InDetail: Force India Front Corner

Not everything in F1 is aggressive, extreme, radical or innovative. In fact in many areas the car’s are very close in general design terms. Some time it’s enough just to soak up the detail engineering and explain what all the little bits and pieces do on the car. In this series of short articles, we’ll do just that, thanks to these amazing photographs from MichaelD.
This is the front left corner of the VJM05, seen without the wheel to expose the brakes, suspension mounts, hub and electronics. Details vary from team to team, but what we see here is typical of most F1 cars, indeed some of the components are standard (electronics) or lightly modified by the supplier (brakes).

Brake Caliper

Dominating the picture is the brake caliper. This is supplied by AP Racing and will be designed around Force India requirements, albeit based on their current iteration of an F1 Caliper.
F1 Bake calipers must have no more than six pistons, two pads and two mounting points. The material is restricted by an 80Gpa stiffness requirement; aluminum lithium is most commonly used.
AP have a unique design of caliper for many Formulii, with their RadiCal (Radical Caliper) design. This being the way the inner and outer sections join via the complex bridge structure, to make it as stiff as possible. We can see the caliper is bridged in two places and a radial brace is also used. Keeping his area open is important for cooling the brake disc.
Cooling is also behind the structure around the pistons, the cylinders the six pistons within are nearly completely exposed, with just some links to the calipers structure and internal passageway to route the brake fluid. This allows the most airflow around the cylinderpiston to keep them cool. The pistons themselves are made in titanium and have a series of radial holes machined into them to also keep heat from getting into the brake fluid.
We can see the brake line entering the caliper at the bottom, having been routed through the lower wishbone. At the top of the caliper are the two bleed nipples, these allow bubbles trapped within the system to float up and be removed for better brake feel.
The carbon panel on the outer section of the caliper is either an aero piece or some protection for the caliper when the wheels are slammed back on during pitstops.

Discs and Pads

F1 moved to Carbon discs and pads in the eighties, having moved straight from Cast iron discs. Strangely ceramic discs have not been a development seen at races. Rules limit the diameter and thickness of discs, but no other regulatory restrictions are placed on these parts.
Disc and pad material varies according to their manufacturer (Carbon Industrie & Hitco). It is also tuned for each race and even for each driver. Additionally cooling patterns will vary from track to track, For Force India in Melbourne we can see the high density drillings, with three small drillings across the disc. With Melbourne being heavy on braking the pads are also drilled in attempt to keep the brake system cool. Brakes and pads wear at an equal rate, so the few millimeters gap in between disc surface and drillings is all the wear these parts will see, before catastrophic failure. As wear increases with temperature there are sensors measuring the disc surface temperature and also wear sensors for both the inner and outer pads.

Electronics
To monitor all the functions on the front corner, there will be an array of sensors fitted to the parts. These are all linked back to the main SECU, rather than cabling for each sensor passing through the wishbones to the cars main wiring loom, there is a hub fitted to the upright that collects all he signals and passes them back via a single cable. This Hub Interface Unit (HIU) is a common part supplied by MES to all the teams. It has inputs from the aforementioned Pad wear and disc temperatures sensors, as well as two wheel speed sensor (two in case one fails), also a load cell for measuring pushrod (or pullrod) loads.

Wishbone mounting


Although the aluminum upright can barely be seen beneath the brake ducts, the key function of the upright is joins the hub to the suspension. F1 does not use adjustable suspension in the same way as many racecars. That is with threaded adjusters, but instead solid suspension links are mounted the hard points with shims. These shims are used to alter the camber, ride height, pushrod offset and castor.
Teams are no longer aligning the track rod for steering with the FTWB. So often the track rod needs a separate lower mounting point on the upright. When adjusting camber, a different FTWB shim will alter the steering toe angle, so an additional shim needs to be fitted to the track rod clevis t maintain toe angle.
In this picture, we can see the upper clevis that mounts the front top wishbone (FTWB) and track rod. Force India have done this with the VJM05, but have still been able to join the FTWB and track rod to the same clevis assembly. This way camber can be adjusted with a single shim, rather than separate but matched shims for separate clevises.
We can also see the extremely high front lower wishbone position (FLWB); it’s nearly at the front axle height. Having wishbones spaced further apart is better for reducing the loads fed through them, but aerodynamics demand a higher position. We can’t see the outboard joint with the upright; neither can we see the outer pushrod joint. It’s probably that FIF1 mount these mount to the upright in a set up called ‘pushrod on upright’ (POU), this helps eight transfer with steering angle in slow corners.

 

Tech Files F1 : Technical side of F1

Tech Files F1 : Technical side of F1.

I am collaborating with Greek F1 site, GoCar.gr.  We are starting a series of features, that aim to explain F1 tech from the basics through to the detail of every system on the car;  Aero, Mechanical, Safety and Driver Equipment. 

We start with a simple view of the facts and figures and what we can see from the outside. Next we peel off the bodywork and explain some of the major mechanical parts.

For English click here : http://www.gocar.gr/en/races/f1-tech-files/t1,Technical_side_of_F1.html

Για Ελληνικά πατήστε εδώ : http://www.gocar.gr/gr/races/f1-tech-files/t1,Technical_side_of_F1.html

Mercedes AMG: Engine Build Challenge


During my visit to Mercedes AMG before Christmas, the company set us a challenge that’s been put to other more notable visitors. In the engine build area, two engines were arranged in each bay, but without the coil pack, heat shield and exhausts fitted. Our task was to fit these parts to one side of the engine, along with tightening each fastener to the correct torque setting. A dozen journalists attended the day, the challenge being made even greater as the two current Mercedes AMG drivers had also previously completed the challenge.

The coil pack is handed over and the challenge starts...

The first job was to fit the coil pack. The four-pronged carbonfibre cased unit is a press fit atop each spark plug, then the we needed to connect CAN electronics interface near the front of the airbox.

Next the heatshield goes on... (eventual challenge winner watching intently behind)

A small reflective coated carbonfibre heatshield goes over the coil pack, attached with three small bolts, one of which is smaller and requires a different torque setting.

Access to the 24 exhaust studs under the engine was surprisingly good

Then onto the exhaust system, weighing about 3kg each exhaust is hand made from thin sections of inconnel welded together. Although the 4-into-1 exhaust is one assembly, there is some play in the primary pipes joints with the collector, so fitting the four exhaust pipes to the studs on the engine requires a little fiddling. Each exhaust pipe bolts to the exhaust port with three nuts, two above and to the side of the exhaust pipe, and one centrally below.

