DESIGN ANALYSIS
of AC's post-war 2 Litre Saloon (page 6)
BODY STYLE


Any good artist knows that there are solutions (or partial solutions) to any styling problems. To make the windscreen look smaller from the front view, the front wings need to be enlarged. On the AC, the wings are taller than on most contemporary cars, and also mark the widest part of the car (5' 7" / 170cm). From a close up front view, the wings totally dominate and the screen looks relatively small. As one moves further back to view the car, the effect diminishes and the screen eventually dominates from a more distant view. So, it wasn't a total solution, but it was pretty effective.
The rear window area was less restrictive to styling, since traditionally, rear windows were so tiny at that time. From a side elevation of the car, it is very easy to see how a series of flowing curves were drawn, that are closely related. The roof line, side window, side moulding, and the elongated helmet wings. The compound curve of the radiator grill also gave it an added modern feature that most other cars lacked.
Windows and Doors

The doors are another excellent feature of this design. They are extremely wide, permitting easy access to the rear seats. The doors are incredibly heavy, and need attention over the years to ensure a good fit. A slight sagging, and they will scrape the door-steps. Apart from hinge wear, simply keeping the hinge screws and nuts tight will help. The doors are fitted with little rollers to try and prevent them from scraping the door-step plate.Opinions vs Taste!

1940s articles and road tests showed great enthusiasm for its good looks. By the late 1950s, with second-hand car tests appearing, fashion had changed and its looks tended to fall out of favour. The classic car boom of the 1980s brought highly polarised opinions being voiced. Since then, curves have come back into fashion! As an artist, it often amuses me how individual tastes can change from one extreme to another, as fashions come and go. The AC is the same shape, but it is interpreted differently as time passes - good, bad, good, etc.!
Aero-Dynamics
This is one of the most mis-understood of technical topics related to cars. In my school days (1970s), enthusiasts were convinced that a sharp wedge shape was needed to "cut through the air"! Nothing could be further removed from the reality of fluid dynamics. There are really two criteria for cars here: Aero-dynamic stability, and aero-dynamic drag. Simply rounding the front end with compound curves can be a substantial improvement for drag, over alternative car styling. Actual air resistance depends on the frontal area as well as the shape, and the AC presents a fairly large object for the air to negotiate. Simple fluid dynamics of a moving object becomes modified because said "object" is so close to the stationary road surface. Limiting the amount of air passing underneath is a more modern practice that would improve this AC's performance.
For stability, it helps if the side area of the bodywork is concentrated towards the rear, behind the centre of gravity. This is the same principle as the tale-fin on an aircraft, racing car or an arrow. Air flowing alongside this rear-biased area, will tend to keep the car pointing in the direction it is travelling. The higher the speed, the greater the effect. The AC's long bonnet and high roof-line ensures that its shape is very stable in this respect. The 2 Litre Saloon carries about 52% of its unladen weight on its rear wheels, and up to about 58% if heavily laden. But the aero-dynamics are such that stability is maintained. A lecturer once argued with me that cars are more stable with front biased weight, because "...it's the front wheels that steer"!!! Hmmm... correct me if I'm wrong, but the rear wheels have a say in the matter too!!! Or better still, check out Formula 1 car design. Rear weight bias, and rear wing supports that double as tail-fins.
As an aside from aero-dynamics, that slight rearward weight-bias is also a help for traction in slippery conditions. The next best thing to 4 wheel drive is a rear weight bias for rear wheel drive. I recall an AC owner in the 1960s writing that the last cars to get stuck in the snow were Minis and ACs. The rear drive also helps when weight is transferred to the rear when hill climbing or simply accelerating in moderately slippery conditions.

