The Defiant was a single-engine interceptor aircraft. It used a monoplane structure which was coupled with main landing gear which retracted into a broad mainplane section. The pilot's cockpit and rear turret were faired into a streamlined upper fuselage section. Tankage for up to of fuel was housed within the wing centre section along with a large ventral radiator that completed the resemblance to the Hawker fighter. The center section employed a two-spar arrangement, and the wing itself had removable wingtips. The rear fuselage comprised two metal cones connected by a two-foot transitional section and a flat upper deck. The Defiant employed an all-metal stressed skin monocoque structure, which was built in sections that were subsequently bolted together, a manufacturing method previously used on other Bolton Paul-designed aircraft. It was a relatively clean design and made use of a simple, weight-saving structure.