Mercedes W03 – A first analysis

Mercedes officially revealed today their 2012 challenger, the W03. We now have the time to take a slightly closer look at it, and some of its detailing.

W03 in Barcelona, 2012 pre-season testing

The front wing is a complete redesign (1). Mercedes have produced this three-element front wing (which is the first time they are adopting the concept), which has all these intricate and elaborate details, with very pronounced cascades and turning vanes under the nose. The nose itself (2) represents a slightly extreme interpretation of the rules, with the side bulges rising very high in comparison to the height of the nose. The smoothed 3-D surfaces between the bulges look very well thought-out and designed. It definitely looks to be more efficient and less draggy than, say, Ferrari’s or Sauber’s solutions. Behind the air intake for the engine (which, as we have already said, has 2 exposed structural members) we can see an additional air intake (3) for gearbox / hydraulics cooling. The front suspension (4) utilises pushrod architecture. Finally, if rumours about their front F-duct are correct, this (5) is the entrance of the air going into the air valve that we described in our previous blog posts.

W03 - Barcelona launch 2012 - overhead view

The exhausts (6), as we have already explained, are situated quite far forward, but this is not expected to be the final solution. As you can see in the picture below, the car was running yesterday (20/02) during filming with additional gills right next to the exhaust outlets, so we expect to see similar solutions from Mercedes during testing. The rear beam wing is supported by a swan-neck mount (7), similar to other solutions already seen this year. The rear suspension (8) features a pullrod (like all other 2012 contenders) and heat shields. Finally, as you can see (9), the DRS mechanism is not apparent. It seems that all hydraulics are directed via the endplates and they will be using a step motor to operate the rear wing upper element.

Cooling exits by the exhausts during W03 filming, yesterday

All in all, this seems to be a very contemporary and elegant interpretation of the rules, with a lot of scope for development. Provided that the basics of the car are OK, then Mercedes should be able to take the next step and challenge the top 3 teams with a bit more credibility and consistency.

Mercedes W03 – the spy shots saga continues…

Another spy shot of the Mercedes W03 was revealed today, from their private testing in Barcelona. The car, which is due to be “officially” launched tomorrow @ 8:20CET, features extremely slim sidepods, as you can see in the photo below, just like we had noticed in the 1st spy shot revealed late last week. It seems that the W03 is extremely tightly packaged at the back – tighter than any other 2012 car we have seen so far, including Red Bull, and by quite a margin. Apparently Mercedes have used their packaging knowledge from 2011, when they had to work with the shorter wheelbase of all 2011 cars, and put it to good use in 2012. It all bonds well for the season ahead, provided the car is reliable…

Mercedes W03 in Barcelona - Extremely slim and low sidepods

….and a few hours later, even more photos prop up – better ones…

Mercedes W03 spy shot - During filming (a)

Mercedes W03 spy shot - During filming (b)

The sidepods are amazing. Not only they are non-existant at the back, they also feature a heavy undercut under the air inlets, making them, arguably, the tiniest and slimest sidepods I’ve ever seen in a modern F1 car. Some say that it’s aerodynamicists who rule the game in F1, but I’m ready to argue that it’s still mechanical engineers. Without them, this tight packaging (and all the nice aero benefit that comes with it) wouldn’t have been possible.

Aerodynamic W-duct

I just saw a very interesting video clip in YouTube, which explains the functionality of the aerodynamic W-duct, more commonly known as a “front F-duct”. This system was allegedly run by Mercedes GP in some of the final races of the 2011, with the drivers reportedly unhappy about the effect it had on the handling on the car. This is the clip:

What the author of this clip is suggesting is that the duct has two different functions. In straights, it channels the air through a central tunnel of an “air valve” towards the main components of the front wing in order to stall them (i.e. minimize drag and downforce). Then, in corners, the air is re-directed via the air-valve to the part of the front wing that is at the inside (i.e. in left-hand corners, it channels the air to the left part of the front wing). However, the reason for doing this is exactly the opposite. The air passes under the wing elements creating additional downforce and, at the same time, it brings the whole left part of the wing closer to the ground (it therefore negates the roll effect to the wing).

