The first major production model was the IIID, which was an improved IIIC, with provision for a third crewmember and capable of being fitted with either a floatplane or a conventional wheeled undercarriage.[4] It first flew in August 1920,[5] powered by a Rolls-Royce Eagle, and initial production for the Fleet Air Arm, together with aircraft produced for Australia and Portugal retained the Eagle, while later aircraft were powered by the more powerful Napier Lion.[5] The naval variants were usually three-seaters; pilot, observer and gunner and the wings would could be folded back parallel to the fuselage for storage aboard ship.