Pan Am Sikorsky S40 and S42 seaplanes

Sikorsky S40 art

S42 undergoing maintenance in Florida (State Archives of Florida)

A 1936 illustration for "Fortune" magazine.

The Sikorsky S40 four-engine clipper was produced in three units in 1931 for Pan Am, the largest commercial airliner of the time. The S-40s could carry 38 passengers, a significant increase over the predecessor S-38's capacity of eight passengers. The aircraft featured a pantry with an electric refrigerator and stove as well as beautifully appointed smoking lounge with book-ended mahogany wood paneling. Six life rafts were carried on board. Despite the significant capacity increase, the S-40s were not the most aerodynamic aircraft due in large part to the numerous flying wires and strut braces that were used as an exterior support framework, hence the nickname "Flying Forest". Only the three were built as Sikorsky was designing (during the maiden flight of the S-40) and building the better S-42 as a replacement, introduced in 1934.

The ten S42 four-engine clippers were important for Pan American in developing its system of global routes. The S42 carried up to 37 day passengers or 14 sleeper berths plus 4 crew and had a gross laden weight of 38,000 lb (17,273 kg). It was used on Latin American, Atlantic and Pacific routes by the U.S. international airline.   In 1935 a Pan Am Sikorsky S-42 flying boat took off from San Francisco in the first commercial flight from the US mainland to Hawaii, landing 17 hours later. None has survived.  more pics here