Santos-Dumont Demoiselle

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Alberto Santos Dumont flying the Demoiselle (1909).jpg
Role Experimental aircraft
National origin Brazil / France
Designer Alberto Santos-Dumont
First flight 1907

The Santos-Dumont Demoiselle ("Damselfly") was a series of aircraft built in France by Brazilian aviation pioneer Alberto Santos-Dumont. They were light-weight monoplanes with a wire-braced wing mounted above an open-framework fuselage built from bamboo. The pilot's seat was below the wing and between the main wheels of the undercarriage. The rear end of the boom carried a tailwheel and a cruciform tail.

No. 19[edit]


The first aircraft of the type was the Santos-Dumont No. 19. Powered by a 15 kW (20 hp) liquid-cooled Dutheil & Chalmers flat-twin engine mounted on the leading edge of the wing. Wingspan 5.1 m. There was a pair of hexagonal rudders surfaces below the wing on either side of the pilot, a forward mounted hexagonal elevator in front of the pilot and a cruciform surfaces, mounted at the end of a substantial single boom, which pivoted on a universal joint to function both as elevator and rudder. There was no provision for lateral control.[1]

Santos-Dumont made three flights on 17 November 1907 at Issy-les-Moulineaux.[2]

Later, Santos-Dumont repositioned the engine, placing it below the wing in front of the pilot.

The No. 19 was damaged beyond repair when crashed by Hélène Dutrieu in 1908.[citation needed]

No. 20[edit]

Santos-Dumont's next Demoiselle, the No. 20, featured an 18-kW (24-hp) Antoinette engine, later replaced with a Darracq-built liquid-cooled opposed twin engine of approximately 3.2 litre displacement and similar power output, and some additional wing reinforcements. Both the Antoinette and Darracq-powered versions had a pair of lightweight thin-tube radiators mounted under the wing roots and just below the lower layer of fabric wing covering, running the entire 1.70 meter chord of the wing root panels. It also utilised wing warping for lateral control, with control cabling that only pulled down alternately on the outer section of the rear wing spar with no "upwards" warp capability. Due to structural problems and continuing lack of power Santos-Dumont introduced additional modifications in the No. 21: a triangular and shortened fuselage made of bamboo; the engine was moved back to its original position, in front of the wing; and increased wingspan. The design of No. 22 was similar to No. 21. Santos-Dumont tested opposed-cylinder (he patented a solution for cooling this kind of engine) and water-cooled engines, with power settings ranging from 15–30 kW (20–40 hp) in the two variants. A feature of the water-cooled variant was the liquid-coolant pipeline which followed the wing lower side lofting to improve aerodynamics.

The Demoiselle could be constructed in only fifteen days. Possessing outstanding performance, easily covering 200 m of ground during the initial flights and flying at speeds of more than 100 km/h, the Demoiselle was the last aircraft built by Santos-Dumont. He performed flights with it in Paris, and made trips to nearby places. Flights were continued at various times through 1909, including the first cross-country flight with steps of about 8 km, from St. Cyr to Buc on 13 September 1909, returning the following day, and another on 17 September 1909 of 18 km in 16 min. The Demoiselle, fitted with a two-cylinder engine, became rather popular. The French World War I ace Roland Garros flew it at the Belmont Park, New York, in 1910. The June 1910 edition of the Popular Mechanics magazine published drawings of the Demoiselle and affirmed that "This machine is better than any other which has ever been built, for those who wish to reach results with the least possible expense and with a minimum of experimenting."[3] American companies sold drawings and parts of Demoiselle for several years thereafter. Santos-Dumont was so enthusiastic about aviation that he released the drawings of Demoiselle for free, thinking that aviation would be the mainstream of a new prosperous era for mankind. Clément-Bayard, an automotive maker, constructed Demoiselles, they planned a production run of 100 units, built 50 and sold only 15 for 7,500 francs for each airframe.[4] (or 50,000 francs.[citation needed]) It was the world's first series production aircraft. By 1909 it was offered with a choice of 3 engines, Clement 20 hp; Wright 4-cyl 30 hp (Clement-Bayard had the license to manufacture Wright engines); and Clement-Bayard 40 hp designed by Pierre Clerget. It achieved 120 km/h.[4]

An example of a No. 21 with a Darracq engine is preserved in the Musée de l'Air et de l'Espace. Several flyable replicas were built by Personal Plane Services Ltd for the 1965 film 'Those Magnificent Men in Their Flying Machines' and others have been built since then.


  • No. 19
  • No. 20
  • No. 21
  • No. 22

Specifications (No. 20)[edit]

Data from Flight, 2 October 1909, p. 604

General characteristics

  • Crew: One
  • Length: 6.07 m (20 ft 3 in)
  • Wingspan: 5.49 m (18 ft 0 in)
  • Height: 2.40 m (7 ft 10 in)
  • Wing area: 10.68 m2 (115 ft2)
  • Gross weight: 110 kg (243 lb)
  • Powerplant: 1 × Darracq, 26 kW (35 hp) each


  • Maximum speed: 90 km/h (60 mph)

See also[edit]


  1. ^ "L'Aéroplane "Santos=Dumont 19"". l'Aérophile (in French): 313–5. November 1907. 
  2. ^ Gibbs-Smith, C. H. (1974). The Rebirth of European Aviation. London: HMSO. p. 249. ISBN 0 11290180 8. 
  3. ^ Joerin & Cross 1910, p.778
  4. ^ a b Hydro Retro, Clement-Bayard, pdf (French) Clément-Bayard, sans peur et sans reproche par Gérard Hartmann


External links[edit]