The world’s first jet-propelled aircraft was actually a jury-rigged prop plane.
There have been several claimants to the distinction of being the first jet- propelled airplane—including the Caproni Campini N.1 and Heinkel He-178—but a strong case can be made for a most unlikely candidate. In mid-1939 the second prototype of the propeller-driven Heinkel He-118 was modified to carry a prototype turbojet beneath its fuselage. Thus an unsuccessful contender for a Luftwaffe dive-bomber contract became the first plane to fly using a jet engine.
The story of this awkward matchup began in late 1934, when Ernst Heinkel started developing a pair of combat aircraft for the emerging Luftwaffe. The airplanes were similar in appearance, inspired by the design of the firm’s successful He-70 single-engine transport. Both were streamlined monoplanes with inline engines, elliptical gull wings and outward-retracting landing gear. The smaller of the two, the He-112 single-seat fighter, achieved limited production, though it lost out to the soon-to-be-legendary Messerschmitt Bf-109.
The larger plane, originally designated the He-113, was a two-seat attack bomber that Heinkel proposed to fulfill the Luftwaffe’s newly issued dive-bomber specification. Before the prototype was completed, he changed the 113 designation to 118, to preempt any superstition among test pilots.
First flown on February 14, 1936, the He-118 competed against three rival designs: the Arado Ar-81, Blohm und Voss Ha-137 and Junkers Ju-87. Arado’s otherwise promising entry ended up being ruled out because it was a biplane, and the Ha-137 was eliminated because it was a single-seater. Of the two remaining contenders, the He-118 was clearly more advanced and performed better. But Ernst Udet, the Luftwaffe’s head of procurement, favored the Ju-87 even though its first prototype had been destroyed in a fatal crash. Apparently Udet, a proponent of dive-bombing, preferred the Ju-87 because it was able to dive vertically, whereas the He-118 was limited to a 50-degree dive angle.
Udet’s prejudices notwithstanding, the Luftwaffe high command initially favored the He-118, and Heinkel was supposedly expecting a production contract. But all that changed when Udet—Germany’s second ranking World War I ace and a renowned stunt pilot— crashed the first prototype.
On June 27, 1936, Udet took the He-118 V-1 up for a test flight. Although he had been briefed about how to fly the airplane, he apparently forgot to adjust the propeller pitch prior to entering a dive, which resulted in propeller over-speeding, shredding the reduction gears. Udet managed to bail out, but the He-118 V-1 was completely destroyed, along with any possibility of Heinkel securing a production contract. Junkers would go on to produce thousands of the infamous Ju-87 Stukas, while Heinkel built only 15 He-118s, two of which were sold to Japan.
The He-118’s story would have ended there were it not for a young Heinkel engineer, Hans von Ohain. In 1936 von Ohain patented his version of a new engine that needed no prop, a centrifugal-flow turbojet. Assisted by Max Hahn, a mechanic friend, he built a prototype in 1937 to demonstrate the feasibility of his concept. Intrigued, Ernst Heinkel engaged both men to further develop their design on behalf of his company.
Von Ohain and Hahn ground-tested a number of prototypes before finally producing a model considered suitable for flight testing, the HeS3a. The enthusiastic Heinkel began developing a specially designed airframe in which to test the new engine, the He-178. While that was in the works, however, he had the second prototype of his failed dive bomber modified to flight-test the HeS3a turbojet. The He-118 V-2 was regarded as a suitable choice for that purpose thanks to the relatively high ground clearance afforded by its tall undercarriage and its ability to carry heavy loads in the bomb crutch beneath its fuselage.
Slung under the He-118 V-2’s fuselage, the turbojet was flown for the first time in July 1939. Although the modified dive bomber took off and landed on conventional piston power, its pilot lit the jet engine while airborne and flew on jet power—predating the purpose-built He-178 by at least a month.
There’s another postscript to the story of the ill-starred He-118, thanks to the two examples Germany allowed Heinkel to sell to the Japanese. Apparently more impressed with the plane’s potential than the Luftwaffe, the Imperial Japanese Navy directed the Yokosuka Naval Air Technical Arsenal to develop a somewhat simpler, more compact version as a carrier-based dive bomber. The result was the D4Y Suisei (Comet), which was built in large numbers and saw extensive service in the Pacific during World War II.
Powered by von Ohain’s jet engine, the He-178 flew for the first time on August 27, 1939, just days before Germany invaded Poland. Unbelievably, although both aircraft and engine were successfully demonstrated, the Luftwaffe brass initially showed little interest. Heinkel then built a twin-jet fighter prototype, the He-280, at his own expense. Demonstrated for Udet in the spring of 1941, that revolutionary jet still failed to impress him, despite a top speed of 512 mph. The Luftwaffe eventually began to see sense in developing a jet fighter. But as with the He-112, Heinkel’s fighter was once again pipped at the post for the production contract by a competing Messerschmitt design—the Me-262.
After the war, von Ohain came to the United States, one of the many eminent German scientists recruited through Operation Paperclip. In 1956 he became director of the Aeronautical Research Laboratory at Wright-Patterson Air Force Base, and by 1975 he was the chief scientist of the Aero Propulsion Laboratory. Among his many contributions was the development of the “jet wing,” in which lift was augmented by directing part of the jet exhaust over the wing surfaces. Enshrined in the National Aviation Hall of Fame in 1990, he died at his home in Melbourne, Fla., in 1998.
Originally published in the March 2012 issue of Aviation History. To subscribe, click here.
