Formula 1 2017 • Digital edition • … · 2019. 10. 14. · Racecar Engineering (October 2016,...

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CONTENTS/COMMENT

Gone, it seems, are the days when engineering excellence delivered an outstanding result. Decisions today seem to be based on

fairness and equality. Racing is no longer simply about winning; today’s decisions are based on encouraging more competitors, and therefore more money. The new Formula 1 regulations for 2017 appear to bear this out. In an interview with Racecar Engineering (October 2016, V26N10), Max Mosley admitted that the reason for hybridisation of F1 was to give the manufacturers more corporate responsibility for their racing. It has nothing to do with improving the competition.

Today’s new regulations similarly have nothing to do with improving the racing; the wider, more aggressive stance was designed to increase the audience wow factor, while also requiring more of the driver. However, it seems to be that the Formula 1 cars, and incidentally the WEC cars, are more about safe and effi cient delivery of power than cornering.

The drivers are actually less relevant now than they were in the past, when there was no downforce and a need to be able to execute more racecraft. That is not to say that the current crop of drivers don’t have that racecraft, but there

FORMULA 1 2017 www.racecar-engineering.com 3

CONTENTS4 THE DANGER FACTOR Peter Wright assesses the analysis of risk in modern Formula 1 racing

6 F1 TEST UPDATE The Barcelona tests showed the cars to be as quick as expected, but also very sensitive to set-up changes

10 CFD ANALYSIS F1 has piled on more downforce, but does this mean less overtaking?

18 MERCEDES POWER UNIT The rumour is that the Merc PU now runs with over 50 per cent effi ciency. Peter Wright investigates

24 NEW ENGINE RULES Do the 2017 Formula 1 power unit regulations really allow for technical innovation and closer competition?

30 F1 FUELS We take a look at the hi-tech blends that power modern Formula 1 cars

37 TECH DISCUSSION Is Formula 1’s aero approach based on fl awed thinking?

40 PETER WRIGHT Racecar’s technical consultant considers the best way to fi x F1’s problem of a lack of overtaking

Cars have bulked up for the 2017 Formula 1 season, but will that improve the racing, or just lead to drivers needing to do the same?

Racing improves the breedis a danger that the skill will be lost if the cars continue down this current path.

Maybe I don’t need to worry. F1’s in good hands, and I hope that the technical regulations are opened up suffi ciently under the new management to allow technical innovation. Ross Brawn’s most recent title was thanks to a clever double diff user, and throughout the history of F1, engineers have been free to experiment.

One thing that is clearly lacking in F1 at the moment is the need for the drivers to look after the car during a race. The tyres are harder, and Pirelli expects there to be fewer pit stops. Arguably this puts more emphasis on overtaking on the track, but we have seen that these facts don’t necessarily go hand-in-hand. A return to steel brakes would be better, or a reduction in brake cooling would help to increase the braking distances, the latter also encouraging a little bit of mechanical sympathy. At least there is the issue at some circuits of needing to conserve fuel, although this has already been compensated for in the new regulations with a larger fuel tank.

I hope that the new season goes well in F1, that the issues highlighted in this edition, brought together from our coverage in previous magazines, don’t hold completely true, and that the competition will be as fi erce as ever. This is the start of a new era, with new ownership, a new helmsman, and a wealth of opportunities.

ANDREW COTTON

Editor, Racecar Engineering


WRITE LINE – PETER WRIGHT

4 www.racecar-engineering.com FORMULA 1 2017

Motorsport is dangerous – it says so on the ticket. It always has been and always will be, just as descending stairs is dangerous. It’s an activity which is right up there as a cause of accidental death with pedestrian road accidents, drugs and alcohol. Or, to put it another way, motorsport is remarkably safe; if you are going to have a high-speed crash in a car, make sure it is in a racing car. But this was not always the case.

The early races, city-to-city contests, had only been going a few years before nine fatalities during the Paris-Madrid caused the French government to halt the race in Bordeaux and ban all open road racing. Governments do not want to have to control any sport, let alone motorsport, and will only step in if sporting fairness or safety is compromised; instead they look for sanctioning bodies capable of doing the job properly. In international motorsport, that organisation is the FIA, with its affiliated member clubs acting as the national sanctioning bodies.

Explosive issueHigh on the agenda of anybody responsible for any form of motorsport is safety. The sport is still inherently dangerous, because of the level of energy embodied in a high-speed car, the use of flammable fuels, high voltages in electrical energy stores, and the number of people involved in the running of the sport. The nature of the contest requires this concentrated energy to be conducted by a human at the limit of control – the kinetic energy of an LMP1 car at maximum speed is equivalent to over 1kg of TNT; while the full fuel tank is over 0.5 tonnes of TNT. And accidents will happen.

The job of the sanctioning body is to keep any sudden release of this energy away from humans. Track workers and spectators must be protected by the circuit layout and design, but officials, teams, marshals, and drivers are inevitably likely to be exposed. This is where the management of risk becomes necessary. Motorsport cannot be 100 per cent safe; there are always risks and they need to be understood and managed.

The instruments by which these risks are managed are the Sporting and Technical Regulations. The way the drivers, officials, marshals, teams and all engineers involved conduct themselves are laid down here. Also set out are how they will be policed and the sanctions for non-compliance. These regulations have been developed over more than 100 years, with variations for all the different forms of motorsport from bikes, to trucks, to dragsters, to rally cars, and to F1.

Four forces have shaped the evolution of these regulations: experience, technology, social

pressures, and the nature of the competition. At any time they combine to form a set of rules that define and limit the risks. Those who participate in the sport, as opposed to watching it, know what these risks are and accept them. They volunteer to expose themselves to these risks and can always walk away if they believe they are unacceptable.

Experience and technology have been applied by the motorsport industry to steadily reduce the risks, but occasionally social pressures intervene and demand a further reduction in risk. Examples include: 1907 Paris-Madrid; 1955 Le Mans, and 1994 Senna and Ratzenberger at Imola.

Risk factorsInfluencing this steady evolution of risk is the nature of the competition. Leaving bikes aside, the four main categories of wheeled motorsport are: Karts; open-wheel, open-cockpit, single-seaters; closed-wheel, closed-cockpit circuit cars, and closed-wheel, closed-cockpit rally and cross-country cars.

They do not have identical safety risks, so why is that tolerated? Neither do they have the same risk as racing motorbikes, downhill skiing, base jumping, cross-country horse eventing, scuba diving, or flying home-built aircraft.

They are all different, they all involve different risks, and participants understand and accept the risks, or at least they should do so, as their racing

licence requires it. To try and unify risk in all forms of motorsport would result in closed-wheel, closed-cockpit cars on circuits, and would eliminate karting, rallying, and single-seaters. Nobody wants that.

Acceptable risksWhat is an acceptable risk has changed with time. If we take the highest class of racing, initially road-racing, then grands prix, and now F1, in the early days the driver and his unfortunate mechanic sat on top of the car with little protection. In an accident they were usually thrown clear and hoped the car didn’t land on top of them. Even after the occupants were lowered and surrounded by bodywork in the interests of performance, being thrown clear was the preferred option. Anything that inhibited the driver escaping from a car that was on fire was rejected. In the late ’60s, aided and abetted by Jackie Stewart, F1 drivers started to not accept the unnecessary risks involved. Over the next decade, standards were established to completely change the philosophy of protecting a driver in an accident.

This resulted in the cockpit becoming a survival space, particularly by the installation of a roll over hoop. Also, the driver was restrained in this survival space using a full harness, he wore fire protection clothing, and fuel tanks were fitted with bladders.

Alongside these fundamental changes to driver protection, changes to the race circuits, the

Calculating riskIs Formula 1 forgetting the fundamentals when it comes to risk management?

The kinetic energy of an LMP1 racecar at maximum speed is equivalent to 1kg of TNT

While F1 is nowhere near as dangerous as it once was it still has its moments. This was at last year’s Russian GP

XPB


a statistical science, with development normally being based on experiments rather than theory. Any safety feature introduced into an activity can only be assessed in a limited number of experiments, which will never cover all eventualities. Once sufficient confidence in the benefits has been established it can be introduced and the actual benefits, measured against the downsides, assessed statistically. In motorsport there is usually a competitive benefit from taking risk, which must be balanced. Unfortunately motorsport safety statistics are very hard to establish reliably. With one fatality in Formula 1 every 20 years the data is not statistically significant. Head strikes by loose objects occur about once a decade. However, drivers themselves are expert at assessing risk, they do it every time they brake into a corner at racing speeds: ‘If I leave my braking later and enter the corner faster I will take pole. If I brake too late, I shall not get pole and may damage the car or myself, which will affect my chances in the race.’

