Arado Ar.E.500 Twin-boom attacker project. In 1934, the RLM issued a requirment for a destroyer airplane to several aircraft firms, who were requested to submit proposals of a heavily-armed multi-seat twin-engined aircraft the size of a medium bomber. It would possess a heavy concentration of cannon armament. Arado submitted E.500 project, incorporated an advanced armament concept. This consisted of a pair of turret-mounted 20mm cannon which could be rotated through a full 360 degree. To provide the gunners an almost unrestricted field of fire, the tail surfaces were placed on the outboard portion of the twin fins and rudders. The RLM considered the armament idea worthy of further development up to prototype stage, but following the full-scale mock-up, work on the project was stopped as it was not prepared to further Introduction of movable turrets.