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.

Interesting move for Jules…

If you haven’t heard yet, Jules Bianchi is moving to Force India, to take up the 3rd driver role and participate in Friday free practice sessions. The Frenchman, who comes from a family with racing pedigree (his grandfather was 3x world champion in the GT category and his father’s brother was a winner of Le Mans and a F1 racer from 1959 – 1958) has an ongoing collaboration with Ferrari. He is managed by Nicholas Todt (also a manager of a certain Felipe Massa) and has climbed the motor sport ladder in convincing fashion. From karting, to French Formula Renault champion, to Masters of Formula 3 winner, to dominating the F3 Euroseries alongside team-mates Valtteri Bottas (2012 Williams’ 3rd driver) and Esteban Gutierrez (2012 Sauber’s 3rd driver).

His Ferrari association peaked when he participated in the 2011 Abu Dhabi Young Drivers test, where he displayed maturity and speed. However, his meteoric rise to the top seems to have stalled a bit, following two consecutive fruitless seasons in GP2 Asia and GP2 Series, which yielded few race wins or poles and no championships, against decent but not mouth-drooling competition.

Bianchi had the option to remain in GP2 for another year, but his move to Force India makes a hell of a lot more sense. To start with, another season in GP2 would not have guaranteed a championship, and in that case the perception of him by the F1 circus would suffer as a result.

Furthermore, Force India are known to test drivers who are seriously considering for a race seat. He is, hence, going to a team who will consider him for a driver if he delivers the kind of performance and maturity that they expect. His contract with FI allegedly assures at least 9 Fridays of running, which is a great opportunity for Bianchi to get some exposure and put his name out there, next to some decent laptimes.

Once cannot help but consider the possibility that Ferrari had a role in this deal and that they will be monitoring the young Frenchman’s performances very closely. In my opinion, it’s an indication that they have started to accept the fact that Massa will not continue in 2013 and are preparing all the alternative solutions. One is Sergio Perez, who has acquitted himself nicely in his rookie year. Mark Webber is the 2nd one, and now Jules Bianchi could be the third, but definitely not for 2013 (Ferrari won’t take a rookie) but for the years to come, provided Jules does well and lands a race seat in 2013.

Anyone else sees Perez moving up to Ferrari and Bianchi stepping in at Sauber? Kobayashi should be alarmed with the news of Bianchi signing for FI’s, for it’s his job on the line in 2012. Sauber will be happy to go with Gutierres and Bianchi if Kamui doesn’t show considerable steps of improvement, particularly in qualifying which remains his weak spot.

Is this Mercedes’ secret Reactive Ride Height (RRH) stability system?

For a long time there have been rumours that Mercedes are about to run an innovative ride height stability system. A friend of mine just sent me this picture, which shows what could be Mercedes’ secret ride height stability system. It involves hydraulically interlinking the front and rear suspension. The system works around the basic equation for hydrostatic pressure (relative density (rho) of the fluid x g (acceleration) x L (length of the cylinder), taking advantage the different density of the fluids involved (i.e. 13.5 for mercury and circa 0.88 for typical hydraulic oil), by using the pressure difference under acceleration to work the piston. The design, which is copyrighted as per the image below, is legal since it does not involve any driver input and it doesn’t alter the configuration of the suspension. It’s a step forward from what teams are already doing by linking their left and right suspensions (see scarbsf1’s blog for more on that). The system proposed below by my friend can be termed as a “Mercury anti pitch / anti squat” system and is along the lines of what Mercedes GP are rumoured to be using…

Anti-Pitch & Squat Control with Mercury interlinked suspension

Caterham CT01 – more…

Caterham has released photos of their 2012 contender (nothing new, just better quality), so we have a first chance to take a look at the back of the car:

Caterham CT01 - Rear view

As we can see, the similarities with RB7 are very obvious: The team are using a pullrod arrangement at the back. The sidepods are very sculpted and tight, “hugging” the gearbox. There is one main cooling outlet, which is situated at the fin tale, while there are no other cooling outlets that we can see. From this photograph we cannot determine the angle that the exhausts have been installed with regards to the reference plane, so we cannot tell if Caterham have decided to blow the rear wing or not. It remains to be seen whether this is the final exhaust solution. Overall, the rear of the car is very tightly packaged, leaving a lot of the floor exposed. It’s a very neat design, and definitely the most modern and contemporary that Caterham (ex Team Lotus) have ever produced. It bodes well in their efforts to bridge the gap to the midfield. It certainly looks the part. It’s also clear that their technical collaboration with Red Bull and Renault will continue to bear fruit in the future. With the rules remaining relatively stable in 2013, Caterham need to throw all they’ve got in developing this car, which can make or break their entire F1 participation project.

