Principles of Automobile Motion

1 Principles of automobile motion ost pictorial representations of motorcars become successful as an automobile artist you generally depict them in motion both on have to understand vehicle aerodynamics, but it and off the track. With this in mind, I have does help to understand, to a certain degree, how decided to devote this first chapter to and why various cars act in different ways when in Mprecisely that subject, but will only briefly outline motion. the principles which apply. Talk of drag coefficients The two most obvious forces which could and aerodynamics won’t really mean that much influence how the artist portrays an automobile in to the artist; what is important is for the student motion is pitch and roll. If you are portraying cars of automobile art to understand, especially with at speed, especially Formula One or Group C sports racing cars, is that aerodynamics increase a car’s cars, they will pitch back around their Y axis (see performance by helping it go faster and stick to fig 4). This pitching moment is related to the angle the road like glue when cornering, etc. of attack of the wind over the car’s nose, or if you Three aerodynamic forces act on an are depicting a car cornering hard, the side forces automobile: Drag, Lift and Side Force, combined come into play showing roll around the X axis. with parallel forces acting on three axis – X, Y and Aerodynamics, of course, play a major role Z – as well as the moments rotating round these in the design of modern Grand Prix cars: as well axis: X = Roll (Mr); Y = Pitch (Mp) and Z = Yaw as the all-too-familiar rear wing, we now have (My). bargeboards, winglets, diffusers, aero flaps and I am not saying for one moment that to chimneys; the list is endless because of the 1414 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. 24 Fig 3.2/1 Using 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 3232 Fig 8.11/1 Shown 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 8.11/2 For 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. 120 Motorsport – racing & rallying Fig 8.11/3 The architecture of Monte Carlo is essentially light 1937 Monaco Grand Prix – Watercolour beige with Terra Cotta, Yellow Ochre and all shades 53.7 x 37.5cm/21 x 14½in in-between. Likewise, the paving on the harbour front that the cars were racing along is a sandy beige colour. For this particular painting, I decided to create a view For the background, I laid on a basic light wash of Burnt looking back at the famous waterfront as the cars race Sienna and Yellow Ochre mix, working in various along it. If you stood on the same spot today, fewer than shades of the two colours. six of the buildings from 1937 remain. The cars themselves were, of course, silver, so I left the The first thumbnail sketch (see Fig 8.11/1 opposite, top) basic white of the paper with a wash of Ultramarine Blue was created virtually as a doodle using fine line pens, on the top surface; Paynes Grey was added for the lower plus markers in cool and warm greys. body sides with background colour. For the shadows, I During my visits in recent years, I have taken photos to never use black, but a mix of Sepia and Phaleo Blue, with use as reference material to check on colour and period odd dashes of Burnt Sienna, finished off with flicks of architectural accuracy. To create the two W125 Mercedes Permanent White to add movement. Benz GP cars, photo references from Mercedes Benz’ own One trick I use is to paint the portion of the car nearest museum in Stuttgart were used. Eventually, I mated (this could apply to a rear view) in a deeper, crisp colour, together the two pencil sketches of the background and whilst fading away in colour depth the furthest portion; cars. (See fig 8.11/2 opposite.) this helps give the illusion of speed and movement. 121.

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