|S42 NC-822M, "Brazilian Clipper", 1934|
|Role||Flying boat airliner|
|National origin||United States|
|First flight||March 29, 1934 (prototype)|
|Status||Retired, none remaining|
|Primary user||Pan American Airways|
|Developed from||Sikorsky S-40|
The Sikorsky S-42 was a commercial flying boat designed and built by Sikorsky Aircraft to meet requirements for long-range flying boat laid out by Pan American World Airways (Pan Am) in 1931. The innovative design included wing flaps, variable-pitch propellers, and a tail-carrying full-length hull. The prototype first flew on 29 March 1934, and, in the period of development and test flying that followed, quickly established ten world records for payload-to-height. The "Flying Clipper" and the "Pan Am Clipper" were other names for the S-42.
Design and development
During the S-40's inaugural flight on November 19, 1931, the pilot and Pan American Airways consultant, Charles Lindbergh, who considered the S-40 a monstrosity, engaged designer Igor Sikorsky in a conversation about what he thought the next airplane should look like. The conversation continued that night at the hotel in Jamaica. Sikorsky argued that design development should be incremental and that the safe approach would be a larger S-40. Lindbergh argued for a sleeker design and that a still air range of 2,500 miles was necessary.
In June 1931 Pan Am president Juan Trippe had requested designs from six aircraft companies for an aircraft able to span the oceans. The new design would need increased lifting capacity to carry enough fuel and 300 pounds of mail, but no passengers, for a 2,500 miles (4,023 kilometers) nonstop flight against a 30 mph (48 km/h) wind, at a higher cruising speed than the norm for similar flying boats at that time. Of the six companies tenders had been sent to, only Sikorsky and Martin provided submissions. Sikorsky offered the S-42. The other offer was the more ambitious Martin M-130.
The new Sikorsky design, the S-42, had major aerodynamic improvements over the S-40. Igor Sikorsky said, "in its very outline the S-42 represents simplicity. Diverting sharply from the past Sikorsky designs, external bracings have been reduced to a minimum. The tail, instead of being supported by outriggers, is attached directly to the hull." The S-42 had a high wing loading which required flaps to provide acceptable take-off and landing speeds.  Though Lindbergh approved of the S-42, it fell far short of his proposed range Stripped of all accommodations, with extra fuel tanks in the fuselage, the S-42 was just able to fly proving flights across the Atlantic and Pacific oceans. Pan Am would have to wait for the Martin M-130 to have an airliner capable of flying the Pacific with a paying load.
Pan Am's S-42s were used primarily on the Miami - Rio de Janeiro route. In 1937 S-42s also operated a New York to Bermuda service. 1940 saw S-42 flights between Seattle and Alaska. An S-42s was also used between Manila and Hong Kong.
British Marine Aircraft Ltd. was formed in February 1936 to produce S-42A flying boats under license 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.
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 flew for Pan American Airways. The S-42 Pan Am Clipper surveyed the route from the US West Coast to China, making the first survey flight from Alameda, California to Pearl Harbor, Hawaii in April 1935. (It never flew scheduled passengers from California to Hawaii.)
In March 1939 a Pan Am S-42 was scheduled to leave Miami at 0730, stop overnight in San Juan, Port of Spain, Belem and Recife, and arrive Rio de Janeiro at 1530 on the fifth day. (It returned to Miami, and passengers to Buenos Aires continued on DC2/DC3s.)
All Sikorsky S-42s were either scrapped or destroyed in accidents.
- Production aircraft with four 700 hp (522 kW) Pratt & Whitney Hornet S5D1G radial engines, three built: NC 822M, NC 823M, NC 824M.
- 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.
- 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 April 11, 1936, a Pan Am S-42 named Puerto Rican Clipper crashed on takeoff from Port of Spain, killing three of 25 on board. The pilot swerved to avoid a fishing boat that was in his path but one pontoon struck the boat and the aircraft overturned.
On January 11, 1938, Pan Am Flight 1, an S-42 named Samoan Clipper (formerly Pan American Clipper II), exploded near Pago Pago. The flying boat developed an engine problem shortly after takeoff. The pilot elected to dump fuel before making an emergency landing, but the aircraft exploded while fuel dumping was in progress. All seven crew members (including famous aviator Captain Ed Musick), died in the crash.
February 19, 1939, Pan American S-42 NC 15376 "Dominican Clipper," while landing at San Juan, Puerto Rico, the aircraft bounced, then waterlooped, injuring one crew member and damaging the aircraft.
October 23, 1940. Pan Am S-42B NC 16735, Bermuda Clipper, waterlooped upon landing off Darrel's Island, Bermuda with little damage and minor injuries to passenger Mrs. Virginia Gilcaby.
On September 23, 1941, Pan Am S-42B, NC 15374, Antillies Clipper, received minor damage when the aircraft waterlooped following landing when the flaps were retracted. Biscayne Bay, Miami Florida.
On October 3, 1941, Pam Am Flight 203, an S-42A named Dominican Clipper, crashed on landing in the harbour at San Juan, Puerto Rico, killing two of 27 on board. After the approach to San Juan, the aircraft hit the water in a nose-low attitude while moving sideways; after the first contact the aircraft swerved violently to the right and broke apart.