A blur of hand movement gets each nut threaded on...

Each of these 24 nuts being tightened to the same torque setting. With the engine up on the stand and being able to kneel below the engine, getting access to each fastener was surprisingly easy, none of the exhaust pipes being particularly obstructive. I’m sure doing the same job with the engine in the car and the floor fitted is a very different story.

A quick check that each nut is torqued correctly and the job's done.

I completed the challenge in 4m 30s and I was satisfied I’d done a good job. However ex Racecar Engineering magazine editor, Charles Armstrong Wilson completed the challenge in an impressive 3m 30s! Even though one (un-named) journalist took as long a 7m 57s, as group us journalists were confident we’d done a good job. But the teams Drivers had soundly beaten us all. Nico Rosberg did the challenge in 3m 15s, while Michael Schumacher did it thee minutes dead!

The job of the F1 engine builder and mechanic is a difficult and skilled one, the skills of the F1 driver are ever impressive and I’ll stick to drawing racecars and not working on them!

Mercedes AMG: KERS development

One of Max Mosley’s lasting legacies in F1 was the introduction of his vision of a green initiative in F1. As a result KERS (Kinetic Energy Recovery System) was introduced 2009, as part of a greater package of rule changes to change the face of F1.
KERS is a system which harvests energy under braking and stores it to provide the driver with an extra power boost each lap. A simple technical summary of KERS is here (http://scarbsf1.wordpress.com/2010/10/20/kers-anatomy/ ).
During the 2009 season McLaren were applauded for running Mercedes KERS at every race and it was widely reported as the best KERS in use that year. Along with a few other journalists, I was invited along to Mercedes AMG Powertrains in Brixworth, UK to hear about KERS development since 2009. With Managing Director Thomas Fuhr and Engineering Director Andy Cowell giving a presentation on the range of work Mercedes AMG does with its F1 teams.

Mercedes AMG Powertrains reside on the site that was previously Mercedes Benz High Performance Engines (MBHPE). Now renamed to reflect the wider application of the groups knowledge, both to uses outside F1 and to areas other than engines. Powertrain is a catch all term covering; engine, transmission, electronics and of course KERS Hybrid systems.
The company have built a purpose designed Technology Centre on the site, which historically was the Ilmor engine plant and positioned just a few miles from Cosworth in Northampton. Clearly this area has a rich seam of Engine knowledge.
Formed around three buildings the entire F1 engine and KERS development is carried out on site, only specialist functions such as the casting of the crankcases is carried out off site. Additionally other Mercedes AMG work is carried out here, such as the AMG E-cell car.

KERS 2009
Mercedes AMG (MBHPE as it was known then) developed their first KERS for 2009 in house. At the time McLaren were the primary customer for the system, although Force India and at the last minute Brawn GP were also customer teams that year.  Force India had a chassis prepared to run KERS, but chose not to during the season.  Brawn had a chassis designed before their switch to Mercedes engines, so their car was not designed to accept the Mercedes KERS.

Mercedes AMG: 2009 Battery pack and water cooling radiator

In designing the system, Mercedes AMG had a specific requirement from McLaren. As the effectiveness of KERS was unknown, McLaren didn’t want to compromise the car if KERS was removed. So the system was packaged to fit into a largely conventional car. Whereas other KERS suppliers went for a battery position under the fuel tank, McLaren and Mercedes AMG placed theirs in the right hand sidepod. Low down and far forward, on the floor between the radiator and the side impact structures. The battery pack contains not only the array of individual cells, but also the pump and pipe work for its water cooling circuit. As well as the electronic interfaces for its control and monitoring. The assembly is around 7cm high, 12cm wide and 40cm long. The KBP is probably the single heaviest KERS component. In 2009 this sidepod package was acceptable as the teams were still on Bridgestone tyres and seeking an extremely forward weight distribution. Thus the 5cm higher mounting in the sidepod was offset by its forward placement.

2009 KERS and the batteries sidepod location relative to the engine

Conversely the smaller Power Control Unit (PCU) was placed in a similar location in the other sidepod, ironically the PCU is around the size and shape of road car battery. This left the monocoque uncompromised, aside from the smaller cut out for the MGU in the rear bulkhead.

The 2009 Zytek developed MGU

Then the Motor Generator Unit (MGU) is mounted to the front of the engine.  This device generates and creates the power for the KERS. Its driven from a small set of gears mounted to the front of the crankshaft.  the unit remains with the engien when the car is dismantled and is oil cooled along with the engine.

All of the components are linked both to the SECUs CAN bus and to each other by High Current Cable. The latter taking the DC current between the Batteries and MGU. With this packaging Mercedes AMG quotes the total system weight as 27kg.
Designed and developed by Mercedes AMG, but other partners were involved; the unique battery cells were supplied via A123 and the MGU was partnered with Zytek. Although the power control electronics were solely a Mercedes AMG in house development.
Through the 2009 season both McLaren drivers had a safe and reliable KERS at each race. The system was safe even after crashes and was fault free despite rain soaked races. Safety was designed in from the outset, all electrics were double insulated. Teams can also measure damage to the unit via accelerometers and insulation sensors, so any impact or incidental damage can be monitored and the car retired if the need arises. Additionally each cell in the battery has its temperature monitored. KERS batteries are sensitive to high and low temperatures, each cell needing to operate in a specific thermal window. Too low and the unit is inefficient and too hot and there’s the danger of explosion.
Perhaps the only criticism was the sidepod battery mounting, despite several incidents, this never put any one in danger, so this never proved to be an unsafe installation.

KERS 2011

2011_Mercedes_AMG_engine

For a variety of non technical reasons KERS was agreed not to be raced from 2010 until the planned 2013 rules. However this plan changed, but not before Mercedes AMG had made new strategic plans around KERS.
Mercedes AMG set out a longer term strategy to work on research for KERS in preparation for 2013, as well as working with AMG to develop the road car based E-cell technology.
(Link Mercedes AMG E-Cell chassis  )
This changed when the plans for the 2013 engine were pushed back to 2014 and KERS was agreed to be reintroduced for 2011. Thus the 2013 development plans had to rebased and deliver a refined version of the 2009 KERS for 2011. Moreover there were now three teams to be supplied with KERS. There was no Christmas for Mercedes AMG staff 2010!
As a result of the research work carried out after 2009, Mercedes AMG now solely design, develop and produce the entire KERS package, aside from the Battery cells. So now the MGU is a wholly Mercedes AMG part.

