The X 4 is an antiaircraft rocket designed by the Germans to be launched from planes. It was manufactured and reported to have been successfully tested, but never reached the point of combat operation. It is a wire-controlled, rocket-propelled, fin-stabilized missile fitted with a proximity fuzed warhead. The propulsion system is a bi-fuel rocket. Stabilization is achieved by means of four large fins fitted to the body of the rocket, and four smaller fins fitted to the tail. The smaller fins bear solenoid-operated control surfaces through which two-dimensional directional control is achieved. These are operated from the parent aircraft by means of a control unit and two insulated wires leading to the rocket. These wires are about 3 3/4 miles long.

Precise information about the warhead and fuzing system has not so far been recovered. The warhead consists of an uncased moulded grain of dinitroglycol-based explosive which depends on high blast effect. The fuze is a combination of acoustic proximity, impact, and self-destroying type. The proximity feature is functioned by aircraft propeller noises and a delay of 1/50-second is provided to enable the missile to approach the target after the acoustic impulse initiates the fuze. The body of the rocket houses the helical aluminum tube fuel tanks and combined two-compartment steel air bottle. The venturi protrudes from the tail portion. The rocket is made to rotate about its axis at the rate of one rotation per second. This permits stabilization in line of flight by a single gyro. The missile is carried on the parent aircraft on a conventional bomb carrier modified for this special purpose

SPECIFICATIONS*

Length (overall) 200 cm (6 ft., 6 3/4 ins.) Length of warhead 45 cm (1 ft., 5 3/4 ins.) Diameter of warhead (at base) 22 cm (8.675 ins.) Total weight before launching 60 kg. (132.3 lbs.) Weight of warhead 20 kg. (44.1 lbs.) Fuel 4.5 liters (approx.) 98-100% nitric acid 2 liters (approx.) 57% crude m-xylidine 43% triethylamine Thrust Initial 270 lbs. to 315 lbs. falling off progressively to 45 to 68 lbs. after 30 seconds.

*Not verified.

German: p. 375 (August 1, 1945)