Short Empire S.30 Mk I

The S.30 series replaced the Pegasus with four Bristol Perseus XIIc sleeve valve engines. Each Perseus was 85 lb lighter than the engine it replaced and 17.3 per cent more fuel efficient, though it developed less power. Fuselage and wings were strengthened with heavier gauge sheeting. Maximum take-off weight rose to 46,000 lb — 21,000 kg — with a corresponding range of 2,400 km, and overall performance stayed similar to the preceding S.23s.

The first S.30 was registered G-AFCT and named Champion. In December 1938 the second, G-AFCU, named Cabot, flew. The last three aircraft of that order, initially named Captain Cook, Clare and Aotearoa, were renamed and re-registered for use by TEAL. In 1939 a final S.30 was ordered, registered G-AFKZ and named Cathay, delivered to Imperial Airways in late March 1940.

Four S.30s — Cabot, Caribou, Clyde and Connemara — were equipped with in-flight refuelling equipment and extra fuel tanks for a scheduled transatlantic airmail service. The procedure was to take off light and, once airborne, take on extra fuel to reach an all-up weight of 53,000 lb, giving a range of over 2,500 miles. The extra fuel reduced payload to 4,270 lb against the 6,250 lb of the standard aeroplane. Refuelling was performed by three converted Handley Page Harrow bombers, one operating out of Ireland and two out of Newfoundland.

The S.30 series split into sub-marks: besides this Mk I, the material documents an S.30 Mk I (Cathay) with Pegasus Xc rather than Perseus engines, an S.30 Mk II New Zealand, the Mk III Atlantic and the Mk IV New Zealand. Nine S.30s were built in total.