Tag Archives: Flying Boat

12 April 1918

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Malcolm and Allan Loughead in cockpit of their F-1 flying boat, 1918. (San Diego Air & Space Museum)

12 April  1918: Allan and Malcolm Loughead, owners of the Loughead Aircraft Manufacturing Company of Santa Barbara, California, set speed and distance records as they flew their twin-engine, ten-place F-1 flying boat from Santa Barbara to San Diego. The F-1 traveled 211 miles (340 kilometers) in 3 hours, 1 minute.¹

The F-1 took off from the waters off West Beach at Santa Barbara at 9:21 a.m., passed Point Fermin at 10:40 a.m., Oceanside at 11:55 a.m., and arrived at North Island at 12:23 p.m.² The airplane was flown by the two Loughead Brothers and carried two passengers.

The Southern California shorline from Santa Barbara, at the upper left, to San Diego, at the lower right. (Google Maps)

GREAT SEAPLANE MAKES RECORD ON FLIGHT

     SAN DIEGO, April 12.—The big seaplane F-1, piloted by Malcolm Loughead and carrying three passengers, arrived here at 12:23 this afternoon.

     The F-1 left Santa Barbara at 9:21 this morning and the estimated distance of 190 miles between that city and San Diego was therefore covered in exactly three hours and two minutes, a speed of approximately 63 1-3 miles an hour. The big seaplane was first sighted over Point Loma and within a few minutes alighted on the surface of San Diego Bay a short distance from the United States army aviation station at North Island. At 12:23 the seaplane reached the North Island landing and was hauled ashore by army men in waiting. According to Pilot Loughead, the trip was made without incident, although during the latter part of the trip headwinds were met with which retarded the speed of the aircraft.

————

     Three hours and two minutes by air flight to San Diego from Santa Barbara—that’s the record established today by Allan and Malcolm Loughead, in their big hydroplane, F-1, carrying as passengers Alfred Holt and Carl Christopherson, employees of the Loughead Aeroplane Manufacturing Company.

     The distance of 190 miles, by airplane, was made without mishap. The start from Santa Barbara gathered quite a group of citizens, among them being a number of stockholders in the Loughead company, and thousands would have been there to witness the notable start had it been known at what hour the flight would start.

     During the morning the Lougheads received a dispatch from government officials at the aviation headquarters on North Island, San Diego, informing them that air and ocean conditions were perfect all the way south, and asking that the flight be made today.

     The Lougheads were even at that moment getting ready for the departure, and arrangements were hastened. The bay was ruffled by a breeze, and the combers sparkled in the warm sunlight, as the hydroplane motors were started, and the big fans began to whirr. There were hasty farewells, and every man waved his hat and every woman present shook a kerchief, while the cheers broke forth from all as the big plane sped down the ways, and went skidding into the sea.

     At the wheels were Allan and Malcolm Loughead, while Christopherson and Holt occupied places in the passengers’ quarters at the head of the big plane. The machine was guided in a half circle, taking a southwesterly course at first, until beyond the pleasure pier, where it rose from the bosom of the sea, and rapidly ascended to an altitude of about 500 feet, when it took a southeasterly course, and heading down the channel toward Oxnard.

     It was a perfect get-away, and no bird ever took to the air more gracefully than the big plane rose above the sea and soared away, easily, the very hypothesis of graceful motion, and the speed at which it was travelling soon took it out of sight to the south.

     From Ventura and Hueneme the flight was witnessed by a large number of citizens, and at Point Fermin, near San Pedro, the passing of the plane attracted great interest. In fact, all the way south, great crowds watched eagerly and it was a continuous ovation that greeted the airmen from the land.

     At San Diego the fliers were met by a big crowd, and their stay in the southern city is being made one prolonged reception. From many points along the coast today telephone and telegraph messages have flashed, reporting the passing of the machine, whose eventful trip is the biggest sensation of the day in aviation circles.

     It is stated that the flight establishes a long distance record for a passenger-carrying hydroplane. The plane will be tested out by the government aviation officials, and it is expected that within a very few days the announcement will be made of a contract awarded the Loughead Brothers by the government for other machines.

     Experts who have examined the F-1 state that it is perfectly built, and the finest machine of its class afloat.     