It’s a very interesting idea. The author argues that the air is directed via the central channel between -1 / +1 degrees of turning, whereas it is directed via either the left or the right channel when the degrees vary from between 1 to 6. Such a system is completely passive and it doesn’t involve driver’s input, nor does it incorporate moving parts. Having said that, it’s clear to see why such a system would be very sensitive inside a corner, where the rate of turning is never steady and consistent. A sudden correction of a slide, for example, would cause the airflow to switch to either the central channel or the exact opposite, meaning a completely different aero balance at the front. It would also be a challenge for the aerodynamicists to ensure that the airflow detached and reattaches smoothly and quickly.

It is rumoured that Mercedes haven’t binned their front F-duct program, and that they will be running a revised version of it during the Barcelona pre-season tests (starting tomorrow). It will be interesting to hear the drivers’ comments and, more importantly, get some info from the journalists on track on how the cars seem to behave, visually. To anyone how hasn’t read it, I strongly recommend subscribing to Autosport Plus and reading Jerome d’ Ambrosio’s track-side impressions from Jerez testing…

W03 – first spy shot

Thanks to F1 fanatic, we now have our first serious glimpse of the Mercedes W03 car, from the shake down that took place yesterday at Silverstone, and we can make our first few, brief observations. The nose (2) is very rounded both on the vertical and horizontal planes. The famous platypus step (1) is more pronounced arguably than in any other car we’ve witnessed so far, although from that photo I am inclined to believe that what we are seeing are 2 huge vertical bulges (channels running left and right of the nose), and the “inside” part is void (unlike Ferrari which is completely solid). The front suspension (3) is typically pushrod, so Ferrari will officially be the only team on the 2012 grid to feature a pullrod arragenement at the front (we can safely predict that neither Marussia nor HRT will have a pullrod). The sidepods (4) seem to be surprisingly slim (actually ridiculously thin and tiny at the back of the coke bottle shape), with a heavy undercut; also the air intakes seem to be lower than usual. There is an additional cooling inlet (5) for gearbox and (possibly) KERS cooling. The roll hoop construction (6) follows the trend of having the pillars exposed (it’s not the carbon mono-blade design anymore). The exhausts (7) seem to be situated very far forward and we cannot judge the angle from that photograph (more will come, I’m sure, as the days go by…). The rear suspension (8), although it’s not clear in this photograph, will have a pullrod suspension, as per every other car so far and, finally, we cannot see any cooling outlets so I presume the main one will be that over the gearbox (9).

Roll on Barcelona, 21st of February…….

Mercedes W03 - first decent spy shot from Silverstone shake down

2014 Engines – some considerations

As most F1 fans know by now, the engine regulations have been altered for 2014 onwards. The main changes can be summarized as follows: Cubic capacity drops from 2.4 lt to 1.6 lt and, at the same time, the number of cylinder goes down from 8 to 6, always in “V” configuration, revs are limited to 15,000 RPM, direct fuel injection is limited to 500 bar, single turbo charger is allowed and, finally, the fuel flow will be controlled (i.e. limited). For those interested in reading more, you can find the changes here. We will have the pleasure of watching turbo engines again after 26 years, for it was back in 1988 when the McLarens of Ayrton Senna and Alain Prost dominated the season, using a 1.5 lt V6 Honda turbocharged engine.

Many people believe that F1 engines are no longer the great differentiator in performance that they used to be, and that’s true. However, the level of competition is such at the moment, that one can never rest and there is always scope for development and investment. Recently imposed regulations such as the DRS have brought engine performance back under the spotlight. Renault, according to their F1 director Mr. Francois Caubet, have developed an engine so efficient that it allows Red Bull to start a race with 15 – 18 liters of fuel less than their opposition, even though it is slightly down on power in comparison to Mercedes (by about 15 BHP). Teams like Mercedes and Ferrari will be spending millions of dollars developing their engine plants, so I believe it’s worth examining the new engine regulations a little bit further.

Let’s start with the most intriguing aspect, which is of course the fuel flow rate limitation. The upper limit is set at 100 kg/h, and below 10,500 RPM the fuel mass flow must not exceed the amount of Q (kg/h) = (0.009 x RPM) + 5. This means, that the fuel flow tops up @ 10,500 RPM and has the linear graph shown below. Of course, the curve below represents the maximum allowed fuel flow in all circumstances and does not represent the actual flow graph, which will be considerably different.

