Sikorsky S-45 Flying Boat
Only Boeing showed any interest in Trippe's 1936 competition. Their design would result in the most successful flying boat in history, the Boeing 314. Igor Sikorsky, irritated by Trippe's cavalier treatment, declined to submit another money-losing spec flying boat bid without some kind of prospect of recovering development costs.
In 1938, Sikorsky designed a six engined large flying boat project for Pan-American service. Designed in 1939-1941 to carry 100 passengers in comfort but never built. First-class passengers were to be accommodated in state rooms. The design of this aircraft started before the design of the S-44 (XPBS-1) was initiated.
The 1938 competition was between the Sikorsky S-45 and the Boeing 314. Sikorsky's S-45 of 87,000 pounds was a markedly superior proposal. As a bare airplane it was 34,930 pounds, disposable load 52,070, the basic ratio a startling 59:41. The S-45 was never built, so it cannot be known if Sikorsky would have made good on these figures. But his weight control was among the best in the industry, and he had a record of "going one better." Charles Lindbergh, technical adviser to PanAm, appreciated this, and he objected vigorously to the selection of the Boeing 314. Lindbergh was puzzled by PanAm's settling for less than the best.
The S-45 design was iterated many times between 1938 and 1940. A drawing dated March 15, 1938, depicted the S-45 as having a wing span of 236 feet, a one step hull, a length of 155.5 feet, a height of 25.75, and a three fin tail with a horizontal surface 43 feet wide. The aircraft was designed to carry 100 passengers or a payload of 25,000 pounds, with a range of 5,000 miles and a speed of 200 mph. A drawing published on 06 April 1939 showed the Sikorsky S-45 North Atlantic project as a very large aerodynamically-clean high-wing cantilever monoplane with six engines. The drawing depicted the S-45 as having a wing span of 210 feet, a length of 125 feet, a three fin tail, and a gross takeoff weight of 210,000 pounds.
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