The Airplane - Jay Spenser [109]
Many nations would build a great variety of military and civil flying boats in the 1920s and 1930s. They tended to be larger machines than landplanes because they weren’t constrained by airfield lengths. But with engine development chronically lagging behind that of airframes, some of these flying boats turned out to be too big.
The Dornier Do X was the ultimate scaling up of metal-airplane pioneer Claudius Dornier’s flying-boat design formula. First flown in 1929, this giant transport was 131 feet (40 meters) long, had a 157-foot (48-meter) wingspan, and weighed a maximum of 105,000 pounds (48,000 kilograms). Power was supplied by twelve engines mounted front to back in six strut-supported nacelles atop the wing.
Tested on the Bodensee (Lake Constance), where Germany, Switzerland, and Austria meet, the Do X lifted 169 people in October 1929. Despite this feat, it was underpowered and performed so poorly that it could only cruise at low altitude. Luft Hansa (today Lufthansa) had no interest in the Do X, which likewise failed to find orders on a tour through the Americas at the start of the 1930s.
Advancing technology made this next decade the heyday of boat-hulled airplanes. Pan American Airways conquered first the Pacific with island-hopping services and then the Atlantic, using four-engine flying clipper ships built by Sikorsky, Martin, and Boeing. These audacious services pushed the era’s airplane range capabilities to the maximum.
Too heavy, the Dornier Do X of 1929 performed poorly despite twelve engines.
Museum of Flight, Seattle
Other flying boats also transported passengers before World War II, notably the Empire series developed by British manufacturer Short Brothers (today based in Northern Ireland). Created to link Britain with Africa, India, Australia, Singapore, and Hong Kong, these deep-bellied transports flew littoral routes, which provided opportunities for landings almost anywhere.
Short, Sikorsky, and most other flying boats featured floats mounted on the wings to keep them on an even keel in the water. In contrast, Pan Am’s Martin M-130s and Boeing 314s used Claudius Dornier’s excellent idea of sponsons, which are stub wings set low to also serve as floats, eliminating the need for drag-inducing wing floats.
The crowning culmination of the flying-boat era was the Boeing 314 Clipper, which entered service in 1939. Here was the finest and most capable flying boat of them all, a plane that could fly 3,600 miles (5,800 kilometers) at a stretch. In contrast, the Short Empire series flew 1,500 miles (2,414 kilometers) and could cross the Atlantic only when filled with so much fuel that no payload could be transported.
In an effort to fly airmail between England and North America on the eve of World War II, the British took to mounting a four-engine floatplane atop an even bigger four-engine flying boat, these being the Short Mercury and Short Maia, respectively. Collectively they were known as the Short Mayo composite aircraft. Imperial Airways used this cumbersome but successful system beginning in 1938. The Mayo would lift off from Foynes (today Shannon) on Ireland’s west coast. Once aloft and at altitude, the smaller Mercury would start its engines and—its tanks not depleted by the takeoff or climb—head west for a water landing at Montreal, Canada, some twenty hours later.
The Germans, who had inaugerated the world’s first aerial passenger services across the North and South Atlantic with dirigibles, had already pioneered a different kind of hybrid airmail service. In 1929, they began catapulting floatplanes off the decks of the Bremen and Europa when those liners were still far from their destinations. It shaved two days off the arrival of international mail.
Flying boats flew with many nations’ military services during and between the world wars. Growing in size and capability, these winged ships performed maritime patrol, antisubmarine warfare, air-sea rescue,