Fuel Flow (kg/hr) Vs Engine RPM

The question is, how do we get more power in the 10,500 – 15,000 RPM range when our fuel flow is limited? Many people traditionally associate increase in power with increase in fuel supply, which is of course wrong. You can have an increase in power by using different (leaner) air/fuel ratios (and/or different ignition advance settings), and all modern engines are managed that way through air/fuel ratio maps which are embedded in the cars’ computer (and, quite often, tweaked afterwards…). Typically, a road car achieves 100% (or even slightly more) of fuel injector duty cycle at about 80% of its RPM range, and then has 20% more RPM to give (and, often, more power) by changing the air/fuel ratio and increasing the advance (i.e. increasing the degrees before TDC that the ignition takes place). So, you may end up getting 1,000 more RPM and at the same time the fuel injectors workload has dropped to 80% (these are ballpark figures).

The logical question is, how do we get more power by increasing the air/fuel ratio? The reason is stoichiometry. A stoichiometric mixture is considered an air/fuel mixture that has just enough air to burn the entire fuel quantity. For typical gasoline that we put in our cars, this ranges anywhere between 12.5 to 13.3. In F1 fuels, this may be slightly lower (due to the additives that have the effect of lowering the stoichiometric ratio). In reality, however, cars never run stoichiometric mixtures. There are three main reasons for that: (a) a stoichiometric mixture burns very hot and can impart severe thermal stresses to the engine components, (b) the temperature is further increased because we no longer have the cooling effect of the fuel spray on the combustion chamber and, (c) due to the high temperatures, early detonation of the mixture is possible, causing the famous “knocking” effect under load. All cars therefore (even F1 single seaters) use rich mixtures (i.e. air mass / fuel mass less than the stoichiometric one).

The new fuel flow rate limitation nevertheless means that F1 engineers will be forced to explore the upper limits of the air/fuel ratio. The increased ratios combined with increased advance will cause severe thermal stresses to the engines and will dramatically increase the cooling needs of the power plant. Also, since the cars will be turbo-charged, the charge air (i.e. the compressed air supplied by the turbo compressor wheel to the combustion chamber) must also be cooled down. Overall, thermal management of the engines will be crucial in 2014, and I expect most early reliability problems to come from that, as the aerodynamicists will be pushing for leaner sidepods and smaller coolers and air intakes. The engines themselves may be smaller, but this is more than countered by the addition of the turbo and the complexity of the exhaust piping arrangement (see further down in this post).

The problem of cooling is further exacerbated by one addition to the 2014 rules (5.8.2) which states that “over 80% of the maximum permitted fuel flow rate (author note: i.e. over approximately 8400 RPM), at least 75% of the fuel flow must be injected directly into the cylinders”. This means you have a very small time window to get all the fuel delivered directly via the fuel injectors (which are also limited to 500 bar), since you can only direct 25% of the fuel via the air intakes, which would help to keep the valves clean and to achieve more homogeneous mixtures inside the combustion chamber.

Also, the exhaust gases (having worked the turbine wheel) will have lost a lot of their kinetic and thermal energy, so there will be less scope for using them for aerodynamic purposes. Since only one, single-stage turbo is allowed, we will now get a single exhaust outlet from the turbo, although I don’t see anything in the rules preventing the teams from splitting the exhaust manifold in two after the turbo.

How does the 100 kg/hr compare to today’s F1 cars and consumption figures? Typically, contemporary F1 cars consume 75 lt / 100 km (4 mpg). 75 liters are about 68 kg. A typical race distance is around 310km and is done (again, typically) in about 1 hour and 30 minutes. This means that, currently, F1 cars consume on average 140.5 kg/hr of fuel. Please remember that the 100 kg/hr is the maximum amount allowed, we therefore expect the average number to be even less. Assuming (and that’s a big assumption) that the average figure will be around 80 kg/hr, this means that the new generation engines will be about 43% more economical than the current power plants. A 2011 car had to start the race with about 180 kg of fuel – in 2014 they will be starting with 120 kg. This means considerably smaller fuel tanks; and there’s a reason right there for the aerodynamicists to feel a bit better after all.

