The Royal Air Force also contributed to the minesweeping boom with a modified Wellington bomber. The R.A.F. Gunnery Research Unit fitted the bomber with a 2.5-ton electromagnetic ring that could project a magnetic field far below the aircraft.
The 51-foot diameter balsa wood ring housed an aluminum coil powered by a Ford V-8 car engine. The R.A.F. called the new variant the Wellington Directional Wireless Installation—a deliberate misnomer designed to keep the aircraft’s true purpose secret.
On Jan. 8, the R.A.F. detonated their first mine from the air, but had to fly slow and close to sea level. Five days later, the Wellington destroyed its second mine—but did so at less than 35 feet above the waterline.
The explosion threw the robust plane up into the air with no serious damage. It was a successful proof of concept, and the R.A.F. commissioned three further DWIs. In June 1940, the Gunnery Research Unit deployed to Egypt, and the DWIs continued their work in the Suez Canal.