It is the drivers who accept the risk. No one can do that for them. The problem comes when they collectively say the risk is unacceptable; something has changed. At this point they can walk away, as Niki Lauda did on occasion, or lobby for a risk-reduction technical or procedural solution.

Dangerous liaisonsEnter the other stakeholders; the fans (‘something must be done’ or ‘I shan’t watch F1 if there is no danger involved,’); the sponsors (Mercedes after Karl Wendlinger’s accident at Monaco in 1994 ‘We are not in this for a driver to be so injured in a car with a three-pointed star on it.’); the sanctioning body (must regulate safety to a level such that governments do not step in); the Commercial Rights Holder (against anything that puts fans off watching); the teams (‘tell us what the rules are in time to implement them.’ And

then there’s the lawyers (‘it is too complex to define; depends on which territories are involved in any resulting action’).

Any proposed reduction in risk that also changes the nature or perception of the activity is bound to cause controversy. Safety doesn’t work with clear, irrefutable numbers, and this is why the Additional Frontal Protection proposed for F1, is creating so much discussion; how much does the Halo reduce risk? How much does it increase it? Would a screen reduce it further? Or increase the risk? Is there an alternative? How much would it cost to apply to GP2, F3, and F4 etc.? How many people would it put off watching F1?

Risk management is possible when clear numbers exist, although the unintended consequence can still rear its head. Without firm numbers it is just a battle of opinions. It should be resolved by the drivers (the risk takers), and by the guardians of motorsport, the sanctioning body (the sport) and the CRH (commercial rights holder), but in a world dominated by social media, everyone believes they have a right to have their views heard. From risk management to democratic government, it is becoming harder and more complex to find the right path in such an environment.

emergency intervention, and the medical facilities at the tracks were also taking place.

Once the driver was strapped into the cockpit, he was subjected to the deceleration of the car if it impacted a solid object. These were steadily removed from the edges of tracks and replaced by impact attenuating barriers. Standards for the strength of the car chassis were developed and thought given to impact attenuating structures on the cars themselves. Unfortunately, at that time the sides of the car structure were mainly fuel tanks. However, the spaceframe and aluminium chassis of cars in the 1960s and 1970s would not hold up well in an accident and intrusion injuries became prevalent, for example with Clay Regazzoni and Ronnie Peterson. And so the driver was moved back to put his feet out of harms way and fuel was stored in a single, central fuel tank.

Driving changeDrivers drove these changes, new technologies enabled them, and there was little pushback against the changes, as they did not infringe on the F1, open-wheel, open-cockpit concept. The advent of CFRP monocoque chassis then led to the concept of the strong survival cell for the driver, surrounded by impact attenuating structures of regulation-prescribed performance.

The risks reduced dramatically as intrusion injuries became rare and deceleration injuries were addressed with better harnesses, helmets, cockpit surrounds, and HANS developments.

The cars were still open-wheel and open-cockpit, and fans could just about see and identify with the drivers. Drivers started to take more risks as the consequences of a mistake were reduced. Circuit design, run-off areas and barriers, race direction, and intervention protocols applied throughout motorsport meant that a new generation of drivers arrived in Formula 1 who had never experienced a fatality at a motor racing event. Until Imola 1994.

Three accidents involving two fatalities occurred where the injuries incurred could be attributed in part to the lack of head protection in an open-cockpit. Measures were put in place to reduce the risks, but none impinged significantly on the concept of the open-wheel, open-cockpit single-seater formula. The risks became acceptable again.

We are now in a new era following a number of accidents where loose objects have hit the driver’s head, and the risks are being reassessed once again. This time there is a difference, as the only potential solutions affect the open-cockpit concept of motor racing’s premier formula, and inevitably, all the rungs of the single-seater ladder up which the young drivers climb to Formula 1.

Risky businessHow are the risks assessed for acceptability in a volunteer activity? How are the sanctity of a concept and the image of a sporting activity determined? Who decides these issues? Risk is usually analysed statistically as it relates to the probability of uncertain future events. Safety is

Halo looks set to come in to Formula 1 in 2018 and is sure to be used on other single seaters too. But have the risk factors been properly assessed and is it worth diluting the essence of open cockpit racing if they have not?

The race drivers themselves are experts at assessing risk, they do this every time they brake in to a corner at racing speeds

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FORMULA 1 – TESTING UPDATE

A sensitivesubjectWith new higher downforce aero regulations and fatter tyres, quicker F1 cars were a given at the pre-season tests. But Barcelona also provided a surprise or twoBy SAM COLLINS



‘It does seem that things are quite amplified with these cars, because you are going that much quicker’


In 2017 Formula 1 has a new look, new aerodynamic regulations and much bigger tyres, all designed to improve the show and make the cars more challenging to drive. It is those tyres, though, that appear to be the biggest factor following pre-season testing.

‘It is now clear that this season is a big contest not just of aerodynamics, but also the tyres,’ says Paddy Lowe, chief technical officer at Williams. ‘It’s going to be a lot about how you use those tyres which will give you an advantage. These new wider tyres are going to create a huge challenge and the people who are best at understanding them will profit.’

Following the eight days of winter testing at Barcelona and a few shakedowns and filming runs at Fiorano, Silverstone and Misano much more is now known about the new generation of Formula 1 racecars, and it has emerged that they have one unexpected trait.

‘From our experience they seem to be more sensitive to change,’ Toro Rosso technical director James Key says. ‘We knew the tyres would be more sensitive to tyre parameters, where you change the onset angle of the tyre to the road. So I think that’s proven to be the case, but maybe more sensitive than we expected. I think even things like front flap angle changes and this sort of thing all seem to be more noticeable than they were last year. It could be that last year’s cars were quite mature so the teams and the drivers understood the diminishing returns, they were maybe a bit more benign than these cars are, but it does seem that things are quite amplified with these cars, because you are going that much quicker.’

Early daysDuring testing some teams were clearly working hard on understanding the new rubber, though the general feeling in the paddock was that there is still much work to be done. ‘Some of the parameters we expected to be sensitive are sensitive and some of the compounds characteristics are not that far away,’ Key says. ‘But I’d say the majority of it is a learning process. However well you try and model a tyre, until you hit Barcelona in the morning or the afternoon, or with a different fuel load or whatever, you don’t know exactly how it’s going to respond. I think every run we’ve learnt something new about how the tyre responds to changes and how the driver needs to drive his out-lap and this kind of thing. I think in terms of modelling and prediction there’s no nasty surprises, but certainly a few differences in how sensitive they are to certain things’.

Pirelli, too, is investigating the performance of not only the tyres but also the cars and how they work on its product. It had not been able to test the new rubber at any time before the new cars were launched in February and has been outspoken about its concerns about that lack of running, though following the tests in


FORMULA 1 – TESTING UPDATE


Catalunya its spokespeople all seemed broadly positive about how things were going.

‘The degradation level is lower than last year, that’s what we expected and that is what we saw in testing,’ Pirelli’s head of Car Racing Mario Isola claimed during his test review. ‘When you overstress the tyres they come back quickly, that was a key objective for us. I think the cars will have a huge amount of development during the season so the rate of degradation will probably increase as they gain downforce and power through the year, as you might expect.’

However, the Pirelli engineers also noticed the increased sensitivity of this generation of grand prix car. ‘They are more sensitive to any change in set-up, talking with the teams it is

clear that these cars are very, very sensitive. Any small change has a big effect on balance and the performance of the cars, so of course the tyres are a key factor in that.’

Perhaps making car set-ups somewhat easier are the limitations on tyre pressure and camber angle which have been in force in Formula 1 for some time. ‘The original set-up we set in testing was 3.5 degrees maximum camber on the front with a pressure of 22psi, but we then gave the option of going to four degrees of camber but at a minimum of 23psi. The pressures and camber will again be restricted during the season, the pressure will be checked as the tyres go on to the car, the camber is policed by the FIA,’ Isola says.

Under pressureIn 2016 Pirelli was criticised by some, including drivers, who thought that the tyre pressures were too high, but as Isola explains, if anything the minimum pressures are going to increase. ‘The restrictions will be fairly similar even with the new tyres. Last year the minimum pressure limit was 21.5psi on the front. At the rear it is 18psi and I think it was 19.5psi last year, so the minimum pressure is higher at the front and lower at the rear as that is what our simulations

suggested was right. Now we are receiving data from the teams from testing and it is generally in line with the simulations. In 10 to 12 races time, with the cars getting much faster, we will have to increase the minimum pressures as the stress on the tyres will be higher.’

