China Clipper

by Robert Gandt

  Sikorsky’s bombers accounted well for themselves. Altogether some seventy-five models were delivered, half of which saw active combat. The bombers flew a total of about four hundred raids with a loss of only one aircraft. Faster and more powerful versions were in the works when, in the spring of 1917, the life of Czarist Russia came to an end. In the Bolshevik revolution that convulsed Russia, Igor Sikorsky, like thousands of his countrymen, became a refugee.

  He was a jobless immigrant, nearly thirty years old, when he stepped ashore in New York on 30 March 1919. Quickly he learned what every designer and builder of airplanes in America was discovering. Aviation, in the postwar world, was a moribund enterprise. There was a glut of flyers and flying machines. Sikorsky was forced to support himself by teaching mathematics to other immigrants, living in a six-dollar-a-month single room on New York’s East Side. In the evenings he delivered lectures on aviation and astronomy. The glory days of the Ilia Mourmetz seemed gone forever.

  But among the growing Russian colony in New York, Sikorsky’s name still carried considerable weight. By the spring of 1923, he was able to raise enough funds through a stock subscription to found the Sikorsky Aero Engineering Corporation. A principal supporter, stockholder, and vice president of the corporation was the famous Russian pianist and composer, Sergei Rachmaninoff.4

  The first Sikorsky aircraft built in the United States was designated the S-29A (the A appended as a salute to the builder’s adopted country). Money was always insufficient. Sikorsky’s “factory” was a makeshift shop on Long Island, near Roosevelt Field. Tools and components came from hardware stores and junk yards. The power plants were sickly war-surplus Liberty engines. The tires were worn and prone to blowing out while the aircraft stood parked.

  On its initial test flight in May 1924, with eight optimistic Russians on board, the S-29A’s engines lost power and the aircraft crashed on a nearby golf course. There were no injuries, but the new airplane—as well as the builders’ morale—suffered grievous damage.

  Sikorsky’s backers dug deeper in their pockets. The S-29A was revived and went on to live a productive life. Despite the continuing hard times, the small company stayed in business, producing several small training airplanes and a trimotored long-range aircraft designated the S-35. This sleek machine possessed a range and load-carrying capability unequaled by any other airplane of her day. Selected by the French ace, René Fonck, for his 1926 attempt to fly the Atlantic, the S-35 might have become the most famous airplane in the world. Instead, the venture ended in disaster when the heavily loaded aircraft’s gear collapsed on takeoff. In the flaming crash at the end of the runway, the S-35 was destroyed. Two of Fonck’s four crewmen lost their lives.5

  New aircraft orders were few. The S-35 debacle had left the company demoralized and nearly bankrupt. Its successor, the S-37, was a twin-engined, long-range aircraft with which Fonck was to have another try at the Atlantic. Lindbergh’s stunning triumph in May 1927 ended the transatlantic race.

  For a while Sikorsky had hopes of marketing the S-37 as a commercial transport. One of his potential customers was the manager of Colonial Air Transport, an affable young man named Juan Trippe. After a ride in the new aircraft, with Sikorsky at the controls, Trippe decided the big airplane was unsuitable for Colonial.6

  A twin-engine amphibian, designated the S-34, was completed in 1926. This experimental design had numerous flaws, and during a test flight the aircraft developed engine troubles and crashed. But the project provided invaluable test data for a new lineage of Sikorsky aircraft. In 1927 came the S-36, a further refinement of Sikorsky’s twin-engined amphibian concept. Several of these were produced and sold, including one model to the U.S. Navy.

  During the early months of 1928 the Sikorsky company produced a ten-seat amphibian, the S-38. This air-land-sea craft, powered by two 400-horsepower Pratt and Whitney Wasp engines, became an immediate success. It possessed performance unlike any other waterborne aircraft of the day, climbing at 1,000 feet per minute with a full load, cruising at 100 miles per hour, with a maximum speed of 130 miles per hour. The amphibian could stay comfortably airborne on one engine, a powerful selling point in 1928.

  The first order, placed by the U.S. Navy, was deferred in favor of the new airline, NYRBA. The next series of S-38s went to Pan American, serving as the workhorse for the airline’s push into the Southern Hemisphere.

  The S-38 resembled a prehistoric flying reptile, with its long, bill-like prow of a nose and a chopped-off, blunt, aft fuselage. Its high, upper wing, built of wood and covered with fabric, spanned seventy-one feet eight inches. The two Wasp engines were suspended beneath the upper wing. The thirty-six-foot one-inch lower sesquiplane was, like the hull, covered in aluminum to withstand the pressures of water handling. The tail surfaces were appended by twin booms to the upper wing and supported by a strut connected to the aft fuselage.