—The Santa Barbara Daily News and the Independent, Friday, 12 April 1918, Page 1, Column 6

Loughead Aircraft Manufacturing Company F-1. (Lockheed Martin).

Designed by friend and employee John Knudson (“Jack”) Northrop, and built in a garage on State Street, the F-1 was launched on a wooden ramp at West Beach.

The airplane was intended for the U.S. Navy, but the end of World War I ended the requirement for new airplanes.

The Loughead F-1 was a twin-engine, three-bay biplane flying boat operated by a crew of 2. It could carry 8–10 passengers. The airplane was 35 feet (10.668 meters) long. The span of the upper wing was 74 feet (22.555 meters) and the lower wing was 47 feet (14.326 meters). The height was 12 feet (3.658 meters). The F-1 had an empty weight of 4,200 pounds (1,905 kilograms) and gross weight of 7,300 pounds (3,311 kilograms).

Loughead F-1 at Santa Barbara, 1918. (San Diego Air and Space Museum)
Loughead F-1 at Santa Barbara, 1918. (San Diego Air & Space Museum)

The F-1 was powered by two right-hand tractor, water-cooled, normally-aspirated 909.22-cubic-inch-displacement (14.899 liters) Hall-Scott A-5-engines. These were inline six-cylinder single-overhead-camshaft (SOHC) engines with a compression ratio of 4.6:1. It was rated at 150 horsepower and produced 165 horsepower at 1,475 r.p.m. The engines were mounted on steel struts between the upper and lower wings. The engines were direct-drive and turned two-bladed, fixed pitch propellers with a diameter of 8 feet, 8 inches (2.642 meters). The Hall-Scott A-5-a was 5 feet, 2.5 inches (1.588 meters) long, 2 feet, 0 inches (0.610 meters) wide and 3 feet, 7.875 inches (1.114 meters) high. It weighed 595 pounds (270 kilograms).

The F-1 had a cruise speed of 70 miles per hour (113 kilometers per hour) and maximum speed of 84 miles per hour (135 kilometers per hour).

The F-1 was converted to a land plane with tricycle undercarriage and redesignated F-1A. During an attempted transcontinental flight, it twice suffered engine failure and was damaged. Reconfigured as a flying boat, the airplane was used for sight-seeing before being sold. It was abandoned on a beach at Santa Catalina Island, off the coast of Southern California, and was eventually destroyed.

Loughead F-1, 1918. (San Diego Air & Space Museum)

The Loughead Aircraft Manufacturing Company would go on to become one of the world’s leading aerospace corporations.

¹ The certifying source for this “record” is not known. The distance flown and elapsed time for the flight cited here are from Wikipedia. The Great Circle distance from today’s Santa Barbara Airport (SBA) to NAS North Island (NZY) is 193 statute miles (311 kilometers). However, contemporary news reports suggest that the Loughead brothers flew the F-1 along California’s southern coastline, rather than making a direct flight across the Santa Barbara Channel, Santa Monica Bay, the Catalina Channel, and on to San Diego Bay. At the time of this flight, the governing body for aviation in the United States was the Aero Club of America, while official flight records were certified by the Fédération Aéronautique Internationale, which was based in France. The ACA ceased to exist in 1923, replaced by today’s National Aeronautic Association. The FAI online records database list only two world records set in 1918, both altitude records set by Major Rudolph Schroeder, 18 September 1918, at Dayton, Ohio.

² The Los Angeles Times, the Oakland Tribune and the San Bernardino Daily Sun state that the time of the takeoff was 9:23 a.m. The Tribune cites the arrival time as 12:24 p.m., while the Daily Sun reported the time as both 12:32 and 12:24. Various newspapers reported the distance flown by the F-1 as 190 miles (306 kilometers), while The Salt Lake Herald-Republican-Telegram printed that it was 200 miles (322 kilometers).

© 2023, Bryan R. Swopes

5 April 1950

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Martin JRM-3 Mars Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)
Martin JRM-3 Mars Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)

While on a test flight following an engine change, a United States Navy Martin JRM-3 Mars seaplane, Marshall Mars, Bu. No. 76822, suffered an engine fire (inboard, left wing) and made an emergency landing at Ke’ehi Lagoon, off Diamond Head, Hawaii, 5 April 1950. The airplane’s crew was rescued but the airplane exploded and sank.

