Short Cromarty

The Short N.3 Cromarty was a prototype British twin-engined biplane flying boat designed towards the end of the First World War. Only a single example was built, first flying in 1921 and being wrecked in 1922.

Development
In April 1917, the British Admiralty developed a requirement for a long-range patrol flying boat to work in support of the Fleet, and issued Specification N.3(b) (later re-issued as Air Ministry Specification XXX) to meet this need. This resulted in designs from Vickers (for the Valentia) and Shorts of Rochester, who although better known at the time for floatplanes, had gained experience of flying boats building Felixstowe F.3 and F.5s under license from April 1917.

Short Brothers received an order for three prototypes just after the Armistice ended the First World War. Short's design, the N.3 Cromarty, was a large, twin engine biplane. It was powered by two 650 hp Rolls-Royce Condor engines, and had a similar, but larger hull to that of the Felixstowe flying boats, with a biplane tail. It featured a side-by-side cockpit for the two pilots, a large box cockpit for a gunner, who was armed with a COW automatic cannon, and a dorsal position for another gunner armed with a Lewis gun.

Production of the prototypes started in February 1919, but the second and third were cancelled before completion, with the first prototype eventually being launched in March 1921, being first flown on 11 April 1921.

Operational history
After extensive testing, the Cromarty was handed over to the RAF's Seaplane Development Flight on 17 June 1922. In August, the Flight, comprising the Cromarty, two Felixstowe F.5s and a Phoenix Cork set out on trials of operating large flying boats away from support faciliites for extended periods of time. Arriving at St Mary's, Isles of Scilly on 21 August, the Cromarty successfully weathered out a storm, but was taxied onto a reef, holing the hull. The damage was declared uneconomic to repair and the Cromarty was scrapped in place.

While the Cromarty had performed well in its limited service, one problem (as with all wooden hulled flying boats) was soakage of water into the hull, with as much as 600 lb of water absorbed after a few weeks of service. Tests with a metal-hulled Felixstowe F.5 resulted in an order for a prototype of an improved, metal-hulled flying boat based on the Cromarty. This became the prototype Short Singapore I.