Hard driveThroughout the test a number drivers noticeably struggled with the handling of their cars, some suffering high speed spins and a few hitting the wall as a result of them.

‘I think in terms of tyres, from my feeling, it is not a massive difference in terms of how sudden the loss of grip is, only in the case if the tyre is not hot enough, especially with the harder compounds, sometimes it can be quite tricky to get them to work,’ Mercedes driver Valtteri Bottas says. ‘The cars are quite snappy if you have oversteer, it’s very sudden. But with the softer compounds, once you get them to do the temperature, it felt like very much the same rate of sliding or losing the grip as last year.’

Once the car has lost the rear it seems that drivers are struggling to bring it back under control. This was very apparent watching them tackle some sections of the circuit in testing, and it could lead to more crashes during races. ‘To

Rookie Lance Stroll was caught out by snap oversteer three times, his final spin resulting in this crash and a damaged monocoque. New breed of cars seem much more prone to sudden oversteer than the 2016 racecars

Pirelli was unable to test new rubber before the Barcelona tests, where most of the cars were launched. Despite concerns over lack of running it was broadly happy with performance of its product


Pirelli’s wet woes

Eight large tankers slowly toured around the Circuit de Catalunya during the second pre season test. They deposited a quarter of a million litres of water around the whole track; twice. Pirelli had demanded this slightly odd-looking activity as a way to get some running on its new wet and intermediate tyres before the season got underway. Unfortunately, not everything was as the Italian tyre maker had hoped, not least because the Catalan sunshine saw the track dry rapidly.

‘With the new wet tyres we focussed on two things; firstly a tyre which could work in cooler conditions and switch on easily,’ Mario Isola says. ‘We have the new regulations about standing starts in the wet, where you can see the cars driving around behind the safety car for a few laps and then they have to stop and make a standing start, so we need the tyres to work right away. Aquaplaning was another big area, with the bigger tyres the risk of aquaplaning is higher, so we designed the tyres with more grooves, different sized grooves and different angles, but we have to test them. At Barcelona the track is not flat and the water just ran off, so there were no rivers or pools, so we could not really test that unfortunately.’

Global warming Paul Hembery, Pirelli’s former head of motorsport says: ‘We have some work to do on switching on the compound, we are working on that. We could see there was an issue warming up the tyres. We found that the intermediate was not switching on how we wanted it to, so we know that there is a bit of an issue and we are working on it. We already suspected that it would be an issue and the test confirmed it, but work is already well advanced. There is probably a case for having two types of wet tyre, one for the warmer wet races and one for the Silverstone or Spa type of wetness, where it is a lot cooler. If we confirm what we are working on we could introduce a wet tyre compound change for the Chinese Grand Prix.’


The track was soaked to evaluate Pirellis’s wet rubber, but the Spanish sunshine and the circuit drainage spoilt the exercise

catch the car is much harder, so you can go off, whereas before, you had a slide and you could catch it. This year it is harder to catch it,’ Esteban Ocon, now a Force India driver says. ‘You go at such a speed in the corners, it is already hard to find the limit and when you start to lose the car, the car is heavier, obviously. The tyres especially are wider, so when you start to lose the car, the snap you get is much bigger than [in] previous years. That has caught out some of the drivers in winter testing.’

Snappy daysThis snap oversteer tendency is, according to Isola, really a consequence of the aerodynamic regulations allied to the increased tyre grip. ‘Snap oversteer is possible as the cars have increased grip, so I know a lot of the teams are

working to make the cars a lot more predictable, working on set-ups that are more driveable. It’s clear that when you have more grip and more downforce that when the grip is lost the car becomes snappy,’ Isola explains.

Temperature and the working window of the cars, as well as keeping them drivable yet fast, is likely to be the deciding factor in many races this season, and with the cars so sensitive to any changes it is likely that almost every Formula 1 team will get it wrong at some point and that could lead to unpredictable results. It will be fascinating to watch.

Front camber and the tyre pressures are to be limited, which has been the case for the last few seasons. The pressures will be checked as the tyres go on to the racecars, while camber is to be policed by the FIA

Tyre degradation will be low in 2017 if the tests are anything to go by. But Pirelli expects the rate of deg’ to increase throughout the year as the teams find more power and downforce through in-season development

It is highly likely that almost every one of the Formula 1 teams will get it wrong at some point


TECHNOLOGY – F1 AERODYNAMICS


Follow the leaderDownforce levels have increased in F1 for 2017 but will the new regulations improve or reduce the ability of cars to run close together or overtake?By SIMON McBEATH

With official F1 testing scheduled to take place at the end of February, time is now short for the teams to complete the build of their initial aerodynamic packages to the new regulations that come into force for 2017. And with limits on the amount of wind tunnel testing and CFD that the teams are permitted to do under the Resource Restriction Agreement, it is improbable that any of them have indulged in the relative luxury of running their new designs in multi-car scenarios to see how they will perform in traffic. Their focus will inevitably have been on hitting the track with a

package designed to achieve the best lap time, and one which will form the basis for ongoing developments.

However, with designs and CFD services provided by Miqdad Ali (MA) at Dynamic Flow Solutions, Racecar Engineering can show the results not only of optimisation work on the 2017 rules model introduced in our December issue (V26N12,) but of running that car in two-car line-astern drafting scenarios that we can compare to the similar trials we have conducted in the past 18 months.

The rationale behind our line astern two-car simulations has been that the effect on the aerodynamics of a following car has an enormous

influence on a driver’s ability to get close to the car in front. And being able to get close is the essential preliminary to being able to overtake, which definition here excludes artificially assisted passing manoeuvres that use DRS, or ‘push to pass’ engine modes, or the release of stored energy. The FIA’s passing reference (pun intended) to the topic of overtaking was seemingly just to request that the new rules should not make the current situation any worse. Now we can demonstrate what the initial ‘following car’ simulations on our 2017 rules model have indicated, and our findings are surprising indeed. But first, let’s look at the optimisation

work that MA has performed on the new 2017 car model to bring its balance and downforce closer to expected levels so that he had a good basis on which to conduct the line astern simulations.

ImprovementsThe 2017 rules model introduced in last month’s issue did not quite achieve the desired aerodynamic balance or the expected total downforce level in initial simulations. With the statutory weight distribution in F1 requiring around 45 per cent of the weight on the front axle, the aerodynamic balance target was also to have 45 per cent of the total

2017 F1 car models in tandem-running simulation. There’s the usual messy spaghetti, but will it be easier for the following car to stay close or overtake?

Now we can demonstrate what the initial following car simulations on our 2017 model have indicated, and our findings are surprising indeed


Follow the leader


downforce on the front axle. In its first design iteration our model generated a 50/50 per cent split in downforce, so clearly more work was required to generate some more rear downforce, and/or to reduce front end downforce. At the same time MA was also looking to achieve greater total downforce, as he explained: ‘In the previous feature we compared three cars at equivalent balance levels of roughly 50 per cent front and that gave us an idea of where things were, as shown in Table 1. The next target was to optimise our 2017 car both for balance and downforce. We also wanted to compare the optimised 2017 car with our earlier optimised 2013 car (at 45 per cent front), against which our following-car simulations on various design configurations have been compared in previous articles, and run the optimised 2017 car at various separations behind a leading

2017 car to see how it performed when following. This would give us an idea of how it compared to the 2013 racecar at various line astern separations and whether the 2017 rules had made things any better.’

MA continued: ‘To improve both balance and increase downforce there were several things on the baseline 2017 car which obviously needed work straight away. One would expect this anyway when you make simple changes to a car which works well under one set of regulations to meet a different set of regulations. The first thing to address on the 2017 baseline model was the size of the front tyre wake. The results and visualisations showed that the baseline front wing and its endplate did not do a good enough job of diverting the airflow outboard of the wider front tyres. Secondly, the ‘y-250’ area [where the neutral section of

the front wing terminates, 250mm from the centreline] of the 2013 front wing worked well with a raised nose where the resulting y-250 vortex interacted well with the vane-vortex coming from the under-nose turning vane. The lowered nose on the 2017 car changed the flow in that area considerably. We were not getting the flow conditions needed for producing efficient downforce. There is also the presence of the bigger bargeboard, which would need careful placing in the context of all the other flow structures around the area. Also, the baseline front wing produced more downforce than required.