The wreck was discovered on the sea floor in August 2004 at a depth of approximately 1,400 feet (427 meters).

The Martin JRM Mars was a large four-engine flying boat transport built by the Glenn L. Martin Company for the U. S. Navy. originally designed as a patrol bomber, the prototype XPB2M-1 Mars made its first flight on 3 July 1942, Only five transport variants were built, four designated JRM-1, with the last one being a JRM-2. Each airplane was given an individual name derived from the names of island chains in the Pacific Ocean: Marianas Mars, Hawaii Mars, Philippine Mars, Marshall Mars and Caroline Mars. These airplanes were used to transport personnel and cargo between the West Coast of the United States and the Hawaiian Islands. All were upgraded to JRM-3.

Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)
Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)

The Martin JRM-2 Mars had a normal crew of 4, with accommodations for a relief crew. It was designed to carry 138 combat troops or 34,000 pounds (15,422 kilograms) of cargo. It was 120 feet, 3 inches (36.652 meters) long with a wingspan of 200 feet, 0 inches (60.960 meters) and height of 43 feet, 8 inches (13.310 meters), with beaching gear. The wing area was 3,686 square feet (342.4 square meters). The flying boat had an empty weight of 80,701 pounds (36,605 kilograms) and a maximum takeoff weight (MTOW) 0f 165,000 pounds (74,843 kilograms).

Martin JRM-2 Mars three-view illustration with dimensions. (U.S. Navy)

A NASA publication states, “A zero-lift drag coefficient of 0.0233 and a maximum lift-drag ratio of 16.4 made the JRM the most aerodynamically efficient of any of the flying boats. . . .”

Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)
Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)

The Martin Mars was powered by four air-cooled, supercharged, direct-fuel-injected, 3,347.662-cubic-inch-displacement (54.858 liter) Wright Aeronautical Division R-3350-24WA (Cyclone 18 825C18BD1) (also known as the Duplex-Cyclone), a two-row 18-cylinder radial engines with a compression ratio of 6.70:1 and water/alcohol injection. This engine has a normal power rating of 2,000 horsepower at 2,400 r.p.m at 5,500 feet (1,676 meters) and 1,800 horsepower at 2,400 r.p.m. at 15,000 feet (4,572 meters). The engine’s takeoff power rating is 2,500 horsepower at 2,900 r.p.m. 100/130 octane aviation gasoline was required. The engines drove four-bladed 16 foot, 8 inch (5.080 meter) Curtiss Electric variable-pitch propellers through a 0.4375:1 gear reduction. (After modification to the JRM-3, the propellers on the inboard engines were reversible.) The R-3350-24WA is 6 feet, 8.58 inches (2.047 meters) long, and 4 feet, 6.13 inches (1.375 meters) in diameter. Its dry weight is 2,822 pounds (1,280 kilograms).

The JRM-3 had a cruise speed of 165 knots (190 miles per hour/306 kilometers per hour) and a maximum speed of 211 knots (243 miles per hour/391 kilometers per hour) at 15,600 feet (4,755 meters). The service ceiling was 19,700 feet (6,005 meters) and its range was 3,790 nautical miles (4,361 statute miles/7,019 kilometers).

A U.S. Navy Martin JRM Mars. (Glenn L. Martin Co.)
A U.S. Navy Martin JRM Mars. (Glenn L. Martin Co.)

© 2019, Bryan R. Swopes

30 March 1934

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Sikorsky S-42 NC822M, Brazilian Clipper, first of three of the initial S-42 variant. (NASM)

30 March 1934: At Bridgeport, Connecticut, Sikorsky Aircraft Company test pilot Boris Vasilievich Sergievsky made the first flight of the prototype Sikorsky S-42, a large, four-engine flying boat which had been designed for long range passenger and cargo flights.

In discussions with Igor Sikorsky, Charles A. Lindbergh, acting as technical advisor to Pan American Airways System, the two aviation icons established the specifications for a new flying boat. The new airplane would be a significant improvement over Sikorky’s previous S-40.