An interesting addition to the rules is 5.19, which states: “Engine exhaust gases may only exit the cylinder head through outlets outboard of the cylinder bore center line and not from within the “V” centre”. The way I understand this is that exhaust piping must travel outboard the engine and cannot be located in the middle, between the two cylinder banks, as shown in the figure below (the green area is where it’s not allowed to installed the exhaust outlets). This would have been an obvious solution for the engineers, i.e. to join the exhaust outlets from the two cylinder banks in one common manifold running between the V. Now, they will have to keep the exhaust outlets from the cylinder heads pretty much as they are at the moment and resort to more elaborate and complicated exhaust piping arrangements in order to feed the turbo charger.

Not allowed location for exhaust outlets

So, what should we expect from the 2014 engines? I am really not willing to get into the debate of how they will “sound”. They will sound terrific, just like they always have. For those who are interested in the technology, it will be fascinating to observe the new engines and the various solutions that the engineers will come up with.

Ferrari F2012 – Technical Analysis

Ferrari have clearly chosen to go their own way in 2012. Their design marks a departure from the 2012 “common wisdom”, as displayed in the cars that we have seen so far (CT01, MP4-27 and VJM05). It also marks a departure from previous years and design philosophies, adopting a more explorative and anti-conventional path. The Ferrari F2012 really is an interesting car, so let’s dig our technical teeth into it:

Ok, the most striking feature is the nose. This, by itself, is a strange decision. I can see what Ferrari are trying to do, i.e. maximize the airflow travelling underneath the tub and towards the rear of the car. This is why they have adopted a completely vertical underside (matched with a completely vertical upper side), pushing the nose dimension to the limits allowed by the rules. In my opinion, however, a flat underside is less effective than a curved one (which is the solution that Force India and Caterham have adopted). Furthermore, the gap at the upper part between the two “bulges” is now completely filled (and this was necessary because the upper contour follows the lower, which is also flat). I imagine that this surface that meets the air straight-on is not ideal either for drag or for the airflow trying to go to the back. A case of what were they thinking? Time will tell.

Ferrari F2012 - front view

Staying at the front, the major surprise is the pullrod arrangement. With the nose sitting so high, I was very surprised to see Ferrari adopt this (although rumours were going about) and I even went on record that such an arrangement would not be adopted. I was wrong. The question is, though: were Ferrari right? As you can see in the photo above, the pullrod is nearly parallel to the ground – I calculate the angle to no more than 10-12 degrees. It’s going to be a complete nightmare for Ferrari to restore the suspension dynamics of a pushrod arrangement at such angles (even normal pullrods at increased angles suffer a small disadvantage in that area in comparison to pushrod arrangements).

One of the advantages of a pullrod arrangement is a slightly better CoG, but frankly, in that case, I don’t see it, due to the parallel orientation of the pullrod. You can see that clearly in the picture below, where I have marked where a pushrod would have been. The pullrod definitely sits higher. The other advantage is that a pullrod allows for more and clearer air to travel from the front wing to the back. I have to say that I fail to see how this is necessary and I highly doubt it can balance out the negatives of the substantially altered suspension dynamic characteristics. It may be a strange car to drive.

Ferrari F2012 Pullrod Vs Pushrod

The last car to feature pullrod suspension at the front was the European Minardi PS01 (and PS01 B), which was driven in 2001 by none other than Fernando Alonso himself. It’s a bit ironic, and he will definitely be hoping that his Ferrari’s handling characteristics don’t match those of his old Minardi. Check out the picture below, and you can see for yourself how much more radical Ferrari’s solution is in comparison with a normal pullrod, due to the increased nose of the F2012.

