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Principles ofautomobile motion

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Most pictorial representations of motorcars generally depict them in motion both on and off the track. With this in mind, I have decided to devote this first chapter to

precisely that subject, but will only briefly outline the principles which apply. Talk of drag coefficients and aerodynamics won’t really mean that much to the artist; what is important is for the student of automobile art to understand, especially with racing cars, is that aerodynamics increase a car’s performance by helping it go faster and stick to the road like glue when cornering, etc.

Three aerodynamic forces act on an automobile: Drag, Lift and Side Force, combined with parallel forces acting on three axis – X, Y and Z – as well as the moments rotating round these axis: X = Roll (Mr); Y = Pitch (Mp) and Z = Yaw (My).

I am not saying for one moment that to

become successful as an automobile artist you have to understand vehicle aerodynamics, but it does help to understand, to a certain degree, how and why various cars act in different ways when in motion.

The two most obvious forces which could influence how the artist portrays an automobile in motion is pitch and roll. If you are portraying cars at speed, especially Formula One or Group C sports cars, they will pitch back around their Y axis (see fig 4). This pitching moment is related to the angle of attack of the wind over the car’s nose, or if you are depicting a car cornering hard, the side forces come into play showing roll around the X axis.

Aerodynamics, of course, play a major role in the design of modern Grand Prix cars: as well as the all-too-familiar rear wing, we now have bargeboards, winglets, diffusers, aero flaps and chimneys; the list is endless because of the

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Fig 2.8 (below)Another workshop pencil sketch, this time a famous sports car from the 1950s, the Italian-built Lancia

D24. It was this model, driven by Alberto Ascari, which claimed victory in the 1954 Mille Miglia.

It’s workshop scenes like this that make interesting compositions in their own right, and this car was in for a major transmission overhaul with its wheels off

and front suspension dismantled. Remember, under a car’s bodyshell there are a host of components, so try to

understand as much as possible about how it works.This sketch was drawn in an A3 wire-bound 90gm

sketchbook using soft pencils; i.e. B and 2B, plus a 4B for

emphasising darker shaded areas.

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Fig 3.2/1Using the centre lines on the perspective

box grid (fig 3.2) for the X, Y and Z plots (X = length, Y= width and Z

= height), you can adopt whatever scale you feel is appropriate in any measurement which suits

the subject you are drawing – the larger the object in real life – i.e. an aircraft carrier

– the smaller the scale, otherwise you might need a very large piece of paper!

another method: isometric projection, where all lines remain parallel, drawn at 30 degree right angles to one another, all vertical lines remaining vertical (see fig 3.2/3), but more about this later.

Throughout my career as a Technical Illustrator in the aircraft and automobile industries, the more common perspective grid was used (see fig 3.2), and I found this to be the most useful method with the convenient three axis, the X, Y and Z centre lines, as used in the automobile design process.

A car’s basic dimensions can be plotted using any scale required on these centre lines, thus enabling the illustrator to construct the basic overall dimensions of the vehicle portrayed i.e. X = length, Y = width, and Z = height. Once these

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Fig 8.11/1Shown here is my very first thoughts for this painting,

drawn on a piece of 6 x 4½in/15 x 11cm scrap paper,

using a fine line ballpoint pen, marker pens and correction

fluid.If an idea comes to you at any time, get your thoughts onto paper as quickly as possible,

then develop the idea when you have more time, eventually creating the final image.

Fig 8.11/2For this painting I produced two

separate working drawings, eventually mating them to create the final

composition. This was necessary as I had to undertake very detailed research

about which buildings were actually there in 1937 (when this painting is

based).The two W125s were produced from many photographs supplied from

Daimler Chrysler Classic archives.

Motorsport – racing & rallying

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Fig 8.11/31937 Monaco Grand Prix – Watercolour

53.7 x 37.5cm/21 x 14½in

For this particular painting, I decided to create a view looking back at the famous waterfront as the cars race

along it. If you stood on the same spot today, fewer than six of the buildings from 1937 remain.

The first thumbnail sketch (see Fig 8.11/1 opposite, top) was created virtually as a doodle using fine line pens,

plus markers in cool and warm greys.During my visits in recent years, I have taken photos to use as reference material to check on colour and period

architectural accuracy. To create the two W125 Mercedes Benz GP cars, photo references from Mercedes Benz’ own

museum in Stuttgart were used. Eventually, I mated together the two pencil sketches of the background and

cars. (See fig 8.11/2 opposite.)

The architecture of Monte Carlo is essentially light beige with Terra Cotta, Yellow Ochre and all shades

in-between. Likewise, the paving on the harbour front that the cars were racing along is a sandy beige colour.

For the background, I laid on a basic light wash of Burnt Sienna and Yellow Ochre mix, working in various

shades of the two colours. The cars themselves were, of course, silver, so I left the

basic white of the paper with a wash of Ultramarine Blue on the top surface; Paynes Grey was added for the lower body sides with background colour. For the shadows, I

never use black, but a mix of Sepia and Phaleo Blue, with odd dashes of Burnt Sienna, finished off with flicks of

Permanent White to add movement.One trick I use is to paint the portion of the car nearest

(this could apply to a rear view) in a deeper, crisp colour, whilst fading away in colour depth the furthest portion;

this helps give the illusion of speed and movement.