‘A new front wing was designed to address the above issues. The outboard section diverted the flow around the front tyres a lot better, resulting in a smaller front tyre wake. A reduction in chord length of the main element reduced front wing

downforce by the required amount. The strength of the y-250 vortex was increased through the use of smaller flap elements at higher AoA. Moreover, the y-250 vortex was moved outboard (to y-320) (through reduced span of the flap elements) and worked better with the bigger bargeboard in deflecting the front tyre wake away from the underfloor. All these produced a more favourable flow condition behind the front wing which helped the underfloor produce more downforce and shifted the balance to the rear.

‘To improve the underfloor further, several vertical slots were added to the bargeboard, which kept the flow attached to the inner face of the bargeboard; this in turn kept the pressure low and improved mass flow in that area. It also increased the strength of the bargeboard vortex (which added downforce in the

Table 1: The basic aerodynamic parameters on our baseline 2017 FIA rules F1 model at 50 per cent front balance level

CD -CL -L/D

2013 1.17 3.94 3.362016 0.87 2.84 3.272017 1.20 3.91 3.26

The visualisations showed that the baseline front wing did not do a good enough job of diverting the airflow outboard of the wider front tyres

Figure 1: Areas optimised on our 2017 model are highlighted in red. The front wing, bargeboard, rear wing flap and rear wheel brake duct cascade were all re-designed

Figure 2: The effects of our optimisation work on the 2017 Formula 1 racecar model. Gains in downforce were made from the underbody and the rear wing areas of the car

Figure 3: Comparing downforce contributions with our 2013 model. It’s clear here that the underbody of the car has become even more important with the 2017 configuration




forward underbody) due to a bigger pressure difference across the two faces of the bargeboard.

‘Moving to the rear of the car, minor changes were made to the rear wing flap profile, reducing its camber to fix some trailing edge flow separation. The slot gap between the main element and flap was reduced from 12mm to the minimum permitted 10mm. And gills were added to the rear wing endplate leading edge to deal with flow separation there. Rear wheel/tyre assembly lift was reduced via the use of brake duct cascades. All these changes increased overall downforce by over 10 per cent over the baseline 2017 car, with a desired downforce balance of 45 per cent front and 55 per cent rear,’ [Figures 1 to 7]

Table 2 shows the basic aerodynamic data for this optimised 2017 model and compares it to our earlier optimised 2013 rules model. The 2017 model now generated over 10 per cent more downforce than the 2013 model. Given that the 2014 to 2016 regulations caused a marked decrease in downforce compared to the pre-2014 rules, it looks as though our optimised 2017 model was producing significantly more downforce than our 2016 model would have done at the same balance level, had it too been optimised.

From this we might conclude that, following the optimisation work MA carried out, our model may not be too far from expected Formula 1 aerodynamic performance levels amid the reported predictions by F1

Table 2: The basic aerodynamic parameters on our optimised 2017 FIA rules Formula 1 model compared with our earlier 2013 Formula 1 model racecar

CD -CL %front -L/D

2017 optimised 1.20 4.31 45.0% 3.592013 optimised 1.17 3.89 45.0% 3.32

It was felt that minimising this rearwards shift in downforce balance was key to mitigating the problem of being able to follow a car closely

Figure 4: This delta-Cp plot shows where pressure reductions were achieved with optimised 2017 model, leading to downforce gains, especially in the rear underbody

Figure 5: Turning the airflow more effectively outboard around the tyre also produced reductions in front tyre drag, as shown by the pressure reductions (blue) on front of tyres

Figure 6: A total pressure slice taken 200mm above ground level clearly shows the reduced front tyre wake on our optimised 2017 Formula 1 racecar model

Figure 7: A total pressure slice 900mm behind the front axle line shows how the flow structures were modified by the optimisations; note the front wheel wake reduction

insiders of up to 25 per cent more downforce in 2017 than in 2016.

Tough act to followSo, coupled with increases in mechanical grip from the bigger tyres being imposed for 2017, Formula 1 lap times will certainly decrease for cars running in isolation. But how will following cars in line astern formation fare? We have seen in our various studies over the past 18 months that the car’s basic aerodynamic configuration can alter the total downforce and aerodynamic balance that a following car can generate. MA created one configuration, among others, that saw zero balance shift on the following car across the range of longitudinal separations from eight car lengths to half a car’s length, and another that saw much reduced total downforce losses when following, although achieving both certainly looked like the search for the Holy Grail. Meanwhile, out on track in all the recent rule-defined aerodynamic configurations we have seen how cars have suffered from aerodynamic

understeer when closing on the car in front, and our simulations on models to recent rule sets have shown this rearwards shift in aerodynamic balance at ever closer line astern separations too, which has made it manifestly difficult for following cars to close up on the car in front.

It was felt that minimising or eradicating this rearwards shift in downforce balance was key to mitigating the problem of being able to follow closely, and we saw in V26N2 (February 2016) how increasing the influence of underbody aerodynamics was one of the important factors in minimising balance shift on the following car. The 2017 rules enable a greater downforce contribution from the underbody, so could we be optimistic of change for the better?

The data from our 2017 rules model in two-car line astern is outlined below, and Figure 8 illustrates the changes to the usual aerodynamic parameters across the range of horizontal separations from half a car’s length to eight car lengths. It is immediately obvious



that there are some major and very surprising differences with this 2017 configuration. The most obvious difference is in how the aerodynamic balance on the following car changes across the separation range.

Initially there was zero balance shift at eight and four car lengths separation, which does indeed give ground for optimism that cars could run closer. This minimal balance shift at these separations, combined with just a modest initial decline in total downforce, and the increased mechanical grip of the 2017 cars, should make things easier for the following driver as he first starts to close on the car in front.

However, the subsequent forwards balance shift at closer separations is the complete opposite of what we have become used to and is an intriguing and – if it translates to reality on track – a slightly worrying response for the closer separations.

The plot lines in Figure 8 showing the front and rear downforce changes with car separation confirm the forwards balance shift, with front and rear downforce declining similarly and modestly from eight to four car lengths separations, but at closer separations both ends declined further, but rear downforce declined much more.

Translating the relative data in the graph to absolute numbers, what we saw on our model was the balance figure change to about 50 per cent front at two cars’ separation, 55 per cent front at one car’s separation and about 61 per cent front at half a car’s separation, compared to the 45 per cent front figure on our model in isolation and at eight and four car lengths’ separation. If this were to transfer out on to the track, what we could see in 2017 when cars try to run close together in line astern through ‘aero speed’ corners is that

the following car might initially be able to get closer more comfortably than in previous configurations but then, as it closed more, become prone to aerodynamic oversteer. This may simply manifest itself as just that, oversteer. But could it be that drivers will risk spinning off if they get too close to the car in front?

The detailFigures 9, 10 and 11 isolate the downforce changes of the front and rear wings and the underbody across the range of longitudinal separations to help understand why our 2017 rules model responded the way it did. In contrast to previous car configurations, with our 2013 rules model shown here for comparison, the 2017 model’s front wing maintained a good proportion of its downforce at all separations. This in isolation was quite a step forwards; previously the loss of front wing

downforce as cars closed up on the one in front was the dominant cause of rearwards balance shift and aero understeer when following through a corner. But our 2017 rules model did not suffer this to anything like the same extent as we had seen on earlier models, and had this been the whole story then we might be contemplating – indeed celebrating – a scenario in which balance shift when following closely was minimal.

It was unfortunate, then that, after the initial modest downforce losses at eight and four car lengths the rear wing then lost considerably more downforce as the car got closer to the one in front. A not dissimilar pattern affected the underbody, and the rear wing’s losses will have been directly related to the underbody losses because of the interaction between the two; once the rear wing lost downforce, so too did the underbody. Thus we appear to have a

This may simply manifest itself as just that, oversteer. But could it be that drivers will risk spinning off if they get too close to the car in front?

Figure 8: Changes to the principal aero numbers on optimised 2017 car when following Figure 9: Changes to front wing downforce on our optimised 2017 car when following

Figure 10: Changes to rear wing downforce on our optimised 2017 car when following Fig 11: Changes to underfloor, diffuser downforce for optimised 2017 car when following




configuration that saw this forwards balance shift at close quarters. The question is, why did it happen?

