DRZEWIECKI, Stefan

Drzewiecki immigrated to France in 1859 and studied at L’École Centrale des Arts et Manufactures in Paris. In 1867 he patented his first invention – a kilometre counter for cabs/cabmen. In 1873 he presented some of his inventions at the Vienna world exhibit: an automatic railway carriage clutch, a device for measuring the speed of steam engines, a regulator for steam and water turbines, a parabolic regulator and a pair of compasses for drawing cones. He also received two awards. His inventions attracted a lot of attention in Russia. The Grand Duke Konstantin invited Drzewiecki to St. Petersburg and Drzewiecki lived there between 1873 and 1877, working for the Royal Navy. He designed a device that automatically determined the route of the ship on the map. From 1877 to 1879 he dedicated himself to constructing submarines for one to four people. At first he used a type of drive where the crew would steer with their legs, but from 1877 onwards he was planning a screw propeller drive. The first tests of his submarines were carried out during the Russo-Turkish War. In 1889 he submitted a plan for a 12-man submarine, but it was never executed. It would have been the first electrically driven submarine with the use of batteries.
In 1891 he returned to Paris and continued his work on submarine construction. A year later he submitted a theory on calculating the size of a screw propeller to a French company for submarine technology. In 1897 he was awarded second place for his submarine construction in an international competition (first place was not awarded). The submarine was equipped with two torpedoes, which used condensed air. He made drafts of battleship safety, based on water layers between the inner and outer hull.
His inventions were used by the French and Russian armed forces. Russia used his design to build a submarine with an internal combustion engine and a 350 ton displacement. He received an award from the Royal Navy for his ship designs, as well as the British honorary title Naval Architect of Great Britain.
After 1880, he was also interested in aviation. In 1885 he held his first lecture on aerodynamic flight and in 1887 published the book Aeroplanes in Nature, in which he presented a thesis that the principle of monoplane aeroplanes should be used on devices that are heavier than air. This sort of opinion was considered revolutionary at that time and people were very reserved in accepting it. The general opinion was that flying devices could only stay up in the air by using the principle of oscillating aeroplane or helicopter. In 1887, at an international congress in Paris, Drzewiecki presented his theory of mechanical flight and wrote an article entitled Les oiseaux considérés comme des aéroplanes animés for the newspaper L‘Aéronaute.
His theoretical reflections on the flight of insects were used for calculating propeller constructions. It was the first practical method of planning and brought him worldwide fame. As a result of his many years of work on theories of propeller construction, he published the book Les hélices aériennes in 1909. He formulated a theory of similarity and propeller optimisation based on individual plane characteristics. His ideas were used by the French company Ratmanoff for producing Normale propellers, which, due to their great effectiveness and number of rotations (3000 turns per minute), became a big hit. In France in 1909 Drzewiecki patented the draft of a self-stabilising aeroplane. His prototype, Canard, was equipped with a pressure propeller and an automatic stabilisation device and was presented at an international airshow in Paris. War prevented any further improvements of this aeroplane.
Drzewiecki deserves a lot of credit for suggesting that aviation test research should be conducted in aerodynamic laboratories, which he described in his book De la nécessité urgent de créer un laboratoire d'essais aérodynamiques destinés à fournir aux aviateurs les éléments nécessaires à la construction des aeoroplanes, published in 1909. The book was very well received and contributed to the foundation of the AeroTechnic Institute of Saint Cyr in Versailles, the first international aviation research centre.
Drzewiecki was awarded the Chambre Syndicale des Industries Aéronautiques medal in 1913 in France for his projects and research; in Poland the general assembly of the League of National Air Security presented him with the title of honorary member. In 1920 he was decorated by the French Academy for his work Théorie générale de l’hélice. Drzewiecki was a regular member of the Warsaw Academy of Sciences.