First pictures of Caterham 2012 car leaked

The first pictures of the Caterham 2012 car have been leaked today and we present them to you here. The team was supposed to launch the car via the upcoming issue of F1 Racing. One would presume F1 Racing is not thrilled to bits about it. Oh, well, here goes:

Caterham 2012 car - side view

Caterham 2012 car

Caterham 2012 car - front view

Our first observation has to do with the nose. It has been raised to reach the maximum allowed height of 550 mm, in order to maximize the airflow travelling underneath and towards the rear of the car. Behind it, we find these 2 “bulges” that are used to raise the car up to 625 mm, in order to conform with the rules. The bulges are also used as housing hard points for the upper front wishbones and the push rod. The result is this “platypus” styled nose, which is a trend most F1 teams are expected to follow. It will be interesting to see which teams will go for a slightly lower or slightly more rounded nose, and what kind of benefits / drawbacks such a choice may present.

In terms of suspension, Caterham have gone for pushrod at the front and, although I can’t see what’s going on at the back, I presume it will be a pullrod. Rumours that have Ferrari going for a pullrod at both ends are probably unfounded.

The sidepods is a big departure from the past. They are heavily sculpted, with an undercut, to increase airflow to the back, which will be critical in 2012 (ok, arguably it’s always critical, but with the ban on EBD’s that’s where all the loss in downforce has to be regained). The roll hoop is of conventional design (gone is the blade) with parts of the supporting members showing. The exhausts are not shown and just like the front wing (which is nothing new, we’ve seen it before and it’s there for presentation purposes only) the final solution may not appear until the first pre-season tests.

Although we don’t have a clear view of the back, we can surmise that it will have a lot of 2011 Red Bull features, since Renault is supplying the Engine and the KERS, whereas Red Bull themselves will be supplying the gearbox and the hydraulics.

Witnesses in Sutil’s case

According to F1 enigma (writing for the Greek site “Go Car” – you can find the like here, but it’s in Greek), the list of witnesses to testify in Sutil’s trial has been given to publicity and it does not include Lewis Hamilton, who has requested to be excused (a request which was subsequently granted, arguably with prosecution’s consent who would probably not want to see one of Sutil’s close friends on the stand).

Some names that are listed are:

Jerome d’ Ambrosio – Ex F1 driver for Marussia Virgin team.

Emma Brixton – That’s how she’s spelled at the Greek site, but I presume they are referring to Emma Buxton, who worked as contact press officer for Force India at the 2011 Australian, Malaysian, Chinese, British and Indian Grand Prix’s.

Manfred Zimmermann – Adrian Sutil’s manager

Youssef Hammad – I’ve never heard of before.

Eric Lux is also, obviously, called as a witness. The trial, which is due to take place on January 30 and 31 will more or less determine whether Adrian Sutil will have any future dealings with F1. One also has to wonder whether Caterham’s delay to announce that Trulli won’t be driving for them, as well as HRT’s delay in naming a 2nd driver has to do with waiting for the outcome of the trial.

Time will tell.

Is Kimi’s return already hurting Lotus?

I presume you are all aware that Kimi Raikkonen has started testing with Lotus @ Valencia this week. The team use the 2010 car with last year’s tyres, in an effort to bring Kimi up to speed, i.e. familiarize with the electronics, the tyres and the various procedures. Reports state that Kimi completed 300 kms yesterday (23.01) and will do another 400 kms today.

At this point, it is clear that Lotus aren’t testing anything meaningful for the 2012 season. They can’t do that with their 2010 machine and it would make very little sense. It’s all about assessing Kimi and helping him find his feet. However, the team (as per the Article 22.3 of the FIA Sporting Regulations) are limited to 15,000 kms of testing, per calendar year. A chunk of that time has already been wasted during the season in straight-line testing and the Abu Dhabi young drivers’ test day. Kimi’s Valencia test means that another 700 kms must be deducted from that amount; 700 kms that have nothing to do with car development or reliability testing. That’s a big chunk of mileage to give away.

Pre-season testing will be crucial for 2012. Many teams will be experimenting with radical exhaust solutions, marginal cooling (just look at all those different sidepod ideas floating about) and other mechanical solutions such as uber-slim gearboxes, liquid mass dampers, etc. Pirelli will also introduce new tyre compounds, which will require testing and understanding. Some teams, if you recall, had problems with some of the Pirelli compounds throughout the entire last season.

