Sikorsky S-42

S-42
Role	Flying boat airliner
National origin	United States
Manufacturer	Sikorsky Aircraft
Designer	Igor Sikorsky
First flight	March 30, 1934 (prototype)
Introduction	1934
Status	Retired, none remaining
Primary user	Pan American Airways
Number built	10
Developed from	Sikorsky S-40

The Sikorsky S-42 was a 1930s commercial flying boat designed and built by Sikorsky Aircraft to meet a 1931 requirement from Pan American World Airways (Pan Am) for a long-range transatlantic flying boat.

Design and development

Based on the earlier Sikorsky S-40 that flew in 1931, Igor Sikorsky and Charles Lindbergh (who was working at the time as a consultant to Pan American Airways) laid out plans for a new, larger flying boat. During the S-40's inaugural flight on November 19, 1931, the two visionaries began preliminary sketches on the back of a menu in the S-40's lounge.^{[citation needed]}

Pan Am's president, Juan Trippe, had a similar vision of an aircraft able to span oceans. The new design provided for an increased lifting capacity to carry enough fuel for a 2,500 mi (4,000 km) nonstop flight against a 30 mph (48 km/h) wind, at a cruising speed far in excess of the average operating speed of any flying boat at that time.^{[citation needed]} Pan Am was also courted by Glenn Martin, but Sikorsky's S-42 was delivered first, as the Martin M-130 was still almost a year away from completion.

Operational history

Sikorsky S-42, aircraft registration NC-822M, "Brazilian Clipper", Pan American Airways, 1934

Flying for Pan American Airways, a total of 10 S-42s were built, manufactured by the Vought-Sikorsky Aircraft Division of the United Aircraft Corporation in Stratford, Connecticut. The prototype first flew on March 30, 1934.

The S-42 only served with Pan American Airways. It was used on many routes, including the San Francisco - Hawaii, New York - Bermuda, and Hong Kong -China^{[citation needed]}. The S-42 named the Pan Am Clipper was used to survey the route from the US West Coast to China, making the first survey flight from Alameda, California to Pearl Harbor, Hawaii in April 1935.

The S-42 was also known as the Flying Clipper and the Pan Am Clipper.

British Marine Aircraft Ltd. was formed in February 1936 to produce S-42-A flying boats under licence in the United Kingdom but nothing came of this. The company built a factory on the western side of the Hamble peninsula with a slipway to Southampton Water. When the deal fell through the company was sold to Henry Folland, who renamed it Folland Aircraft Limited.

In 1938 and 1939, this type of flying boat was the only one known to land in the Kingman Reef (on its journey between Hawai'i and American Samoa).

All Sikorsky S-42s were either scrapped or destroyed in accidents.

Variants

A PAA S-42 taking off.

S-42

Production aircraft with four 700 hp (522 kW) Pratt & Whitney Hornet S5D1G radial engines, three built: NC 822M, NC 823M, NC 824M.

S-42A

Production aircraft with four 750 hp (559 kW) Pratt & Whitney Hornet S1EG radial engines, longer wings and a 2,000 lb (907 kg) increase in maximum takeoff weight, four built: NC 15373, NC 15374, NC 15375, NC 15376.

S-42B

Production aircraft with aerodynamic improvements, constant-speed Hamilton Standard propellers and a further 2,000 lb (907 kg) increase in maximum takeoff weight, three built: NC 16734, NC 16735, NC 16736.

British Marine BM-1

Proposed licence-built variant of the S-42A, not built.

Accidents and incidents

On January 11, 1938, a Sikorsky S-42, named the Samoan Clipper (formerly Pan American Clipper II) and operating as Pan Am Flight 1, exploded over Pago Pago. The flying boat developed an engine problem shortly after takeoff. The pilot elected to dump fuel before making an emergency landing, but due to the weight of the aircraft, the flaps were fully extended to maintain lift while fuel dumping was in progress. This method of fuel dumping had not been tested by Sikorsky and Pan Am; eventually, the fuel/air mixture created by the airflow over the wings extended to the exhaust manifold, which led to a catastrophic detonation that destroyed the aircraft in flight. All seven crew members (including famous aviator, Captain Ed Musick), died in the crash.

On July 27, 1943, a Pan Am Sikorsky S-42B named the Bermuda Clipper (formerly Pan American Clipper III) caught fire while docked at Manaus; there was no one on board.

On August 8, 1944, a Sikorsky S-42, named the Hong Kong Clipper (formerly West Indies Clipper and Pan Am Clipper I) and operating as Pan Am Flight 218 on a return trip from San Juan to Miami with intermediate stops at Port-au-Prince and Antilla, Cuba, crashed shortly after taking off from Antilla. After striking, bow first, the flying boat left the water in a slightly nose-high attitude, then returned, and by the third time, stalled. There were 17 fatalities (all passengers) out of the 26 passengers and five crew.

Surviving examples

Sikorsky S-42 NC823M is fully submerged near Antilla airport (MUAT) in Cuba. It crashed in 1944 during takeoff, the aircraft striking the water with such force as to cause the hull to fracture and completely separate at a point just aft of the pilot's compartment. There are no plans to recover the wreck.

Another sunken wreck is located near Botwood, Canada, which was one of the stops on Pan Am's trans-Atlantic Clipper service. The Avalon Historical Aircraft Recovery Association is looking for this S-42.

Specifications (S-42-A)

Data from Sikorsky S-42 Clipper Data SheetFlying Boat, 1934

General characteristics

• Crew: 4
• Capacity: up to 37 day passengers or 14 sleeper berths
• Length: 68 ft (20.73 m)
• Wingspan: 118 ft 2 in (36.03 m)
• Height: 17 ft 5 in (5.3 m)
• Wing area: 1,329 ft² (123.5 m²)
• Empty weight: 19,764 lb (8,984 kg)
• Loaded weight: 38,000 lb (17,273 kg)
• Powerplant: 4 × Pratt & Whitney R-1690 Hornet, supercharged radial engine, 660 hp (492 kW) each

Performance

• Maximum speed: 188 mph (300 km/h)
• Range: 1,930 miles (3,088 km)
• Service ceiling: 15,704 ft (4,788 m)
• Rate of climb: 1,000 ft/min (305 m/min)
• Wing loading: 28.6 lb/ft² (140 kg/m²)
• Power/mass: 0.07 hp/lb (0.11 kW/kg)

See also

• Samoan Clipper

Related development

• Sikorsky S-40

Aircraft of comparable role, configuration and era

• Boeing 314
• Martin M-130
• Short Empire

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

• Sikorsky S-42 photos and history
• Sikorsky S-42
• "Atlantic Routine," Flight 1937, contemporary article on S42 and British Caledonian operating across Atlantic
• "The Long-Range Flying Boat, Its Development and Characteristics: A Precis of a Lecture Delivered by Igor Sikorsky," in Flight, 1934 article on the S-42 design
• "Thirty-Two Passenger Flying Boat Meets First Tests," Popular Science Monthly, June 1934, article bottom of p. 37
• "Giant Plane to Cut U.S. - Argentine Time" Popular Mechanics, October 1934, cutaway drawings of purposed S-42, pp. 488–489
• "Sikorsky Sees Dawn to Dusk Trans-Atlantic Flight by Airliners" Popular Mechanics, January 1935, pp. 44-46
• "Pan Americans Flying Boat the Sikorsky S-42", YouTube 3.33 minutes, excellent rare photos of S-42 in service