.

The incendiary filling is a brown liquid consisting of 11 1/4 gallons of petrol/oil mixture.

The bursting charge consists of a cylinder of penthrite wax surrounding the gaine contai-ner.

The incendiary igniter is contained in a soldered thin sheet cylinder, 24.1 inches long, placed axially in the shell with one end butting against the base of the gaine container.

The fuze used in one of the Wgr.Z. 50+ type reffered to elsewhere in this pamphlet.

The tail unit has an overall length of 19.9 inches and weighs approximately 49 lb. 8 oz. filled. It consists of the following principal components: tail tube, venturi block, propel-lant charge, a grid, spacing ring and an ignition system. Typical stencilling in the tail tube and venturi block is shown in Fig. 21. The internal metal parts are not rust proofed.

The steel cylindrical tail tube weighs 23 lb. 14 oz. and appears to be a solid forging ma-chined inside and out to a diameter of 5.5 inches and 5.05 inches respectively, and in-ternally to a depth of 18 inches; it is closed at the forward end and screwthreaded ex-ternally for insertion in the base of the bomb body. The venturi end has a coned opening screwthreaded externally to receive the venturi block.

The solid venturi block weighing 9 lb. 6 3/4 oz. is cup-shaped to an overall depth of 3 in-ches and an internal depth of 1.75 inches; it is screwthreaded internally for attachment to the tube. Externally, it is chamfered towards the top. Twenty-six venturis equally spaced, are formed in the base near the periphery; each has a throat diameter of ap-proximately 0.22 inch and the cones are inclined at 14 degrees of approximately 0.22 inch and the cones are inclined at 14 degrees to rotate and stabilize the rocket in flight. The venturis of rockets suitable for hot climates are sealed on the outside by a "soldered on" flat tinned iron ring which blows off on ignition. The aera of the base surrounded by the ring of venturis is recessed to a depth of 0.1 inch, also bored centrally and screw-threaded to recei-ve an adapter screwed in form the inside. The base is stamped "DOVT 15 WU 26 x 5,5 Ø 14°, all 8c 41". The stamping includes characteristics of the venturi, i.e., the number, throat diameter and inclination.

The propellant charge, weighing 14 lb. 6 3/4 oz. is a single multi-perforated stick of double base propellant of the Digl. type, having eight longitudinal "V" section channels formed in its exterior when extrudes from press. The propellant of the round examined consisted of nitrocellulose 62.5 per cent, diethylene-glycol-dinitrate 33.6 per cent, vola-tile matter 0.6 per cent, stabilizer (probably akardite) 0.6 per cent, graphite 0.12 per cent, ash (cabonated) 0.75 per cent and error and undertermined matter 2.43 per cent. The stick is 16.27 inches long and 4.79 inches in diameter, with a central perforation, star shaped in section, surrounded by eight circular perforations equally spaced on a circle 2.6 inches in diameter. The tropical propellant is marked "Dgp. DOP. 15 Wu (Digl. Ngl.) Tp. dbg. 142/2" and the non-tropical "DO Wu. P.15 (Digl.) dbg 1942 12". The base of the propellant is supported by a grid.

The grid consists of an annular ring 3/16 inch thick, 4 5/8 inches external and 3 1/8 in-ches internal diameter, supported by six small cylindrical distance pieces 1/2 inch in dia-meter and 3/8 inch high from a flat plate 3/10 inch thick and 4 3/8 inches in diameter. The grid is bolted to the front face of the venturi block by the adapter.

The adpater is a cylindrical tube with a hexagon flange formed at one end. The stem portion is screwthreaded externally for insertion in the block and internally to receive the electric ignition fuze. The adapter is inserted from the front; for tranportation it is closed by a screwed plug.

Between the grid and the block is a thin aluminium washer which closes the venturis.

The free space at the forward end of the propellant is taken up by a split spacing ring with ten pairs of lugs bent inwards to form a "U" shape in section.

The ignition system consists of a forward and rear igniter, eight inflammable tubes in the channels round the exterior of the propellant stick and one primed inflammable tubes in the centre perforation, and an electric ignition fuze.

The forward igniter consists of a pressed pellet of gunpowder with a perforated strip of nitrocellulose across its face, in a flat circular aluminium container. The igniter is held in a holder in the form of a washer fitting in the head of the tube with its inner edge turned over to hold the igniter centrally within the spacing ring. The open side of the igniter fa-ces the propellant stick.

The rear igniter consists of a flat rough circular bag containing 10 grains of igniter com-position in the form of six pointed star-shaped flakes; its is housed centrally between the base of the propellant and the adapter. The bag is marked Nz.Man. St.P. (2 x 55/23) dt 1938/5. WO. 7.8.42 W.

The inflammable tubes found in the "V" channels in the side of the sticks are slightly shorter than those in the central hole and are not primed. The tube in the central hole contains what appears to be quickmatch and each end is closed by a gunpowder pellet. The forward end is housed centrally within the forward grid opposite the forward igniter. The rear end is in contact with the rear igniter.

The electric ignition fuze, enclosed in an aluminium tube and bakelite container, is scre-wed into the central hole of the adapter. It may be fired from a 4-volt battery. Rounds may be fired singly. For firing from the Wurfgerät, four ignition fuzes, externally similar appearance, are wired series. One only, tagged "O", is instantaneous, the remainder, tagged "2", "4" and "6" respectively include powder pellets so as to fire at intervals of 2 seconds.

Fig. 21