Looking first at streamline images of the wings at four cars’ length separation, in Figures 12 and 13 we can see that both the front and the rear wing of the following car received flow with reasonably high total pressure, or energy, as shown here by the relatively high coefficient of total pressure. Furthermore, the flow direction was reasonably well aligned

with the ideal. Thus, the wings were able to generate a high proportion of what they would have generated when the car was running on its own.

If we now look at Figures 14 and 15 at half a car’s length apart, in the case of the front wing we can see that streamlines impinging on it were not just reasonably high energy but also had reasonably good flow directionality, too. MA picked up the explanation here: ‘When we look at the streamlines approaching the front

wing at half a car’s length we can see that most of the flow was high energy coming from outboard of the lead car thanks to the in-wash caused by the highly cambered rear wing, which is a lot closer to the ground [than under 2016 rules] and therefore so was the in-washed flow to the front wing. This helped the front wing keep its performance. Furthermore, the swept back nature of the 2017 front wing worked well with the in-washed flow since the flow direction was aligned

with the front wing. In fact, the front wing only lost six per cent of its downforce at half-car length whereas the rear wing lost around 55 per cent. When we look at the delta Cp plots in Figures 16 and 17 we can clearly see that the front wing maintained most of its downforce since the pressure changes were less, whereas the rear wing showed significant changes in static pressure.’

Looking at Figure 15 showing the streamlines impinging on the rear

The wings were able to generate a high proportion of what they would have generated when the racecar was running on its own

Figure 12: At four car lengths separation the front wing of the following racecar received a reasonably energetic and a well aligned airflow

Figure 13: At four car lengths separation the rear wing of the following racecar also received a reasonably energetic and a well aligned flow

Figure 14: At half a car’s length the front wing of the following car still received decent airflow; in fact the swept back shape seems to align with the onset airflow

Figure 15: However, the rear wing did not fare quite so well at closer separations, receiving lower energy and a disturbed airflow

Figure 16: Here the delta Cp plot of the underside at half a racecar’s length separation shows that the front wing incurred relatively minor pressure changes

Figure 17: At half a racecar’s length separation the rear wing saw pressure increases on its suction surface that created significant downforce loss




Dynamic Flow Solutions

Dynamic Flow Solutions Ltd is an aerodynamics consultancy led by director Miqdad Ali, ex-MIRA aerodynamicist, who has performed design, development, simulation and test work at all levels of professional motorsport from junior formula cars to World and British touring cars, Le Mans prototypes, up through to Formula 1 and Land Speed Record cars. Contact: [email protected]: www.dynamic-flow.co.uk

Ex-MIRA aero man Miqdad Ali (‘MA’), is boss of Dynamic Flow Solutions

not ideal either.’ Thus, the relatively benign situation at eight and four car lengths’ separation had turned into a significant and intrinsically unstable forwards balance shift at separations of two lengths and less.

Total pressure slices in line with the front and rear wing leading edges at four car lengths and half a car’s length separation (Figures 18 and 19) complete the story and show how the energy of the airflow encountering the front wing remained high even at the closest separation, whereas that which impinged on the rear wing had lost significant energy at half of a racecar’s length.

Cause for optimism?Could our findings just be a particular characteristic of our interpretation of the 2017 rules, or is the forwards balance shift at closer separations likely to be a generic effect? MA commented that ‘our model has the same basic architecture as the cars will have, with the bigger wheels and tyres, and the wings to the sizes and in the locations they have to be, so the main flow structures will be pretty similar. But I’m optimistic that things will be better in 2017, and it looks as though the initial response when closing will be to allow the cars to get closer more easily – I hope so anyway!’

So now we wait to see what happens when the cars hit the track, and in all likelihood it won’t be until the first race of 2017 that we get an idea of how running in traffic has or has not changed. It will be fascinating to see if the new aerodynamics and mechanical layout do provide any help to drivers trying to close up on the car in front through a corner. The FIA’s brief to the rule writers was to not make ‘the overtaking problem’ any worse. Would the response we have seen here fit that requirement?

In one sense perhaps it would, although it might simply change the reason for the fact that the underlying problem, at least in part, remains! But let’s remain optimistic that what looks to be at least a partial fix for the aerodynamic reasons for the difficulty in following closely, combined with an increase in mechanical grip, will improve the situation overall.

Figure 18: Energy of airflow impinging on front wing leading edge didn’t change much from four car lengths to half a car length

Figure 19: Here it can be seen that the energy of the airflow impinging on the rear wing’s leading edge was much reduced at half a car’s length separation compared to the situation at four car lengths separation

wing of the following car at half a car’s length separation the story was quite different, as MA related: ‘The in-wash which was beneficial to the front wing also had to go around the front tyres. The resulting front tyre wake headed to the rear wing along with the rear wing vortex coming from the lead car. The streamlines approaching the rear wing clearly show this. By the time the flow reached the rear wing it had lost a significant amount of energy and the direction it approached from was

Could our findings just be a particular characteristic of our interpretation of the 2017 rules?

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FORMULA 1 – MERCEDES PU

Halfway to impossibleOne hundred per cent thermal efficiency is simply impossible, but with its 2016 F1 power unit Mercedes HPP was halfway there – Racecar went to its Brixworth base to investigateBy PETER WRIGHT




In 2012 the FIA announced new powertrain regulations with two radical features: firstly it determined that power output was to be a function of thermal efficiency and energy recovery, and secondly it constrained the configuration of the system – IC engine, and energy recovery and storage – to align the technologies with those of the road car industry. For the first time in 64 years of Formula1, the technical objectives of the engineers in both disciplines were very nearly the same.

Since the first powertrains ran in early 2014, half the F1 paddock has been decrying these devices on the basis of: ‘not noisy enough’; ‘too complicated’; ‘too expensive’, and ‘his is more powerful than mine; it’s not fair!’ All to be expected. The other half of the paddock has kept quiet, and this is the extraordinary thing. Instead of extolling their achievements in radically improving the thermal efficiency of an IC gasoline engine, and the power density of energy storage systems, power electronics and machines, they, being racing engineers, have kept their heads down looking for the next improvement and competitive advantage. A consequence of this is that the bath water, baby and all, very nearly got thrown out, with a reversion proposed to return to irrelevant, high-revving, fuel-guzzling powertrains.

Racing’s relevanceThe relevance of motorsport engineering to road cars has always been a debated topic, and never more so than with powertrains. The problem is that motorsport requires the maximum output within the regulatory constraints, regardless of cost, while road car engineering sets out to provide adequate output for minimum cost.

With a swept-volume engine regulation dominating throughout F1’s history until 2014, power output has been the quest for RPM. Pneumatic valves are an example of an expensive F1 technology that removed a development constraint but had no road car relevance. An opposite example is GDI (gasoline direct injection) – present on the W196 Mercedes of 1954, which

revved to 10,000rpm, at that time twice the RPM of a high performance road car engine, such as the Jaguar XK. GDI did not return to racing until the late 1990s with the Audi R8. The engine for this produced its peak output at 6500rpm, while at the same time F1 engines, in particular the Mercedes engine which won the World Championship that year, turned at up to 18,000rpm, where GDI is not feasible. GDI is one of the technologies that has had a big influence on road cars, but was not possible to use in F1 until now, when it has been made central to the current F1 regulations.

As a prelude to the 2016 season, with two successive World Championships under the new regulations in the bag, Mercedes HPP decided it was time to tell the world what it had achieved to date, how it did it, and the relevance of the technologies developed to its passenger cars. No one is better placed to do this than Andy Cowell, managing director of Mercedes HPP, and the architect of this success.

Measuring efficiencyCowell was at pains to ensure that what is meant by efficiency is correctly understood, which in an era of energy recovery and energy storage, is not always the case. True thermal efficiency is the ratio of the power delivered at the crankshaft to the power delivered to the engine as fuel. And 100 per cent is thermodynamically impossible. In F1’s case,

100kg/hour of fuel is delivered at a peak rate equivalent to 1240kW or 1686PS. The crank power must not include any that derives its energy from an electrical storage system. Cowell then gave some interesting numbers, starting in 1876, the year that Karl Benz invented the automobile – see Table 1.

Pressed to be a little bit more specific about the thermal efficiency achieved today, based on the fact that through reverse engineering all his competitors will probably know the figure anyway, Cowell admitted, ‘not far short of 50 per cent’. Halfway to impossible, then … (Table 2).

A one per cent gain in efficiency yields 18ps, so it is easy to see both why HPP is working so hard on efficiency, and why Cowell is somewhat cagey about exactly where they have got to. With additional energy sent to the MGU-K from the battery to top it up to its permitted maximum, there is at certain times greater than 900PS available to the driver at the flywheel.