The MGU fits to the front of the engine and driven from a small set of gears

With KERS effectiveness proven in 2009, it was possible to have the cars designed around it, rather than it be an optional fitment. So the packaging was revised and the entire system integrated into just two units. The MGU remains attached to the front of the engine, still driven off a spur gear on the nose of the crankshaft. While the KBP and PCU are now integrated into a much smaller single package and fitted under the fuel tank. The unit bolts up inside a moulded recess under the monocoque, the unit being attached using four vibration mounts, and then a closing panel and the cars floorplank are fitted under it.

The 2009 battery pack (yellow) is now integrated with the power electronics (not shown) in a single unit under the fuel tank (red).

It’s this integration of the batteries and power electronics that has has really slimmed the 2011 system down. Mercedes AMG now quote 24kg the entire KERS, much of the 3kg weight loss being down to the reduction in the heavy power cabling between these units.
Not only is the packaging better, but the systems life and efficiency is too. Round trip efficiency stands at a stated 80%, which is the amount of power reapplied to the engine via the MGU after it has been harvested and stored. Improvements in efficiency being in both the charge and discharge phases.
Battery pack life was extended to as much as 10,000km, several times the 2009 predictions that batteries would need replacing every two races (2,400km). Over this period, the cells do not tend to degrade, as the team manage the unit’s condition (‘State of Charge’ & temperature) throughout the GP weekend to maintain their operational efficiency.
The 80hp boost KERS provides, stresses the engine. This was well known back in 2009, but for 2011 along with DRS the car can be several hundred revs higher than the usual EOS (end of straight) revs. Mercedes AMG quoted 15-25% more stress for a KERS and DRS aided lap, this needing to be taken into account when the team monitor the engines duty cycle, thus deciding when to replace it. Mercedes conducted additional dyno development of the engine being kept on the rev limiter to fully understand and counter this problem. This work paid benefits; Hamilton ran many laps at Monza bouncing off the rev limiter along the main straight, while chasing Vettel.

KERS in use
Although the max 60KW (~80hp) output can be reduced from the steering wheel, its normal for the driver to use the full 80hp boost each time they engage the KERS boost. With a reliable KERS, the driver will use the full 6s boost on every lap. Media reports suggest Red Bulls iteration of the Renault KERS does not use this full 60kw. Instead something like 44kw, providing less of a boost, but allowing smaller batteries to be used. The loss in boost being offset by the overall benefit in car packaging.
The driver engages a KERS boost either via a paddle or button on the steering wheel, or by the throttle pedal. The latter idea being a 2009 BMW Sauber development, where the driver pushes the pedal beyond its usual maximum travel to engage KERS. Nick Heidfeld brought this idea to Renault in 2011 and the over-extended pedal idea has also been used for DRS too.
Once the driver is no longer traction limited out of a turn, they can engage KERS. Usually a few small 1-2s boosts out of critical turns provides the ideal lap time. It’s the driver who has to control the duration of the boost, by whichever control. As with gear shift the drivers can be uncannily accurate in their apportioning of the boost around the lap. It’s suggested that the 2009 Ferrari system apportioned the duration of the KERS boost via a GPS map, the driver simply presses the button and the electronics gives them the predetermined amount of boost. This solution came as surprise to Andy Cowell, so one wonders if this is legal or perhaps if the report is true.
From on board shots, we’ve seen the steering wheel has an array of LEDs or numerical displays to show the driver the boost remaining for that lap. The SECU will have control code written to prevent overuse of KERS around a lap.
Typically the battery will hold more charge than a laps worth of harvestingdischarge. So that any unexpected incidents do not leave the driver without their 6s of boost.
In use KERS can be used in several different ways. When lapping alone KERS typically gains 0.45s per lap, although this varies slightly by track. Along with DRS is can boost top speed by 12kmh. As explained the driver uses a pre-agreed amount of boost, decided from simulation work done at the factory before the race. So the planned strategy of KERS usage will be used in practice, qualifying and in parts of the race. However in the race the driver can use KERS tactically to gain an advantage. Drivers are able to use more a KERS boost to either overtake or defend a position. One feature of 2011 along with the Pirelli tyres being in different condition during the race, was the driver’s freedom to alter their racing line and use their grip and KERS to tackle their rivals.

KERS future
KERS continues in its current guise for another two years, then for 2014 along with all new engine regulations there will be a new format KERS. Energy recovery will be from different sources, so the overriding term for the hybrid technology on the car will simply be ERS (Energy Recovery Systems). However KERS will still exist, harvesting energy from braking, but will have a greater allowance for energy stored and reapplied. But, there will also be TERS (Thermal Energy Recovery), which a MGU harvesting energy from the turbocharger. Overall ERS will provide a third of the engines power for some 30s of the lap. No longer will the driver press a button for their KERS boost, it will be integrated in their demand for power from the throttle pedal. The electronics will be constantly managing the Powertrains energy, harvesting and applying energy based on whether the driver is on or off the throttle. In 2014 Powertrains and ERS is set to become very complicated.

F1 2012: Rules, Designs and Trends

For 2012 we will have a raft of rules changes that will alter the look and performance of the car. For most of the new cars, we will immediately see the impact of the lower nose regulations. Then the big story of 2010-2011 of exhaust blown diffusers (EBDs) comes to an end with stringent exhaust placement rules and a further restriction on blown engine mappings.
Even without rule changes the pace of development marches on, as teams converge of a similar set of ideas to get the most from the car. This year, Rake, Front wings and clever suspensions will be the emerging trends. Sidepods will also be a big differentiator, as teams move the sidepod around to gain the best airflow to the rear of the car. There will also be the adoption of new structural solutions aimed to save weight and improve aero.
Last of all there might be the unexpected technical development, the ‘silver bullet’, the one idea we didn’t see coming. We’ve had the double diffuser and F-Duct in recent years, while exhaust blown diffusers have thrown up some new development directions. What idea it will be this year, is hard, if not impossible to predict. If not something completely new, then most likely an aggressive variation of the exhaust, sidepod or suspension ideas discussed below.

