Docile sport biplane built with straightforward standard construction methods. Size and flying characteristics are similar to a Hatz CB-1 with a more simplified design to ease the construction process.

Construction of the Kelly D is traditional steel tube fuselage with some wood formers and stringers to fair it to shape, steel tube tail surfaces and all-wood wings. The entire airframe is fabric covered, with the usual exception of the cowling and first bay of the fuselage which are sheet aluminium. The aircraft is plans built and is associated with the Hatz society.