X-4 (GERMAN)
The air-to-air rocket-propelled winged missile X-4 was designed by Max Kramer beginning in June, 1943. About 250 missiles were built and about 150 tested. The gross weight is 132 lb of which 44lb is war head. Propulsion is by means of a liquid fuel rocket weighing 31 lb (empty) and giving a thrust of 242 lb for 17 sec. About 19 lb of fuel were provided.
The missile is approximately 75 in. long, 8.7 in. in diameter, with wing span of 23 in. The speed is about 790 ftl sec, the horizontal range about 1.2 miles.
The missile has four sharply swept-back wings near the center of gravity and four tail fins. Aerodynamic control is by means of spoilers on the tail fins. Tabs on the wings cause the missile to spin. Two of the wings carry at the tips spools of fine wire 0.009 in. in diameter and long enough to permit a range of about three miles while maintaining direct-wire connection to the control aircraft. A gyrostabilized commutator in the missile and a suitable filter system permit direct electrical transmission of the control from the operator to the spoilers on the control surfaces of the missiles by means of the connecting. wires which can feed out at speeds of more than 650 ft/sec.
A document dated 11 January 1945 stated that 130 trials had been made. It was stated that the missile was in the early testing stage to prove its fundamental correctness of functioning. At one time the Air Ministry had a requirement for 5000 missiles by the middle of 1945 but this was later reduced. In February, 1945, SS leader Kammler ordered a lower priority and the closing out of the project at the end of the development period.
Kramer designed an acoustic proximity fuse for this missile known as "Kranich." About 30 were built and some preliminary fly-over and fly-by tests were made. The effective range was expected to be 45 ft. The tests which had been completed were promising. Work was also under way to develop an acoustic homing device with a hoped for range of from 1650 to 3300 ft.