2012 noses

The most obvious rule change for 2012 is the lowering of the front of the nose cone. In recent years teams have tried to raise the entire front of the car in order to drive more airflow over the vanes and bargeboards below the nose. The cross section of the front bulkhead is defined by the FIA (275mm high & 300mm wide), but teams have exploited the radiuses that are allowed to be applied to the chassis edges, in order to make the entire cross section smaller. Both of these aims are obviously to drive better aero performance, despite the higher centre of Gravity (CofG) being a small a handicap, the better aero overcomes this to improve lap times.


A safety issue around these higher noses is that they were becoming higher than the mandatory head protection around the cockpit, in some areas this is as low as 55cm. It was possible that a high nose tip could easily pass over this area and strike the driver.

The front section of chassis will be as high as possible (at 62.5cm) and radiussed into a "V" shape

So now the area ahead of the front bulkhead must be lower than 55cm. However the monocoque behind this area can remain as high as 62.5cm. Thus in order to strive to retain the aero gains teams will keep a high chassis and then have the nose cone flattened up against this 55cm maximum height. Thus we will see these platypus noses, wide and flat in order to keep the area beneath deformable structure clear for better airflow. The radiussed chassis sides are still allowed so we will also see this 7.5cm step merged into the humps a top of the chassis.
Areas below and behind the nose are not allowed to have bodywork (shown yellow in the diagram), so small but aggressive vanes will have to be used, or a McLaren style snowplough. Both these devices drive airflow towards the leading edge of the underfloor for better diffuser performance.

New exhausts

Exhausts must be high up on the sidepod, so cannot blow the diffuser

Having used the engine via the exhausts to drive aerodynamic performance for the past two years, exhaust blown diffusers will be effectively banned in 2012. The exhausts must now sit in small allowable area, too high and far forward to direct the exhausts towards the diffuser. The exhausts must feature just two exits and no other openings in or out are allowed. The final 10cm of the exhaust must point rearwards and slightly up (between 10-30 degrees). Allied to the exhaust position, the system of using the engine to continue driving exhaust when the driver is off the throttle pedal has also been outlawed. Last year teams kept the engine throttles opened even when the driver lifted off the throttle for a corner. Then either allowing air to pass through the engine (cold blowing) or igniting some fuel along the way (hot blowing). The exhaust flow would remain a large proportion of the flow used when on the throttle, thus the engine was driving the aero, even when the driver wasn’t needing engine power. Now the throttle pedal position must map more closely the actual engine throttle position, thus if the driver is off the throttle pedal, then the engine throttles must be correspondingly closed.

Blown rear wing (BRW): The exhausts will blow upward to drive flow under the rear wing for more downforce

Teams will be faced with the obvious choice of blowing the exhausts upwards towards the rear wing, to gain a small aerodynamic advantage, when the driver is on the throttle. These Blown Rear Wings (BRWs) will be the conservative solution and certainly will be the first solution used in testing.
However, it’s possible to be aggressive with these exhaust designs too. One idea is blowing the rear wing with a much higher exhaust outlet; this would blow tangentially athte wing profile, which is more effective at increasing the flow under the wing for more downforce. Packaging these high exhausts may cause more problems than gains. But last year’s exhausts passing low and wide across the floor suffered a similar issue, but proved to be the optimum solution.

A more aggressive BRW raises the exhaust and blows tangentially under the wing profile, which is more efficient

Even more aggressive solution would be directing the exhausts onto the vanes allowed around the rear brake ducts. If avoiding the brake cooling inlet snorkel, the fast moving exhaust gas would produce downforce directly at the wheel, which is more efficient than wings mounted to the sprung part of the chassis. However the issue here would be the solution is likely to be so effective, that it will be sensitive to throttle position and rear ride height. If these issues can be engineered out, then this is an attractive solution.

An extreme but legal solution is to blow the exhaust on the rear brake duct fins creating downforce directly at the wheel.

Wing ride height and Rake
With rules setting a high front wing ride height and small diffusers, aero performance is limited. So teams have worked out how to work around these rules by angling the entire car into a nose down attitude. This is known as ‘Rake’, teams will run several degrees of rake to get the front wing lower and increase the effective height of the diffuser exit. Thus the front wing will sit closer to the track, than the 75mm when the car is parallel to the ground. While at the rear, the 12.5cm tall diffuser sits an additional 10cm clear of the track, making its expansion ratio greater. Teams were using the EBD, to seal this larger gap between the diffuser and the floor. Without the EBD teams will have to find alternative way to drive airflow into the gap to create a virtual skirt between the diffuser and track.
Furthermore teams have also allowed the front wing to flex downwards at speed to allow it to get closer to the ground, further improving its performance. Although meeting the FIA deflection tests, teams are allowing the wing bend and twist to position the endplate into a better orientation, either for sealing the wing to the ground or directing airflow towards the front tyres wake. Both creating downforce benefits at the front or rear of the car, respectively.
One issue with allowing the wing to ride closer to the ground through rake or flexing, is that at high speed or under braking (when the nose of the car dives), the front wing can be touching the ground. This is bad for both aero and for creating sparks, which will alert the authorities that the wing is not its normal position relative to the chassis. So teams are creating ways to manage front ride height. Traditionally front bump rubbers or heave springs will prevent excessively low ride heights. Also the front suspension geometry runs a degree of geometric anti-dive, to prevent the nose diving under braking.

Antidive geometry in the front suspension is one way to reduce pitch under braking

Last year we saw two additional solutions, interlinked suspension, where hydraulic suspension elements prevent nose dive under braking by displacing fluid in a hydraulic circuit one end of the car to the other end, creating a stiffer front suspension set up. This prevents dive under braking, while keeping a normally soft suspension for better grip.
We have also seen Lotus (nee LRGP) use torque reaction from the front brake callipers to extend the pushrod under braking, creating an anti-dive effect and prevent the nose dipping under braking.

An interpretation of the Lotus Antidive solution, using the brake caliper mounting to operate a hydraulic circuit and extend the pushrod (legally) under braking

These and probably other solutions will be seen in 2012 to maintain the ideal ride height under all conditions.

