Features - Technical
MARCH 8, 1999
1999 Formula 1 cars
BY PETER WRIGHT
The FIA has limited the width of the front wheels/tyres to 355 mm, to stop any increase in overall tread width being added to the cars, and demanded a fourth groove in the front tyres, to slightly reduce their performance. However, much more significant is the withdrawal from Formula1 of Goodyear, thereby calling a truce in the tyre war. Bridgestone, as the sole supplier, neither has to take risks with tread compounds nor has to continue expensive tyre development. This "peace dividend" effect far outweighs that of the extra groove. When comparing lap times at races this year with last year's, it is important to take into account the chassis and tyre development that has taken place since the cars last ran at a given track. The intense competition between McLaren and Ferrari in 1998 probably improved the cars, in general terms, by 2-3 seconds per lap. The fact that the speeds at Melbourne were nearly identical to last year means that the harder tyres and the additional groove have slowed the cars by that amount. That was the intention. Another effect is to make the timing of pit stops less critical on some circuits. Designers, sensitive to the debacle of weight distribution and wheel base variations they were forced into last year, will have concentrated on trying to get it right first time, in spite of having different tyres again; those teams with Bridgestone experience have the best chance in this respect.
Having been forced to narrow the track of the cars last year, one would have guessed that designers would have tried to shorten the wheelbase in order to maintain an optimum ratio of track to wheelbase (assuming of course that the ratio was optimised in 1997...). Instead, after the experience of last year, wheelbases are getting longer. Ferrari in particular have not only pushed the rear wheels rearwards, to put more weight on the front axle, but have also moved the front axle forward, thus cancelling that effect and significantly lengthening the wheelbase. The most likely explanation for this design trend is that, if it is not possible to make the cars truly stable, then at least it is better to increase yaw damping by lengthening the wheelbase. The ratio between the width of the front and rear tyres (355 versus 380 mm i.e. 48:52) cannot be matched with weight distribution (43:57), and so the cars are inevitably nervous especially under braking. Increasing yaw damping gives the driver a better chance of catching the car when the back tries to overtake the front.
Some re-arrangement of major masses, not possible in the middle of a racing season, has enabled a more forward weight distribution without increasing the polar moment of inertia too much. The move to longitudinal gearboxes is complete, with Williams being the final convert. Several cars have followed Prost, Arrows and Stewart's lead by taking the oil tank out of the bell housing and installing it in the rear of the monocoque, behind the fuel tank or recessed into it. Thus positioned, it allows neater plumbing between engine, oil tank and oil cooler.
At the request of certain Technical Directors, the regulations governing the use of control systems have been re-written in order to clarify exactly what is permitted and what is not. At the same time, the range of permitted devices and their all important algorithms has been limited. It should now be clear that the following are not allowed:
1. Energy storage devices
2. Driver-selectable engine/throttle maps
3. Ignition and fuelling maps that do anything other than optimise combustion
4. Clever anti-stall, anti-overrev, anti-speeding and clutch-control systems that might possibly help driveability or traction control in the lower gears. Indeed, anything that even smells of traction control.
5. Driver-selectable, electro-hydraulic differentials
6. Side-to-side brake balance
7. Active fore-and-aft brake balance
The main changes to the regulations, as opposed to clarifications, concern safety and environmental issues. Two new safety features are introduced this year - a wheel-retention system and a driver-extraction seat. Each wheel must be fitted with an 8mm-diameter cable attaching the upright to the chassis. The braking load of 50KN means that the cables will be made of a fibre such as Kevlar and they will be located within the front leg of the lower wishbone. First indications as to how they perform are good (e.g. Herbert's testing accident and Hakkinen's Melbourne practise incident). However, to determine just how these devices cope with major accidents, it will take another incident like the first lap at Spa last year to test them comprehensively.
The driver-extraction seat is to provide the medical teams with the means of extracting a driver with suspected spinal injuries while he is still strapped into his rigid seat. The seat must be fitted with supplementary straps and quickly releasable seat fasteners. Lear Corporation have shown that their product meets this requirement.
The frontal crash test has been revised, the impact speed rising from 12m/s to13m/s (17% more energy) and it goes up again to 14m/s (another 16% energy) in 2000. In order to make the current nose-cone less of a stiletto, and to maximise the energy absorption capabilities, the crush performance has been revised:
1998: Average g <25g
Peak g <60g for 3ms
1999: First 150mm: average g <5g
Remainder: average g <40g
Peak g <60g for 3ms
The clearance over the driver's head provided by the rollover structures, has been increased from 50mm to 70mm, and a requirement that they must also provide 50mm clearance over the steering wheel has been added.