The Hartford Courant reported:

New Giant Sikorsky Tries Its Wings

Sikorsky S-42 (Associated Press Photo)

    Bridgeport.  March 30.—(AP)—America’s greatest passenger plane, the S-42, destined for the South American service, took to the air for the first time and passed two test flights with flying colors.

     Once for 10 minutes, and again for a longer period, the giant flying boat hovered over Long Island Sound and its shore. Captain Boris Sergievsky, accompanied only by a lone mechanic, was at the controls.

     “Congratulations, sir,” Igor Sikorsky, designer of the plane, hailed the pilot as he came ashore after the flights.

     “The congratulations,” Captain Sergievsky replied, “are yours, sir.”

     “I am very pleased with the results,” Sikorsky said. “It was most thrilling to see the ship take off. Everything seems excellent.”

     Frederick W. Neilsen, president of the Sikorsky Aviation Corporation, who watched the flights with Sikorsky and hundreds of residents of Bridgeport and shore towns, said, “The tests were most successful and we are all pleased.”

     The ship, built for Pan American Airways on specifications by Colonel Charles A. Lindbergh, technical advisor for the line, is the first of six such planes to be completed for Pan American.

     Powered with four engines, it is 76 feet long, has a span of 114 feet 2 inches, and a gross weight of 38,000 pounds. It will be fitted with 32 passenger seats, and will have a non-stop range of 1200 miles with a full complement of passengers, five members of the crew and 1000 pounds of mail.

—The Hartford Courant, Vol. XCVII, Saturday, 31 March 1934, Page 18, Columns 4 and 5

Interior of a Sikorsky S-42. (NASM)

The Sikorsky S-42 was a four-engine long-range flying boat built for Pan American Airways by the Vought-Sikorsky Aircraft Division of United Technologies at Stratford, Connecticut. It was 67 feet, 8 inches (20.625 meters) long with a wingspan of 114 feet, 2 inches (34.798 meters). The S-42 had an empty weight of 18,236 pounds (8,272 kilograms) and gross weight of 38,000 pounds (17,237 kilograms). It could carry up to 37 passengers.

A Pan American Airways Sikorsky S-42.

The S-42 was powered by four air-cooled, supercharged, 1,690.537-cubic-inch-displacement (27.703 liters) Pratt & Whitney Hornet S1E-G nine-cylinder radial engines with a compression ratio of 6.5:1. The S1E-G had a Normal Power rating of 750 horsepower at 2,250 r.p.m., to 7,000 feet (2,134 meters), and 875 horsepower at 2,300 r.p.m., for Takeoff. The engines drove three-bladed Hamilton Standard constant-speed propellers through a 3:2 gear reduction. The S1E-G was 4 feet, 1.38 inches (1.254 meters) long, 4 feet, 6.44 inches (1.383 meters) in diameter, and weighed 1,064 pounds (483 kilograms).

Boris Vasilievich Sergievsky

The S-42 had a cruise speed 165 miles per hour (266 kilometers per hour) and maximum speed of 188 miles per hour (303 kilometers per hour) at 5,000 feet (1,524 meters). The service ceiling was 16,000 feet (4,877 meters). It could maintain 7,500 feet (2,286 meters) with three engines. Its range was 1,930 miles (3,106 kilometers).

During flight testing of the S-42, Boris Sergievsky, with co-pilot Raymond B. Quick, set three Fédération Aéronautique Internationale world records for payload and altitude.¹  Later, Captain Edwin Musick, with Sergievsky and Charles Lindbergh, flew the S-42 to set eight Fédération Aéronautique Internationale world records for speed.²

Ten Sikorsky S-42, S-42A and S-42B flying boats were built for Pan Am. None remain in existence.

A Pan American Airways Sikorsky S-42, NC16734, moored at Honolulu, Territory of the Hawaiian Islands. (hawaii.gov/hawaiiaviation)

¹ 26 April 1934 FAI Record File Numbers: 11583: Greatest load to 2,000 meters (6,562 feet): 7,533 kilograms (16,652 pounds). 17 May 1934: 11582 and 11978: Altitude with a 5,000 Kilogram (11,023 pounds) Load, 6,220 meters (20,407 feet).