  The rugged little machine made history. In 1929 an S-38 was flown by Charles Lindbergh to inaugurate service between the United States and the Panama Canal. Another S-38 appeared prominently in motion pictures, painted in zebra stripes, as the jungle vehicle of the African explorers, Osa and Martin Johnson. The government of Chile ordered an S-38 to provide transportation for an official visit of the Prince of Wales. Many models of the S-38 were delivered to private sportsmen and adventurers. At least ten airlines ordered the S-38, including Pan Am, Pan American–Grace Airways, Inter-Island Airways, Curtiss-Wright Flying Service, Colonial Western Airways, Canadian Colonial Airways, and NYRBA. Both the army and the navy ordered substantial numbers of the S-38.7

  For the hard-pressed Sikorsky company, the S-38 was the breakthrough. The first series of ten aircraft sold out immediately. The next series went into production and was also sold out. The Sikorsky company found itself, in the midst of a numbing depression, with more business than it could handle.

  The company was reorganized as the Sikorsky Aviation Corporation, capitalized at $5 million, and moved to a sprawling new factory complex in Stratford, Connecticut. In place of the original makeshift, war-surplus and secondhand equipment, the corporate headquarters was outfitted with new machinery, research laboratories, drafting rooms, offices, and a wind tunnel. The site adjoined deep-water facilities for the testing of the new generation of Sikorsky seagoing airplanes. In 1929 the Sikorsky Corporation became a subsidiary, and then a division, of the United Aircraft Corporation.

  On 20 December 1929, Sikorsky was approached by Juan Trippe, who now headed Pan American. He wanted an oceangoing craft with four engines, amphibious capability, and a size, range, and load-carrying capacity unmatched by any airplane in the world. Could Sikorsky construct such a flying boat?

  Igor Sikorsky’s “mysterious faculty” was already at work. He would build Trippe’s flying boat. It would be superior, at least in performance, to the giant flying boat, the Dornier Do X, that had startled the world that summer with its first flight in Germany.

  8

  Teutonic Ambitions

  All the pent-up frustrations of postwar Germany crystallized in the immense form of the Do X. Teutonic in scale and spirit, she was the largest airplane in the world. The Do X had been built to be a transatlantic airliner, but her very enormity outreached the technology of the day. The appearance of the German-built Do X delivered a signal to the rest of the world. The race had begun for a transatlantic airplane.

  Claude Dornier, designer of the Do X, began his career in 1910 with the German airship company Luftschiffbau Zeppelin. When the firm established a subsidiary in 1914 for the construction of metal flying boats, thirty-year-old Dornier was put in charge.

  In August of that year, Germany went to war. For the next four years Dornier designed a succession of metal-clad flying boats for the military. One of these, a twin-engined craft designated the Gs I, was nearly completed when the armistice was signed. Dornier modified the flying boat as a civil transport, equipping it with an open cockpit and a six-seat cabin in the bow.

  The Gs 1 first
flew in July 1919. She was intended to enter service with Ad Astra Aero (a forerunner of Swissair). The innovative flying boat featured a broad-beamed hull fitted with Flossenstümmel (sponsons, or sea wings), which were to become a Dornier trademark. Her single, square-tipped, untapered wings were mounted above the hull. Two tandem-mounted 260-horsepower Maybach engines were installed above the center section.

  The Gs I might have left her mark in history. In performance she outclassed any comparable aircraft possessed at the time by the allied countries. Instead, the unthinkable happened. The victorious allies, in their fervor to disarm their former antagonists, committed the stupidity of destroying the Gs I in 1920 and sinking her to the bottom of the North Sea.1

  In the early twenties Dornier produced a series of single-engine flying boats given the collective name, Delphin (Dolphin). These peculiar-appearing aircraft were of steel and duralumin construction with the single water-cooled engine mounted high above the nose and, in its initial version, an open cockpit located abaft the engine. An enclosed cabin for five or six passengers lay directly behind the cockpit. The final variant of this design, the Delphin III, appeared in 1927 and had an enclosed cockpit beneath the engine and a cabin accommodating twelve to thirteen passengers.

