1935 Voisin C25

Gabriel Voisin was one of France's aviation pioneers, building the first practical aeroplane capable of leaving the ground under its own power in 1907 and his Avions Voisin company was the first mass producer of aircraft in the world. During World War I, his company produced over 10,000 airframes and engines, licensed from Salmson and Hispano-Suiza, to power them. In 1918, after World War I had come to a close, Voisin's aviation venture was in decline, so he explored other means of keeping his workforce employed. Voisin experimented with motorized bicycles and a light two-seater economy car before deciding to produce an automobile that would compete among the most prestigious and powerful in the world. To that end, they purchased the rights to the Knight-type sleeve-valve engine which had been developed for André Citroën. Other notable marques that employed the sleeve valve technology included Daimler, Mercedes-Benz, Minerva, Willys, Peugeot, and Panhard.

Among the benefits of Sleeve Valve technology were its volumetric efficiency, favorable exhaust scavenging, detonation-free combustion of the charge, engine longevity, and lower operating temperatures of all power-connected engine parts, cylinders and pistons. Its operation was nearly silent and its torque delivery was smooth, qualities similar to that of a steam engine. High oil consumption and cylinder-assembly lubrication issues were among the disadvantages.

A 4.0-liter Sleeve-Valve unit was used to power the Voisin M1 in 1919 which was later re-designed 'C1' in honor of Gabriel Voisin's deceased brother Charles, though the mechanical specification remained the same. To demonstrate the vehicle's speed and economy, a special version competed in speed trials and hill climbs, and in 1921, a C1 chassis was taken off the production line and clothed with lightweight aluminum coachwork. In this guise, it beat the Blue Train from Paris to Nice by six hours.

Voisin's background in aeronautics led to an appreciation for lightweight construction, aerodynamics, and a low center of gravity, and they were among the first automakers to take these into consideration when designing and building an automobile. The Sleeve Valve engines, advanced technology and construction methods, unconventional designs, and high prices made them particularly popular with the elite in society, including royalty and celebrities. Among the famous artists of the era who favored the Lumineuse (or 'light,' in reference to its glassy greenhouse and angled windows) style were Rudolph Valentino, Maurice Chevalier and Josephine Baker as well as the modernist architect Le Corbusier.

Subsequent models adopted four-wheel brakes, a three-point engine mounting system, and advanced body engineering and design, using flat sheets of aluminum for the outer panels. While most automakers hide mechanical workings behind wood or upholstery, Voisin chose to expose them, highlighting the mechanical quality of its engineering.

The C2 was introduced at the Paris Salon and it came equipped with a 7.3-liter V12 engine and four-wheel brakes actuated by compressed air. This model was far too big and expensive to be profitable, but many of its technologies and lessons learned were implemented into future models. Most of the Voisin models that followed were powered by four or six-cylinder engines, the exception being the C13 of 1927 which used an eight-cylinder engine.

The C4 of 1921 had a 1,243cc, four-cylinder, 8CV engine, which later grew to 1,328cc in the C4s and finally to 1,550cc in 10CV form in the C7. The Voisin C5 was manufactured between 1923 and 1928 and its 4.0-liter four-cylinder Knight engine produced approximately 100 horsepower, and depending on the coachwork, could achieve speeds of around 80 mph. Approximately 1,200 examples of the C7 were built, most wearing standard factory bodies. The most popular of all Voisin models was perhaps the C11 equipped with a six-cylinder sleeve valve engine and sold well into the 1930s. The C12 displaced 4.5-liters, the C14 used a 2.3-liter 13 CV engine, and the C16 had a 5.8-liter engine. The C23 was introduced in 1930 and its six-cylinder engine displaced three liters, corresponding to 17 fiscal CV (approximately 80 horsepower). A total of 355 examples of the C23 were manufactured through 1936. The C24 had a lighter and lower chassis along with the engine from the C23, but with higher compression and two carburetors replacing the previous single one. Approximately one hundred examples were built, all with bodywork by Voisin.

Voisin C25
The Voisin C25 was introduced in 1934 at the Paris Salon and it used many of the mechanical components of the C24, including the underslung chassis, the retractable roof, and electromagnetic gearbox. The roof is operated via a pneumatic suction motor located in the trunk. The 2,994cc inline sleeve valve six-cylinder engine produced 95 horsepower and was paired with a two-speed-and-reverse electromagnetic gearbox. The 3,280mm wheelbase chassis was suspended by a solid front axle and live rear axle with semi-elliptic leaf springs. The shock absorbers were adjustable. Hydraulic drum brakes were located at all four corners.

Voisin gave his chassis distinctive names like Chasse, Chasseur and Diane, and the C25 and 27 chassis had Olympic themes including Bob, Luge, and Ski. The body designations were equally imaginative and included Lumineuse, Myrte, and Aérodyne. C25s are known in the Aérodyne, Cimier and Clarière styles. The Aerodyne was a four-door saloon while the Cimier was a two-door, four-seater coupe.

A total of 28 examples of the C25 were built.

by Daniel Vaughan | Sep 2022