WITH TWO brand new models making their debut at Kyalami, plus some interesting modifications to the Tyrrell, there was plenty to keep racing car afficionadoes happy in South Africa although, earlier, models had been expected. One five new thing that both the new cars have in common is the trend back towards totally enclosed bodywork, although the Shadow DN1 goes a little further in this respect than the McLaren M23. Both cars have been designed to meet the latest safety regulations of the CSI. These are included in Article 792 and state:
“Crushable structure: the entire fuel tank area of the car in direct contact with the open air stream must incorporate a crushable structure conforming to the specification hereafter.
“The term licked by the open air stream is considered to define the complete external area of the body monocoque construction irrespective of such added items as water radiators, inlet ducts, windscreens, etc.
“(a) The crushable structure should be sandwich construction based on fire resistant core of minimum crushing strength of 25 lb./sq. in. It shall be permitted to pass water pipes through this core.
“The sandwich construction must include two sheets of 1.5 mm. thickness, one of which shall be a sheet of aluminium sheet having a tensile strength of 14 torts/ sq. in. and minimum elongation of 5%.
“(b) The minimum thickness of the sandwich construction should be 10 mm. The fore and aft fuel tank area, however, should provide for a crushable structure of at least 100 mm. thickness at such crushable structure’s thickest point the position of this widest point to be at the constructor’s discretion over a length of at, least 35 cm, after which it may be reduced gradually to 10 mm.”
Taking this as a basis McLaren designer Gordon Coppuck, who had not previously completed a Formula One design, having concentrated on Can-Am and Indianapolis cars, set about the new M23. Another factor he took into consideration was that the current McLaren M19 was not the fastest car in a straight line but that the suspension system including the raising rate front set-up worked extremely well.
He obeyed the safety regulations by designing a monocoque which utilised a sandwich construction with each outside skin being made up of two sheets of 16-gauge aluminium in between which a polyester foam filling had to be added. This was done by injecting through an aerosol. In fact there are two fluids which are kept in separate until they are injected and only meet at the spray nozzle. This has proved to be a costly and timely operation but McLaren believe that in so doing they have complied with both the letter and the spirit of the regulations.
The next problem was to design a car with more straight line speed than the M19. Coppuck went for a wedge-shaped design with side radiators and a sharply pointed droop nose. The radiators are contained within ducts which, unlike previous designs, are not simply fibre-glass cowlings but an integral part of the chassis. Every effort was made to keep the passage of the airflow clean and to this end all the various ancillaries, oil tank, oil radiators and battery have been tucked out of the way. The oil radiators, for instance, are mounted directly behind the water radiators. The wing mounting is just a single streamlined monocoque strut. There is a very tall airbox, which also acts as a partial engine cover, although the plugs can be reached without removing it.
The suspension is very similar to the M19 although the rear is much lighter but was tried on the M19 at Brazil. The steering is now aft of the front wheel centre line. Coppuck believes that the reduction of the polar moment of inertia is still worth striving for, even if this doesn’t mean placing the gearbox inboard, which tends to have its problems. Instead the main fuel tank of the M19 is situated between the driver and the engine. The CSI rules allow only 80 litres in one tank and this is the amount McLaren have in the central tank while the rest is situated in tanks either side of the driver although they do not fill the whole side of the monocoque as is the case with so many cars. This central tank necessitates the driver sitting very well forward: The cockpit is much smaller than the M19 and, because of this, a quickly detachable steering wheel has been fitted.
The finished car looks tremendously attractive in the Yardley colours and Denny Hulme has already shown that it is effective on the track. The M23 is the kind of racing car any enthusiast would travel hundreds of miles to see. On the circuit it tends to be a very neutral handling car, so if you see Hulme with the tail hung out you know he is trying very hard. Chassis number one was at Kyalami and will also be seen at Silverstone while a second will be ready for Peter Revson in time for Spain. A third will be built at a later date.
The Shadow project is an interesting one in several ways. Tony Southgate is a very talented young designer who sometimes felt a little cramped at BRM. He wasn’t allowed the time or money to develop the BRM P180 and this was undoubtedly one of the reasons he left Bourne. With the Shadow he started with a clean sheet of paper, but this time had a Cosworth V8 engine and Hewland engine to incorporate rather than the BRM engine and box. The P180 BRM, of course, had its radiators at the rear behind the rear wheels but, for the Shadow, Southgate has abandoned this idea but mounted them slanting backwards at the front of the engine bay. However twin oil radiators are mounted at the rear of the car. Although the car is flat-topped it bulges out in the middle to accommodate the fuel, mainly in the sides, and also the deformable polyurethane foam, which has been inserted in between the aluminium sheets in a similar way to the McLaren.
The suspension is reasonably conventional along Southgate’s thinking and thus is very similar to that of the P180 with very steeply-angled spring damper units at the front. Apart from the wheels and the cockpit, the car is totally enclosed in attractive black fibreglass bodywork which appears to be thinner than on any contemporary car. The whole lot is topped by a strangely-shaped air box which has a triangular-shaped orifice and looks in profile like a nun’s headgear. Removing this, and the engine cover, to change plugs is at present an extremely tedious business. But the overall effect is extremely impressive. The large rear wing is mounted well to the rear although at Kyalami modifications were made to bring it closer to the centre line of the rear wheels. Incidentally the cars run on the spun MelMag wheels and Goodyear tyres. Apart from a coloured Stars and Stripes all the decals and signwriting on the car are in white. The fuel it uses is lead-free and is produced by refinery equipment manufactured by sponsors—Universal Oil Products. Fuel from Kyalami was flown in all the way from UOP’s Chicago headquarters.
Two cars were complete for South Africa, DN1/1A for Jack Oliver and DN1/2A for George Follmer this car having a slightly larger inside dimension of the monocoque to accommodate the American’s hips. A third car is currently under construction at Northampton which will be run privately by Graham Hill and a spare for the works team will follow.
So it was the McLaren and Shadow that were creating the most interest as Kyalami although Team Tyrrell were also trying quite a few new combinations on their cars. They had available new rear wings which mounted much further back behind the rear wheels, and there was a new tubular subframe for Stewart’s car which gave much more angle to the rear spring damper units. At first only Cevert tried the new wing position and various aluminium strips were tried on the nose at the same time. Stewart later tried the new rear wing arrangement and preferred it. Certainly Tyrrell are not complacent and are working hard to improve their cars.
The only other team in South Africa who tried anything new was Lotus. Following the failure of a Mel-Mag rear wheel on Peterson’s car in Brazil, Lotus had designed some cast 13 in. rears to their usual pattern, as previously they only had 15 in. rears of their own design available. Also on the wheel front they tried some tiny 12 in. diameter wheels and tyres for the first time in public but did not persevere with them. By the Spanish GP there will be many more interesting new ears and developments to tell you about.—ARM.