Front end

A three element endplate-less front wing

Towards the end of last year, front end aero design was converging into a set of similar ideas. Aside from the flexible wing option, already discussed above. The main direction was the use of a delta shaped threefour element wing, sporting no obvious endplate. The delta shape means that most of the wings downforce is created at the wing tip; this means less energy is taken from the airflow towards the inner span of the wing, which improves airflow at the rear of the car. Also the higher loading near the wing tip creates a stronger vortex, which drives airflow around the front tyre to reduce drag. Three wing elements are used, each being similar in chord length, rather than one large main plane and much smaller flaps. This spaces the slots between the elements out more equally, helping reduce airflow separation under the wing. More slots mean a more aggressive wing angle can be used without stalling. At the steepest outer section of wing, teams will mould a fourth slot in the flap to further manage airflow separation.
First introduced by Brawn in 2009, the endplate-less design is used as it’s more important to drive airflow out wide around the front tyre, than to purely maintain pressure difference above and below the wing. Rules demand a minimum amount of bodywork in this area, so vanes are used to both divert the airflow and meet the surface area regulations. This philosophy has now morphed into the concept, where the wing elements curl down to form the lower part of the endplate. Making the wing a homogenous 3D design, rather than flat wing elements and a separate vertical endplate.

Arched sections (yellow) of wing, help drive vortices to divert airflow along the car

A feature starting to emerge last year was arched sections of wing. Particularly near the mandatory neutral centre 50cm section of wing. These arched sections created elongated vortices, which are stronger and more focussed than tip vortices often used to control airflow. In 2012 many teams will create these unusual curved sections at the wings interface with the centre section.

Extending the front wing mounting pylons helps to make use of the middle 50cm of wing

Above this area, the pylon that mounts to the wing to the nosecone has been exploited to stretch he FIA maximum cross section to form the longest possible pylon. This forms the mounting pylon into endplates either side of the centre section of wing and along with the arched inner wing sections, help create the ideal airflow 25cm from the cars centreline (known as the Y250 axis).

Pointing a section of front wing profile at a suitable vane on the front brake ducts is one way gain aero performance.

In 2011 Mercedes GP used a section of the frotn wing to link up with the fins on the brake ducts, this created an extra long section of wing.  Vanes on the front brake ducts are increasingly influential on front wing performance and front tyre wake.
Mercedes GP also tried an innovative F-Duct front wing last year. This was not driver controlled, but rather speed (pressure) sensitive. Stalling the wing above 250kph, this allowed the flexing wing to unload and flex back upwards at speed, to prevent the wing grounding at speed. But the effect altered the cars balance at high speed, and the drivers reportedly didn’t like the effect on the handling. I’ve heard suggestions that the solution isn’t planned for 2012.

Sidepods
With so much of the car fixed within the regulation, it’s becoming the sidepods that are the main area of freedom for the designers. Last year we saw four main sidepod concepts; Conventional, Red Bull lowtapered, McLaren “U” shape and Toro Rosso’s undercut.
Each design has its own merits, depending on what the designer wants to do with the sidepods volume to get the air where they want it to flow.

An undercut in the sidepod is one way to drive good flow around the sidepod to the diffuser

This year I believe teams will want to direct as much airflow to the diffuser as possible, Red Bulls tiny sidepod works well in this regard, as does the more compromised Toro Rosso set up. Mclarens “U” pod concept might be compromised with the new exhaust rules and the desire to use a tail funnel cooling exit. However the concept could be retained with either; less of top channel or perhaps a far more aggressive interpretation creating more of an undercut.

Using a slight McLaren "U" shape to the sidepod may still work in 2012

Part and parcel of sidepod design is where the designer wants the cooling air to enter and exit the sidepod. To create a narrower tail to the sidepod and to have a continuous line of bodywork from sidepod to the gearbox, the cooling exit is placed above the sidepod, in a funnel formed in the upper part of the engine cover. Most teams have augmented this cooling outlet with small outlets aside the cockpit opening or at the very front of the sidepod.

The tail funnel (light yellow) is a good cooling outlet method, as it reduces the size of the coke bottle section of sidepod

To let more air into the sidepod, without having to create overly large inlets, teams will commonly use inlets in the roll hoop to feed gearbox or KERS coolers.

Other aero
Even without the exhaust blowing over the diffuser, its design will be critical in 2012.
As already mentioned the loss of the exhaust blowing will hurt the team’s ability to run high rear ride heights and thus a lot of rake. Unobstructed the EBDs exhaust plume, airflow will want to pass from the high pressure above the floor to the lower pressure beneath it. Equally the airflow blown sideways by the rear tyres (known as tyre squirt) will also interfere with the diffuser flow.

The Coved section of floor between the tyre and diffuser will be a key design in 2012, as will cold blown starter holes and trailing edge flaps

Before EBDs teams used a coved section of floor to pickup and accelerate some airflow from above the floor into the critical area between the diffuser and rear tyre. I predict we will see these shapes and similar devices to be used to keep the diffuser sealed at the sides.
Last year we saw teams aid the diffusers use of pulling air from beneath the car, by adding large flap around its trailing edge. So a high rear impact structure raised clear of the diffusers trailing edge will help teams fit these flaps around its entire periphery. Red Bull came up with a novel ideal by creating a duct feeding airflow to the starter motor hole; this improves airflow in the difficult centre section of the diffuser. Many teams will have this starter motor hole exposed by the raised crash structure, allowing airflow to naturally pass into the hole. However I expect some vanes or ducts to aid the flow in reaching this hole tucked down at the back of the car.

Tapered flaps and top mounted DRS pods will be a direction for 2012

DRS was a new technology last year. We soon saw teams start to converge on a short chord flap and a high mounted hydraulic actuator pod. DRS allows the rear wing flap to open a gap of upto 50mm from the main plane below it. A smaller flap flattens out more completely with this 50mm gap, reducing drag more effectively than a larger flap.
As drag is created largely at the wing tips, I would not be surprised to see tapered flaps that flatten out at the wing tip and retain some downforce in the centre section. Teams may use the Pod for housing the actuators, although Mercedes succeeded with actuators hidden in the endplates. Having the pod above the wing clears the harder working lower surface, thus we will probably not see many support struts obstructing the wing.

Structures

Variations on William low line gearbox and differential will be followed for this year

Super slim gearboxes have been in vogue for many years, Last year Williams upped the stakes with a super low gearbox. The normally empty structure above the gear cluster was removed and the rear suspension mounted to the rear wing pillar. Williams have this design again for 2012, albeit made somewhat lighter. With the mandatory rear biased weight distribution the weight penalty for this design is not a compromise, while the improved air flow the wing is especially useful in 2012. So it’s likely the new cars will follow the low gearbox and low differential mounting in some form.

