[Lee Stewart]

the Royal Navy and the Royal Air Force began working on ways to counter the German aquatic magnetic mines. The RAF decided to detonate them from the air.

the German mines used dip needle detonators that worked “on the same principle as a compass,” to detect the passing disruption in the earth’s magnetic field caused by a metallic ship.

RAF engineers had Vickers equip a Wellington twin-engine long-range bomber with a 51-foot-diameter balsa wood ring that housed an aluminum coil.

Inside nestled a Ford flathead V-8 engine hooked up to a 35-kilowatt Mawdsley generator that in turn energized the aluminum coil to create a magnetic field that would trigger the dip needle detonators.

The aerial minesweeper had to fly at between 60 feet and 35 feet to trigger but avoid damage from the mines.