German Explosives
15.2-cm Anti-Aircraft Rocket, Fin Stabilized
Overall Length: 58.2 inches
Diameter: 7.09 inches
Total Weight: 150 pounds
Propellant Weight: 11 pounds 10 ounces
Length of Grain: 11.7 inches
Cable Length: 950 yards
Diameter:
Main Parachute: 11 feet
Pilot Parachute: 6 feet
Type of filling:
Upper H.E. Charge: RDX/Wax (95/5)
Lower H.E. Charge: RDX/Wax (95/5)
Weight of Filling:
Upper H.E. Charge: 2 pounds 6 ounces
Lower H.E. Charge: 1 pound 10 ounces
Description: This projectile is of the "aerial-wire-barrage" type and is used to project a steel cable into the air by means of a rocket. One end of the cable is fixed to the ground and the other to a large support parachute and a smaller drag parachute. When the cable has paid out, the parachutes are pulled from their housing. The projectile is fin-stabilized and consists, from nose to tail, of the rocket motor, parachute housing, and upper and lower cable housing.
Rocket Motor: The rocket motor consists of a motor body, which is screwed into the parachute housing, and an ogival nosepiece containing a TNT destruction charge. The motor body is a cylinder closed at the forward end and open at the rear. There is no base plate, but the propellant gases are allowed to escape through four venturi drillings in the forward end of the parachute housing. The propellant is a single, cylindrical, multiperforated stick and is ignited by means of an electrical base igniter, a train along the central drilling, and an ignition charge in a grid at the forward end. Leads to the electrical igniter pass through one of the venturi drillings. A delay fuze in the forward end of the motor body ignites the destruction charge in the nose piece.
Parachute Housing: The parachute housing, which is a cylinder closed at the forward end, serves not only to house the large main support parachute and the smaller drag parachute, but also as a base plug for the rocket motor. The forward end has four venturi drilled obliquely in the sides of the body.
At the forward end of the parachute housing is a TNT destruction charge enclosed in asbestos. Although this has a primer, there is no means of initiation; it is assumed, therefore, that this charge is set off by sympathetic detonation from the charge in the nose of the projectile. Below this destruction charge is the main parachute wrapped in asbestos and below it the small drag parachute.
Cable Housing: The cable housing is constructed in two separate halves. The upper half is attached to the base of the parachute housing and accompanies the projectile on its flight. The lower portion of the housing has a flanged base, which fits into the mounting and remains on the ground. The finned tail unit is spot welded to the upper half and fits over the lower portion. This maintains the projectile in position until it is fired. A slot is provided in two of the fins through which a wire is passed, holding the lower section in position; this wire should be removed before firing.
A continuous length of approximately 950 yards of 1/8-inch steel cable is coiled in equal lengths inside each portion of the cable housing. The end of the cable in the upper portion is attached to the parachute, and the other end passes through a hole in the bottom of the lower portion and terminates in an eyebolt secured to the launching frame.
Operation: The actual barrage consists of the support parachute, drag parachute, and cable. The projectile is evidently launched from some kind of frame (no specimen of this had yet been recovered, to which the lower portion of the cable housing is fixed. When the propellant charge is ignited, the projectile climbs until, theoretically, the whole of the cable has paid out. The drag parachute and the main support parachute are then withdrawn from the parachute housing and the main unit continues on its course, leaving the cable suspended in the air.
When the propellant burns out, the destruction charge in the nose piece, actuated by the delay fuze, destroys the rocket motor and parachute housing. It is presumed that the charge in the forward end of the parachute housing is at this point set off by sympathetic detonation to assist in this destruction.
20-cm Anti-Aircraft Rocket, Fin Stabilized
Overall Length: 64.3 inches
Diameter: 8 inches
Total Weight: 159 pounds 3 ounces
Propellant Weight: 11 pounds 9.5 ounces
Description: This rocket is similar in design and operation to the 15.2-cm anti-aircraft rocket but is much cruder in construction. The round consists of a rocket motor at the forward end, a middle compartment containing the parachute and the cable housing surrounded by the fin sleeve.
Operation: On firing, the cable housing remains on the ground, and the rest of the assembly is projected into the air, uncoiling the cable from its housing. When the cable is completely unspooled, the parachute is withdrawn through the fin sleeve. The separation of parachute and motor operates a pull igniter, which initiates a demolition charge contained in a central tube in the motor.
Remarks: The round is painted dark green overall.
21-cm H.E. Anti-Aircraft Rocket, Spin Stabilized
Overall Length: 49.2 inches
Diameter: 8.27 inches
Total Weight: 241.3 pounds
Propellant Weight: 39.5 pounds
Length of Grain: 21.67 inches
Diameter of Grain: 2.46 inches
Type of Filling: Amatol 40/60
Weight of Filling: 22.4 pounds
Description: This is a streamlined aircraft rocket projectile, consisting of an H.E. shell, externally threaded at the base to screw into the rocket motor and at the nose to receive a ballistic cap. A booster container is threaded into the nose of the shell and receives the nose fuze. A wooden actuating rod separates the fuze from the tip of the ballistic cap.
The motor body is a cylindrical steel body machined externally to form fore and aft bourrelets. A venturi assembly, drilled to form 22 jets, threads into the base of the motor. The jets are inclined at an angle of 16 degrees to impart a rotary motion to the rocket in flight. An electric squib is threaded into the center of the venturi assembly. The propellant charge consists of 7 single-perforated grains supported by a metal grid at the after end. A ring-shaped black powder igniter is placed at the base of the charge and a second igniter is located at the forward end of the charge. These two ignition charges are connected by a length of quickmatch in a celluloid tube, which passes through the perforation of the central propellant grain.
Remarks: The German designation for this round is "21 cm Wgr. 42 Spr."
This round is painted green overall.
Next Time: Rockets (Part 18)
Source: German Explosive Ordnance Vol. 1: Bombs, Rockets, Grenades, Mines, Fuzes & Igniters
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