The Ruhrstahl X-4 was the world's first wire guided air-to-air missile.
Work on the X-4 began in June 1943, by Dr. Max Kramer at Ruhrstahl.
It had a solid rocket propelled motor. It was about 6 feet long and the world's first MCLOS missile.
The first flight test occurred on August 11, 1944 using a Focke-Wulf Fw 190 for the launch platform.