Rear pull rod suspension will be all but universal this year

A lot is said about Pull rod rear suspension being critical for success. In 2011 only a few teams retained push rod rear suspension (Ferrari and Marussia). I would say the benefits between the two systems are small; pushrod trades a higher CofG for more space and access to the increasingly complex spring and damper hardware. Whereas pull rod benefits from a more aerodynamically compact set up and a lower CofG. I still believe either system works well, if packaged correctly.
At the front it’s unlikely pull rod will be adopted. Largely because the high chassis would place a pull rod at too shallow an angle to work efficiently. Regardless the minimum cross section of the footwell area, discounts any potential aero benefits. Leaving just a small CofG benefit as a driver to adopt this format.

Undercut roll hoops with internal metal reinforcement will be a common feature to drive airflow to the rear wing

Most teams now use a metal structure to provide strength inside the roll hoop; this allows teams to undercut the roll hoop for better airflow to the rear wing. Even though last year two teams followed Mercedes 2009 blade type roll hoop, for Caterham at least, this isn’t expected to return this year. Leaving the question if Force India will retain this design?

Electronics and control systems
The 2012 technical regulations included a large number of quite complex and specific rules regarding systems controlling the engine, clutch and gearbox. It transpires that these are simply previous technical directives being rolled up into the main package of regulations. Only the aforementioned throttle pedal maps being a new regulation to combat hot and cold blowing.


While I still try to crack that deal to make this my full time job, I do this blog and my twitter feed as an aside to my day job. In the next few weeks I plan to attend the launches and pre-season tests. If you appreciate my work, can I kindly ask you to consider a ‘donation’ to support my travel costs.

Lotus Renault GP: Fluid Inerter

Lotus Renault GP (LRGP) have been on one of the teams most innovative with their suspension over the past decade. As RenaultF1 They introduced the Tuned Mass Damper (TMD) back in 2006 and have since raced conventional Inerters. Inerters are a special component in the suspension to counteract spring effect of the TyresSuspension, using a spinning mass on a threaded rod to control these loads.

LRGP have also been one of the teams racing hydraulically interlinked suspension and have looked at other ways to legally alter the suspensions performance. It seems this work has lead to the discovery of a new form of Inerter, primarily using fluid for the Inerter effect. This new development has been termed by the team a “Fluid Inerter”.

A cross section of the patented Fluid Inerter

The intellectual property rights to this development have been safeguarded by Patent, allowing the details to be freely accessible in the pubic domain (the source for the picture at the top of this article). My attention was drawn to this development by Italian Mechanical Engineer Rodolfo De Vita, a specialist in Torsional Dampers and Dual Mass Flywheels (DMF).

Background
Becoming ever more complex the suspension in an F1 car has a number of devices to counter loads fed into the chassis, in order to maintain the ideal conditions at the tyre contact patch. We understand the role of springs and dampers, but there remain other spring effects within the suspension system, not least from the high profile tyres. Their spring effect goes undamped and hence is largely out of the control of the teams in setting up the car. Being able to counteract these uncontrolled forces in a suspension will allow the tyre to main better contact with the ground for more consistent grip. In 2003 Cambridge Universities, Dr Malcolm Smith proposed a mechanical method of controlling these loads via the Inerter. McLaren took up this idea and tested the idea in 2004 then went on to race an Inerter in 2005.
In size and construction the Inerter looks like any other damper. Being placed in the same position as a Heave Damper it was well hidden and unknown to most people. Until the “Spygate” saga in 2007, when the design was referenced as both the “J-Damper” and “a Damper with a Spinning Mass”. It wasn’t until May 2008 that I was able to understand and expose the details of the Inerter concept, publishing its details in Autosport.com (subscribers only http://www.autosport.com/journal/article.php/id/1554 ). Co-incidentally this article is cited in the patent documentation!

A Mechanical Interter

An Inerter can be configured in two ways: a linear and a rotary format. In both guises the device uses a toothed drive to spin a mass. Likened to the same effect as a bicycle bell, the load fed into the bells lever is dissipated by the spinning element. In F1 teams use a cylindrical mass screwed onto a threaded rod inside a damper body. One end of the rod is affixed to one side of the suspension and the damper body to the other side of the suspension. Reacting to the acceleration of the suspension, the Inerter absorbs the loads that would otherwise not be controlled by the velocity sensitive conventional dampers.

The Renault 2006 Front Tuned Mass Damper (TMD) - Copyight: Craig Scarborough

The Inerter predates Renaults TMD, which aimed to achieve the same effect. With the TMD a weight is suspended on spring to offset the same forces being fed into the chassis as the Inerter. Renault first raced the TMD in 2005, its discovery by Giorgio Piola around Monaco of that year; both forced a development race and an enquiry by the FIA. It was subsequently banned on what proved to be false grounds. The FIA citing a movable aerodynamic effect as the reason for its ban.
Unaware of its effect on the contact patch, I initially saw the device as a means to prevent the front wing pitching downwards when braking. The inertia of the suspended mass keeping the nose from pitching downwards during the initial braking phase. This I thought would prevent the car from being pitch sensitive. Despite a lengthy court room case, this “aero” function was upheld as the reason for the ban of the device.
Ironically the McLaren was using the Inerter at the time, and despite it being used for the same function was not banned and remains legal and in universal use to this day.

