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the test flights

by Philippe Ricco

One of the ramjet's main problems is its absence of thrust when it is motionless. To obtain an initial speed necessary for the startup of the engine, Rene Leduc thought of releasing his apparatus at altitude from a transporter aircraft. The selected aircraft was a four-engine transport SE-161 "Languedoc" especially modified.

Thus on November 19th 1946, with test pilot Jean Gonord at the controls of the Leduc 010 mounted atop Languedoc number 6, the first flight was accomplished in composite from the small airfield of Blagnac. The transporter pilot was Colonel Jean Perrin, who became the principal specialist for this type of missions. It would be several months before the 010 would be released in free gliding flight for the first time, which occurred on October 21st, 1947. At the end of this first free gliding flight, the plane overshot the short runway and the tires blew out. The enthusiasm of Gonord for the aircraft however, overcame the reservations of the official specialists presents at the demonstration and the flights would continue.

Thus, after some flights in composite, two free gliding flights, followed by a long period of inactivities while waiting for the arrival of the essential equipment, the historical flight would finally take place. On April 21st, 1949, after being released overhead Blagnac, test pilot Jean Gonord lit up the engine and established a climb using only the ramjet engine.

During the war, various tests had been conducted (particularly in the USSR and in Germany, but also in the United States) on ramjet engines installed experimentally on transporter airplanes. This type of propulsion was even used on some gun shells to increase their range, and many other projects were born as well. However, the flight of the Leduc 010 on April 21st 1949 with its ramjet operating represents the first flight of an aircraft solely propelled by a ramjet engine.

After this success, the tests were conducted with full force, and in just a few flights, the Leduc 010 proved the extraordinary capabilities of the "athodyd" engine, in particular its incredible rate of climb.
Even before the cabin was pressurized, Gonord found itself propelled to 11, 000 meters in just a few minutes. During another flight, it was the high-attained airspeed, which took him by surprise: upon reaching Mach 0.85, he encountered the violent effects of compressibility, which resulted in bounces of more than 600 meters of altitude. It was undoubtedly the first French airplane to experience this phenomenon.

Rene Leduc was unable to go further as a private engineer, while he was still working part-time for the Breguet Company. Therefore, he created a company and returned to the Paris area, settling down in Argenteuil. Obtaining several state contracts for the construction and the testing of other prototypes, a second 010 was built. The flight testing performed in the Paris area being strongly handicapped by the unfavorable meteorological conditions, Rene Leduc in 1951 continued the testing in the South of France, at Istres in the Provence region.

Two 010 were tested there by Jean Gonord, helped by a second pilot: Yvan Littolff, under the direction of engineer Jean Corriol. A third prototype was built, equipped with two additional engines mounted on the wingtips. It was designated Leduc 016. Unfortunately, the development of the 016 model proved very delicate, and after various attempts, the wingtip engines were removed.

A trial run was carried out by the CEV (French flight test center), with Jean Sarrail as the principal pilot, and under the direction of Jean Sarrail the test engineer. Unfortunately, following a technical failure, this trial run was ended with the destruction of the one of the 010, and with its pilot seriously wounded. The following year, it was Yvan Littolff who was also seriously wounded, in an other accident, which resulted in the destruction of the second 010. Jean Gonord having ended his test pilot career, it was Jean Sarrail who continued the tests.

The flights continued on the 016, which was then joined by two new much larger planes: the Leduc 021s. Sarrail and Littolff shared the test flights on these two airplanes, which relegated the 016 to the Museum in 1953. The two Leduc 021s totaled 385 flights, including 248 releases in free flights. Once again, other test flights took place at the CEV in 1955, shortly before the presentation at Le Bourget airshow. The CEV test pilot was Bernard Witt, with test engineers André Bourra for the airframe, and especially Charles Bourgarel for the propulsion portion of this "flying engine".

It is interesting to note that, in addition to the originality of their propulsion system, the Leduc airplanes were the basis of numerous innovations. Among them, the use of one of the first turbines produced in France, used to drive the instruments, the supply of energy, the jettisoning of the cabin, the hydraulic servos, and the wings milled in the mass acting as integral structural tank.

The two 021s completed their career when the Leduc 022 accomplished its first flights, in December of 1956. It was equipped with a centrally mounted turbojet, which enabled it to take off and fly on its own power, without the assistance of a transporter airplane. It totaled 141 flights during the following year, until a taxiing incident caused damages to the fuselage.

Meanwhile, the progress made by the turbojet engines equipped with afterburners, and France budgetary difficulties during the period of crisis in the Algerian war, it signaled the end for the prototypes in process of development during this period (Trident, Gerfaut, Durandal, Baroudeur, Griffon, Leduc...).

The tests were definitively cancelled in 1958, and Rene Leduc was constrained to give up his work as an aircraft manufacturer. Despite a massive personnel layoff, and very reduced activities, René Leduc's company still exists, and it is now located in Azerailles, in the Meurthe-et-Moselle region (east of France), where it manufactures hydraulic components.

Aérostories, 2001

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The Leduc 010-01 atop the Languedoc 31 (F-BCUT). This system permitted to observe the proper functioning of the engine at altitude during the composite flights before the free flights.

SHAA                                       Clic

The Leduc 010-02 in Istres. Sweptback wings, Karmann fairing.  Conceived in 1938, this aircraft was truly advanced.   Clic

The 53rd  composite flight of the Leduc 010-01 took place for a brief public presentation at the Orly Airshow on the 11th of June 1950.

Keystone.                    Clic

August 17 1953: second airdrop of the Leduc 021 Nbr 01 releasing from its Languedoc transporter.

Photo M. Dufay.                    Clic

Brétigny 1953: front view of the Leduc 021. This photo shows the contrast of this aircraft with the others of the era.

Aline Leduc document.                      Clic

Test pilot Yvan Littolff in the "glass ring" cockpit of Leduc 021. René Leduc took great care with all the details of his aircraft.

Keystone                   Clic

The two Leduc 021 prototypes were presented to the public at Le Bourget in 1955.

Document Dassault               Clic

The Leduc 022, the last of the Leduc series on December 26th 1956 just before its first flight. As its rival the Griffon, it was powered by a combined turbo-ramjet engine. The wing sweepback of the 022 was more pronounced that its predecessors.

Photo J. Descroix                Clic