Gabriel Voisin made his name in aviation being the manufacturer of Europe’s first powered, and controllable, flying machine. His company “Avions Voisin” did well for itself through military contracts in WWI. Once the war was over times suddenly became much harder and Voisin diversified into the automobile industry, they built some truly beautiful road cars through the 20’s and 30’s.
Voisin won the 1922 “Grand Prix de Tourisme”, held at Lyon, with a C3 touring bodied road car. The organisers felt aggrieved at Voisin’s rather liberal interpretation of the rules and being unhappy with the result banned Voisin from the next years race. Voisin’s response was to design an entirely new racing car; the C6 Laboratoire.
Not having an engine to meet the current 2Ltr Grand Prix formula, Voisin would be using one of their own 6 cylinder, inline, sleeve valve engine designs with Zenith carb’s which would give a top speed of 175 kmh, somewhat less than their rivals.
To compensate for the lower power of the engine André Lefèbvre (who later worked for Citroen where he designed the Traction Avant and the DS) was asked to design a light weight car with good aerodynamics. The chassis was made using airframe techniques, a wood frame having lightweight metal sheet riveted to it and metal brackets bolted through in load bearing areas. The C6 design was the first time a monocoque chassis was put to work and probably the first time that aerodynamic shaping was used to aid stability, as well as speed, on a racing car. The rear wheels were tucked inside the body having a track width of only 750mm. This clearly helps airflow over the rear portion of the car but one can’t help wondering about the stability of the chassis under heavy cornering loads. That said many three wheel car experts insist the Morgan system of two wheels at the front and one driving from the rear is far more stable than the Reliant Robin system where the single steering wheel at the front has often lead to those cars overturning.
A team of four cars were entered for the 1923 French GP but being little tested didn’t fair well. Sleeve valve engines seldom get anywhere near the power output of normal engines and the lightweight aerodynamic body was not enough to compensate for the lack of power, even after the rear differential was removed to reduce weight. Unfortunately lack of power wasn’t the only problem. Clever use of otherwise wasted energy of running at over 100 mph was made by having a propeller drive the water pump to cool the engine. A neat solution that saved any power drain on the engine, sadly it was insufficient to meet the engines cooling needs. Only one of the team cars finished the race, that driven by the designer himself. Lefebvre finished in fifth, and last, place. This turned out to be the best result that the C6 would achieve.
Any lack of high profile results cannot detract from a truly innovative design, the benefits of which remained unrealised until the Lotus 25 of 1962.
Scratch built 1/24th scale model.
model Built by Ian.
This model was built in a rather unconventional way and from an unusual material. Ian wanted to make one of these historically important cars for a long time but although having plans, drawings and a few photos never quite found the impetus to get started. That was untill being told of a card model whilst at the Sutton Coldfield model show in 2010. The gracious gentleman who had built the card model gave us the web address of the French company that made the free down-loadable model and Ian saved a copy along with his other Voisin C6 references. Then, during the spring clean of 2011, Ians wife passed him some printers lithograph aluminium sheet left over from her fathers old printing business. Immediately thinking of the Voisin card model Ian saw a quick way of building up the body shape.
As well as developing a new found respect for card modellers, and the absolute accuracy such a method requires, Ian was able to build up a strong body, fairly close to the required shape, in a very short time. It is a testiment to the strength of the design shape that the body could stand all the handling, cutting and scribing without any problrms at all. One of the downsides to working from a card model set is that they tend to rely on the printed images for much of the details and shaping, so some planing ahead is required for locations where additional shaping will be required. Isopon 38 proved very useful in this area as it can be mixed and shaped easily, dries quickly and sands very easily and to a smooth finish.
Much of the models other details were also made from the lithograph plate which is fairly easy to cut sand and shape. In order to glue these metal parts together thinned down "Gator grip" and Cyano Acrylate were employed depending on the circumstances.
Once the body shape was done then the problems started to come up. Usually with a car model you build up a series of sub-assemblies untill the body shuts on top of the interior and chassis. Well here Ian had a body with no chassis or interior and needing to build it inside the already closed body shell, along with and engine and all the cockpit details. To cut an long story short the technique required is to build the parts in the order the car is built. chassis, engine-gearbox, cockpit..... then each section is building over the previous one untill the final little details go on. The methods and skills for scratch building will be found in our articles and projects pages.
The wheels were made from one master which was moulded and four resin cast wheels taken from the mould, a technique also used for the hub knock offs.
Final paint finish was by simple acrylic paints from Hobby craft sprayed through an ordinary airbrush over Halfords car primer. Detail painting was all by Citadel acrylics and some Humbrol enamels.
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