Closely related to Handley Page's Hastings military transport, the Hermes was a low-wing monoplane powered by four piston engines. Twenty-nine were built, serving briefly with BOAC in the early 1950s and later with several charter airlines. The Hermes was built to meet the 1944 Air Ministry specification for a pressurised civil transport capable of carrying 34 first-class or 50 tourist-class passengers, at the same time as the RAF required a new transport to replace its Handley Page Halifax, for which Handley Page designed the very similar Handley Page Hastings. Unlike the tailwheel Hastings, the Hermes was planned to have a nosewheel undercarriage, although the first two prototypes used a tailwheel undercarriage, of which the first was an unpressurised "bare shell" and the second to be pressurised and fully equipped. It was intended to introduce the Hermes before the Hastings, but production was delayed after the first prototype (HP 68 Hermes 1), registered G-AGSS crashed on its maiden flight shortly after takeoff on 2 December 1945. Handley Page's chief test pilot and the chief test observer were both killed. Development of the civil Hermes was delayed to resolve the instability that caused the accident to the first prototype, and the chance was taken to lengthen the second prototype, producing the HP 74 Hermes II (G-AGUB), first flying on 2 September 1947. Meanwhile, orders were placed on 4 February 1947 for 25 of the definitive HP 81 Hermes IV, fitted with a tricycle undercarriage and powered by 2,100 hp (1,570 kW) Bristol Hercules 763 engines, for BOAC and two HP Hermes V, powered by the Bristol Theseus turboprop engines. . Variants All 29 aircraft were built at Radlett Aerodrome, Hertfordshire, England. HP.68 Hermes I Prototype powered by four 1,650 hp (1,230 kW) Bristol Hercules 101 radial engines. One built. HP.74 Hermes II Prototype powered by four 1,675 hp (1,249 kW) Bristol Hercules 121 engines and a 13 ft (4.57 m) longer forward fuselage. One built. HP.81 Hermes IV Production aircraft with tricycle landing gear, powered by four 2,100 hp (1,570 kW) Bristol Hercules 763 engines. Twenty-five built. HP.81 Hermes IVa Hermes IV modified to use 100-octane fuel, with the engine redesignated Hercules 773. Most converted back to Hermes IV standard. HP.82 Hermes V Development aircraft with four 2,490 hp (1,860 kW) Bristol Theseus 502 turboprops. Two built.
