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World War II – The Pioneer Jets

World War II  – The Pioneer Jets

The history of technology is replete with a concept called “multiple independent discovery.” Examples are the incandescent lightbulb by the American inventor Thomas Edison and the British inventor Joseph Swan in 1879, and the computer by Briton Alan Turing and Polish-American
Emil Post in 1936.

During the 1930s, on opposite sides of the English Channel, two gifted aviation designers worked toward the same goal. Royal Air Force (RAF) Pilot Officer Frank Whittle, a 23-year-old prodigy, envisioned a gas-turbine engine that might surpass the most powerful piston designs, and patented his idea in 1930.  

Slightly later, after flying gliders and
savoring their smooth, vibration-free flight, German physicist Hans von Ohain—who had earned a doctorate in 1935—became intrigued with a propeller-less gas-turbine engine. Despite Whittle’s head start, both visionaries ran their prototype jets in April 1937.

Jets 101
Turbine (jet) engines operated on two differing principles, as explained by Dr. Richard P. Hallion, historian emeritus of the U.S. Air Force. “Centrifugal turbojets used large-diameter compressor wheels that, essentially, flung the incoming air outward in a swirling flow pattern towards their rim, compressing it before mixing the air with fuel.

“Axial turbojets had smaller-diameter air compressors stacked in a row along the engine shaft, compressing the incoming flow in stages and then mixing it with fuel. Potentially more efficient than centrifugal-flow designs, axial-flow engines were more difficult to perfect but produced more thrust for their size and engine weight than centrifugal ones.”

During the late 1930s, the German air ministry contracted with four manufacturers for gas-turbine engines, including Heinkel, which absorbed some Junkers engineers. Each fac­tory opted for axial compressors. Ohain and Whittle, however, independently pursued centrifugal designs, and both encountered problems, even though both were ultimately successful. Ohain’s design powered the Heinkel He 178, the world’s first jet airplane, flown in August 1939. Whittle, less successful in finding industrial support, did not fly his own engine until May 1941, when it powered Britain’s first jet airplane: the Gloster E.28/39. Even so, he could not manufacture his subsequent designs, which the Air Ministry handed off to Rover, a car company, and subsequently to another auto and piston aero-engine manufacturer: Rolls-Royce.

Ohain’s work detoured in 1942 with a dead-end diagonal centrifugal compressor. As Dr. Hallion notes, however, “Whittle’s designs greatly influenced American turbojet development—a General Electric–built derivative of a Whittle design powered America’s first jet airplane, the Bell XP-59A Airacomet, in October 1942. But even though centrifugal-flow engines powered many of the first American, British, French, Soviet, and Swedish jet airplanes, the future belonged to the more efficient, quicker-to-respond, axial-flow turbojet, which opened up the era of the supersonic jet fighter and bomber.”

The Jet Race
After Heinkel’s successful demonstration in 1939, progress lagged for a German jet partly because the war went in Adolf Hitler’s favor. But Messerschmitt persisted, designing an advanced twin-engine airframe that was first tested with a piston engine in April 1941.

Messerschmitt’s chief test pilot, Fritz Wendel, flew the all-jet version at Leipheim Airfield in July 1942. The original tailwheel was subsequently moved to the nose, producing a tricycle gear that became standard for jets. When Luftwaffe fighter general Adolf Galland strapped into a prototype in April 1943, he savored the smooth, vibration-free sensation of jet flight and enthused, “It was as if the angels were pushing.”

About that time, Allied intelligence sources learned of the nascent Me 262 Schwalbe, prompting a scramble to bridge the technology gap.

Read the full article from the August 2017 issue of Flight Journal, click here.

Updated: May 29, 2018 — 2:12 PM
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