Eole/Clément Ader

The Eole Project had already taken shape in the mind of Clément Ader in 1882.
This unusual flying machine with wings similar to those of a bat was regarded as a technological masterpiece in its time and provided irrefutable evidence of Clément Ader’s genius.

Ader designed bat-like wings to lift his Eole, which was constructed with stretched fabric. He imported the bats from India and kept them in a Volière in rue Jasmin. If you take a closer look at the wings of the Eole, the Avion III or the Aquilon, it becomes apparent that the structure of the wing resembles the skeletal structure of bats. Ader used this structure for the wings of the Eole because he believed that bat wings provided the best wing profile. The wings of the Eole were made up of a wooden frame with a linen membrane that was fastened with about 6,500 buttons.

The total wing span of the flying machine was about 13.70 m.
The three-wheeled chassis resembled a bicycle. The Eole had no control mechanisms and no tail unit for steering.

It had a bamboo propeller and four blades made of feathers. The propeller was powered by a two-cylinder steam engine weighing 17.5 kg and packing 20 hp.

Irrespective of the complexity of the design and the weight, Ader took the wings of a bat as the basis for the Eole. He retained this structure because it offered two advantages: the wings could be folded together to facilitate transport and allow the contraption to be stored in a garage. The design also allowed the wing surface and geometry to be modified quickly and improvements to be carried out easily.

At the time, a flight with this kind of flying machine was considered to be virtually impossible. Ader had therefore considered carefully which solution might prove to be a successful design. He believed that the profile and shape of a bat’s wing provided the optimum structural design, and his selection of this model was an attempt to achieve maximum stability for the shape of the wing.

At the first attempt in Armainvilliers on 9 October 1890, the speed Ader achieved was too low for take-off, and when he designed the Avion II, he added a second throttle lever which he called the “accelerator lever”.

After the attempted flights with the Eole 1890 in Armainvilliers and later in Satory, Clément Ader had already conceptualized the design of a single-engine flying machine of 30 hp that was three times as powerful as the Eole could be, but also had 30% more empty weight: the Zéphir or the Avion II.

A lighter wood replaced bamboo to construct “Avion II”, and silk was used to cover the wooden structure instead of linen. The components of Avion II were not as solid, the frame area was optimized and given a better design, and the quality of the wood was now improved. The wing assembly of the Avion II was also lighter than that of the Eole (2.5 kg/m² in the Eole by comparison with 1.5 kg/m² in the Avion II). The fuselage of the Avion II was thirty centimetres higher and more than 40 centimetres wider, and was designed for a weight of 500 kg (instead of 300 kg in the Eole). After all, the Eole had lifted off and moved at a height of up to 20 cm off the ground, covering a distance of 50 m.

After convincing engine tests, Ader decided to abandon the Avion II project in favour of a twin-engine solution called Avion III or Aquilon.

1894 saw work starting up on building this twin-engine flying machine at the production buildings in the Rue Jasmin. The contraption had a wingspan of more than 15 m and construction work continued until the start of 1897. The Avion III still had the shape of a bat. It was fitted with two engines each delivering 20 hp and also equipped with two propellers. Wood and silk were the main materials used. Ader decided to use lighter wood instead of bamboo and also opted for silk because this material was still permeable to air, although it had a tight weave.

The Avion III was to have the same shape as the Eole, at least as far as the general geometry of the flying machine and the wings was concerned. The wings of the Avion III could move as in the Eole, and the wing curvature and surface could be modified during flight. Ader used the wings of birds as a model. Bird’s wings were flexible and provided optimum control of the flying machine, and they could be inclined for banking during turns.

He provided the Avion III with a rudder that could be directly controlled by pedals attached on both sides of the flying machine. The visibility problem was still not solved because the pilot had to lean sideways out of the cabin even further than before to see where he was going because the fuselage of the Avion III was substantially wider than the Eole. The rudder was configured under the wings.

The pilot still sat in the cramped conditions behind the steam boiler.

On 14 October 1897, the maiden flight with the Avion III was scheduled to take place in front of representatives from the War Ministry. There was a strong wind on that day and the sky was cloudy. Despite unfavourable weather conditions, Ader decided to attempt to get his flying machine airborne. The Avion III crashed, probably because Clément Ader lacked experience. He was a gifted engineer and designer but he wasn’t an experienced pilot. The flying machine was almost entirely destroyed when it crashed 200 m from the end of the track: wheels, engine and wings were no longer usable. After this accident in Satory in 1987, Clément Ader was no longer able to repair the Avion III since the French government withdrew financial support. He abandoned the project.

On 9 October 1890, Clément Ader probably achieved the first “flying hop” on the land of Armainvilliers owned by Isaac Pereire. The machine lifted off the ground, carrying out a “hop”. This may even have involved a certain amount of lift over a distance of 50 m at an “altitude” of 20 cm. However, we’re not talking about a real flight since this has to be consistent and controlled. This was to be achieved for the first time by the Wright brothers on 17 December 1903.

Clément Ader never asserted that he actually flew. But it should be recognized that he was an ingenious engineer and that his flying machines were technologically very advanced for the time. This technology allowed him to lift off from the ground of his own accord. His attempted flights during the years 1890 and 1897 meant that he played an important pioneering role in the history of aviation. He is the father of the first attempted flights and therefore undoubtedly the first pilot to successfully leave the ground in a flying machine powered only by its own engine.

The polemic surrounding the date of the first motorized flight in history started up in 1903 after the flight by the Wright brothers. A small French group attempted to refute the claims made by the Wright brothers and claimed that Clément Ader made the first flight in the history of aviation. This polemic increased with the flight of Santos Dumont. Clément Ader was attributed with carrying out heroic deeds that he himself never claimed to have done. These controversies tarnished the reputation of Clément Ader, who was a remarkable inventor and whose inventions are all too often forgotten today. (Clément Ader registered some 48 patents).

Clément Ader was the first human being in the history of aviation to succeed in getting a flying machine to leave the ground powered by its own engine. This fact isn’t disputed by any of his opponents. It isn’t disputed by Charles H. Gibbs Smith in his book Les mensonges d’Ader (The lies of Clément Ader), and he even concedes that Clément Ader succeeded in taking off with a motorized flying machine for the first time in human history on 9 October 1890.

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