LRGP’s Fluid Inerter Concept
Reading the detail of the LRGP patent, it’s clear this was at least partly a surprise discovery. The Patent states the discovery was “based on lab testing of another hydraulic suspension device”, when it was found that the effect of the fluid within the system “has a very significant inertia effect”.
I would suspect this discovery was made during the development of the linked suspension system. Where fluid lines are used to link the suspension in a similar manner to the Mercedes system I detailed earlier this year (http://scarbsf1.wordpress.com/2011/10/17/mercedes-innovative-linked-rear-suspension/). Perhaps the longer fluid lines to link front and rear suspension provided the discovery, rather than the very short left to right linking pipework. I understand Renault have had hydraulically linked suspension on the car since at least 2009.
With this insight LRGP have proposed a Fluid Inerter using both the inertia of the fluid and a spinning mass. By making the Inerter device more like a damper, where by a damper rod displaces fluid; this fluid is then piped into a circuit to spin the mass. There by both effects can be created. It is the inertance of the fluid that differentiates the LRGP patent to the conventional Inerter proposed by Dr Malcolm Smith.
Inertance is a new term and I’ll quote the patent for LRGP’s explanation of the effect.
“Hydraulic fluid inertance means” concerns an arrangement in which the presence of a hydraulic fluid provides an inertance, where inertance is a measure of the fluid pressure which is required to bring about a change in fluid flow rate in a system. Between the terminals this translates to an inertial force which resists acceleration.
LRGP found that the fluid used was critical to the efficiency of the design. In particular to make it effective for the lightweight and small packaging volume required to make the device work within the tight confines of an F1 footwell or gearbox. Needing to be incompressible and low viscosity, they have proposed several fluids, such as water and oil, but the preference appears to be for Mercury. Although a metal, it’s liquid at ambient temperatures and very dense. This means smaller fluid lines filled with mercury will provide the necessary inertance, compared to larger amounts of less dense fluids. Passing from one chamber in the damper body via the fluid line to the other chamber, the detail design of the length and diameter of the fluid lines are key in creating the correct tuned inertance effect. Just “1 to 50g” of fluid is required to get the desired effect. The range of inertial reaction is quoted as “10 to 500kg, which is a typical range required in Formula One racing cars”.
As a side note McLaren decouple this inertial reaction force into different measured units. Rather than Kg of Inertial force, McLaren use the term “Zog”, this allows them to hide the actual units set up on their Inerter.
Renault suggests winding the lines around the damper body as one solution for the packaging of the fluid circuit. Additionally a valve or shim stack in the damper rod would also alter the amount of fluid displaced, to further tailor the Inerters effect.
With Mercury having a high coefficient of thermal expansion, the patent suggests using a relief valve emptying into another chamber is used to ensure the system has a constant volume of fluid.
Clearly the emphasis is on the fluid to provide the inertance effect, the patent citing a minimum 50%, up to as much as 90% of the inertance coming from the fluid.

In Detail

The device uses the left hand casing as the fluid cylinder & the right hand casing for bump rubbers

Not only does the Patent contain the conceptual information on the Inerter, but also detailed cross sections. I have simplified these to explain the Inerters construction. LRGP have been able to condense the entire solution into a single self contained component, which fits into the same volume as the conventional Inerter.
The device is made up of a main body and a damper rod. The main body split into left and right sections bolted together. The left hand casing forms the cylinder, not only contains the fluid, but also channels machined in the outer casing form the fluid lines. Such that no external pipework is required. The right hand casing allows the damper rod to pass through and also houses bump stops to prevent the device bottoming at the end of its 16mm of bump travel or 23mm of droop travel. In total the device is just 220mm long (eye to eye).
In cross section we can see the casing is a complex machined part. With the right hand chamber formed with bushes, seals and endplates to create the cylinder for the damper rods to pass through. The damper rod along with its shim stack valve pass through the cylinder like piston as the suspension compresses and rebounds. The mercury within is displaced and passes through channels into the channels machined into the wall of the body.

Installation

The Inerter (yellow) is mounted between the rockers

LRGP provide a diagram for the Inerters mounting. This being a typical position between the pushrod rockers. No doubt a similar mounting is found between the rear pull rod rockers. Externally it would be hard distinguish the Fluid Inerter from a Mechanical version. Albeit the Renault front bulkhead design shows almost nothing of the Inerter inside the footwell. The steering rack and anti roll bar getting in the way of the small aperture inside the front of the monocoque. Thus we cannot be clear if the device has raced.

Benefits
One benefit is the technology is proprietary to LRGP and not used under license via Penske or Dr Malcolm Smith. Thus LRGP are free to use and develop this technology freely.
I couldn’t state whether the Fluid Inerter has any compliance benefits over a mechanical one. Perhaps it’s easier to tune via the shim stack in the damper rod, rather than the fixed specification of the mechanical Inerter. Equally it may be easier to maintain, teams needing to strip clean and re-grease their Mechanical Inerters frequently to maintain their smooth operation.
It seems one advantage to this device might be lightweight. The tiny amount of fluid required would be lighter than an equivalent spinning mass. As Inerters tend to be mounted relatively high a weight saving will aid CofG height, as well as ballast placement.
One negative issue is that Mercury is a hazardous material. Considering the unit is positioned ahead of the driver’s legs, any mercury leakage as a result of a major accident will only complicate the health issues for the Driver and Marshalls. I am not aware of Mercury being specifically restricted by the FIA approved material list. Although with just a few CC’s of the liquid contained within the cylinder, this might not be regarded as an issue by the FIA.

Conclusion
However the team came across this solution, it is a new direction for Inerter development. The solution is totally legal, as set by the precedent of the mechanical Inerter being allowed to race, even when the TMD wasn’t
It will be interesting other teams come forward with new Inerter or linked suspension solutions. The only problem is few teams patent their design to allow us such insight to their design.

A view of the outer casing

A cross section of the Inerter

An exploded view of the parts

More references on Inerters

http://www.montefiore.ulg.ac.be/doc/smith09.pdf

http://www.ieeecss.org/sites/ieeecss.org/files/documents/IoCT-Part2-14FormulaOne-HR.pdf

Analysis: Rotary Dampers

The Rotary damper has been an innovation that has recently come and gone in F1. Typically F1 cars use Lineartelescopic dampers. However, in 2003 Sachs Race Engineering developed a Rotary version of a classic monotube damper for Ferrari. This was a tidier solution for packaging the dampers at the rear of the car. Since 2003 several teams have used Rotary dampers, Toyota, Midland and most notably Brawn GP. Who won the 2009 championship with these fitted at the rear of the car. I have recently come across a Rotary damper as fitted to the Midland car in 2006 and thus we have the chance to look into the detail of this development. I’ve also been in touch with two of the designers who have raced this device and they have given us some unique insight into its use.

Firstly John McQuilliam, who is now Designer for Marussia, but back in 2006, was the designer for Midland F1 (previously Jordan, latterly Spyker and Force India). The Midland M16 was the first of the teams’ cars to exploit Rotary dampers, as McQuilliam explains “I remember we were working with Sachs, as we had their Clutches on the car at the time. The Ferrari had Rotary dampers and it looked to be such a neat installation, we wanted to do something similar “. But this was not a total success, as their use on the Midland was short lived as they were replaced mid season with Linear dampers.