² 1 April 1934 FAI Record File Numbers: 11517: Speed over a closed circuit of 1,000 Kilometers (621.3 statute miles), 253,60 km/h (157.58 m.p.h.); 11518: . . . with a 500 Kilogram (1,102 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11519: . . . with a 1,000 Kilogram (2,205 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11520: . . . with a 2,000 kilogram (4,409 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11521: Speed over a closed circuit of 2,000 Kilometers (1,242.7 statute miles), 253,18 km/h (157.32 m.p.h); 11522: . . . with a 500 Kilogram Payload, 253,18 km/h (157.32 m.p.h.); 11523: . . . with a 1,000 Kilogram Payload, 253,18 km/h (157.32 m.p.h.); 11524: . . . with a 2,000 Kilogram Payload, 253,18 km/h (157.32 m.p.h.).

© 2019, Bryan R. Swopes

11 January 1938

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A Pan American Airways Sikorsky S-42.
A Pan American Airways Sikorsky S-42.

11 January 1938: Pan American Airways’ Sikorsky S-42B NC16734, Samoan Clipper, took off from Pago Pago, American Samoa, enroute Auckland, New Zealand. The airplane had a crew of seven, commanded by Captain Edwin C. Musick, the airline’s senior pilot, and a cargo of mail.

About two hours out, the number four engine began leaking oil. Captain Musick ordered the engine shut down. The flight radioed that they were returning to Pago Pago. They never arrived. Wreckage, a large oil slick, various documents and articles of the crew’s clothing were found by the U.S. Navy seaplane tender USS Avocet (AVP-4), 14 miles (22.5 kilometers) west of the island. It was apparent that the S-42 had exploded in mid-air.

The cause of the explosion is not known with certainty but based on Captain Musick’s handling of a similar problem with one of  Samoan Clipper‘s  engines on an earlier flight, a possible cause can be suggested.

Pan American Airways’ Samoan Clipper. (Hawaii Aviation)

On the earlier flight, the number four engine had begun seriously overheating and Musick ordered the flight engineer to shut it down. Because of the decreased power with only three engines, Captain Musick ordered the crew to begin dumping fuel to decrease the weight of the airplane before landing.

Pan American had tested the fuel dumping characteristics of the Sikorsky S-42 using dye, and had learned that because of the air flow patterns around the wings, the fluid tended to accumulate around the trailing edge of the wings and that it could actually be sucked into the wings themselves.

As fuel was being dumped on the previous flight, fuel vapors were present in the cabin, requiring all electrical systems to be shut off—even though it was night. Liquid gasoline was also dripping into the cockpit from the wing above.

Pan American Airways’ Sikorsky S-42B NC16734 at Pago Pago, 24 December 1937. (Unattributed)

Samoan Clipper had been very heavy with fuel when it departed for the long transoceanic flight to Auckland. Presuming that Captain Musick once again ordered fuel to be dumped prior to landing back at Pago Pago, and that the vapors collected around the wings, the fuel could have been detonated by the electrical motors which were used to lower the flaps for flight at slower speed, or by coming into contact with the hot exhaust of the engines.

Two independent investigations were carried out by Pan American and by the United States Navy, and both came to this conclusion.

Captain Edwin Charles Musick, Chief Pilot, Pan American Airways. (1894–1938)

There were no survivors of the explosion. Killed along with Captain Musick were Captain Cecil G. Sellers, Second Officer P.S. Brunk, Navigator F.J. MacLean, Flight Engineer J.W. Stickrod, Flight Mechanic J.A. Brooks and Radio Operator T.D. Findley.

The Sikorsky S-42B was a four-engine long-range flying boat built for Pan American Airways by the Vought-Sikorsky Aircraft Division of United Technologies at Stratford, Connecticut. It was 68 feet (20.726 meters) long with a wingspan of 118 feet, 2 inches (36.017 meters). The S-42 had an empty weight of 19,764 pounds ( kilograms) and gross weight of 38,000 pounds ( kilograms). It could carry up to 37 passengers.

