Sikorsky S-40

S-40
Sikorsky S-40 PanAm 1931
Role	amphibious flying boat
National origin	United States
Manufacturer	Sikorsky Aircraft
First flight	1931
Primary user	Pan American
Number built	3
Developed into	Sikorsky S-42

The Sikorsky S-40 was an American amphibious flying boat built by Sikorsky in the early 1930s for Pan American World Airways at a cost of $250,000, it was the largest commercial airliner of its time and the world's largest amphibious aircraft.

Design and development

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 onboard. 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:

• NC80V - Caribbean Clipper
• NC81V - American Clipper
• NC752V - Southern Clipper

Operational history

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.

The S-40 was Pan American's first large flying boat. The American Clipper served as the flagship of Pan Am's clipper fleet and this aircraft model was the first to earn the popular designation of "Clipper" or "Pan Am Clipper". The three S-40s served without incident during their civilian lives, flying a total of over 10 million miles. They were turned over to the US Navy during World War II and were used as trainers for four-engined flight instruction. All three of the S-40s were eventually retired and scrapped starting in 1943.

Specifications (S-40)

General characteristics

• Crew: four
• Capacity: 40 passengers
• Length: 76 feet 8 inches (23.37 m)
• Wingspan: 114 feet 0 inches (34.75 m)
• Height: 23 feet 10 inches (7.26 m)
• Wing area: 1,875 square feet (174.2 m²)
• Empty: 24,748 pounds (11,226 kg)
• Loaded: 34,000 pounds (15,000 kg)
• Maximum takeoff: lb (kg)
• Powerplant: 4x Pratt & Whitney R-1690 radial engines, 575 hp (429 kW) each

Performance

• Maximum speed: 135 miles per hour (217 km/h)
• Range: 875 miles (1,408 km)
• Service ceiling: 13,000 feet (4,000 m)
• Rate of climb: ft/min (m/min)
• Wing loading: 18 lb/ft² (89 kg/m²)
• Power/Mass: 0.07 hp/lb (0.11 kW/kg)

See also

Related lists

• List of seaplanes and flying boats
  

References

Notes

Bibliography

• Davies, R.E.G. Pan Am: An Airline and its Aircraft. New York: Orion Books, 1987. ISBN 0-517-56639-7.
• Yenne, Bill. Seaplanes & Flying Boats: A Timeless Collection from Aviation's Golden Age. New York: BCL Press, 2003. ISBN 1-932302-03-4.

External links

• "World's Largest Amphibian Takes Flight", Popular Science, October 1931
• Virtual Aircraft Museum
• The Sikorsky S-40 in the film Flying Down to Rio
• "Huge Amphibian Will Carry Forty-Six Passengers" Popular Mechanics, July 1931 article and photos of construction of first S-40.
• "This Sea Going Airliner Is Like A Clipper Ship", Popular Mechanics, September 1931, early cutaway drawing on announcement of construction
• "Luxuries Found In Air Travel On Huge U.S. Planes", Popular Mechanics, July 1932, interior of S-40 showing passenger accommodations