To improve the environmental image of Formula1, and to back up the FIA's political stance on road car environmental issues, the fuel specification has been brought into line with EEC limits for 2000, with the additional warning that when the Final Directive for 2005 is published, further changes will take place. Most significant are reductions in permitted benzene and sulphur:
1998 1999 2000
Benzene 5%v/v 1%v/v
Sulphur 1000mg/kg 150mg/kg 50mg/kg
There is also a tightening up of permitted quantities of certain hydrocarbons and oxygenates. These changes may give the fuel companies some headaches, but are unlikely to affect power output to a noticeable extent.
In spite of some team principle's odd definitions of the terms "evolutionary" and "revolutionary", all the cars appear to have evolved from last year's. The only revolutionary feature that is apparent so far is the Benetton Front Torque system (FTT). It is not every day that technology flows from Super Touring Cars to Formula1 but, with both Benetton and Williams testing front axle differentials, this is exactly what has happened, it was Audi that led the way.
Audi understand just about everything there is to know about individual wheel torque control. Masters of the centre and axle differential, they have explored almost every mechanical and electronically controlled device in racing (STC and DTM) and rallying, as well as on their Quattro road cars. They know from experience that when tyres are near their limit under braking or accelerating, control of torque across an axle can be used for stability and directional control. Forced by the regulations to go FWD in STC in 1998, Audi were confronted by the tendency of FWD racing cars to lock their inner rear wheel while braking into a corner. However lightly loaded, a locked wheel will disturb the car as it regains contact with the road.
Audi's solution was to apply 4-WD technology to solve the problem, connecting the two, undriven, rear wheels together with half-shafts and a viscous differential. The differential transfers torque whenever there is a speed difference between the wheels, enabling the brake torque from the unloaded (slower) wheel to be transferred to the outer (faster) wheel, rather than locking it up.
Around the same time, McLaren had explored the potential for steering the car using differential braking on the rear wheels. Subsequently banned, it was inevitable that thoughts turned to other ways of controlling braking torque across the car and Audi's solution caught the attention of Formula1 teams.
Much of the difference between a qualifying lap and a race lap is the speed held by the driver as he brakes and turns into a corner. This is also the time when most overtaking occurs and where most loss of control takes place. How hard the driver can brake as he turns in is limited by how much of a disturbance he can tolerate as the inner front wheel locks and then grips again. Connecting the front wheels together, as per the Audi rear wheel system, potentially improves this situation and enables more braking to be applied to that axle. Just what kinds of differential Benetton are using is well covered up down in the depths of the footwell. A fairly stiffly set-up viscous differential would not be a bad place to start, though electro-hydraulic units are likely to appear before long.
Although STC banned the Audi system on the grounds that it constituted an anti-lock system, Formula 1 has so far judged that the rear differential performs the same function under braking, and so it must be permitted. The difficulty with writing regulations is that they can only ever cover that which has been imagined up to the point in time when they are written. While other teams have fought to have it banned, and presumably developed and tested similar devices at the same time, Benetton continue to gain experience using it. Exactly how much benefit it gives only racing will show, but if it helps driver confidence when braking, it will provide a measurable benefit in qualifying and assist with overtaking - two vitally important areas.
Benetton have also hinted at a new development in the transmission, but one can only guess at what it might be. Rumours have suggested that a twin-clutch system that ensures no loss of engagement with the engine is a possibility. The benefits of such a system would not be during up-changes (they are so short already as to cause almost no loss of acceleration, and the clutch is not actually disengaged during the cycle), but in smoothing down-changes to minimise disturbing the rear end of the car under braking. A number of road car gearboxes have set out to achieve gearchanges without loss of drive, and Porsche experimented with such a device on their Le Mans sports cars some years ago. It is also a useful feature on heavy earth-moving equipment, where loss of drive during a gear change may cause the vehicle to come to a halt. In principle, two gears can be engaged simultaneously but, by the use of two clutches, only one drives the car at a time. Handover between gears is achieved by careful timing on clutch disengagement/engagement - somewhat similar to a person transferring a glass of water from one hand to the other. If he lets go of the glass before the other hand has taken it, it will probably spill. The arrangement usually requires additional shafts and bearings and so is both heavier and incurs more losses, but Benetton may have found a good solution. Pure speculation....
The quest for smaller, lighter and lower engines gathers pace, with 100kg being the new standard by which engines are compared against the Illmor-Mercedes. Mercedes had suddenly become rather coy about details of their engine's weight and dimensions, even though they have plenty to boast about. Could it be that BMW's imminent arrival has made them more cautious? Power and RPM are now definitely over 800ps at 17,500+rpm, but the actual figures are even more closely guarded.