At times like this, it’s hard to justify throwing away testing mileage like that. If Kimi turns out to be his pre-2006 self, then it might be worth it. Although I have no doubt with regards to Kimi’s talent or ability behind the wheel, his motivation remains a big question mark. Whether Kimi retains his motivation after a few races fighting for 12th place remains to be seen.

Tweet tweet

Braking the trend that has all serious “F1 people” on twitter, I decided to join and bring the overall respectability level down a notch.

You can find me @AbulafiaF1

🙂

Exploring the legality of the Lotus anti dive system

Although the FIA has now found the device to be illegal, it is yet unclear on what grounds this decision was based on. There are a few possible reasons, and I would like to go through them with you. It’s an interesting exercise and, in a sense, reveals the ambiguity that is often embedded within the rules. It also serves to show how brilliant engineer minds can invent stuff that are well beyond anything the FIA technical rules can foresee.

Before we start, let’s get our basics straight. The Lotus device is a project that is being developed since, allegedly, January 2010. Bob Bell who recently switched from Lotus (Renault, at the time) to Mercedes apparently took the idea with him and the Brackley based team are said to be ready to run such a system in 2012. The same more or less applies to Ferrari who are reported to have developed a similar system. The rumours that go round, and which have not been verified at this stage, are that Red Bull have been in fact running such a system for at least a year and a half, which allowed them to run increased rake without fear of the endplates touching the ground, and possibly run softer suspension solutions. It’s not clear at the moment whether McLaren or any other team had plans to run the device in 2012. Judging by how stiff the McLaren was sprung at the front end, one would imagine that they didn’t have any such solution in 2011.

The device was a simple technical solution, and it’s a development of ideas that first appeared in motorbikes in the early 80s. It consists of a master hydraulic cylinder which is powered by the brake torque to raise the push rod of the suspension, thereby preventing the car from diving under braking. This apparently means that the pushrod will be of a telescopic design. The consequences of that will be examined later on.

Let’s see now on what basis the device may have been banned. We will refer to the 2012 Technical Rules, which is a good read anyway.

1. Paragraph 3.15 – “Aerodynamic influence”

“No part having an aerodynamic influence and no part of the bodywork, with the exception of the skid block in 3.13 above, may under any circumstances be located below the reference plane”

One would expect that the cylinders, located at the lower part of the brake ducts, would always be above the reference plane. However, it’s questionable whether this can be guaranteed for an entire race and under any circumstance. Imagine a scenario where a F1 car goes hard over a kerb. The suspension will compress and the wheel will rise dramatically in relation to the sprung part of the car. It would be hard to prove that every part of the device remains above the reference plane, unless (a) the limit of the suspension travel is such that the device remains above the reference plane or (b) they install proximity sensors which can provide data at the end of the race regarding the relative position of the lower part of the device to the ground. In any case, this rule was specifically written to prevent the teams from fitting any sort of flaps, turning vanes, etc below the reference plane, but if we accept that this device alters the aerodynamic characteristics of the car, then the rule should apply to it as well.

2. Paragraph 3.15 – “Aerodynamic Influence”

“Any device or construction that is designed to bridge the gap between the sprung part of the car and the ground is prohibited under all circumstances.”

As we have explored in previous blogs, the device does indeed contribute to manipulating the ride height of the car during braking. More specifically, the device is designed to increase the gap at the front (in comparison to what the gap would be if the device was not fitted) and, as a consequence, decrease the gap at the back.

It then all depends on how one interprets the term “bridge the gap”. Apparently this rule was written as such to prevent side skirts that completely connect the ground to the car, creating the notorious ground effect. Most engineers would translate “bridge the gap” as connecting the car to the ground. However, one may argue that this term can also refer to bringing the car closer to the ground artificially; it’s a matter of interpretation. One can say why such an argument may be a bit thin, but if the FIA want (for political reasons, or whatever) to ban the device, then it is a possibility.

3. Paragraph 3.15 – “Aerodynamic Influence”

“With the exception of the parts necessary for the adjustment described in Article 3.18, any car system, device or procedure which uses driver movement as a means of altering the aerodynamic characteristics of the car is prohibited.”

That’s a juicy one. There is no question that the car alters the aerodynamic characteristics of the car. That’s partly what it’s designed to do. A car that approaches the corners at the designed rake is aerodynamically more balanced and predictable than a car which exhibits dive characteristics. There is the counter-argument that every component of a car actually alters the aerodynamic characteristics of a car – from the brakes to the steering wheel. However, none of these parts’ purpose and design is to change the aero characteristics.