European Minardi PS01 - pullrod suspension

Moving on, the sidepods are very slim and the inlets are small. Another prediction that we made was that Ferrari would be sporting crash structures separate from the sidepods in the shape of wings, in front of the sidepod inlets (rumours which were encouraged by the news that Ferrari had failed early side-impact crash tests). We were wrong too. The sidepods are highly sculpted and undercut, but conventional. The interesting bit comes if we move a bit further to the back…

…and examine the exhaust and cooling outlets. Apparently Ferrari are not adopting the central cooling outlet, a la Red Bull, that has been common in all 2012-spec cars so far. The cooling outlets are merged with the exhaust in the fairings shown in the photograph below. The exhaust outlets are positioned as low and as outboard as possible – Ferrari clearly intend to blow the rear brake ducts (we again have to thank ScarbsF1 for that, who was the first to suggest it a long while back). How the exhaust-flow will combine with the cooling outlet air-flow is a mystery at this point, but I presume both will be directed at the brake duct fins. This fact, combined with the very weird front suspension geometry, could give unwanted handling characteristics to the car. It has long been argued that downforce applied straight to the wheels is very effective, but sudden loss of it (in off-throttle mode) can cause severe unbalance. Have Ferrari, in their quest for ultimate downforce, forsaken mechanical grip and driveability?

Ferrari F2012 - exhaust and sidepod cooling outlets

At the back, the bodywork is very tight around the gearbox which has been redesigned. It is now narrower and sits lower – you can also see the driveshafts which are ever so slightly angled upwards, a la Williams FW33 but nowhere near that radical. Another feature that is different in Ferrari F2012 is the air intakes at the top and the roll hoop. Ferrari are the only team thus far to retain the mono-blade carbon-fibre construction, and they have added an additional cooling inlet, apparently dedicated for the gearbox and hydraulics.

Ferrari F2012 - Rear view

All in all, and with the benefit of hindsight (having seen the other 2012 cars so far), it seems that Ferrari were trying to do something radically different to all the rest in 2012, and have accomplished it. A check list would look like that:

Nose shape different? Check.

Cooling and exhaust different? Check.

Front suspension different? Check.

Roll hoop and air intakes different? Check.

Ferrari fans can only hope that Ferrari will be justified for going radical and against the grain. It’s a make-or-break year for several people within the Ferrari organization (from the technical to the management side) and the sheer amount of change from last year’s car to the F2012 could be an indication of a very slight panic building within the team, under the pressure for immediate results.

Force India VJM05 – Technical Analysis

Force India revealed their 2012 car (coded VJM05); in fact, in the hands of Paul di Resta, it became the 2nd 2012-spec machinery to turn its wheels in anger (ok, mild annoyment) for one installation lap today, at Jerez (Williams already shook their car down yesterday, away from the eyes of the press). Allegedly the team was encouraged by di Resta’s feedback (wow, guys, cool new LED’s on the steering wheel!).

Ok, joking aside the new Force India car looks to be a well-thought out and accomplished design, which manages to incorporate some pretty impressive details. I was mostly impressed by the amount of free air allowed to travel to the back and the way the bottle-neck shape at the back is really tight around the gearbox – arguably tighter than whatever we’ve seen so far. This is clear in the picture below (please also mark the opening for the motor starter, marked with yellow).

Force India VJM05 - tight packaging at the back

The exhausts’ angle is at the lower allowable range (as you can see in the photo below, I calculate it to about 13 degrees). The exhausts are mounted quite close to the car’s centerline (as opposed to McLaren’s, as we’ve seen before), and it seems that Force India are planning to blow the lower part of the rear wing. Nevertheless, it is clear that the exhaust outlets have a scope for experimentation, and we expect to see a varying degrees of angles during pre-season testing. There is a winglet mounted atop of the beam wing, which will probably be using the air coming from the central cooling outlet that the team has adopted. With all those exhausts and cooling outlets blowing in the wings, the ducts and around suspension members in 2012 cars, I expect to see all the cars run thermo-strips in their suspensions and wings (at the back) for the first tests. This may be an issue during the year.

Force India VJM05 - exhausts location

The nose, which clearly follows the rules literally, is more refined than Caterham’s version, and definitely more refined than Ferrari’s (the technical analysis of the F2012 will follow soon). As several F1 journalists have already remarked, VJM05 will not be a platypus but a hammerhead shark; check out the onboard cameras mounting at the front. Although I find their nose design quite pretty and streamlined in fact, this black monstrous tip ruins it for me.