On December 8, 1941, a Pan Am S-42B named Hong Kong Clipper II (formerly Bermuda Clipper and Alaska Clipper) was destroyed on the water at Kai Tak Airport, Hong Kong, during a Japanese bombing raid.
On August 8, 1944, Pan Am Flight 218, an S-42 NC 824M, named Hong Kong Clipper (formerly West Indies Clipper and Pan Am Clipper I) 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.
Sikorsky S-42 NC823M is fully submerged near Antilla airport (MUAT) in Cuba. It crashed in 1944 during takeoff, the aircraft striking the water and fracturing the hull just aft of the pilot's compartment. There are no plans to recover the wreck.
Data from Sikorsky S-42 Clipper Data SheetFlying Boat, 1934
- 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
- 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)
- Related development
- Aircraft of comparable role, configuration and era
- "The S-42, The Development and Characteristics of a Long-Range Flying Boat (A presentation by Igor Sikorsky to the Royal Aeronautical Society, London, 15 November 1934". Sikorsky Aircraft. Retrieved 7 December 2015.
- King, H.F. (1969). Milestones of the Air (McGraw-Hill ed.). New York: Jane's All the World's Aircraft Publishing Company. p. 80.
- Daley, Robert, An American Saga, 1980, Random House, New York, ISBN 039450223X, pages 102-103
- Delear, Igor Sikorsky: His Three Careers in Aviation, Dodd, Mead & Co., 1969
- Daley, Robert, An American Saga, 1980, Random House, New York, ISBN 039450223X, page 103
- Daley, Robert, An American Saga, 1980, Random House, New York, ISBN 039450223X, pages 109-110
- Delear, Igor Sikorsky: His Three Careers in Aviation, Dodd, Mead & Co., 1969
- Gunston, Bill, The Illustrated Encyclopedia of Propeller Airliners, 1980, Windward, London, ISBN 0711200629, page 86
- Daley, Robert, An American Saga, 1980, Random House, New York, ISBN 039450223X, pages 169-175
- Daley, Robert, An American Saga, 1980, Random House, New York, ISBN 039450223X, page 320
- Cruddas, Colin, In Hampshire's Skies, 2001, Tempus Publishing Limited, The Mill Brimscome Port. Stroud, Gloucestershire, GL5 2QG, ISBN 0 7524 2140 9, page 26
- Fagan, Dave. "Hamble." Aviation in Hampshire UK 1900 to 2000. Retrieved: July 5, 2009.
- "Clipper Conquers Pacific on Hawaiian Hops." Popular Mechanics, July 1935.
- Donnelley, James E. "The Crash of NC 15376." webstart.com. Retrieved: April 3, 2010.
- Accident description for NC824M at the Aviation Safety Network. Retrieved on 2014-6-24.
- "Statement of Probable Cause Concerning an Accident Which Occurred to an Aircraft of Pan American Airways Company near Pago Pago, Tutuila, Samoa, on January 11, 1938". Department of Commerce Bureau of Air Commerce. Retrieved December 14, 2015.
- "Clipper wrecked, all 7 fliers dead in sea after fire; Fragments of Big Flying Boat Are Found in Pacific 14 Miles From Her Pago Pago Base." The New York Times, 1938. Retrieved: December 12, 2011.
- "Accident involving aircraft NC 15376 of Pan American Airways, Inc., in the San Juan Harbor near San Juan, Puerto Rico, on February 19, 1939". Civil Aeronautics Board. Retrieved December 14, 2015.
- "Investigation of an Accident Involving Aircraft in Scheduled Air Carrier Operation". Civil Aeronautics Board. Retrieved December 14, 2015.
- "IREPORT OF THE CIVIL AERONAUTICS BOARD Of the investigation of an accident involving civil aircraft of the United States NC 15376 which occurred in San Juan Harbor, Puerto Rico, On October 3, 1941". Civil Aeronautics Board. Retrieved December 14, 2015.
- "Statement of Probable Cause an Accident Which Occurred to an Aircraft of Central Airlines, Incorporated, at Pittsburgh, Pennsylvania, on November 16 , 1935". Civil Aeronautics Board. Retrieved December 14, 2015.
- Accident description for NC15376 at the Aviation Safety Network. Retrieved on 2014-6-24.
- Accident description for NC16735 at the Aviation Safety Network. Retrieved on 2014-6-24.
- Accident description for NC16736 at the Aviation Safety Network. Retrieved on 2011-12-12.
- "Accident Investigation Report, August 8, 1944 Flight 218 of Pan American S-42 NC 823M". Civil Aeronautics Board. Retrieved December 14, 2015.
- Accident description for NC823M at the Aviation Safety Network. Retrieved on 2011-9-5.
- McKinney, Michael. "The First Clippers: The 'Sikorsky S-42." flyingclippers.com. Retrieved: April 3, 2010.
|Wikimedia Commons has media related to Sikorsky S-42.|
- 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