The S-42B was powered by four air-cooled, supercharged, 1,690.537-cubic-inch-displacement (27.703 liters) Pratt & Whitney Hornet S1E-G nine-cylinder radial engines with a compression ratio of 6.5:1. The S1E-G had a Normal Power rating of 750 horsepower at 2,250 r.p.m., to 7,000 feet (2,134 meters), and 875 horsepower at 2,300 r.p.m., for Takeoff. The engines drove three-bladed Hamilton Standard constant-speed propellers through a 3:2 gear reduction. The S1E-G was 4 feet, 1.38 inches (1.254 meters) long, 4 feet, 6.44 inches (1.383 meters) in diameter, and weighed 1,064 pounds (483 kilograms).

The S-42B has a cruise speed 165 miles per hour (266 kilometers per hour) and maximum speed of 188 miles per hour (303 kilometers per hour) at 5,000 feet (1,524 meters). The service ceiling was 16,000 feet (4,877 meters), and it could maintain 7,500 feet (2,286 meters) with three engines. Its range was 1,930 miles (3,106 kilometers).

Boris Vasilievich Sergievsky. (Test & Research Pilots, Flight Test Engineers)

During flight testing of the S-42, Sikorsky test pilot Boris Vasilievich Sergievsky, with co-pilot Raymond B. Quick, set three Fédération Aéronautique Internationale world records for payload and altitude.¹  Later, Captain Musick, with Sergievsky and world-famous aviator Charles A. Lindbergh, flew the S-42 to set eight Fédération Aéronautique Internationale world records for speed.²

Ten Sikorsky S-42, S-42A and S-42B flying boats were built for Pan Am. None remain in existence.

Pan American Airways' Sikorsky S-42B NC16734, Samoan Clipper, moored at mechanic's Bay, Auckland, New Zealand, December 1937. The flying boat in the background is a Short S.23 Empire, G-ADUT, named Centaurus. (Turnbull Library)
Pan American Airways’ Sikorsky S-42B NC16734, Samoan Clipper, moored at Mechanic’s Bay, Auckland, New Zealand, December 1937. The flying boat in the background is a Short S.23 Empire, G-ADUT, named Centaurus. (Turnbull Library)

¹ 26 April 1934 FAI Record File Numbers: 11583: Greatest load to 2,000 meters (6,562 feet): 7,533 kilograms (16,652 pounds).  17 May 1934: 11582 and 11978: Altitude with a 5,000 Kilogram (11,023 pounds) Load, 6,220 meters (20,407 feet).

² 1 April 1934 FAI Record File Numbers: 11517: Speed over a closed circuit of 1,000 Kilometers (621.3 statute miles), 253,60 km/h (157.58 m.p.h.); 11518:  . . .  with a 500 Kilogram (1,102 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11519:  . . . with a 1,000 Kilogram (2,205 pounds) Payload, 253,60 km/h (157.58 m.p.h.);  11520: . . . with a 2,000 kilogram (4,409 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11521: Speed over a closed circuit of 2,000 Kilometers (1,242.7 statute miles), 253,18 km/h (157.32 m.p.h); 11522:  . . . with a 500 Kilogram Payload, 253,18 km/h (157.32 m.p.h.); 11523:  . . . with a 1,000 Kilogram Payload, 253,18 km/h (157.32 m.p.h.); 11524: . . . with a 2,000 Kilogram Payload, 253,18 km/h (157.32 m.p.h.).

© 2019, Bryan R. Swopes

10 January 1935

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“L’ hydroavion Latécoère 521 Lieutenant-de-Vaisseau-Paris à six moteurs Hispano-Suiza, type 12 Ydrs1, 880 CV.” (Cliché N.Y.T./Revue & Bulletin Technique de la Société Française Hispano-Suiza)

10 January 1935: At Biscarosse, on the Atlantic coast of France, the Latécoère 521 made its first flight. Flight testing was supervised by Capitaine de Corvette Jean Marie Henry Roger Bonnot, who had set a world record for distance in another Latécoère seaplane, Croix-du-Sud, the previous year. The pilots were Pierre Crespy and Jean Gonord.

Designed by aeronautical engineer Marcel Moine, the airplane was constructed in sections at the Société industrielle d’aviation Latécoère factory at Montaudran, Toulouse, then transported overland to the seaplane base at Biscarosse for final assembly and testing. The airplane had been named Lieutenant de Vaisseau Paris in honor of a record-setting French pilot, Paulin Louis Gérôme Paris.