Force India VJM05 - aka The HammerHead

Other than the above, the overall designed looks very accomplished and contemporary. The sidepods are slim and heavily undercut, increasing the quality and quantity of the air travelling at the back. The roll hoop structure is substituted with the typical-for-2012 design (with 2 extra mounting pillars, just like Sauber in 2011) that we’ve seen so far (as ScarbsF1 has predicted way in advance, this solution is actually lighter than the full carbon-fibre mono-blade type). The front wing is one which we haven’t seen in the past as well. The suspension solution is typical for 2012 (so far), with pullrod at the back and pushrod at the front. Tried and tested.

The team have set their goals high for 2012, hoping to secure 5th place (i.e. go one better than their best ever finishing position, which was 6th in 2011). This, practically, means that there will be a lot of pressure on the shoulders of Paul di Resta and Nico Hulkenberg, two young and relatively inexperienced drivers. It means that the drivers will have to display maturity and work together towards securing constant points finishes. A good example to follow would be the way Sergio Perez and Kamui Kobayashi operated last year.

Join me in wishing them good luck….

The story behind the “Mercury” suspension – Part A

Again, thanks to my friend for this article below…:

There has been a lot of discussion going on in various websites and forums about our proposed system, over the last couple of days. Sadly, most of this discussion has revolved around its legality and/or the impact of Mercury on the environment, rather than its merits and the technical reasons behind it.

We will leave it to the self-proclaimed “experts” on the different forums to argue about its legality, as we trust that finally the real experts (i.e. the FIA) will decide if it’s legal or not. Just an interesting observation. ScarbsF1’s report on the new McLaren MP4-27 mentions that he asked Paddy Lowe regarding the Lotus anti-dive brake system and he said that the team looked into it but dismissed it immediately because the engineers felt that it was illegal. However, when ScarbsF1 inquired with regards to interlinked systems, the team refused to comment…

Enough with that. In the meantime, we will try to explain over the next couple of days, to the few fans with an interest in the technical aspects of the sport, the idea behind the system, and more specifically:

1. Why it is not just another” interconnected /hydro-elastic suspension” – as some like to claim,

2. Why it is not “enough” to just “lock out” the front suspension under braking, and

3. Which specific characteristics of an F1 car, have been  leading  to the development of the Lotus –Renault “reactive ride height” system [now banned by the FIA] and our proposed system.

In order to do so, let´s first take a look at a “generic” F1 car according to the 2011 rules.

First, we will define, which loads we have in a hard braking manoeuver at top speed [5G deceleration] and we will later show what this means to the front ride height [front wing height over the ground] of the car.

We will show all the maths [no panic – it´s simple], and we will make some assumptions along the way. Now as is the case with every assumption, we can make some “wrong” assumptions, but this will not take away from the general principle or overall concept, nor will it render the final conclusion void. So, if you feel we have made some wrong (or inaccurate) assumptions in terms of overall downforce levels, centre of gravity [CoG] height, % of front downforce or tyre stiffness, we encourage you to do the calculations based on your own numbers, and to see what the end result looks like. We are confident, that it will not be night and day different from our final values.

So let´s look at some numbers:

To comply with the 2011 rules, a Formula 1 car must have a minimum weight of 640 kg including the driver.  To complete a race distance of approximately 300 km without refueling, the car will need an estimated 160 kg of fuel. The weight distribution between the front and the rear axle is set by the rules to 45.5-46.7% front and 53.3-54.5% rear and we assume a maximum downforce value of 15000 N [1523 kgf] and a distribution of 43% at the front axle [feel free to use your own values here].

Therefore the fuel load changes the total weight of the car by approximately 25% between Qualifying and the start of the race. This in itself is already a great challenge when it comes to choosing the appropriate setup for the car. On top of this, the amount of downforce generated by current Formula 1 cars will change the load at the wheels by about 300% at the front and about 322% at the rear. For the suspension and the tyres, the car appears to be three times as heavy at high speeds, than it is at low speeds. Combine this 300% increase in vertical load with the very low ground clearance of a Formula 1 car, and you start to see, where the challenge for the race engineers lies. The lower the car can run to the ground, the more downforce it will produce, as long as a minimum clearance is maintained, and the skid block/plank does not get excessively worn.