  And then in 1922 appeared the aircraft that established Claude Dornier as one of the world’s foremost designers of seagoing aircraft. The Do J Wal (Whale) was an outgrowth of the unfortunate Gs I. The Wal was an all-metal monoplane with an untapered wing mounted on struts above a streamlined fuselage. Showing her Dornier heritage, she featured the familiar sea wings—air-foil-shaped sponsons at water level instead of outrigger floats—and tandem-mounted, pusher-puller engines atop the center section.

  By the terms of the postwar restrictions imposed on Germany, Dornier was forbidden to build the Wal in his own country. Thus, from 1923 the Wal was produced in Italy by Construzioni Meccaniche Aeronautiche SA (CMASA) and later by the Piaggio Company. In all, a total of 117 Wals were built in Italy. The aircraft was eventually constructed by factories in Spain, the Netherlands, Japan, and finally again in Germany after the ban had expired. For fourteen years the successful Wal continued in production, appearing in some twenty versions and powered by a variety of engines, including the 300-horsepower Hispano-Suiza, the 360-horsepower Rolls-Royce Eagle, the 450-horsepower Napier Lion engine, and eventually twelve-cylinder BMW VI engines of 600 horsepower each. Her maximum gross weight swelled from about 8,000 pounds to over 22,000 pounds.

  Like the sturdy Sikorsky S-38, the Wal found employment around the world. The Italian airlines SANA and Aero Espresso used Wals throughout their Mediterranean networks. The German airline, Aero Lloyd, flew Wals on their Scandinavian service, and the enterprising Deutsche Luft Hansa, founded in 1926, began operating the Wal on their Baltic routes. The German-owned SCADTA of Colombia purchased Wals, as did Syndicato Condor in Brazil and Nihon Koku Yuso Kaisha in Japan.

  Wals served several pioneering and exploration efforts. The Norwegian explorer, Roald Amundsen, used two Italian-built Wals in his 1925 attempt to reach the North Pole. One of his two flying boats, renamed the Amundsen Wal, later gained fame as the aircraft flown by Wolfgang von Gronau in 1930 from Germany, via Iceland and Greenland, to America. An Italian, Count Locatelli, and a Briton, Captain Frank Courtney, each made transatlantic attempts with the Wal.2 In 1926 Major Franco, brother of the Spanish dictator-to-be, made the first successful east-to-west flight over the South Atlantic, flying to Buenos Aires from Palos de Magues, Spain, in a Wal.

  By 1932 it had become possible for Dornier to resume constructing aircraft within Germany. At the Dornier facility in Friedrichshafen, two Wal derivatives were developed, the so-called eight-ton Wal and the ten-ton Wal. These models went into the South Atlantic service of DLH, and in May 1933 a Wal christened Monsun (Monsoon) made a proving flight from Bathurst, on the west coast of Africa, to Natal on the eastern shore of South America. Two ships, the Westfalen and the Schwabenland, were equipped to catapult and retrieve the Wals. By this means over 300 crossings of the Atlantic were accomplished by the doughty Wals.3

  In September 1926 appeared the Super Wal. Though similar in appearance to its predecessor, the Do R4 Super Wal II had a maximum weight of 22,046 pounds, twenty feet more wing span than the original Wal, and was configured both as a twin-engined aircraft and as a four-engined flying boat with two pairs of tandem engines. The Super Wal had fore-and-aft cabins, an enclosed cockpit (as did the ten-ton Wal and all subsequent models) and could accommodate as many as twenty-nine passengers.

  DLH put the Super Wal into service on its northern Europe routes. Several others were flown by the Italian airline SANA, and two four-engined Super Wals, powered by Pratt and Whitney Hornet engines, flew for Stout D & C Air Lines on a Great Lakes service in 1929.4

  The success of the Wal series emboldened Claude Dornier to undertake his most ambitious project. Dornier wanted an aircraft that could cross the oceans. From his drawing boards came the design for the world’s largest aircraft, a flying boat powered by no fewer than twelve engines and a long-range capacity for seventy passengers.

  Do X*, built at Dornier’s Swiss factory at Altenrhein, first flew on 25 July 1929. In October of that year the Do X astonished the world by taking off from the Bodensee with a human cargo of 169 persons—150 passengers, ten crew, and nine stowaways.

