pooper and cooper chassis design

Owen Maddock

Following unsuccessful approaches to HRD and Trojan,[5] Maddock was taken on by the Cooper Car Company, run by father and son team Charles and John Cooper. Charles Cooper had been involved in motorsport since the 1920s, having acted as racing mechanic to Kaye Don for many years, and had built John a racing special as a twelfth birthday present in 1936. Working at the family garage in Surbiton, the pair constructed their first motorcycle-engined 500 cc (31 cu in) racing car in 1946. A string of wins followed, raising the reputation of the Cooper 500 to such an extent that they were able to begin selling replicas to fellow competitors.

Despite their growing popularity, by the time Maddock joined the company in September 1948[6] they were still not large enough to be able to justify taking on a full-time engineer. In addition to his drafting duties Maddock therefore also filled the roles of fitter, storekeeper and van driver, among many.[6] Gradually the Coopers began to make more use of Maddock's drafting skills, however, realising that having proper technical drawings was preferable to sketching designs to full scale on the walls, where they were frequently painted over![7] Some smaller parts were fabricated from crude sketches, or frequently simply by eye. During his time with Cooper Maddock became renowned for the detail and artistry of his blueprints, and with a talent for lateral thinking his contribution to the design of Cooper's cars grew rapidly. By the time of Cooper's heyday the design process was essentially a three-way tag match between Maddock, John Cooper and star driver Jack Brabham. Maddock's protégé and eventual successor, Eddie Stait, later recalled to historian Doug Nye that "John had a lot of the original ideas and then Owen would add some very original thinking in developing those ideas; they were a team ... and Jack of course contributed a lot."[8]

Unusually for the time Maddock sported a full beard. As a result of this he quickly became known around the Cooper establishment as "The Beard", while to Charles Cooper he would always be "Whiskers".[7] His mercurial temperament and volatile temper sometimes grated against his employers' nerves. Once, when a potential new recruit arrived for a job interview, Charles Cooper asked his secretary whether he had a beard. On being told that he did, Cooper told her to "Send 'im home. I've got enough trouble with the one I've got!".[9]

Early Formula Three and Formula Two work[edit]

Eventually Maddock was installed in his own drawing office within the Cooper building, although it was somewhat cramped, being located beneath the works stores.[10] Initially, Maddock's duties revolved around drawing or redrawing existing components and developing refinements on the existing Cooper 500 and 1000 cars. However, in 1953 Maddock was instrumental in introducing two design features that became Cooper trademarks for the rest of the decade: the curved-tube chassis frame and the "curly leaf" leaf spring location bracket. The car that both of these design innovations were pioneered on was the Mark VIII version of the Cooper 500 Formula Three machine.

The curved-tube chassis[edit]

The curved-tube chassis was the more controversial of the two novel ideas.[11] The existing Cooper 500 chassis design process had been one of evolution since the earliest production 500s rolled out of the Surbiton works in 1947, and had been based on simple, traditional twin longitudinal box-section ladder frame. With the introduction of the Mark V in 1950 this was augmented by a beefed-up and stiffened body support structure,[12] creating a semi-space frame chassis. This was refined further over the next two years, with the Mark VI marking a switch to equally sized tubular upper and lower longerons, and the Mark VIIA introducing tubular upright sections as well.[13] However, for 1953's Mark VIII the Coopers decided to start afresh with a completely new chassis design.

A true space frame design uses only straight tubes, properly triangulated to pass loads either in tension or compression.[14] Following proper engineering practice, when he started to develop plans for the new chassis design Maddock sketched out various straight-tubed space frame designs. However, when he showed each to Charlie Cooper his response was "Nah, Whiskers, that's not it..."[11] Frustrated, Maddock finally went away and drew a frame in which every tube was bent. To his surprise, rather than dismissing it Cooper's reaction was to snatch the plans out of Maddock's hands and exclaim "That's it..."[11] Although the curved tube design broke several engineering rules Maddock and the Coopers later rationalised their decision. Their arguments were that curved tubes could be located and routed so as to leave adequate space for mechanical components, and as the tubes could be run close under the car's bodywork this could be attached directly to the frame, saving the weight and complexity of a dedicated bodywork frame.[11] Although the idea started as a joke Maddock would later defend the design, even in the teeth of strong criticism from Cooper's star driver Jack Brabham. Brabham would come to recall that Maddock was latterly an even more staunch defender of the curved-tube concept than Charles Cooper.[15]

The T43 chassis was made of the usual Cooper 1 1/2 inch steel tube. The Mark 1 tall frame hoop encircled the seat back bulkhead and was unbraced whereas here (below) it was unbraced but the top chassis longerons each side of the engine bay were braced against the lower longerons by a three piece ‘Y member’.

What about those Cooper chassis’ which have always offended the purists- a true multi-tubulars spaceframe chassis should use straight tubes only, each stressed in either compression or tension.

Famously, after laying out several straight tube designs for the Mark 8, and in John’s absence having them rejected by Charles Cooper, Owen Maddocks decided to take the piss and presented an option in which every tube was bent- to his surprise it was embraced by Charles, a good intuitive Engineer.

Doug Nye recounts Owens account of the discussion about the approach when John Cooper returned.

’Curving the top frame rails down to meet the bottom ones reduced wracking through the frame. You could run curved tubes where they wouldn’t interfere with fuel tanks and suchlike. One of our very good welders always told me he preferred simple joints- with just one tube jointed into another- to multiple joints with with three or four tubes involved. We didn’t like weld overlapping weld and so tried to arrange things to avoid that. With curved tubes we could follow the body lines more closely, so we didn’t need the old strip -steel frame to support the body panels. What had started as a joke began to look quite logical, and very practical…’