During braking, load will be transferred from the rear axle to the front axle; the underlying calculation for the load transfer is:

Total load transfer = (total weight of the car x longitudinal acceleration x CoG height) / wheelbase

We use a car with a ½ full tank as basis for our calculations. Please see the graphics below for the results.

Load @ the wheels (no braking)

Load @ the wheels - braking & decelerating with 5Gs

5G Braking values

As you can see, from the calculations above, the weight on the front axle increases by +267 kg and decreases by -267 kg at the rear axles during the 5G braking maneuver in our example. What this means to our front ride height and front wing and splitter (tea-tray) height, we will explain in the next blog entry.

Stay tuned…..

McLaren MP4-27 – A first analysis

McLaren took the covers off their 2012 machinery today, the long anticipated MP4-27. The car carries their hopes of winning their first Constructors World Championship since 1998.

McLaren MP4-27

At first look, the car looks more like an evolution of the MP4-25 that was used during the 2010 campaign than last year’s car. It has a shorter wheelbase and gone are some of the striking features of last year’s car. McLaren also have a history of presenting fairly “bog standard” show cars in their car launches, and it’s no different in 2012. I expect several things to “grow” in the car, as they go about their pre-season testing. Nevertheless, several conclusions can be drawn.

First, the packaging at the rear is very slim. The mechanical arrangement (gearbox, drive shafts, etc) is situated a little bit lower than MP4-26, but it’s not as low as the arrangement of Williams FW33 with the extreme angles adopted for their drive shafts (you can see the comparison below). The cooling outlet is now unique (unless some more spring out during testing), it’s much smaller in comparison to last year and is situated directly above the diffuser. The diffuser itself is blanked, so we will get to see it for the first time in testing only. Also gone are the L-shaped sidepod cooling inlets – we have a more conventional arrangement now. Interestingly, there is an additional cooling inlet inside the sidepod inlets, which will probably be dedicated for KERS cooling. The sidepods themselves are heavily undercut and sculpted.

MP4-27 - view from the rear

Williams FW33 - view from the rear

The most interesting feature of the new McLaren is the exhaust outlets location. Situated at this position, so far out from the car’s centerline (the exhaust outlets protrude from the back of the sidepods like cracked bones in a footballer’s foot), it points to the conclusion that McLaren will be exhaust-blowing their rear brake ducts. I therefore expect some heavily finned ducts to appear for the first pre-season tests – stay tuned for that. It will be interesting to read what the drivers have to say about that. Popular wisdom has it that, although the downforce produced directly at the wheels is more efficient, it is expected to affect the handling of the car in off-the-throttle mode. Considering that extreme engine mapping to blow the exhausts is no longer allowed by the FIA, the jury is out on whether the drivers can live with it or not. A tail-happy car in high speeds will definitely suit Lewis but not Jenson. The car is expected to be planted to the ground in corner exits, which is another plus for Lewis, because Jenson is slightly better than Lewis in getting the power down, so that’s another advantage that Jenson will have to give up.

The nose is much smoother than Caterham’s solution, and nothing indicates that the engineers were forced to extreme measures to deal with the 625 mm Vs 550 mm rule. Apparently McLaren feel there’s more to be gained from streamlined bodywork at the front and who are we to argue with their windtunnel calculations.

McLaren MP4-27 - front view

All in all, this appears to be a concept bordering in the conservative, with a few interesting ideas thrown in. We will have to wait of course for their first tests to make a final judgement, seeing as a lot of features on the car have been either blanked or not presented at all. The history of F1 is riddled with winning cars that have been evolved from less successful predecessors – Red Bull being a prime example of that. McLaren seem to have decided that their basic concept is not that bad and all it needs is some innovation in key areas.

The jury is out…

Anti-dive / anti-squat stability system – a further analysis

Following our yesterday’s blog where we revealed the basic concept behind an anti-dive / anti-squat system (possibly similar in scope and design to what Mercedes AMG are rumoured to be running), my friend who is behind this idea was kind enough to provide a few insights into the concept, as well as some figures, which will help everybody understand its application a little bit better.