The flying boat was designed to carry 72 passengers in trans-Mediterranean service. It had an aircraft commander (capitaine-du-bord), two pilots, a navigator, radio operator, and three mechanics. (The engines could be accessed in flight.) The main deck included the captain’s cabin, a salon for 20; six 2-passenger cabins; and an aft passenger cabin for 22 passengers. The upper deck included flight deck, a galley and bar, and a passenger cabin for 18.

Hull arrangement (N.A.C.A. Aircraft Circular No. 202, National Advisory Committee for Aeronautics )

The Latécoère 521 was a six-engine sesquiplane flying boat, primarily of metal construction. The two-step hull was built of duralumin, an age-hardened aluminum alloy; and corrosion-resistant bonded, rolled, aluminum sheet Alclad (known as Verdal in France). The outer wing panels were fabric covered. The hull had two decks, with seven water-tight compartments.

The 521 was 31.62 meters (103.74 feet) long, with a wingspan of 49.30 meters (161.75 feet) and height of 9.07 meters (29.76 feet). The wings were swept aft 5° 20′ and had 5° dihedral. The area was 330 square meters (3,552 square feet). A series of V struts braced the wing to the hull and the stub wings, which had a span of 14.70 meters (48.23 feet) and area of 48 square meters (517 square feet). Each stub wing carried 11,000 liters (2,906 U.S. gallons) of gasoline. At a gross weight of 37,409 kilograms (82,473 pounds), the flying boat had a draft of 1.20 meters (3.94 feet).

L’ hydroavion Latécoère 521. (Revue & Bulletin Technique de la Société Française Hispano-Suiza)

The Latécoère 521 was powered by six liquid-cooled, supercharged, 36.050 liter (2,199.892-cubic-inch-displacement) Hispano-Suiza 12 Ydrs1 single-overhead-camshaft 60° V-12 engines. Four engines were placed on the wings’ leading ages in tractor configuration, with two more as pushers. These left-turning V-12s had a compression ratio of 5.8:1 and drove three-bladed propellers through a 3:2 gear reduction. They were rated at 880 cheval vapeur at 2400 r.p.m., and 890 c.v. for takeoff. The 12 Ydrs1 weighed 470 kilograms (1,036 pounds).

At a gross weight of 40 tonnes, the Latécoère 521 reached 256 kilometers per hour (159 miles per hour) at 3,100 meters (10,171 feet). Its cruise speed was 210 kilometers per hour (130 miles per hour), and its ceiling was 5,800 meters (19,029 feet).

L’ hydroavion Latécoère 521 (Cliché Associated Press/Revue & Bulletin Technique de la Société Française Hispano-Suiza)

At Biscarosse, 27 December 1937, the Latécoère 521, flown by Henri Guillaumet with Messieurs LeClaire, Le Duff, Le Morvan and Chapaton, set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over 1,000 kilometers (621.37 statute miles) with a 15,000 kilogram (33,069 pounds) payload of 211.00 kilometers per hour (131.109 miles per hour).¹

Two days later, 29 December 1937, Guillaumet and his crew flew the 521 over a 1,000 kilometer closed circuit between Luçon and Aurelihan with a 15,000 kilogram payload, for an average speed of 189.74 kilometers per hour (117.899 miles per hour).²

On 30 December 1937, Guillaumet and his crew set two more FAI world records when they carried an 18,040 kilogram (39,771 pounds) payload to a height of 2,000 meters (6,562 feet);³ and 15,000 kilograms (33,069 pounds) to an altitude of 3,508 meters (11,509 feet).⁴

Latécoère 521 F-NORD (Rudy Arnold Photographic Collection NASM XRA-4725)

The 521, with civil registration F-NORD, made a series of flights across the Atlantic to New York City. On one of these, the flying boat was damaged in a storm. It was disassembled and returned to France aboard ship.

After repairs, the Latécoère 521 continued in airline service. With the beginning of World War II, it was modified to a maritime patrol aircraft. When France surrendered to Germany, the flying boat was stored near Marseilles. When Germany retreated in 1944, they destroyed the record-setting airliner.

¹ FAI Record File Number 11509

² FAI Record File Number 11507

³ FAI Record File Number 11579

⁴ FAI Record File Number 11525

© 2021, Bryan R. Swopes