As a more modern replacement for the Airco DH.10 Amiens used on the RAF's airmail service, Imperial Airways used the Hercules effectively to provide long-distance service to far-flung regions. Although the giant airliners were slow and cumbersome, they pointed the way for future airliners. The Hercules was designed for Imperial Airways when it took over the Cairo–Baghdad air route from the Royal Air Force. The Hercules was a three-engined two-bay biplane with room for seven passengers and the ability to carry mail. In order to minimise the risk of forced landings over remote desert areas, the Hercules had three radial engines. De Havilland moved away from the traditional plywood covered fuselage to remove the risk of deterioration in tropical areas and the fuselage was constructed using tubular steel. The cabin and rear baggage compartment were made of plywood suspended inside the steel structure. The two pilots were in an open cockpit above the nose. The cabin had room for a wireless operator and seven passengers. With a contract for five years to run the Cairo to Baghdad air mail service, and a requirement to start a service between Cairo and Karachi, Imperial Airways ordered five aircraft. In June 1926, while the prototype was still being built, the type name Hercules was chosen in a competition in the Meccano Magazine. The prototype, registered G-EBMW, first flew on 30 September 1926 at Stag Lane Aerodrome. Four aircraft were built in 1929 for West Australian Airways. They had modifications to suit Australian requirements including an enclosed cockpit and seating for 14-passengers as well as room for the mail. Two additional aircraft were built for Imperial Airways in 1929 and they had the enclosed cockpit modification used on the Australian aircraft. These were also retro-fitted to the earlier aircraft. For more information on the design and development, and operational history of the Hercules, click here.
