Sikorsky S-40 American Clipper

The Sikorsky S-40 was a large four-engine amphibious flying boat built for Pan American Airways and the first aircraft to wear the famous "Clipper" name. Designed by Igor Sikorsky and entering service in 1931, the S-40 was a luxurious airliner of its day, carrying up to 38 passengers in cabins fitted with a galley, electric refrigerator and a wood-paneled smoking lounge. Its strut-braced wing, twin booms and exposed engines gave it a distinctive, almost ungainly look, but it opened Pan Am's pioneering routes across the Caribbean to Central and South America.

The first scheduled flight, from Miami toward the Panama Canal Zone in November 1931, was flown by Charles Lindbergh. Only three S-40s were built, yet they proved that long, multi-leg overwater airline service was practical and set the stage for the more advanced S-42 and the legendary transoceanic Clippers that followed.