Staggering developmentIn the 137 years since the inception of the IC engine, thermal efficiency has been improved from 17 per cent to 29 per cent, that is 0.00875 per cent per year. From 2012, when HPP started work on the current powertrain, efficiency has risen from 29 per cent to nearly 50 per cent, that is 5.25 per cent per year. This represents a staggering steepening of the development curve.

HPP made a fundamental decision when it heard KERS was to be introduced into F1 in 2009; that it would take on the responsibility for this technology, starting work on it in 2007 (Table 3).

Cowell stated that the specific power had been improved by a factor of 12, which would mean that the ‘less than 20kg’ might in fact be nearer to18kg, based on the firm figures supplied. This weight not only includes the battery itself, but also all the control electronics that monitor the Lithium Ion cells, and control the flow of electrical energy to and from the two MGU’s (H and K) that form part of the powertrain. This latter computer performs a mere 43 trillion calculations in the

From 2012, when HPP started work on the current powertrain, efficiency has risen from 29 per cent to nearly 50 per cent




the desired torque, then the MGU-K can draw energy from the battery and fill in any holes in the IC engine torque curve. Cowell stated that torque feedback from a sensor on the input shaft of the gearbox is not employed as ‘that would look too much like traction control’.

This mastery of the mammoth torque of these powertrains has given the drivers better control than ever before, and has meant that talented young drivers can step up to F1 with ease. Spectacular it is not, and however much power the powertrains deliver, that era is gone.

But does Mercedes ever burn fuel solely to fill the energy store, under braking or mid corner, or for instance when the traction is limited? Cowell says that would be an inefficient use of fuel, to send the energy via the battery, but admitted it would be possible on circuits where the race allocation of fuel (100kg) is not needed, or when there is an extended safety car period and fuel is conserved.

Cowell spoke carefully and somewhat guardedly about how HPP had achieved these remarkable results starting in 2012, when the new regulations became firm. He gives much of the credit to four key groups within HPP: Performance Simulation, tasked with combustion, Dr Nigel McKinley, its team leader; Turbocharger Design (Pierre Godof, team leader); Hybrid Systems team (led by John Stamford); and the Software Development group, led by John Goodman.

Performance simulationThe first powertrain, the GB (the 2016 is the GF), weighed in at 262kg and would never have fitted in to a car. It did not feature the later engines’ split turbo system, but gave the engineers the first validation of the combustion simulation work that is the cornerstone of HPP’s R&D. Using moving-mesh CFD, essential where there are geometry changes, the Performance Simulation group ran hundreds of simulations in order to understand and optimise the synergy between: GDI; charge motion; compression efficiency; gas exchange; and combustion – including molecular-level modelling of fuels with a knock limit being the critical boundary. Results are then proven in a single cylinder research engine, and transferred to the latest spec of the V6 R&D engines.

At the start of the project, HPP found that there was virtually no turbocharging expertise in-house at Brixworth. Turning to parent company Daimler, it ended up talking to both the truck division of Mercedes-Benz and the helicopter gas turbine division of MTU. The truck business is driven by the costs of fuel, and so efficiency is paramount. Also, the power rating of big truck diesel engines is of the same order as the F1 powertrain, so learning from truck turbos is not as odd as it may seem.

Freeing up the size of the compressor by taking it out of the V, and mounting it at the front of the engine, with the MGU-H just

The engine from the first motor car, as invented by Karl Benz back in 1876, which had a thermal efficiency of 17 per cent

Table 1: Thermal efficiency of Mercedes-Benz automobile engines since its inceptionYear Engine configuration Thermal Efficiency

1876 1-litre, 1-cylinder, NA 17 per cent

2013 2.4-litre, V8, NA 29 per cent

2015 1.6-litre, V6, turbo-compound >45 per cent

Table 2: Performance of recent Mercedes Formula 1 powertrainsYear Engine Power Fuel flow Thermal Efficiency

2005 3-litre, V10, NA 900ps @ 18,000rpm 194kg/hr 27.5 per cent

2013 2.4-litre, V8, NA 725ps @ 18,000rpm 148kg/hr 29 per cent

2015 1.6-litre V6, t-c 750-840ps @ 10,500rpm 100kg/hr 45-50 per cent

Table 3: Mercedes-Benz HPP’s work on KERS Year Weight (kg) Power (kW) One-way efficiency (%) Power/Weight (kW/kg)

2007 107.0 60 39 0.56

2008 36.5 60 54 1.64

2009 25.3 60 70 2.57

2012 5.0

2015 6.0

course of a two-hour race. This level of number crunching is needed to manage the recovery and deployment of the energy between the MGUs and the battery, and to ensure that the race driver receives exactly, and repeatedly, the torque that he demands.

The first of these is supervised according to the strategy in use: Friday practice, Qualifying, Race, Safety Car, etc. The software learns and updates the strategy according to what is actually happening out on the track.

The second function reveals an interesting insight about the entertainment value of F1. Many perceive that F1 has become less spectacular, and that this can be corrected with more power – although why more grip is also being prescribed is currently beyond me. However, Cowell explained how HPP engineers spend a great deal of time tuning the torque

delivery response to the drivers’ desires, both on track and in the simulator. When the driver applies the throttle pedal he wants to receive the exact torque at the wheels he desires, and it must be exactly the same as last time. More can lead to loss of control; less to frustration.

In the days of port fuel injection, the fuel droplets ‘made a couple of laps of the trumpets before disappearing down them,’ says Cowell. Mixture distribution was somewhat haphazard, and the response of the engine to a given throttle opening was guesswork. GDI has solved much of this problem with predictable, repeatable fuelling of each cylinder. The throttle pedal is a torque demand, and the computer determines the actual throttle opening according to engine conditions at the time, compensating for RPM, turbo pressure, air temperature etc. If the IC engine cannot deliver



The 125,000rpm rotating parts are monitored by a number of sensors

behind it and the driveshaft extending back to the turbine at the rear, brought a number of benefits: ‘When added together, they are worth the enormous effort needed to make it work – it was very hard,’ says Cowell.

Inspecting the assembly indicates that the 125,000rpm rotating parts are monitored by a number of sensors to ensure that the bearings and shaft dynamics are always within limits. The ‘cogging’ of the electrical machine, combined with the exhaust pulses the turbine experiences, make for a highly ‘excited’ rotating assembly. At the front, the compressor inlet conditions are controlled by variable geometry inlet guide vanes, to maintain the surge margin when the throttle is closed. At the rear, variable geometry is not permitted on the turbine, and in fact is not required as the whole system is constant speed,

controlled by the MGU-H. A wastegate, however, is required for safety, for instance when it is necessary to unload the turbine suddenly due to an electrical short, triggering the total disconnection of the high-voltage power electrical system. It is also sometimes useful to compensate for sudden load shifts during downchanges. It took 600 CFD simulations to arrive at the first design, and many containment burst tests to prove it, at £20,000 a test for the hardware alone. The large diameter compressor allows HPP to run the turbocharger below the maximum 125,000rpm at sea level, and to speed it up and continue to use the 100kg/hr fuel flow rate at altitude, for example at Mexico City, to maintain design power output.

The compressor wheel employs the same alloy as the pistons, an aluminium alloy still

closely related to the piston alloy developed by Rolls Royce for the Schneider Trophy R-engine and the Merlin, 90 years ago. The double entry turbine wheel is a cast, high nickel inconel alloy; ceramics are not permitted. We did not get a chance to look at an exhaust system.

Inspection of the other IC engine components revealed parts that look similar to the V8 equivalent parts, although there were obviously many, many detailed differences. Much lower RPM has relieved the inertial loads, but the gas loads are way higher. The small V6 also needs some beefing up to maintain its structural stiffness as an integral part of the chassis, and this is particularly evident as a larger web at the base of the crankcase, and tubular structures above the cylinder heads.

Electrification It is easy to overlook the development that has gone into the two electrical machines that are part of the powertrain. By their very nature they are densely packed cylinders of copper, steel laminations, and rare-earth magnets, with the smallest of air gaps and only sufficient free space for cooling fluid. Weight reduction only comes from reducing the size for a given power by increasing RPM. Both MGU-K and MGU-H seem to be around the same size, but HPP is neither releasing the power rating of the 125,000rpm MGU-H, nor the RPM of the 120kW MGU-K. From the sizes observed, it is unlikely that either is much under 10kg.