Ford's purchase of Cosworth has given the company new impetus and they have produced an engine that reputedly challenges the Mercedes for size and weight. It would be good if it also endowed Stewart with competitive power and reliability. If Melbourne is anything to go by, the new Stewart will give the established front runners something else to worry about - provided the make the startÉ.. Apart from Ferrari, the engine most likely to challenge Mercedes is the Honda. Now that Honda is heading back with an even greater commitment to Formula1 than they had when they were dominant with McLaren, it is likely that they will employ all the expertise of Honda R&D to gain the sort of success they are enjoying in CART racing. After all, beating Mercedes as they have succeeded in doing in the USA, is the reason why Honda is in racing. How else can they establish an image comparable with Mercedes'?
That Formula1 is becoming a power race, as chassis performance settles down to the major regulation changes introduced in 1998, is evident as more and more cars are equipped with 7-speed gearboxes. As power becomes more important, one method of raising it is to narrow the power band. Using 7 instead of 6 gears can make it possible to narrow the band by 200-300 rpm. Gear-change times are so short that the penalty of an extra change is minimal and hardly an extra distraction for the driver.
The CFRP gearbox, as used by Arrows and Stewart last year, has not proved reliable enough for others to follow their lead. The problems that they experienced seem to have warned off other teams from following this approach to reducing the weight at the rear of the car. Maybe their carbon fibre gearboxes are just not ready yet.
Aerodynamics continued to yield 5-10 % improvement per year, but it now costs a great deal to achieve. 50% wind tunnels and $0.5m models are necessary to maintain this level of yield. It is impossible to interpret what all the tiny changes to front wings, barge-boards, rear wheel flip-ups actually contribute to increasing downforce and reducing drag, let alone how they affect pitch sensitivity, without testing in similar facilities to those that the teams now possess. The most original feature to appear so far, are the turning-vanes on the well-rounded front corners of the side-pods on the Prost. Just what they actually do is being explored in other team's wind tunnels right now! Rear wing failures have reared their ugly heads again, with Ferrari, Stewart, Benetton and BAR suffering them in testing and even BAR in the race at Melbourne. There are two main causes: structural resonance, which might turn out to be flutter (aerodynamic-induced coupling between two or more structural modes), or hot exhaust gases impingeing on the CFRP supports. There were a number of failures in 1997, mainly on Renault-engined cars; this time at least some of the failures are due to the exhaust - the aerodynamicists do not know, or forgot to study, where the airflow is taking the hot exhaust gases. It does appear that several of the teams - Ferrari, McLaren and Sauber have almost admitted it - are running wings that have significant longitudinal flexibility, permitting the wing incidence to flatten on the straights, reducing drag. Until the FIA imposes a load/deflection tests on these devices, they are very difficult to police and the practice is likely to continue, with a safety question mark hanging over them.
Suspensions continue to be refined to improve packaging and installation stiffness. McLaren and Ferrari led the way last year by removing the front suspension units from the top of the monocoque and re-arranging them inside the structure, using longitudinal torsion bars and near vertical dampers. Others now follow. Just as Benetton and Sauber decided to emulate McLaren's steering arms on the wheel centreline (Benetton has to deal with the additional problem of reducing the aerodynamic disturbance of the FTT drive-shafts), McLaren has moved it back up to be level with the top wishbone. At the rear, the compromise between lowering the deck height and keeping the diffuser area around the sides of the gearbox as narrow as possible is still coming out in favour of a narrow gearbox fairing, and so, apart from on the Sauber, suspension units remain on top of the gearbox.
The differences between cars are becoming smaller as the regulations stabilise again and everyone catches up with the teams that designed their cars right first time i.e. McLaren. Hopefully it will be more than a two-horse race this year, though I suspect McLaren and Ferrari will continue to be the ones out front. The scrap between the Jordan-Honda's, the Supertec-engined Williams, Benetton's and BAR's, the newly competitive Gary Anderson Stewarts and the 800ps Petronas (Ferrari)-engined Sauber's should be good. Prost's performance will be a function of how determined Peugeot is and how much John Barnard can influence them from the UK. The Arrows and Minardi will suffer from a lack of power and funds, but may surprise on occasions as Arrows did in Melbourne. As always, reliability may turn out to be the final arbiter of success. Ferrari must be happy to have put 10 points in the bag so early, and Schumacher and Hakkinen are still neck and neck!