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the difficult beginning

by Philippe Ricco

The name of French engineer René Leduc is strongly associated with the world's first development of the "ramjet" engine. In France in the 50's, he built the first and only aircraft in the world using the "Athodyd" principle (aero thermodynamic duct, later known as "ramjet") as the sole propulsion system.

René Lorin, who first published the principle in the technical review "Aérophile" in 1913, invented the ramjet in France. Unfortunately, this visionary engineer could not finalize his ideas, and could not build his invention. Twenty years later, René Leduc, another Frenchman, again re-invented this same device. René Leduc had begun his aviation work at the Louis Breguet's aircraft factory, working mostly on the Breguet 27. This self-educated engineer understood very early in his career the limitations of the propeller engine and tried to find a solution. Initially, he imagined a jet engine, operating with a cycle of admission, power, and cyclic relaxation through a valves system. He requested a patent in 1930 for this device, three months before Paul Schmitt the German engineer who obtained governmental help, enabling him to develop this invention, known nowadays under the name of "pulse-jet". Let us note in passing that this device had already been presented in the previous century by Charles De Louvrier; another Frenchman.

Not being satisfied by the limitations of the "pulse jet" engine, René Leduc imagined a system in which only the streamline flow makes it possible to obtain the necessary compression, and thus obtaining a push force, or thrust, with this type of engine. He requested a patent for this invention in 1933, and then discovered the publications of René Lorin. He tried to contact him, but he learned that René Lorin had been deceased for a few months. René Leduc always paid homage to the work of his predecessor.

René Leduc obtained a small French government contract, which allowed him to carry out tests on a small aero-thermodynamic duct of 30-mm in diameter. After months of efforts, he was able to demonstrate the practical application of this theory during an official presentation in June of 1936. On that day, in front of representatives of the official services, this noisy invention was proven, showing that it could truly obtain a thrust force. Thus, years after Rene Lorin who had been the first to describe this type of engine correctly, René Leduc was the first to make it work.

Then, René Leduc received a French government order for a plane using this type of engine. Accordingly, the Leduc 010 project was established under market number 407/7 (the last figure indicates that the command was signed in 1937). René Leduc was then a lowly engineer, employed by Louis Breguet in his Villacoublay factory. He accepted the challenge with the assistance of Mr. Breguet, and could thus begin the construction of the first French jet. Unfortunately, the war delayed considerably the manufacturing of this plane. The Breguet workshops had to flee the Paris area, and the Leduc airplane was transferred to Toulouse. It was almost completed there, but the bombardment of the factory of Montaudran destroyed part of it, luckily perhaps, because it prevented the Germans from studying this aircraft.  Work began again after the liberation, but because of difficulties in obtaining supplies, work progressed slowly.

Aérostories, 2001

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René Leduc, the first aeronautical designer to successfully make a ramjet aircraft fly. He was self educated, meticulous, and talented.

Collection Jean Sarrail

Drawing from a 1934 Leduc patent: the ancestor of the 010 model was equipped with struts!Clic

The Leduc 010 in 1946 atop its Languedoc transporter. The aircraft was practically ready in 1940. War put its completion and final testing on hold.

Perrin  Collection                     Clic