Blohm & Voss BV 246 Hagelkorn ("Hail") was a controlled sliding aerial bomb used against special purposes (ships, bridges, ...). It had a perfectly smooth jet shape. It was designed by Dr Richard Vogt, initially the designation BV 226 was used for it, only later, on 12 December 1943 the designation was changed to definitive BV 246.
The bomb was placed at the bottom of the bomber (more often the He 111, but the bomb was also hijacked by the Fw 190) and when the plane reached a high height (about 10,000 meters) near the target, it dropped a bomb. That protected the mother plane from anti-aircraft fire from the ground.
The design of the missile was quite simple, small wings were mounted on the jet's fuselage. They had a very unusual construction. There was a thin layer of concrete around the steel-aluminium core. There were cross tail surfaces at the back of the machine.
Several guidance systems have been tested, including "Radieschen"- which was used to guide the radar. Hagelkorn was the first anti-radar missile. Before the project was cancelled, 1100 were produced. Blohm & Voss BV 246 - Wikipedia