The big question is whether it uses driver movement as a means to alter the characteristics or not. As we now know, the device is primarily activated by the brake torque (using a floating-type caliper), which means that it is, actually, not activated by the driver. However, the brake torque comes as a consequence of a driver putting his foot on the brake pedal. Although the device’s primary activating force is the brake torque, it would never become active if the driver hadn’t moved to press the brake pedal. One can see why some tend to argue that it is a driver-operated device. Let’s take this extreme scenario: Instead of the cylinders raising the push rod, they actually raise a winglet that is hidden in the car’s nose-cone (using the same brake torque as a means of power). In such a case, the winglet emerges and adds downforce at the front end at a crucial stage (during braking and cornering), i.e. at the time when more downforce and drag is actually needed. Wouldn’t that be a case of a driver-operated aerodynamic device?

I think it would be.

4. Paragraph 3.15 – “Aerodynamic Influence”

“With the exception of the driver adjustable bodywork described in Article 3.18 (in addition to minimal parts solely associated with its actuation) and the ducts described in Article 11.4, any specific part of the car influencing its aerodynamic performance: (…)

(…) – Must be rigidly secured to the entirely sprung part of the car (rigidly secured means not having any degree of freedom).”

If we accept that this device influences the aerodynamic performance of the car (which it does), then it possibly breaches that rule as well, since it is housed inside the brake ducts, it is therefore not rigidly secured on any part of the sprung part of the car. On the contrary, it enjoys the same degrees of freedom that the brake duct does. One could argue that this device is part of the duct, therefore it should be exempt according to the first sentence, however this is highly debatable. Although they are mounted inside the ducts, they are not part of the duct nor do they contribute in its operation / scope. They are there for entirely different reason than brake cooling.

5. Paragraph 10.3.4 – “Suspension members”

“Non-structural parts of suspension members are considered bodywork.”

I post this rule because I’ve seen several people arguing that the device cannot be considered “bodywork”, because it’s part of the suspension. Actually, the above rule makes it quite clear that, since it’s not part of the suspension members’ structure, it should be considered as bodywork, just like the brake ducts are considered bodywork (and not suspension) and fall under the bodywork rules in terms of dimensions.

6. Paragraph 10.3.5 – “Suspension members”

“Redundant suspension members are not allowed.”

If this device is considered to be part of the suspension, then it can be regarded as “redundant” because it doesn’t contribute in the suspension of the car. I remain of the opinion though that this device should be considered as bodywork, and therefore it’s hard to see anybody referring to this rule.

7. Paragraph 10.2.2 – “Suspension geometry”

“Any powered device which is capable of altering the configuration or affecting the performance of any part of the suspension system is forbidden.”

Another juicy one and it comes down to how you define “powered”. If by “powered” they mean externally powered by a source such as a battery or the car’s engine, then this device would not fall foul of this rule. If however the term “powered” is more general (which can be interpreted as such), then one can argue that the device is indeed powered by the brake torque and it’s not self-actuating (i.e. it’s not a rigid structure reacting to external forces such as a wing providing downforce, but it’s a mechanical device using moving parts who require some form of external power to operate).

In such a scenario, this device clearly alters the configuration of the suspension, since it raises the push rod (by extending its length), and it falls foul of the rule.

8. Paragraph 10.2.3 – “Suspension geometry”

“No adjustment may be made to the suspension system while the car is in motion.”

If you recall at the beginning of this post we talked about the pushrod being of telescopic design. This is necessary to allow the push rod to “raise” and thereby increase the ride height under braking. However, this is a clear adjustment of the suspension system which is being done while the car is in motion.

I’ve seen people argue that the suspension adjusts all the time (springs compressing, dampers going up and down, etc) but this is entirely different, because it’s not a result of the suspension reacting to the forces from the ground and the car; it’s rather an induced adjustment that includes the alteration of a suspension member’s length. It’s hard to see how one can argue that this device is not in breach of that specific rule.

As a brief conclusion, I am not amazed that the device was eventually banned. With so many rules in probable / possible breach of, it’s a small miracle it was allowed in the first place.

So, it’s banned after all…

Just like I had warned a while ago, when news started coming out that the FIA had approved the system, it turns out that the FIA have effectively banned its use and Lotus will be unable to even test the system during the first pre-season tests @ Jerez. The reason for banning it is not yet entirely clear, but we will get back to you on that as it unfolds.