Experimental piggy-back long-range seaplane/flying boat combination, produced by the Irish-based British Short Brothers aviation company, to provide a reliable long-range air transport service to North America and, potentially, to other distant places in the British Empire and the Commonwealth.
The idea was based around the concept of aircraft having the capacity of maintain flight with a greater payload than that possible during takeoff, and so, it involved a small, long-range seaplane, the
Short S.20 Mercury, on top of a larger carrier aircraft, the Short S.21 Maia, using the combined power of both to bring the smaller aircraft to operational height, at which time the two aircraft would separate, the carrier aircraft returning to base while the other flew on to its destination.
The complexity of the whole operation, coupled with the arrival of bigger, longer-ranged boats, waned interest in the project, and the start of WW2, in which Maia was destroyed in a German air raid, killed it for good.
Tupolev ANT-22 or MK-1 with six 619kW M-34R engines was a long-range bomber reconnaissance flying-boat, its twin-hull design clearly inspired by the Italian Savoia-Marchetti S.55. Test flown for the first time on 8 August 1934, it established several weight-to-height world records in December 1936, but was abandoned soon afterwards.
French flying boat of the interwar, designed for maritime reconnaissance and target spotting for naval artillery, 125 units built, used in WW2 by both the French Navy and the Kriegsmarine after the fall of France.
SNCASE-SE-200 The Sud-Est SE.200 Amphitrite (named after Amphitrite) was a flying boat airliner built in France in the late 1930s. It was a large, six-engine design with a high-set cantilever monoplane wing, and twin tails. It was developed in response to a French air ministry specification of 1936 for a transatlantic airliner for Air France with a range of 6,000 km (3,700 mi) and capacity for 20 passengers and 500 kg of cargo.