Designed by Lieutenant J.W. Dunne, who was working with Samuel Franklin Cody on man-lifting kites at the Army Balloon Factory, the Dunne D.1 was a biplane glider whose design embodied Dunne's ideas about achieving inherent stability in an aircraft, which he had developed during two years of experimentation with models. It was a tailless biplane with swept wings whose angle of incidence decreased towards the tips. The wings were of wire-braced wooden construction. The undercarriage consisted of a pair of skids underneath the lower wing. Take-off was achieved by placing the aircraft on a wheeled platform running on a ramped track, similar to the system used by the Wright brothers for their first flights.
The aircraft was assembled in great secrecy at the Army Balloon Factory. To maintain security for the flight trials, the Dunne D.1 was taken to Blair Atholl in Scotland by a team of Royal Engineers in July 1907. It was first flown as a glider piloted by Colonel J. E. Capper and was later adapted to be powered by two Buchet engines with a combined output of only 15 hp (11 kW). During a test in October, the aircraft slipped sideways off the launching ramp and was severely damaged.
The aircraft was repaired and modified to become the D.4. The wing built from the D.1 was mounted on a steel framework mounting a 25 hp (19 kW) R.E.P. engine driving a pair of pusher propellers. and having a four wheeled undercarriage. This projected forward of the wing and was partly covered in fabric, forming a rudimentary nacelle to house the pilot. Fins were added between the ends of the wings. Trials were made at Blair Atholl with Lt Lancelot D.L Gibbs at the controls. The power provided was not sufficient for the aircraft to take off under its own power, but some satisfactory short hops were achieved during November and December 1908.
Although Dunne's experiments were promising and the Army Aeroplane No 1 built by Cody at Farnborough had successfully flown, the War Office decided to stop all support for heavier-than-air research in early 1909. Both Dunne and Cody left the Balloon Factory and were given the aircraft they had built, these now not being wanted by the military.