Lotus and Tyrrell

AS WE CLOSED for press last month a new Lotus and a new Tyrrell for 1976 Formula One racing were shown outside the firm’s experimental departments for the first time. While the Lotus was a refitted and razor:sharp development of existing practice the Tyrrell was so revolutionary that a lot of people did not take it seriously, viewing it as something of a publicity stunt. It was clearly explained by Ken Tyrrell and Derek Gardner, his designer, that the car was an experimental Probe and purely a research Vehicle to test various theories; and that if the theories proved correct the 1976 Tyrrell cart would follow the same design lines. The new Lotus is the long overdue successor to the Type 72 which has had a very successful run for many years, and the ill-fated Lotus 76 which was 3 miserable failure more by reason of incompatability in the cockpit than design. It will be recalled that a major design feature of the Louts 76 was the electrically-operated clutch, from a button on the gear-lever, and a double brake pedal, allowing the driver to brake either with his right foot, as normally done, or with his left foot, thus leaving his right foot free to control the throttle pedal and therefore the driving force applied to the rear wheels and their consequent adhesion and slip angles and subsequent “balance” of the car in a very fast corner. At the time the two Lotus drivers were Peterson and lax, and while the former was prepared to experiment with the idea, the latter showed

no interest at all. Peterson tried but could not convince himself of the merits of left-foot braking and so that part of the new car died a quick death, and as both drivers were more interested in earning Championship points for themselves, and subsequent financial gain, than in any long-term technical progress, they steadfastly avowed that the old Lotus 72 was better than the new Lotus 76 and they dragged on with the obsolete car in a completely misguided attitude that took Lotus fortunes downwards instead of upwards. The Lotus 72 was altered, modified, bodged, hacked about and generally messed around, with no real design philosophy in mind other than to try and appease the drivers. Eventually Ickx just faded from the scene and Peterson became a shadow of his former tell’, so muddled and confused that he had a Lotus 72 assembled to a three-year-old specification, thinking that sonic nostalgic magic would make it a winner again, which of course did not happen. All the while Colin Chapman was heavily involved in business commitments and production car thinking, and he had to leave a lot of the Formula One thinking to other people in his organisation, but eventually he was able to turn his attention whole-heartedly to the design of a new car. Before embarking on it he took a long, close look at the Lotus 72 as it had finally evolved and soon realised how badly out-of-hand the design philosophy had become. A simple example was the oil system, where the oil tank had been moved from the extreme rear of the car to a central position, behind the cockpit, but the oil radiators had been left at the rear and the car was carrying something like 15 ft. of large-diameter oil piping unnecessarily. Numerous small details like this meant that the Lotus 72 was grossly over-weight, not only over the CSI minimum, but compared to rival cars. On the front-brake layout, where the discs are mounted “inboard” on the chassis, there were six face joints between the disc itself and the tyre/road contact point, each one needing an elaborate (and heavy) method of locking together, apart from being a source of

“fretting” and movement. Some serious design work on this layout has reduced the face joints to two, with subsequent weight reduction removal of trouble spots. From front to rear of the car Chapman attacked every problem with the idea of simplifying, saving weight and making sure that every component was earning its keep and there were no “passengers” being carried. While he attacked the basic design thinking himself; he entrusted the details and the execution of his ideas to two of his design staff. The basic chassis problems were dealt with by Geoff Aldrige and the suspension and brake details by Martin Ogilvie, while overall supervision of the engineering was done by Mike Cooke.

When you see the new Lotus going by on the track you could be excused for thinking it no more than a cleaned-up Lotus 72, for the car follows similar lines, with a needle nose with large aerodynamic “fins” on each side, a wedge-shape around the cockpit/side radiator area and the rear aerofoil supported on a single strut, while Cosworth DFV is still the motive force and 5-speed Hewland gearbox provides the transmission. The car is in the black and gold colours of John Player cigarettes and carries advertising for Goodyear tyres and Duckham’s oil, both firms continuing to supply Team Lotus with their commodities. The monocoque chassis is narrower and lower than before, built from 16 s.w.g. aluminium sheet, with the Cosworth V8 engir^ bolted to the rear bulkhead and the He.. land transmission attached to the engine by an alloy bellhousing. At the front of the monocoque chassis is bolted a tubular subframe to which the front suspension and brakes are attached. A selection of these Sub-frames are available to vary the front track and also the wheelbase. At the rear the brakes and suspension are carried by special side-plates to the differential housing. A selection of bell-housing spacers allows the complete rear-end to be moved rearwards from the engine, thus also increasing the wheelbase. With a 6 in. maximum at the rear and a 4 in. at the front, not only can the wheelbase be increased a maximum of 10 in., but the fore-and-aft position of the centre-ofgravity of the car can be controlled.

Analysing the past season of Grand Prix races, Chapman and his design team have come to certain conclusions regarding wheelbase and track, relative to the various circuits in use. They looked closely at the performance of the various successful cars in Formula One, analysing which design philosophy suited which circuit, fur in spite of some people saying “all Formula One cars look the same”, it is far from true. The variations are not radical, but they are significant to anyone studying Formula One intelligently. There are variations in wheelbase, track, position of the C of G, the effects of fuel loads, the effects of suspension movements, roll-stiffness, down forces from aerofoils, spring-rates, shockabsorbers, tyre compounds, wheel rim widths, wheel centre offsets, and all these variations come under the general heading of “fine chassis tuning”. The broad conception of the new Lotus means that the car can be prepared in the factory to any specification they desire, the optimum for any circuit being decided upon by their analysis. As Chapman explained, he set out to provide the fullyadjustable Formula One car; whether they hit the right combination each time, experience will show.

Another factor in the design of the new car was the knowledge that present-day tyres not only gave vastly superior cornering properties, but also vastly superior traction and braking forces, for obviously if rubber can be Made to “stick” better under side loads, it will also “stick” better under driving and braking loads. Therefore more braking power was required, which meant bigger discs and more pad area. In conjunction with Lockheed a double caliper layout was designed, with one caliper at the front of each disc And one at the rear. It could have been Achieved by a single caliper with four pads, but by having two sets of pads diametrically opposed, the calipers could be made to serve for other purposes and the torque reaction was easier to absorb. An “inboard” location for the brakes it retained

as the in. diameter ventilated discs would not fit inside the wheels. While redesigning the brake calipers they were made to function as the pick-up points for the suspension members as well as operating the brake pads. The castings have lugs designed into them to carry the pivot pins for the rose joints and the top :ends of the coil-spring/damper units. Previously Lotus have used torsion-bar springs, but certain characteristics Of the torsion bar do not fit in with present-day thinking on suspension travel and tyre characteristics, so the new car has coil-springs all round, with Koni adjustable telescopic dampers inside the springs. At the front the suspension is by fabricated double wishbones, with fabricated uprights, all from steel sheet. Wheel bearings all round are a new development designed by Ransome Hoffmann Pollard in conjunction with Lotus, whereby the constant-velocity universal joints, the bearings and the hubs are a single unit. Special angular contact twinrow bearings are fitted direct to the outer casing of the universal joint. The wheel driving pegs, their mounting plate and the spindle to take the wheel lock-nut are all incorporated into the outer universal joint, thus offering a great reduction in size and number Of components in each assembly, thus “simplifying and adding lightness”. Between the monocoque and the engine a 2k-gallon oil tank is mounted on a shelf and there are oil radiators on each side of the car. These are mounted directly behind the angled

water radiators, which themselves are situated just aft of the cockpit and are covered by glassfibre ducts. Compatability of oil and water temperatures is more easily controlled and water and oil pipes are kept to a minimum length.

At the front of the car very large adjustable “canard-fins” are mounted on each side of the “winkle-picker” nose, and at the rear the aerofoil is supported on a monocoque pillar structure which contains the gearbox oilcooler and also carries the regulation red rear light as well as the auxiliary battery socket. The front “fin” angles can be altered simultaneously by a screw adjustment in the nose, while the rear aerofoil has two main attitude positions provided by the gearbox mounting brackets, and fine “trim” is achieved by alterations to the separate trailing edge flap.

Taken all round this new Lotus can best be compared to the successful old Lotus 72 as a stiletto compares to a sabre. It represents a functional and orthodox approach to the problems of Formula One, as they exist today, brought down to a razor-edge sharpness. So far the new car, JPS 11, has only undergone “shake-down” tests on the Lotus test-track at Hethel, but already results look promising.

While the Lotus represents some logical thinking along accepted guide lines, the new experimental Tyrrell is in complete contrast in being a radical new approach to the whole conception of a Formula One car. For some time now Derek Gardner has had the idea of a car with vastly improved penetration by reason of greatly reduced drag. Thanks to the financial support to the Tyrrell team by the ELF fuel and oil company, and the technical support of the Goodyear Tyre Company, Ken Tyrrell was able to give his design team the the go-ahead to build a research vehicle to probe new concepts of racing-car design. This vehicle is known as Project 34 and should lead to the 008 series of Tyrrell Formula One cars. Gardner’s main aim was to reduce the drag of the present-day Formula One car, thereby improving penetration of the air and gaining straight-line speed. At the same time he did not want to lose any of the existing cornering power, or braking power. One of the biggest factors in drag on a racing car is the tyres

and CSI regulations forbid designers covering the existing front tyres by bodywork, so Gardner’s idea was to remove the existing front tyres! He has always been a devotee of what he calls the full-width bluff-nose, as against the “needle-nose” with “canard-fins”. Regulations specify a maximum width to the bodywork ahead of the front wheels, and also a maximum height, relative to the wheel rims. Taking these measurements he then inserted the wheels and tyres behind this bluff nose, which called for 10-in, diameter wheels, with wide low-profile tyres. This meant that the front track of his project would be extremely narrow compared to the orthodox Formula One car, with the tyres shrouded by the nose thus improving the car’s penetration through the air. However, the track of a racing car has a known bearing on the cornering power of the front tyres, any reduction in track reducing the potential cornering power. Conversely the wider apart the front wheels are the greater the cornering power, with reservations naturally. Gardner’s tiny wheel project would clearly reduce drag, but at the cost of reduced cornering power, for not only were the tyres closer together, with the very narrow track, but they had a smaller “footprint” than the existing tyres. The answer to these problems was to use more Small wheels, so a second front axle assembly was designed into Project 34 so that the total area of rubber on the road and its cornering potential was at least equal to the existing 007 series Tyrrell car. Before the project could proceed he had to get the support of Goodyear, to make the 10 in. diameter, 9 in. wide tyres, and this was immediately forthcoming from the Goodyear tyre technicians, who viewed the project with keen interest. Then there was the question of brakes, for no existing disc brake assembly would fit inside the tiny wheels. Lockheed and Ferodo co-operated whole-heartedly and special 8 in. diameter disc brakes were made. Koni made some miniscule telescopic shockabsorbers, and all the details of the dual frontaxle layout could be designed down to a minimum of size and weight. The front uprights are machined from a solid block of clektron and incorporate the brake calipers as an integral part, while suspension is Conventional double-wishbone layout. All four front wheels steer and this is achieved by a rack-and-pinion assembly on the front bulkhead controlling the first pair of wheels by conventional track rods to the front of the Pivoting uprights. From the rear, slave-rods transmit the movement inwards to a fore-andaft link on each side pivoted about its centre. From the rear of this link slave rods transmit the motion to the front of the uprights of the second pair of wheels. There is a single antiroll bar connected to a link joining the first and second suspensions on each side, and the connecting point can be moved forwards or rearwards to alter the roll effect on the first or second pair of wheels. Each hub carries a small disc brake and there are cooling ducts running to the discs from the central sunken duct in the nose cowling. The brake pedal has a normal adjustable balance bar in the Cockpit to vary the balance between fore and . aft, but while the left-hand rod operates directly onto the master cylinder for the rear brakes, the right-hand rod operates on a secondary adjustable balance bar mounted ahead of the front bulkhead. The two rods from this balance-bar operate on two master

cylinders, one for the first pair of wheels, the other for the second pair. Thus it is possible to vary the braking between the first and second axles and between the aggregate of the front braking and the rear brakes. From the cockpit rearwards Project 34 follows the 007 series of Tyrrell cars, with the exception of a 3 in. narrower track for the I37in, wheels carrying normal 1975 Goodyear tyres. Taking the wheelbase as the distance from the centre of the first pair of wheels to the centre of the rear wheels, it is actually shorter than an 007 Tyrrell, as is the overall

length of the car, though the small front wheels give a contrary illusion, just as they give the illusion Of the rear tyres being larger than normal. Shortly before Project 34 was announced the CSI came up with new limitations on wheel and tyre sizes, and for a moment hearts stopped beating in the Tyrrell workshop*. Fortunately the rules “froze” the size of rear wheels only, at 13 in. diameter! After the United States GP the Tyrrell team

started “shake-down” tests with Project 34, using the Silverstone Club circuit, and in order to provide more corners and braking applications they coned-off an ess-bend twothirds of the way from the Beckett’s hairpin to Woodcote Corner. Patrick Depailler did the driving and found the car very agreeable and presenting no particular problems or differences in the driving technique. The anticipated heavier feel to the Steering was not evident, though the steering ratio was lower than he would have liked, there being too much steering-wheel movement to put on opposite lock to correct tail slides. Even so he was leaving Copse Corner in “tail-out” power-oversteer slides provoked with the throttle, and the sight of the four tiny wheels on opposite lock was fascinating. Questioned about the effect of not being able to see the front wheels from the cockpit, due to their Small size and the narrow track, he admitted that in the conventional 007 Tyrrell he could not see the front wheels anyway, so there was no difference. Ile was conscious of “placing” the car by overall judgement as with an 007 car, and would have to re-orientate himself to take advantage of the narrow track and get the front of the car closer into the corner. He did not anticipate any trouble with the rear end being wider than the front, explaining that if the Car was set up in a slide the rear would be running on a greater radius than the front. He could visualise distinct benefits on hairpin bends, while the suggestion that the front end would go through smaller gaps in traffic, his rivals moving over knowing that the wider rear end was following through, made him smile wryly. The disposition of the second pair of wheels is such that their centre-line passes under the driver’s knees, his feet being in line with the centre-line of the front pair of wheels. During initial testing, experiments were carried out with the brake balance between the two front sets of brakes and overall front to rear, for in this area alone there is a lot to learn from this research vehicle. There are numerous experiments to be carried out on spring-rates, dampers, roll stiffness, tyre compounds, and so on, on the front double-assembly alone, before relating the results to the whole car. Already one gets the impression that the

back-end of Project 34 is obsolete.

Once the basic parameters for • this new Concept have been established it will be interesting to watch its progress in the Overall performance field. With Depailler’s enthusiastic approach to the whole conception, Derek Gardner should satisfy himself about his theories, right or wrong, with the minimum of problems. This new ELF-Tyrrell will obviously be watched closely by rival teams and rival designer*, and the Coming weeks will be most interesting. Once the car has been sorted out. basically, the team will go to the Paul Ricard Circuit in Southern France for some serious comparative testing.