A 16ps/kg figure is, however, impressive compared to around 10ps/kg of the 900ps of the best V10s. The problem with automotive

The Mercedes F Cell Roadster concept of 2009 (left) was a tribute to the very first car, the Benz Motorwagen (right). The roadster has an electric motor powered by a fuel cell. Mercedes-Benz HPP has now made concept car-like efficiency gains in the real world of F1

Mercedes HPP has achieved a thermal efficiency of close to 50 per cent with its F1 power unit. True thermal efficiency is the ratio of the power delivered at the crankshaft to the power delivered to the engine as fuel



electrification is not the motor; rather it is the storage of the energy

Cowell stressed how hard HPP had worked on the efficiency of the whole power electrical system. The payoff is not just yielding more power, but less cooling of all elements of the system, which compromises the car’s aerodynamics. Every aspect is studied to yield crumbs of performance, which add up to something useful. Aircraft wiring and connector systems are utilised. In aircraft power electric cables, copper is replaced with nickel-plated aluminium wires, which are half the weight for a given resistance. Running the system under full power and inspecting with thermal imaging cameras guides the engineers to hot areas where the losses are occurring. ‘It is like the water and oil systems, you have to eradicate or ease every little restriction,’ Cowell explains.

Yet while all’s clearly very good at HPP now, in an ideal world what would HPP like to do to change the F1 powertrain regulations to yield greater efficiency? ‘Maybe two less cylinders,’ says Cowell. ‘If it must be a V6, then 60-degree or

120-degree rather than 90-degree, for a sweeter sound. Larger capacity with less RPM would increase thermal efficiency. The fuel regulations are okay – a reasonable balance between energy density and knock.’

Tech transferAnother hypothetical question: if Cowell was suddenly and unexpectedly transferred by Mercedes-Benz to design the next C-class powertrain, what would he take from HPP to incorporate into a middle of the range powertrain? After some thought, but still just about off the cuff, these are the features he puts forward: 400cc, 90-degree V-twin, with 200PS; electric turbocharger – but not exhaust energy recovery as this requires full throttle; an MGU-K integrated into the powertrain, with two energy recovery MGUs for each of the front wheels, giving 4WD when necessary; combustion know-how; lower RPM than the F1 internal combustion engine. ‘The IC engine would effectively become a range extender with around 54 per cent efficiency,’ he adds.

Cowell sees no future for the IC engine as a stand-alone powertrain. However, he did also admit that his vision would require clever production engineers to get the costs out without destroying the efficiency.

HPP has a total staff of around 500 at Brixworth, of which Cowell is the managing director. To have an engineer with total management control is unusual in F1, and this, plus the autonomy of Mercedes-Benz HPP, located in a different country to the parent company but close to the racing team, is a major contributor towards its success.

A number of other things impressed me as Cowell led a brief tour of the factory, during which he offered a number of insights, for instance: ‘In general we don’t employ F1 people. Instead we simply look for very good engineers.’

In the middle of the engineering office was the materials group. ‘We tend not to believe the material performance as published by suppliers, so we do our own tests,’ he said. ‘Then, when something breaks, the materials engineers carry out a full forensic investigation. We have developed three or four alloys, unique to HPP, for the powertrain,’ Cowell added.

Machine shopThe machine shop was the next stop. It is laid out in such a way that machine tools can be removed and replaced easily, as new technology comes through. This may be machine tools themselves or new powertrain technology requiring different processes. The machine tools are relatively lightly used, as Formula 1 components generally require light cuts, and so they maintain their value; HPP depreciates them over five years. Cowell said: ‘We encourage a spirit of change in the machine shop, not a production mentality.’

Another point Cowell made related to the company’s staff: ‘The key to a happy workforce is to avoid annoying them with silly little things, like there not being enough parking.‘ But the workload is heavy: ‘We are working 24/7 through January, February and March to build and test engines for testing and the early races, and yet we try to be flexible. We build about 100 engines a year, but we managed to get away with using only three engines for one driver last year. That is good, as it means we have a spare!’

Perhaps the single thing that struck me about how different HPP is from many other F1 outfits was the lack of trophies in the entrance foyer. The trophies, and there are many of them, are displayed around the factory, even in among the machine tools.

HPP is quietly confidant of what it is doing; that is, something that is quite remarkable in automotive engineering, and well worth telling the world about. It is halfway to impossible, and has no intention of stopping there.

Above: The V6, which is smaller than the V8 which preceded it, needed some beefing up to maintain its structural stiffness as an integral part of the Mercedes chassis Left: HPP spends a great deal of time tuning the torque delivery response to the drivers’ desires, both on track and in the simulator, so they always know what’s under their right foot

‘We’ve developed three or four alloys, unique to HPP, for the powertrain’22 www.racecar-engineering.com FORMULA 1 2017


Untitled-5 1 25/01/2017 16:13

http://motorsport.nda.ac.uk


After over a year of debate, dispute and speculation, last year F1 fi nally settled on a new set of technical regulations for the 2017 and 2018 seasons. As expected the rules have seen the cars built to a higher weight limit, with wider bodywork and tyres and more dramatic looking aerodynamic devices. Those changes have largely been detailed elsewhere (see V26N5), but the more recent changes to the regulations relating to the power units have been less widely discussed. In a nutshell, the headlines relating to the design of the units have remained unchanged – a direct injection 1600cc turbo V6 mated to an electro turbo-compound hybrid system – but the details of many sub systems have been adjusted.

From the moment that the new regulations were introduced in 2014 there were a number of very vocal fi gures in the sport who felt that the power unit had become too much of a performance diff erentiator, Red Bull team principal Christian Horner among them: ‘I think Formula 1 has the three elements which should have equal weight: the driver, the chassis and the engine. So if one of those elements isn’t quite right, the other two can compensate. I think in today’s Formula we’ve off set that balance, so you’ve probably got, 50 per cent engine, 25 per cent chassis, 25 per cent driver.’

Convergence of powerUnder pressure from the likes of Red Bull, and notably Bernie Ecclestone, Formula 1’s rule makers have now moved to redress this balance somewhat by adjusting the regulations to allow the performance levels of the four diff erent power units to converge, with the aim of reducing the huge advantage that Mercedes HPP is perceived to have. ‘One our main objectives with the rule changes was to help performance convergence,’ the FIA’s head of powertrain, Fabrice Lom, says. ‘To do that the fi rst big thing that people thought was important is to have stability in the regulations. There was a lot of discussion of changing completely the regulations, going back to normally-aspirated engines, no hybrid. Nobody wanted that because the trend in the world is to go hybrid and low consumption, but also they thought if there’s a big change there will be a redistribution of the cards, and there could be a big diff erence in performance between the power unit manufacturers, so they said that stability of regulations would help a lot.’

To allow for power unit manufacturers to be able to close the gap, the much debated upgrade token system has been dropped entirely, allowing for free performance development during the season; the idea being that the law of diminishing returns will apply and, over time, the performance of the units will converge naturally.

Perhaps in an attempt to accelerate this process a number of component weight restrictions have been introduced, as well as some minor changes in the material specifi cations. Both MGUs will now have a minimum weight applied of 7kg for the kinetic and 4kg for the heat. Inside the combustion engine similar minimum weights are being applied, too, with the minimum piston weight set at 300g, and the connecting rod also at a 300g. The piston weight includes the pin, rings and retaining clips, while the rod weight includes the bolts and bearings.

The crankshaft will be restricted, too, both in terms of weights and dimensionally, the main bearing journal is limited to a minimum of 43.95mm and the pin bearing journal 37.95mm. A complete crankshaft assembly including all balance weights, bolts and bungs must weigh at least 5.3kg. The total power unit minimum weight remains

No smoke without fi re: the debate over Formula 1 power units has been heated and divisive over the past years, but last year the teams and the FIA fi nally agreed a new set of engine rules

FORMULA 1 – 2017 ENGINE REGULATIONS


Power gamesAfter much deliberation the F1 power unit regulations for the next two years were put in place last year. But what were the implications for the engine builders and the teams?By SAM COLLINS


The much debated upgrade token system has been dropped entirely allowing for free performance development during the season


FORMULA 1 – 2017 ENGINE REGULATIONS


unchanged at 145kg. ‘These limits were put where the best [power unit] is today so that people know the target, and also allow us to stop the best ones developing more, to go lighter or smaller, so that we put something like a bit of a barrier to development,’ Lom says.

In 2018, an additional restriction is also being introduced on the temperature of the air in the plenum, which will have to be more than 10degC above the ambient temperature. On top of that more of the ERS control systems will have to be packaged inside the monocoque.

