Coandă was interested in achieving reactive propelled flight as early as 1905, conducting tests of rockets attached to model aircraft at the Romanian Army arsenal in Bucharest.

Positioned along the fuselage centreline, the smaller rear lift propeller was mounted vertically, while the larger front one was inclined slightly forwards at 17 degrees.

It was around this time that Coandă's interest in jet propulsion began, claiming that the aircraft and a jet-propelled model were displayed in December 1907 at the Sporthalle indoor sports arena in Berlin.

As a continuation of his Belgian experiments, and especially looking for a way to test wing aerofoils at higher speeds, he contacted Ernest Archdeacon, the co-founder of L'Aero-Club de France, who in turn directed Coandă to Gustav Eiffel and Paul Painlevé.

With their assistance, he gained approval to test different wing configurations and air resistance on a platform built by Eiffel at the front of a locomotive on the North of France railway.

In contrast to the monoplane described in the July 1910 patent application,[17] the exhibit was a sesquiplane which complicated the construction, but in return solved lateral stability control issues.

Instead of a propeller, a 50 hp (37 kW) inline water-cooled internal combustion engine built by Pierre Clerget at the Clément-Bayard workshop with funding from L'Aero-Club de France,[24] placed in the forward section of the fuselage drove a rotary compressor through a 1:4 gearbox (1,000 rpm on the Clerget turned the compressor at 4,000 rpm), which drew air in from the front and expelled it rearward under compression and with added heat.

[23] The reporter from La Technique Aeronautique wrote, "In the absence of definitive trials, permitting the precise yield of this machine, it is without doubt premature to say it will supersede the propeller ... the tentative is interesting and we watch it closely.

[23] The additional turbo-propulseur patent application 13.502, dated 3 December 1910, was implemented on a double-seat motorised sled commissioned by Cyril Vladimirovich, Grand Duke of Russia.

[48] Henri Mirguet writing for L'Aérophile magazine in January 1912 said that the new 1911 aircraft retained the fuselage, the frame and the wing of Coandă's 1910 design, but did not keep the turbo-propulseur or "the wooden wingloading surface including the forward longitudinal ribs".

During World War II he revived his earlier turbo-propulseur engine when he was contracted by the German Army in late 1942 to develop an air propulsion system for military ambulance snow sledges much like the one made for the Russian Grand Duke.

[54] In 1950's l'aviation d'Ader et des temps héroiques, the authors assert that Coandă flew the first jet aircraft at Issy-les-moulineaux for 30 metres (100 ft), ending with a crash.

[58] Coandă himself spoke on the subject, notably before the Wings Club at New York's Biltmore Hotel on 18 January 1956 where he said "I intended to inject fuel into the air stream which would be ignited by the exhaust gases also channelled through the same circular vent", implying that he never finished the powerplant.

[23] Aubrey wrote that the aircraft engine was "designed by a friend to Coandă's specification", and that its burning exhaust was "directed below and to each side of the fuselage, which was protected by asbestos in vulnerable places.

In further statements, Coandă said that his 1910 aircraft had movable leading edge slots,[nb 1] retractable landing gear and a fuel supply which was held in the overhead wing to reduce fuselage profile and thus drag.

[26] In 1965, Coandă presented a set of drawings, photographs and specifications of the 1910 aircraft to the National Air and Space Museum (NASM), prepared by Huyck Corporation and received by Director S. Paul Johnston and early aviation curator Louis Casey.

[61] In the 1980s after Coandă's death, Stine wrote a magazine article and a book mentioning the 1910 aircraft, including new details such as the name of master mechanic Pierre Clerget as the friend who helped build the turbo-propulseur.

[6] Stine gave his assessment that "Coanda's turbopropulseur had elements of a true jet", but that the patent application had no indication of the "critical stage—injection of fuel into the compressed air".

[62] In 1965, Historian Emeritus Paul E. Garber of the NASM interviewed Coandă, who related that the December 1910 flight was no accident, that he had seated himself in the cockpit intending to test five factors: aircraft structure, the engine, the wing lift, the balance of controls, and the aerodynamics.

"[23] In this interview Coandă said that he brought the aircraft back to earth under control, but the landing was "abrupt" and he was thrown clear of the airframe which was consumed completely by flame, the engine reduced to "a few handfuls of white powder.

"[23] In 1960, Charles Harvard Gibbs-Smith, aviation historian at the Science Museum in London, reacted to the mid-1950s assertion that Coandă built and flew the first jet engine aircraft.

[1] Gibbs-Smith wrote that "there has recently arisen some controversy about this machine, designed by the Romanian-born and French-domiciled Henri Coanda, which was exhibited at the Paris salon in October 1910.

Until recently it has been accepted as an all-wood sesquiplane, with cantilever wings, powered by a 50 hp Clerget engine driving a 'turbo-propulseur' in the form of a large but simple ducted air fan.

He said that the airfield was the "most famous, most used, most observed, and most reported-on 'airfield' in Paris", and that all events, let alone an exciting crash and destruction by fire, would have been carried in local papers and described in military reports, but no contemporary accounts exist of the Coandă-1910 being tested, flown or destroyed.

[1] In 1970 Gibbs-Smith wrote another account of the Coanda-1910, using much the same phrasing as in 1960: "Another unsuccessful, but prophetic, machine was the Coanda biplane (strictly speaking a sesquiplane) exhibited at the Paris Salon in October.

It was of all-wood construction, with fully cantilevered wings—which did not look very robust—and an Antoinette-like fuselage with obliquely cruciform tail-unit; it was equipped with a reaction propulsion unit consisting of a 50 hp Clerget engine driving a large ducted fan in front of it, the latter enclosed in a cowling which covered the nose of the machine and part of the engine: the fan was a simple air-fan driving back the air to form the propulsive 'jet'.

[23] In their regular "Foreign Aviation News" column, Flight magazine reported that the "blank period" of inclement weather at Issy ended on the 19th when Guillaume Busson tested a monoplane made by Armand Deperdussin.

Gunston's 1995 description began: "Romanian Henri Coanda built a biplane with a Clerget inline piston engine which, instead of turning a propeller, drove a centrifugal compressor blowing air to the rear.

"[69] In a later magazine article sidebar, Boyne described more details: "Romanian inventor Henri Coanda attempted to fly a primitive jet aircraft in 1910, using a four-cylinder internal combustion engine to drive a compressor at 4,000 revolutions per minute.

Brown's 1985 A History of Aviation, Tim Brady, the Dean of Aviation at Embry–Riddle Aeronautical University, wrote in 2000: "the development of the jet is, broadly, the story of three men: Henri Coanda, Sir Frank Whittle, and Pabst von Ohain..."[73] His description of Coandă's disputed test flight agreed that fuel injection and combustion had been initiated in the rotary compressor's vent, with the novel detail that the aircraft "flew for about a thousand feet [300 m] before crashing into a wall.