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DID ROMANIAN Henri Coandă fly the world’s first jet aircraft? Or was it a ducted-fan design? Maybe it didn’t fly at all.
The answer, at least in part, depends on whether you’re Romanian. Coandă’s countrymen felt confident enough to name Bucharest’s international airport in his honor and to celebrate the 100th anniversary of the jet engine in 2010. Others respect Coandă’s many achievements in fluid dynamics and aeronautical engineering, but are less certain of his early efforts in flight.
Coandă’s training included being at the head of the first graduating class of aeronautical engineers at Paris’ École Nationale Supérieure d’Ingenieurs en Construction Aéronautique. This was in 1910, the same year he exhibited the Coandă-10 at the Second International Aeronautic Salon in that same city.
The Coandă-10 was a sesquiplane, a biplane with one wing considerably smaller than the other. For its era, the craft was relatively free of wing struts and bracing. Its wing surfaces were covered in thin wood, not fabric, and depended on wing warping (the Wrights’ approach) rather than ailerons for maneuverabilty. Twin control wheels on either side of the open cockpit actuated this wing warping.
The aeroplane’s Coandă Air Reactive Unit, its turbo-propulseur, was its most unorthodox feature. A four-cylinder Clerget engine drove a rotary compressor in the nose, a gearbox translating the engine’s 1000 rpm to the compressor’s 4000.
In theory, this compressor generated a negative pressure at the front of the aeroplane and added thrust through airflow out of the truncated conical nose. The nose contained a pilot-adjustable device for varying this effect.
In fact, there are those who claim the effect was minimal, and that the craft never flew. Years later, Coandă spoke of a brief 1910 flight followed by a crash. He also made claims that the turbo-propulseur was the world’s first jet engine, with fuel injected and combusted for added thrust. What’s more, he produced copies of 1910-era patents allegedly confirming this, documents that were later suggested to have been “altered.”
Coandă’s turbo-propulseur found use in another craft, a two-seat sled commissioned by Cyril Vladimirovich, Grand Duke of Russia.
Suitably blessed by Russian Orthodox priests, it appeared at the 1910 Paris Automobile Salon displayed alongside Gregoire automobiles, with which it shared its engine. A contemporary report predicted a top speed of 60 mph, though there’s no record the sled was ever run.
Coandă’s chief accomplishment in fluid dynamics was his identifying what has come to be known as the Coandă Effect. Briefly, this is tendency of a fluid flow to be attracted to an adjacent surface, a phenomenon with applications in everything from NOTAR helicopters to cardiovascular medicine. In Formula 1—and not without regulatory controversy—the Coandă Effect has enhanced the downforce of cars by directing exhaust gases through their rear diffusers.
I like to think that this and particularly its controversy would make Coandă smile. ds
© Dennis Simanaitis, SimanaitisSays.com, 2012