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The birth of the Goddess

"DS" is a French pun on the word "goddess"

What can one say that has not been said before about CitroŽn's DS? 

Adjectives such as "revolutionary", "ahead of its time", "quirky", "courageous" all spring to mind but all have been used by others in the past. 

Within a few months of the launch of the equally revolutionary Traction in 1934, CitroŽn's engineers set to work on its successor. Early design studies employed the basic underpinnings of the Traction but with a more "streamlined" body.

At much the same time, work was being undertaken on the TPV (Toute Petite Voiture) - the car that would become the 2 CV. Since the TPV would be aimed at the bottom end of the market and the Traction and its successor were aimed at the top end of the mass production market, it was decided that a new model, codenamed AX, should also be developed to cater for the middle market.

In an effort to extend the range of the Traction, a V8 version was developed and shown at the Paris motor show but sadly, the car never made it into production. 

The Traction replacement was given the codename VGD (Voiture ŗ Grande Diffusion or "mass produced car") by Pierre Boulanger and Andrť Lefebvre, the spiritual father of the Traction set about his task with enthusiasm.

He started with a clean sheet - he proposed a monocoque structure in which the centre of gravity would be as low as possible, the roof and bonnet would be of aluminium and the floorpan would support unstressed, lightweight body panels. 

VGD scale model (below) Drawings of the Traction replacement (above)

AX scale model (below)

Then the territorial ambitions of an Austrian corporal intervened and orders were given by the occupying forces that all development work on new models should cease. However, despite these orders, work continued in secret - free from the normal commercial constraints, fervid imaginations were allowed to run riot.

CitroŽn's management foresaw that at the end of the war, there would be an almost insatiable demand for new products. They were also well aware that much of France's road infrastructure was in a very poor state of repair and that any new model(s) would require suspension systems that could cope with this. Fuel would be likely to be rationed and expensive so the new models would need to be economical. In fact much of the design brief for the TPV applied equally to the VGD.

Suspension 

Conventional suspension systems suffer from the dichotomy between, on the one hand, the need for comfort and on the other hand, the need for good roadholding and handling. A softly sprung car is comfortable but has poor roadholding and handling and furthermore suffers from attitude changes depending on the weight and distribution of the load carried. A firmly sprung car offers good roadholding and handling but is uncomfortable on anything but the smoothest of surfaces.

From its inception the car was intended to use either torsion bars or rubber suspension; the requirement being for a very supple system but without excessively long suspension arms since these, by virtue of an ever-changing wheelbase, would cause inconsistent handling.

Two solutions were achieved - that of the 2 CV and that of the D Series and subsequent hydropneumatically sprung CitroŽns. The 2 CV solution is a very soft suspension and works by virtue of its front to rear interconnection and low weight. A number of VGD prototypes were equipped with 2 CV suspension but suffered from excessive body roll, pitching and load-related attitude changes.

AX scale model

Hydraulics 

In 1942, Paul MagŤs had an incredible idea. MagŤs was a junior engineer working on braking systems who concluded that hydraulic power could be applied to provide levelling of the suspension and operation of the steering and transmission in addition to the brakes. Even though the principles were well understood, putting them into practice presented numerous problems ranging from the incredibly fine engineering tolerances required through to the choice of materials and hydraulic fluid. Step by step these problems were solved.

Engines 

Walter Becchia was the man responsible for the 2 CV's flat twin and it was he who was given the task of developing a new engine.

He designed a water cooled flat six of 1 806cc capacity producing 63,8 bhp @ 4 500 rpm.

In 1948 following successful trials of the 2 CV's engine, the flat six was converted to air cooling (below) although all else remained unchanged including power output which was adjudged to be too low.

The project was abandoned in 1954 due to lack of power, excessive thirst and great weight despite the widespread use of aluminium. The flat six would have been mounted ahead of the front axle as in the 2 CV.