One aspect of power unit development which has been at the forefront of Formula 1 research and development work, particularly over the last 12 to 18 months, is the combustion process, and this is an area where significant innovations are now being applied. But the FIA has now moved to restrict performance in this area somewhat, with a maximum compression ratio of 18:1 being enforced from 2017 onwards, again in order to force performance convergence.

Part way through the 2015 season, Ferrari adopted the Mahle Turbulent Jet Ignition concept on its Formula 1 V6, a technology which is thought to have featured on the Mercedes

unit since 2014. The technology, which was patented relatively recently, relies, according to its inventor, the Mahle Group, ‘on a special surface ignition, which in turn allows for higher engine performance. The ingenious trick here is that the air-fuel mixture is pre-ignited in a pre-chamber around the spark plug.’ This results in the formation of plasma jets that reach the piston primarily at the outer edge and ignite the remainder of the mixture. While ignition normally takes place in the centre of the cylinder, with Mahle Jet Ignition it essentially takes place from the outside toward the inside. This allows significantly better combustion of the fuel mixture. The result is more power with considerably less residue. ‘With this lean burn combustion process a substantially greater efficiency can be achieved than with previous ignition concepts,’ Mahle tells us.

High compressionThis is not the only technology under development in this area, as the quest for efficiency grows the levels of compression have risen substantially, to the point where at least partial compression ignition is almost possible. ‘In theory the higher the compression the

higher the potential efficiency, but it also brings a risk of knock with it,’ Yusuke Hasegawa of Honda R&D says. ‘So the level set at 18:1 is high enough for us not to care about it for now. HCCI [see page 16] and pre-chamber systems are very much in the R&D phase at the moment.’

These sentiments are echoed by Renaultsport F1’s technical director (power unit) Remi Taffin, who says: ‘If you look at 18:1 and look at the maximum cylinder pressure it’s frightening, but that new regulatory limit is not a restriction on us. We don’t think we will reach that any time soon. I know what the constraints are, I look at the materials technologies I have around me and I don’t think there is anything to cope with this for the next five or six years. These regulations will not stand for the next 20 years. Look at it in that way, the limit is far away enough that it is not limiting us.’

In addition to the limit on compression ratio, the FIA will also introduce restrictions on the number of different fuels used by each team, with only five fuels allowed per season and two per event. Fuel development has been a major area of performance gain under the current formula, especially when allied with the combustion developments, and the limits have

There has been no major changes in the basic engineering philosophy of F1 PUs in 2017; they are still 1.6-litre turbocharged V6 hybrids

‘There has never really been as much of a link between an engineer developing a Formula 1 engine and an engineer developing a road car engine as there is now’



been introduced for similar reasons. ‘It’s all about how your ICE is working,’ Taffin explains. ‘If you look at how the fuel developed, early on we look to get the best out of the knock sensitivity, then as you develop the combustion chamber you get a bit more freedom to develop the fuel, as you can be a bit less knock sensitive, but get a bit more energy from the fuel.’

Each car will be able to use a little more fuel in 2017, as the maximum amount used on each car for the duration of the race will increase from 100kg to 105kg, to deal with the wider, heavier and more draggy cars defined by the chassis rules. It is not a change all were in favour of. Mercedes boss Toto Wolff says: ‘Claire Williams [Williams deputy team principal] raised [this] in the meeting itself, that the whole world is looking to reduce emissions, and she asked can we possibly vote in favour of an increased fuel allowance from 100kg to 105kg?’ All Mercedes-powered teams voted against the increase, but they were in the minority.

It could be argued (and has been) that the new restrictions, especially those impacting fuel development and compression ratio, could reduce the relevance of F1 to production car R&D – the very reason the current power units were introduced in the first place. ‘When we started to discuss convergence, there were suggestions of defining a power limit, but we were totally against that,’ Hasegawa says. ‘But it is natural to have some kind of limitation as this is a sport, not pure R&D. You cannot have infinite development, so some kind of restriction is necessary. Technical freedom is a good thing, that is our philosophy as a company, but we don’t want to make everything ourselves. Why would we design a coffee cup when we can just buy a perfectly good one?

‘I think restrictions can reduce the value of F1 R&D to production cars, but it very much

depends on the parts restricted, and what those restrictions are. If you restrict everything then the sport has no meaning and it has no value to us anymore. I think the 2017 regulations do not restrict us really, at least not so far.’

R&D relevanceTaffin points out that while some of the combustion techniques under development have some very real applications to the mainstream, the way Formula 1 uses its engines is very different and as a result technology transfer is not all that straightforward. ‘We are using engines that are not all that close to what you see in production,’ he says. ‘We are revving to 11,000rpm or more and we spend a lot of time at full throttle. If you work out how much time you spend at full throttle in your road car, you understand that the duty cycle is not in the same area. But saying that, there has never really been as much of a link between an engineer developing a Formula 1 engine and an engineer developing a road car engine as there is now, and that it is probably the best thing about these rules. Even if the technology cannot be switched directly from race to road.’

With the changes made to the technical regulations aimed at forcing the varying performance levels of the power units to converge, the FIA has decided that it will monitor very closely if indeed convergence is taking place. ‘We have a process agreed with the power unit manufacturers, we don’t look at lap times, we have tools to simulate everything, so we can calculate the performance of the power unit itself on each car and we transform this in a power index,’ Lom says. ‘You have this hybrid system and an engine and you cannot only talk about horsepower, so it is translated into a power index. We check every car, every lap of the first three races. We take the best of

F1 cars will feature a sound generator from 2017, but details of its design and operation were not yet available. The picture shows an earlier attempt to improve the engine noise; waste gate exit pipes

Renault’s has struggled to keep pace with its rivals in recent seasons but the dropping of the engine token system could give it more scope to develop its PU for the 2017 season. Early testing proved inconclusive

‘The new regulatory limit is not a restriction on us, we don’t think we will reach that any time soon’

each power unit for each race and each PU manufacturer, then we do the average over the three races. This should give a power index of performance for each power unit manufacturer.’

If one power unit is found to be substantially above or below the rest on this Index of Performance (Lom stresses that this is not a Balance of Performance) then Lom’s team at the FIA will escalate the situation. ‘We will report to the Strategy Group, and the action is a decision of the Strategy Group. We will check this in the first three races, which is [at a time] that is before the deadline to make a change at the majority for the following year,’ Lom says.

Not all of the changes are directly aimed at encouraging convergence. Many changes to both the technical and sporting regulations are aimed at reducing costs and ensuring that every team in F1 has a guaranteed supply of power units, something which was not the case at the start of 2016, and could have conceivably seen three teams drop out of the sport as a result.

The first step in this process did not quite go as far as a pure cost cap, but is a direct


reduction in the price charged to customer teams. This reduction is €1m in 2017, compared to the price in 2016, and it’s reduced by €4m, compared to 2016, from 2018 onwards. From 2018 a cost cap of €12m is applied to teams working with new suppliers (that is, if they have switched from one supplier to take an engine suppy from another).

In order to get the manufacturers to agree to this reduction in price the FIA had to take other steps, Lom says: ‘We cannot ask the power unit manufacturers to reduce price without reducing cost. So to reduce the cost, firstly in 2017, we will go down to four power units per driver per season, instead of five today, whatever the number of grands prix. In 2018, and this is a big task for them, we will go down to three ICE, plus turbo, plus MGU-H, and only two energy stores, control electronics and MGU-K. So it’s nearly 50 per cent fewer parts, so it should reduce the cost by a nice amount.’

While this is a reduction on total price paid out per team, it is actually an increase in price per power unit with the reduction of number of units allowed per season. Not all of the power unit manufacturers are entirely happy about the reduction in units, and Lom’s comments came as a surprise to some in the paddock.

‘It is very tough even now,’ Hasegawa says. ‘Last year we struggled to achieve the durability. This year it’s much better but we are still struggling, so longer mileage is pretty tough. Bringing in longer mileage, we need some more time to do that, even just for life testing. In some ways that actually increases the cost for us, not reduces it.

‘I think it’s true that when you want to make something last longer you get it heavier, and as a whole vehicle that is not efficient, so it’s a bit controversial. If you want to make a car faster, of course, you would make the power unit lighter, it’s the opposite direction for an endurance car.’

Hasegawa went on to hint that he f

Formula 1 2017 • Digital edition • … · 2019. 10. 14. · Racecar Engineering (October 2016,...

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