By the time Citroën realized that the Comotor joint-venture it had set up with Germany’s NSU was a failure, it was too late and the bulk of the damage was already done. The French automaker had spent an immense amount of time and an almost immeasurable fortune trying to fine-tune the Wankel rotary engine. It had built a single-rotor engine that was fitted to the experimental M35 coupe and a dual-rotor mill that powered the GS Birotor, but it had never managed to solve the engine’s core issues such as its unacceptably high fuel consumption.

As a last ditch effort to make a profit from the Comotor engine, Citroën decided to diversify and allocate its resources to building an aircraft. In the early days of the project the company considered two different possibilities: called RE-1 internally, the first was an autogyro, a hybrid that was part helicopter and part personal aircraft. Dubbed RE-2, the second project was a simple lightweight helicopter.

After months of careful research, Citroën’s top brass decided to move ahead with the RE-2 and quickly recruited Charles Marchetti, a well-known engineer that was responsible for the design of the Alouette helicopter, to help out with the project. According to a book published by the late Xavier Massé, the RE-2’s body was 283 inches (718 centimeters) long, it sat 102 inches (259 centimeters) high and it weighed 1,543 pounds (700 kilos).

The RE-2’s engine was an evolution of the Comotor 624 unit that was found under the hood of the ill-fated GS Birotor but it had larger rotors and its Solex carburetor was replaced with a Citroën-designed fuel injection system. It propelled the aircraft to a cruising speed of 108 miles per hour (about 173 km/h) and up to a maximum altitude of 11,482 feet (roughly 3,500 meters).

As work on the helicopter drew to a close, Citroën realized that it had overlooked a major problem: it did not have a pilot capable of testing the aircraft. Dominique Gilles was recruited at the last minute and the RE-2’s first flight took place on December 24th, 1975. Gilles later reminisced that the doors were removed from the aircraft in case something went haywire and he had to jump out.

Gilles did not have to jump out and the RE-2 completed its maiden voyage without any notable issues, but Citroën still had to obtain a certification from the government before it could legally sell the helicopter to the general public. During the rigorous certification process inspectors realized that the Comotor engine overheated at high rpms, an issue that sent Citroën back to the drawing board.

In the meantime, the French automaker changed hands and found itself part of the newly-founded PSA Peugeot-Citroën group. Peugeot’s view was that there were more pressing issues to deal with than trying to get a Wankel-powered aircraft on the market and it reportedly did little to support the project.

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After many additional hours of development and several more test flights the RE-2 obtained a six-month operating permit on June 14th, 1977. More tests flights followed but the government’s certification was never obtained.

Finally, on May 5th, 1979, Peugeot ordered Citroën to immediately put an end to the RE-2 project. The aircraft was tucked away in the company’s museum after flying a total of 38 hours. Citroën stopped all Wankel-related research that same year, abandoning a rotary-engined CX equipped with fuel injection and a five-speed manual transmission.

The period photos and the video above were kindly provided by Citroën’s archives department.