The first picture is a logical extension of yesterday’s sketch, with a gas (N2) cylinder accounting for the increase in system volume due to thermal expansion. For the benefit of our presentation we will assume that the system operates with mercury (and all calculations have been based on that assumption) but other heavy fluids can be used as well, such as gallium and its alloys (gallium-indium-tin), cesium formate, barium sulfide, sodium metatungstate, etc etc. Less heavy fluids will require pistons & cylinders of increased diameters to reach the required force (due to the inevitably reduced ΔP), but it’s do-able.

The mercury circuit is set at an approximate fixed volume of 500 cc, with a pipe line of 8 mm (inner diameter) connecting the front and the rear heave cylinders at a distance of approximate 3200 mm (i.e. the wheelbase of the car). As you understand, the volume of heavy liquid required is quite minimal.

The oil circuit and the mercury circuit are set at a constant pressure of 200 bar. The accumulator decides the “system pressure”, since lower pressure values can also be used without any primary effect on the system (10 bar would do as well). The benefit of this system, in comparison to the Lotus one that was recently banned by the FIA, is that the car is not “rested” on it, so any changes on its stiffness will not have dramatic effects. The beauty of this system is that it’s not “in-line” with the main suspension load, but “in-parallel”, so it doesn’t carry it all the time.

During the braking phase, a -5g deceleration would produce a delta-P (differential pressure between front and rear) of around 22 bar (similarly, a 1.5g acceleration during the accelerating phase would produce a delta-P of around 6.6 bar), counter-acted by higher spring load at the front and lower at the rear, thereby creating a legal high density fluid anti-dive / anti-squat suspension system.

These 22 bar of ΔP when put into work against a piston of 65mm diameter will produce a force of around 7200N. Assuming that the front downforce is at around 40.6% of the overall, then it’s easy to calculate (taking into consideration the aerodynamic force, the mass of the car, the driver and 1/2 fuel tank) that the force which the system will need to overcome during the maximum (5g) deceleration phase is in the order of 6200N, approximately. All very straightforward and easy, even accounting for a 5% approximation error.

A sealed crossover (utilizing a floating piston) between oil and mercury circuits is provided in order to allow movement in the heave mode – front and rear axles move simultaneously. The high-pressure system is set in order for the deceleration-induced pressure at the crossover not to cause too much of a circuit volume change, and also to secure a low percentage of system-pressure differential from both deceleration and thermal expansion taken up by the accumulator, as well as to increase the “stiffness” of the oil and avoid possible localized cavitation effects in the circuit during operation.

The gas cylinder, as we explained, allows for the thermal expansion. This presents another advantage against the banned Lotus RRH system. The Lotus system would operate in working temperatures of around 130C for the oil (the pistons and fluid lines situated next to the 850C red-hot ceramic brakes). However, the system that we assume Mercedes is running is completely inboard, which means that the working temperatures are not expected to be higher than 70 – 85 degrees Celsius, therefore things like the change of the oil bulk modulus due to temperature and pressure do not come much under consideration.

Another, purely mechanical advantage, is that in order to raise the pushrod (as in Lotus’ system) you will need a higher force to counter the “bad” motion ratio of the inclined pushrod, whereas in this system you can have a 1:1 ratio in relation to force Vs wheel movement.

Anti pitch / anti squat control system with gas reservoir - Mark I

 The second figure below shows an iteration of the above system, that utilizes a position-sensitive valve which controls the maximum amount of lift of the nose. This arrangement is implemented to prevent the nose from “overshooting” the desired position, lifting all the way to the end of the suspension travel. Please do not assume that this can be termed as “fully active” because it’s not – the valve can be triggered mechanically. This closing valve can be arranged just in front of the front and rear heave cylinders and can be mechanically activated by the suspension positioning in order to ensure optimal ride height during braking / accelerating as well as preventing the overshoot.

Anti pitch / anti squat control system with position sensitive valve - Mark III

It is fair to assume that Mercedes are probably using two separate systems, cross-linking the left rear to the right front, and the right rear to the left front. The underlying principle and function remain the same but such a system can also account for combined condition (longitudinal + transverse acceleration), helping in conditions where braking is combined with turn-in (i.e. majority of the cases). By fighting the roll as well as the dive, the overall aero platform is more stable and predictable to drive.