The Airplane - Jay Spenser [94]
Birkigt’s influence cannot be overstated. Modern automobile engines are the technological descendents of his World War I Hissos. So too were the liquid-cooled aero engines of World War II, including the Rolls-Royce Merlins powering the British Spitfire and U.S. P-51 Mustang as well as the Daimler-Benz engine in Germany’s Bf 109.
Lt. John Macready climbed steadily over Dayton, Ohio, home to the U.S. Army Air Service Engineering Division at McCook Field. It was September 28, 1921, and Macready was piloting an open-cockpit LePere biplane.
The test pilot wore several sets of woolen long underwear beneath his regulation Army uniform. On top of that were an electrically heated knit-wool jumpsuit and a down-lined flying suit made of heavy leather. Thick fur-lined gloves protected his hands and fleece-lined outer moccasins his feet. On his head, Macready wore a specially insulated leather flying helmet, face mask, and goggles treated with a gelatin coating to inhibit ice formation. Clenched in his teeth was a pipe-stem mouthpiece attached to a rubber hose. It spewed lifesaving oxygen from a cylinder of compressed air.
The LePere’s 400-hp Liberty engine likewise benefited from supplemental oxygen because Macready was testing an exhaust-driven turbo-supercharger. This experimental device permitted the airplane to continue ascending long after the thinning air would have robbed a normally aspirated engine of power.
Macready’s altimeter read 41,000 feet (12,497 meters) when his engine sputtered and died, although a recording barograph later showed the true altitude to have been 37,800 feet (11,521 meters). The Army flier glided down to a safe dead-stick landing an hour and forty-seven minutes after taking off.
More than just setting an altitude record, this research flight demonstrated new technology that would prove critical almost two decades later.
The United States developed two aero engines for World War I, both of which were built in great number. The big one was the Liberty, the best version of which had twelve cylinders and turned out 400 hp. It clearly reflected German design influence.
The Liberty engine and the American-built version of Great Britain’s de Havilland DH-4 bomber that it powered were the United States’ most important industrial contributions to World War I. A half dozen U.S. companies built Liberties, which powered many U.S. aircraft and remained important right up to the 1930s.
The smaller U.S. engine of World War I was the Curtiss OX-5, an obsolescent 1915 design built for the Curtiss JN-4 Jenny military trainer. OX-5s taught many U.S. pilots to fly. Their unreliability also taught them to be constantly on the watch for possible emergency landing fields.
Aerial daredevil Gladys Ingle prepares to leap from one Curtiss JN-4 Jenny to another. Flown by barnstormers and aerial circuses during the Roaring Twenties, most Jennys had unreliable OX-5 engines.
National Air and Space Museum, Smithsonian Institution
Huge stockpiles of surplus Liberties and OX-5s retarded U.S. aero engine development for much of the 1920s because newer designs and technology could not compete on price. In a dramatic reversal, however, the air-cooled radial would arise before the decade was out to topple the dominance of liquid-cooled inlines such as the Hispano-Suiza, Liberty, or OX-5.
When Lindbergh conquered the Atlantic in May 1927, he did so with an extraordinary engine that ran flawlessly for thirty-three and a half hours. That remarkable piece of engineering was the Wright J-5 Whirlwind, a nine-cylinder, air-cooled radial power plant weighing 500 pounds (227 kilograms) and developing 220 hp. Introduced just the previous year, the J-5 was history’s first fundamentally reliable aero engine. People had achieved reliable airframes a decade earlier; now here was an engine to match, and it existed largely thanks to the U.S. Navy.
In November 1910, a civilian