  The Do X, despite her great size, possessed classic Dornier features, including the familiar Flossenstummel (sea wings), a broad, untapered main wing, and a long, slender, Wal-like fuselage with a two-step hull. She was driven by twelve air-cooled Siemens-built Jupiter Bristol engines of 525 horsepower each, mounted in six Dornier-style tandem nacelles. Each nacelle sat atop a streamlined turret through which a mechanic, via a passageway in the thick main wing, could reach the engine in flight. A narrow secondary wing, atop the main wing, connected each of the nacelles. Each engine drove a fixed-pitch, four-bladed wooden propeller. Her deep hull contained three decks and was divided into cabins that could accommodate sixty-six passengers on long flights or over a hundred on shorter segments. With her wing span of over 157 feet and maximum weight of 114,640 pounds, she easily outsized any airplane in the world.

  From the beginning, though, the giant Do X was plagued with problems, largely because of the number and inadequacy of her power plants. Early in the Do X’s career Dornier decided to replace the inefficient Jupiters with 600-horsepower Curtiss Conqueror water-cooled engines. At the same time, the unneeded secondary wing was eliminated. With the new engines, the Do X’s advertised maximum weight was increased to 123,469 pounds versus an empty weight of 65,036 pounds. Despite this apparent load-carrying capacity—a load-to-tare of 48:52—the Do X stowed scarcely enough fuel to fly a thousand miles. Because of her rear-engine cooling troubles, she had a service ceiling of only 1,540 feet (500 meters).

  On 2 November 1939, amid great fanfare, the Do X departed Friedrichshafen on a grand tour of Europe and the Americas. Bad luck dogged the giant flying boat throughout the journey. She suffered fire damage in Lisbon. She damaged her hull during a takeoff in the Canary Islands. In Brazil her captain was relieved of command because of his objection to giving “joy rides.” After wintering in New York, the Do X recrossed the Atlantic, via Newfoundland and the Azores, but ran short of fuel approaching Lisbon and water-taxied the last six miles up the Tagus River. What was intended to be a triumphal procession of German technology turned into a trail of broken parts, aborted schedules, and wounded Teutonic egos.

  By the time the grand tour was finished, so was the Do X. She was flown briefly by DLH, and then passed to the Deutsche Versuchsanstalt fur Luftfahrt (DVL)—the German aviation research and testing institute. Two more versions of the Do X were constructed for Italy, powered by 550-horsepower Fiat water-cooled engines. These aircraft, however, never entered commercial service and were retired as experimental vehicles.5

  Claude Dornier’s behemoth, an amalgam of good and bad ideas, had foundered largely on the inadequacy o
f her power plants. She entered history as a bold but failed flying boat experiment.

  Meanwhile, another German builder, Adolf Rohrbach, was designing flying boats intended for DLH’s seagoing operations. In 1922 Rohrbach established the Rohrbach-Metall-Aeroplane Co A/S in Copenhagen. There he began producing a series of seaplanes, the Ro I, II, III, and IV, which were squarish, flat-surfaced aircraft, all similar in shape and design but graduated in size and power plant. Rohrbach’s hull-bottom design employed a deep V with a concave contour up to the chines at water level. This feature provided exceptional hydrodynamic lift and at the same time caused the water to spray back and downwards, reducing the spray pattern. Another unusual feature in the Ro III was conventional sailing gear—it had two masts on the hull and sails that could be raised to sail the vessel into port or be used in event of an open-sea landing.

  In 1927 appeared a series of Rohrbach boats intended for DLH’s transatlantic service. The first of these, the Rocco, accommodated up to ten passengers and was powered by two 650-horsepower water-cooled Rolls-Royce Condor engines mounted on struts above the wing. Each engine turned a wooden four-bladed propeller. Though the Rocco operated briefly in 1928 on DLH’s Germany–Scandinavia service, the aircraft did not enjoy great success.

  A follow-on flying boat, the Romar, first flew in August 1928. Like its smaller predecessor, the Romar was a high-winged monoplane with a marked dihedral, single fin and rudder, and large floats mounted under the wing and close to the hull. Her slab-sided hull was covered with duralumin and enclosed two cabins seating a total of twelve passengers. Three BMW 500-horsepower water-cooled engines were fitted atop the wing, each driving a four-bladed wooden propeller.

  Two versions of this aircraft were built, and then came a third powered by 750-horsepower BMW VIuz engines and accommodating as many as sixteen passengers. By contemporary standards the Romar was a sizeable flying boat, larger than any of the Dornier aircraft excepting the Do X. Her wings spanned 121 feet and supported a maximum gross weight of 40,785 pounds. With a cruising speed of 110 miles per hour, the Romar’s operating range was said to be 1,242 miles.6