Since the first racing car was designed the radiator has been a tiresome necessity, and Gottlieb Daimler set us all on the wrong path by water-cooling his first V-twin engine. If water-cooling of the cylinder heads and barrels of the first internal combustion engines had not been invented, who knows where we would be now. At first the radiator was hung anywhere that was convenient and was nothing more than a rectangular cooling element, quite useless as regards power production or car performance, but a necessary evil. In the vintage years resettled in a conventional position at the front of the car and took definite shape according to the whim of the designer. Indeed, the designers used it as a sort of trade mark with which to stamp their complete design. You could easily distinguish one car from another by the radiator shape, from the horse-shoe of Bugatti, through the Gothic arch of Bentley to the square-rigged elegance of Rolls-Royce.
On the racing cars of the thirties it returned to being a simple cooling element hidden away inside a nose cowling, with the designer’s imprint being shown in the shape of the opening in the cowl that allowed air to pass through the radiator block. In the fifties the decorative grilles began to disappear and functional openings led to functional cooling elements and further thought was given to what happened to the air after it had passed through the radiator.
In recent years, with the detail study of air-flow in and around racing cars, the radiator has become an integral part of the overall design of the car, its positioning and size being an important part in the layout of a Formula One car of today. Over the years there have been people who have been very conscious of the importance of the radiator, not from its ability to dissipate the waste heat from the engine, whether it be from the oil or the water, but from its effect on the rest of the car. It is a known aerodynamic fact that an opening in front of a vehicle spoils the air-flow for the rest of the vehicle and many years ago Renault and others put their radiators behind the front-mounted engine, to permit of a smooth bonnet line. Fred Dixon went to the trouble of counting the number of holes in the radiator matrix of his Riley and working out the actual cross-sectional area of all the holes. He then cowled in the radiator, making sure that the cowl fitted tight to the radiator so that all the air that went through the hole in the front went through the matrix, and this allowed him to have a very small slot in the lower part of the cowling, which proved more than adequate at speed. When Reid Railton designed the Bluebird which attained 300 m.p.h. his radiator was fed by a narrow slot in the front, and for a limited period of time this slot could be closed by a flap, to present an unbroken frontal area to the air. In his brilliant Railton-Mobil-Special which attained 400 m.p.h. he did away with radiators altogether and used a vast ice-tank to dissipate the heat from the two Napier Lion engines. Apart from having to provide an opening in the front of the car to feed air to the radiator there is the added drag caused by the air passing through the radiator Reid Radios was clearly conscious of all this in 1938.
In 1956 when Frank Costin designed the Vanwall body with a very keen eye to drag and frontal area the opening necessary to pass sufficient air to dissipate the heat from the 285 b.h.p. engine was remarkably small. Even so, when the complete car was put in the full-scale wind-tunnel at RAE Farnborough it was found that the opening was far greater than was really necessary for a speed of 150 m.p.h., but of course the Vanwall was not always travelling at 150 m.p.h. It would have been interesting to have developed a nose cowl opening like a camera shutter, that could have opened or closed automatically as speed varied. For a few seconds at maximum speed on a straight you could have presented a totally smooth nose cowling to the air, and on hairpin bends there would have been the maximum opening.
In 1960 when Colin Chapman finally swallowed his pride and put the Lotus engine behind the driver, as John Cooper had been telling him for years, he designed the Lotus 18 behind the rectangular radiator necessary to cope with the heat from a 2½-litre Coventry-Climax four cylinder engine. The rectangular radiator was the frontal area permitted for the Lotus 18 design and everything, apart from the driver’s head, had to be contained behind that number of square inches. It was not a pretty car, but it was functional.
The next major trend was to design the radiators into the sides of the car, on each side of the engine, saving the weight of water pipes and simplifying the plumbing, and almost everyone followed this trend until the Lotus 78 when the radiators were laid almost flat within the sidepods and became a vital factor in the air-flow through and over the car. This is the present trend, the usual practice being to bleed air off from the front of the side pod, through the radiators and out over the top of the side pod. In designing the Williams FW07 Patrick Head went one better and did away with the oil radiator, thus eliminating the drag caused by radiators by 50%, for the conventional layout had become to have a radiator for oil in one side-pod and another for water in the opposite side-pod. Head replaced his oil radiator by an enclose, and sealed heat exchanger in which the oil and water pipes dissipated their heat and distributed the surplus to each other, the water radiator being the controlling element. That it worked effectively was instanced in Austria last year when Alan Jones came into the Williams caravan after winning the race and said to Patrick Head. “. . . the car was perfect. Oil pressure never wavered, and oil and water temperatures sat at 90°C throughout . . .” That was a designer’s dream come true.
Along the way there have been many variations and off-shoots and the Porsche designers have been the bravest, with their air-cooled engines, this system saving the weight and drag of radiators totally. They reached their limit with the turbo-charged flat-12-cylinder 917 Can-Am engine, which gave something like 900 b.h.p. By that time the size of the oil cooler was nearly as big as a water radiator and could no longer rely on air from the engine fan to dissipate the heat, so it had to be mounted at the front of the car. The engine was acting as its own heat-exchanger between the oil and the air. Development on the turbo-charged flat-six 935 series has led Porsche to use water-cooled cylinder heads, though the cylinder barrels remain air-cooled.
Gordon Murray attempted to use surface radiators let into the sides of the Brabham-Alfa Romeo, but he got his sums wrong and the idea didn’t work. David Cox developed a brilliant idea for Brabham, where the radiator was laid flat on top of the engine and a fan driven off the hack of the gearbox sucked air from under the car, up through the radiator and out through the fan. As a cooling system it was perfect but it transgressed various aerodynamic parameters laid down by the rule-makers, so it was banned.
From being a tiresome addition to a racing car, hung on where best it could be contained, the radiator went through a period of being the hall-mark of a racing car, to being hidden away where it would cause least trouble, to becoming an important part of the overall design; but it has always been with us and always will be even if it is hard to find at times, until someone develops a new form of heat dissipation or does away with the internal combustion engine. — D.S.J.