Sikorsky S-40

S-40
Sikorsky S-40 PanAm 1931
Role	Sesquiplane amphibious flying boat
National origin	United States
Manufacturer	Sikorsky Aircraft
First flight	1931
Introduction	19 November 1931
Primary user	Pan American
Number built	3
Unit cost	$125,000 in 1931
Developed into	Sikorsky S-42

The Sikorsky S-40 was an American sesquiplane amphibious flying boat built by Sikorsky in the early 1930s for Pan American World Airways.

Sikorsky designed the S-40 in response to a request from Juan Trippe, president of Pan American Airways, for a larger passenger carrying airplane. The S-40s could carry 38 passengers, a significant increase over the 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 its 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 three were built as Sikorsky was designing (during the maiden flight of the S-40) and building the more modern S-42 as a replacement aircraft.

A total of three aircraft were built by the Vought-Sikorsky Aircraft Division of the United Aircraft Corporation in Stratford, Connecticut. The three aircraft in the S-40 series were:

In 1935 a new version, the Sikorsky S-40A, was created by upgrading the original three aircraft. Their 575 hp (429 kW) Pratt & Whitney R-1860 Hornet B engines were replaced by smaller, heavily supercharged 660 hp (490 kW) R-1690 Hornet T2D1 engines, the landing gear was eliminated, and the maximum weight was slightly increased.

Passenger carrying service was initiated on the November 19, 1931, with a S-40 piloted by Charles Lindbergh, flying from Miami, Florida to the Panama Canal Zone with stops at Cienfuegos, Cuba; Kingston, Jamaica and Barranquilla, Colombia.

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