German Explosive Ordnance - Rockets (Part 14)

German Explosives

8-cm Raketen Sprenggranate (H.E. Aircraft Rocket)

Caliber: 78 millimeters

Overall Length: 28.5 inches

Weight (complete round): 15 pounds 3 ounces

Filling: Flaked TNT

Warhead Material: Steel

Rocket Motor Material: Steel

Warhead Length: 8 inches

Warhead Diameter: 3 inches

Rocket Motor Length: 12.8 inches

Rocket Motor (outside): 3.07 inches

Rocket Motor Diameter (inside): 2.75 inches

Rocket Motor Weight: 4 pounds 5.25 ounces

Venturi Material: Steel

Venturi Length: 7.48 inches

Outside length of fins: 5.31 inches

Rear diameter across fins: 

-External: 7.87 inches

-Internal: 3.34

Venturi Weight: 2 pounds 0.25 ounces

Inlet Maximum Diameter: 2.48 inches

Inlet Minimum Diameter: 0.782 inches

Inlet Length: 0.92 inches

Throat Diameter: 0.782 inches

Outlet Maximum Diameter: 1.653 inches

Outlet Minimum Diameter: 0.782 inches

Grid Diameter: 2.72 inches

Grid Thickness: 0.51 inches

Grid Weight: 3 ounces

Propellant: Double base powder in mono perforated stick form.

Description: This is a fin-stabilized projectile with an appearance typical of small caliber aircraft rockets.  The internal arrangement of the projectile suggests that it was possible copied or adapted from a standard Russian aircraft rocket.  Although this rocket almost certainly was designed primarily as an aircraft weapon, it was also fired from a multiple-frame ground launcher known as the 8-cm Raketen Vieflachwerfer.  The projectile consists basically of an H.E. warhead, a rocket motor, and a tail unit incorporating a single venturi and stabilizing fins.

Warhead: The warhead of the projectile is a steel cylinder with an ogival nose into which is built a fuze system.  The rear of the head is closed by an adapter plug which also forms the junction with the rocket motor.

The main H.E. filling consists of a pressed flake TNT and is built up from three perforated pellets which fit around the exploder tube incorporated in the fuzing system.  At the nose end is a small cardboard washer; at the base are two waxed-paper washers; and around the exploder magazine is a waxed-cardboard tube.  Between the shell wall and the explosive is a thin layer of bituminous material.  The outer surfaces of the pellets are waxed.

Rocket Motor: The body of the motor is formed by a cylinder which is machined down slightly between the ends.  The forward end of the cylinder is threaded internally to screw over the adapter plug which forms the junction with the warhead.  Four studs in the body, two at each end, guide the projectile in the launcher.  The base of the motor body is closed by the motor closing plate, which is in the form of a single venturi to which four stabilizing fins are spot welded.

The propellant consists of six sticks, of which two are slightly shorter than the other four.  The four longer sticks are located by a supporting grid which is a push fit in the venturi assembly.  The other two sticks are supported on the two primary igniters attached internally to the walls of the rocket motor.

The ignition system consists of two ignition charges, one at each end of the propellant, and a primary igniter.  The primary igniter is in the form of two copper tubes, each screwed internally over the end of the steel guiding studs which pass through the motor body at the rear end.  A brass rod, insulated by a rubber sleeve, passes through the guiding stud and bears against a brass contact inside the copper tube.  This contact passes through the tube into a small cardboard container holding a loose composition charge of gunpowder.  Wires from the contact to the walls of the copper tube serve to ignite the charge.  The circuit is presumably formed by two leads, one to the brass rod in each guiding stud, and is grounded to the rocket body.

Fuzing System: This rocket has a fuze which has been designed specifically for it.  The fuze consists of a steel nose piece which contains a light alloy striker supported by a light creep spring.  Below the nose piece is a steel magazine tube, into the forward end of which is screwed the detonator housing.  Directly below the magazine tube is the arming mechanism which consists of a metal sleeve, containing a spring loaded screw and the plunger.  Holding the spring loaded screw and the plunger in position is a fusible metal ring.  When assembled, the plunger fits into the lower end of the magazine and the booster pellets rest on it.

When the rocket is fired, the heat of the burning propellant is conducted through the wall of the spigot and melts the fusible metal ring.  The plunger, magazine, and detonator are then free to move forward under the action of the spring.  The extent of this forward movement depends upon the acceleration of the rocket.  Approximate measurements indicate that if this is less than 40-50 grams the detonator is sufficiently forward to be fired by the striker.

8.6-cm H.E. Rocket (Spin Stabilized)

Nature of Projectile: Multiple base-venting, spin-stabilized pusher rocket.

Caliber: 8.6 centimeters

Overall Length: 16.25 inches

Overall weight: 17 pounds 15 ounces pounds

Nature of filling: H.E.

Nature of the fuze: Base

Warhead Length: 9.55 inches

Warhead Diameter: 3.35 inches

Type of Filling: Cast TNT

Rocket Motor Length: 6.7 inches

Length of Propellant Chamber: 6.08 inches

External Diameter: 3.18 inches

Internal Diameter: 2.94 inches

Weight of Filled Motor: 6 pounds 12.25 ounces

Propellant Length: 5.9 inches

Diameter of Propellant: 2.78 inches

Weight of Propellant: 2 pounds 7.75 ounces

Analysis:

-Potassium Nitrate: 75.5 percent

-Carbon: 15.35 percent

-Sulphur: 9.15 percent

-Volatile Material: 0.86 percent

Description: This rocket consists of a H.E. head, a motor, and a venturi assembly.  An integral base fuze, centrifugally armed and pressure fired, is located int he base of the H.E. head.

The H.E. head threads over the rocket motor housing, which contains a single, multi-perforated, propellant grain.  A venturi assembly, with eight jets drilled in it, is threaded to the base of the motor.  A single threaded hole in the center of the venturi assembly contains a percussion primer.  On the forward end of the motor housing is a fitting which receives one of three interchangeable delay trains.  The rockets bear markings to indicate which of the delay trains have been assembled.  Those marked "/400/" and "/800/" contain, in addition to the delay train, a fuze with a striker retained by four arming balls and a spring collar.  A light anti-creep spring is placed between striker and the detonator.

Centrifugal force causes the balls to move outward against the collar and arm the fuze.  The delay train is initiated by the propellant grain, and when the delay expires, the pressure developed forces the striker against its spring and into the detonator.  Impact with some resistant object before the expiration of the delay will force the striker into the cap.  In the case of the round marked "/600/" no striker mechanism is included, and the delay initiates the detonator and booster directly, giving only self-destroying action.

Remarks: This is a naval round, designated "8.6 cm R. Spr. 400 Wsm. (600 Wsm, 800 Wsm)."

The H.E. head is painted canary yellow overall; the motor body, dark green.

It is estimated that this projectile would reach a maximum height of 8,000 feet, if fired at a quadrant elevation of 90 degrees.

Next Time: Rockets (Part 15)

Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters