Features - Technical
JANUARY 6, 1997
Formula 1 Technical Regulation changes for 1998
BY PETER WRIGHT
The announcement read as follows:
With a view to controlling the performances of the cars the following regulations will come into effect:
· All dry-weather tyres must incorporate circumferential grooves square to the wheel axis and around the entire circumference of the contact surface of each tyre.
· Front dry-weather tyres must incorporate 3 grooves and rear dry-weather tyres must incorporate 4 grooves (the grooves will be 14 mm wide tapering to 10 mm and 2.5 mm deep. They will be 50 mm apart and arranged symmetrically about the middle of the tyres).
· The FIA Technical Delegate will monitor wear of tyres and after use, at least 50% of the length of each groove in every dry-weather tyre must be evident unless the absence of a groove is due solely to abnormal wear caused by damage to the car.
In order to reduce cornering speeds and assist overtaking:
· The overall width of the car including complete wheels shall not exceed 180 cm (previously 200 cm) with the steered wheels in the straight ahead position (Article 3 of 1998 Technical Regulations).
· There will be minimum complete front and rear wheel widths of 12'' and 14'' respectively. The maximum complete wheel width of 15'' remains (Article 12 of 1998 Technical Regulations).
Brake calipers and discs
With a view to limiting braking performance, improving the possibilities of
overtaking and reducing costs, the following regulations will come into
· All brake calipers must be made from aluminium materials with a maximum stiffness (modulus of elasticity) of 80 Gpa.
· No more than 1 caliper, with a maximum 6 pistons, is permitted on each wheel.
· The section of each caliper piston must be circular.
· No more than one brake disc is permitted on each wheel.
· All discs are subject to a maximum thickness and maximum outside diameter.
· No more than two brake pads are permitted on each wheel.
· Liquid cooling of the brakes is forbidden.
Satisfied that it now has the means to control overall performance to a safe level, in spite of inevitable continued development, the FIA also announced:
The World Motor Sport Council is satisfied that it now has the means to control performance in Formula One. The current 3 litre engine formula will therefore continue for a further five years (until 2006).
How did this come about, and how will the technical regulation changes that emerge from these decisions affect the design of Formula 1 cars?
Back in 1995, as the new 3 litre, stepped "flat" bottom cars settled down, it quickly became apparent that it would not be long before they were about as quick as the old 3.5 litre, true flat bottom cars. As well as the need to prevent cornering speed escalating again to levels that created circuit safety problems, two further issues raised their heads: drivers were finding it increasingly hard to overtake; and nearly all the great, 4th gear corners had gone, replaced with 2nd gear, stop-go bends, to the chagrin of spectators and drivers alike. Max Mosley tasked the Formula 1 Technical Working Group with making proposals for a means of regulating, and if necessary reducing, all aspects of performance to a level that cancelled out performance gains due to normal development. At the same time, research was to be carried out into ways of improving overtaking, particularly enabling drivers to race their cars close to each other without loss of aerodynamic stability. The Group members (Technical Directors and Chief Designers of all the teams) were given the opportunity to avoid scrapping all their R&D and design work every few years, as had often been the case in the past, and suggesting a means of regulating performance by adjusting some "low cost" feature of the car.
It was popularly supposed that the main culprit in preventing overtaking was the aerodynamics. Powerful front wings, coupled with sensitive flat bottoms, were causing such a change in downforce and aerodynamic balance in the wake of another car, that drivers did not dare get up close in corners for fear of understeering off the track. A significant reduction in front wing and overall downforce was thought to be the answer. 40% model tests of two cars, one behind the other, in the Imperial College's wind tunnel proved otherwise - it's not that easy!
The focus shifted to the tyres. They had been narrowed from 18 ins to 15 ins for 1993 and, quite apart from the cost of new moulds that have to be born by the tyre companies (at least two suppliers in 1998), any further narrowing would put top speeds up above the 340 kph being attained at Hockenheim. Reducing the contact patch area, without reducing the size of the tyres, seemed a possible solution and so discussions were opened with both Goodyear and Bridgestone. Neither were totally negative and the constructors were interested. Putting circumferential grooves in the tread provides a relatively easy way of regulating grip, when or if further reductions in grip are needed in the future. Eventually, tread area will have reduced to a level where compounds have to become harder to last adequately, in spite of tyre competition, and perhaps the dreaded tyre "marbles" that generate a single racing line will disappear and we will return to the days when tyres wore to rubber dust.
The third area of the cars to come under the spotlight is the brakes. Since the banning of power brakes for 1994, the drivers have been unable to lock up the wheels at high speeds. With power brakes they were achieving 5g. Increasing the mechanical advantage was limited by the available movement of the brake pedal in overcoming the compliance's in the brake system - fluid, pipes and calipers. Rigid pipes replaced flexible ones where possible and AP and Brembo took a new look at the calipers. FEA had already pretty well optimised the design, and the small (13 ins) wheels used in Formula 1 squeezed the space between wheel rim and disc, preventing deeper caliper bridge sections.
Around this time, the aerospace materials industry was making available commercial quantities of metal matrix aluminium alloys (MMC). A quick look at the above diagram makes it obvious why it is a suitable material for calipers. Machining was initially a problem, but the appropriate techniques were soon developed and MMC calipers became a must. The increase in system stiffness was such that, master cylinder sizes could immediately be reduced and braking improved.
Last year Brembo produced Beryllium/Aluminium alloy calipers exclusively for Ferrari, and even spectators could see the difference - Schumacher's discs were brighter orange, going into slow corners, than any of the opposition's. With over 2.5 times the stiffness of the old aluminium calipers, he was able to gain the mechanical advantage to really load up the brakes - great for overtaking those without. Once everyone who can afford them gains the advantage, overtaking opportunities will further diminish.
The FIA, supported by the teams, made the decision to return to plain aluminium calipers, and at the same time put a limit on disc size.
By the end of the last year's racing season, no solution to reducing aerodynamic loads had been found. The FIA backed a proposal from some teams for an active front wing - the incidence would be actively controlled to permit a change of balance in the wake of a leading car. Some teams rose to the challenge, while others recoiled from it, and without unanimity it did not get accepted. At the eleventh hour (World Council ratification was needed by the end of the year for introduction in 1998) the suggestion was put forward to narrow the cars by 200 mm, as a means of reducing downforce and even making slightly more space available on the track for overtaking. Within 24 hours there was unanimous agreement and it was put to the World Council. So much for low cost solutions - teams will be lucky if the steering wheel is a carry-over part for 1998!
With an additional limitation on the minimum width of front and rear wheels/tyres - to avoid the use of front tyres on the rear as tried by Tyrrell at Hockenheim last year - the inevitable track reduction hits two aspects of the car's performance: firstly, the intrusion of the wheels into the underbody airflow will have a significant affect on downforce - publicly estimated by Patrick Head to be at least 20%; secondly, the load transfer effect is equivalent to raising the Centre of Gravity by between 25 and 30 mm - the effect of this on the tyres, alone will add 1.0-1.5 seconds per lap.
Designers and aerodynamicists must already be juggling components and carrying out key tests to answer the unknowns about how the width reduction affects downforce, centre of pressure, pitch sensitivity and cooling performance. There are not many new opportunities to lower the C of G beyond what is already achievable. The engine crankshaft is as low as the throw of the crank will allow, clutch diameter no longer being the governing factor since carbon clutches permitted a big reduction in diameter. Fuel C of G is controlled by the length of the fuel tank (width is regulated to 40 cm from the centreline of the car), but a long fuel tank pushes the engine back and moves the C of G of the car rearwards.
These considerations lead quickly to a discussion with the engine supplier: How about a short, wide angle engine to lower the head and block masses and allow a longer fuel tank? What is the widest angle V-8 possible, still allowing good exhaust pipe runs? How would this compare with a wide angle V-10? Which needs the smallest (lowest) radiators?
Before the suspension can be redesigned for the narrower overall width and axle track, the characteristics of grooved tyres must be established. Reducing tread area by 12% must lead to harder compounds for a given life - hand-grooved, A-compound Goodyears have already been tested on Berger's Benetton at Jerez recently: they were over 3 seconds a lap slower and lasted just 3 laps. However, 1998 will be the second year of tyre competition between Goodyear and Bridgestone, and so some soft but tough race compounds will probably have been developed, cancelling out some of the change. Will grooved tyres need a different construction? Will the higher loading, due to the narrower track width, need other changes?
Different wear characteristics, and the essential need to maintain at least 50% of the grooves intact, may lead to new pit stop strategies. It is possible that the driver will be able to monitor the partial loss of a groove and stop before his tyre becomes illegal - we shall see. Arguments about how accurately the groove depth can be measured have been stilled by the way in which the FIA will scrutineer tyres - either 50% of all the grooves remain or they do not.
There are other changes for 1998, but these have been agreed during the normal course of business, by the Formula 1 Technical Working Group. By far the most significant are changes to the dimensions of the survival cell and cockpit aperture.
Since the introduction and universal adoption of the high nose, the monocoque forward of the cockpit has been made as slim as possible, limited only be the need to meet the FIA crash tests, permit the cockpit cross-section template to pass through it, and to meet torsional stiffness requirements. The quest for aerodynamic performance had begun to squeeze the space around the driver's legs. A new template, 50 mm wider and 50 mm taller, combined with minimum outside dimensions for the survival cell i.e. the monocoque forward of the fuel tank, will ensure that there is room for padding around the driver's legs. The resulting structure will be stiffer and should perform better in a crash, provided of course, that designers do not reduce the skin thickness to compensate. The cockpit aperture has also been modified slightly, to widen it around the position of the steering wheel, moving the cockpit sides out and away from likely head impact points in an accident. The overall aerodynamic effects will be measurable, especially combined with the reduction in overall car width.
These new dimensions were introduced for the new Formula 3000 in 1996. They were delayed until 1998 in Formula 1 to allow existing monocoque designs to race until that date.
Other changes are more by way of tidying up the wording of the regulations and bringing them into line with current practice:
It will be mandatory to fit a cover over the re-fuelling connector. Many cars already have one - in order to maintain continuity of their sponsor's name or logo on the side of the car. The regulation change is to provide equality in the time it takes to refuel.
The regulation governing the size of the front brake ducts has been applied to the rear ducts as well. In general the rear cooling requirements are less than the front, so this change is unlikely to affect very much.
The exhaust pipes will be included in the definition of the bodywork, and so they will be governed by all the regulations that concern bodywork. This effectively means that they are restricted to the dimensions that cover the size and position of the diffuser, and that they must remain immobile - this last confirms the regulation that prohibits variable length exhausts.
There is a small change to the way in which fuel tanks are labelled - the makers name must now be clearly stated, not just a code denoting the manufacturer.
The bolt rings, used to reinforce apertures in the fuel tank bladders, may be made from composites, but there are minimum dimensions that govern the position of the bolt holes.
Fuel, water, oil and hydraulic pipes are currently governed by pressure and temperature ratings. These figures have become somewhat dated and so it is now left to the manufacturers to fit suitable specification pipes for the particular application.
The cars for 1998 look as if they may well be clean-sheet-of-paper designs. Maybe that is why the new regulations were agreed to so easily. Formula 1 designers and engineers need challenges, and since control systems were banned in 1994, there has been little for them to really relish. Now they have a set of regulations that need a whole new look at the car; perhaps they just looked at the prospects and thought: "Yes, I'd like a go at that."