Secondly we have insight from the ex-Brawn Designer Jorg Zander, now running his own consultancy (http://jz-engineering.com/). As Honda were leaving F1 and the Brawn GP team was created, due to the Honda link the team had been using Japanese Showa dampers, but Zander was persuaded to switch to a Rotary design. As Zander recalls “Showa did a brilliant job and they would have provided us with continued support, but my boss was keen to go down the Rotary damper path with Sachs”. He adds that “the car still won the championship!”. Along with the Ferrari wins during their use of the Sachs Rotary damper, it’s clear that the technology has had a lot of success in F1. But it is still blighted by a reputation of being a troublesome technology.

Linear dampers
A conventional Linear damper is made up from a cylindrical body in which a damper rod slides in and out of (much like a bicycle pump). A valve at the end of the damper rod passes through the inside of the cylinder which is filled damper oil and the oil passing through the vales controls the rate of movement of the damper. Being cylindrical it is easy to machine in a lathe and oil is kept in place with simple circular seals.
The Dampers are installed on the car by one end being secured to the gearbox case, the other end to a rocker which re-orientates the movement from the pushrod into the movement of the damper. The rocker can be made up of several levers splined to a single shaft and requires several bearings to make the suspension movement friction free. This amasses into quite a lot of separate components which all need space to fit in.

Rotary Damper Anatomy

A top view of the Rotary Damper

Essentially the Rotary damper rotates the axial movement of the Linear damper into a Rotary movement. All the components have the same function, they just move in a different orientation. Thus the damper body is deep “keyhole” shape and the damper rod (known as the vane) rotates in the body, the vanes arm sweeping through a small angular rotation in the keystone section of damper body. The damping valves are placed in the face of the damper vane and work in exactly the same manner as a Linear damper.

Obviously the shape is the biggest difference and manufacturing the damper is far harder due to the fact that the parts have to be CNC milled and not spun in a lathe.

Its clear to see how the Vane moves inside the Casing to provide the Damping effect

Damper body

A view inside the cavity of the Damper Body

We can see the damper body is a robust metal housing machined from solid. Open on one side to allow the damper vane to be installed, there is a closing plate sealed with an “O” ring and 13 small bolts. To allow the damper vane to pivot the body features two bearings and seal arrangements, one on the closing plate the other is the main housing.

Damper body closing plate, with integrated Anti Roll Bar link mounting

As the housing also acts the suspension rocker, there are also elements machined into its outer face to accommodate this function. Firstly the housing acts as the rocker linkage, so a rocker arm is part of the machined shape. One of these eyes in the rocker will mount the heave damper and the other eye has bearing to accept the pushrod. Showing the packaging efficiency of the Rotary damper a further spherical bearing is fitted to a machined section of the cover plate. This accepts the Anti Roll Bar linkage. Thus for the Midland, no further suspension elements need to be fitted to anything but the damper housing. In the case of the all F1 Rotary dampers, the damper body rotates and the damper rod is fixed to the gearbox (via splines). As one part moves and the remains static, the vane moves through the oil filled cavity, the reaction force of these two parts creates the damping effect. To allow the damper body to rotate in the gearbox, two bearing surfaces are machined into the outer face of the housing and cover plate.


One additional external feature is machined into the damper body, a single damper valve. I believe this is a valve to compensate for the effect of heat on the volume of oil inside the casing. The valve offsets the thermal expansion of the oil to ensure there is a constant volume of oil within the damper cavity.

Damper vane

DLC coated Damper vane, the damping valve being bolted into the face of the arm

Inside the damper body sits the damper vane. This is a highly finished and possibly DLC coated component. Even when degreased this part had the feel of a lightly oiled component. The friction reducing coating being there to reduce the friction created by the vane moving inside the housing. Again machined (as most F1 parts are) from solid, the damper vane is formed of two shapes.
Firstly, the spindle that sits in the bearings that allows the arm to the rotate. One end of this spindle has splines machined into it.
Then secondly a flat plate shape is formed into the vane, this is the equivalent of the Linear dampers damping rod. This arm needs to be a close fit to the damper cavity in order to accurately control oil for the damping effect. It’s the edges of this arm that need to be sealed against the housing. A single square edged seal is fitted into a machined groove around the periphery of the vane. There are also four friction reducing pads (two on each side) to aid the movement of the vane against the body.

The three sides of the vane have a seal and friction reducing pads

Providing the damping effect the damper valve is a simply circular shim stack arrangement fitted to hole machined into the vanes face. This valve set up is almost identical to the set up used on the end of a Linear damper. This is perhaps the only aspect of the Rotary damper that directly echoes a Linear set up.

Installation

When installed on the gearbox the damper is clearly visible

As already alluded to, the Rotary damper is fitted to the gearbox casing and forms both the damper and the rocker. The damper vane slides into splines machined into the gearbox casing and a bearing locates on the bearing surface of the cover plate. Then another bracket fits to the rear of the gearbox to locate the rear bearing and secure the damper in place. The torsion bar passes through the damper engaging in splined in the spindle of the damper vane and also on the front face of the gearbox. Splines on the protruding section of the damper body are probably for the preload adjuster arm.

The Heave Spring and Anti Roll Bar are also mounted direct to the Damper

The pushrod passing up from the lower wishbone fits to the rocker, as does the heave springdamper which sits over the top of the damper to attach to the other side damper. One end of the anti roll bar attaches to each spherical bearing and then the installation is complete.

Pros and Cons of Rotary Dampers
As explained the main benefit is the packaging of these units. Typically Linear dampers are operated by rockers and the dampers are then either laid across the top of the gearbox or sit vertically (requiring a recess in the top of the gearbox case). Either option carries complications in the cars structure or aero. With a Rotary damper the unit forms both the rocker and the damper and takes up far less volume.

As the damper vane permanently sits inside the casing, as the vane sweeps through the radial movement, no oil displaced. This is described a constant volume system. Unlike a monotube damper where the damper rod displaces fluid inside the damper body. This requires a method to offset the movement of the excess fluid. Typically separate nitrogen charged cylinder is used, the gas is compressed by the displaced fluid. But this in itself creates a small spring effect inside the damper. Other methods include the though rod damper, whereby the damper rod passes through both ends of the damper body, thus displacing no fluid. However through rod dampers do require additional seals and this creates some additional friction in the design.

Other key benefits of the simpler Rotary design are weight reduction, with fewer parts the 950g damper with its integrated rocker is lighter than a conventional damper and separate rocker set up. John McQuilliam confirms “We did achieve a weight saving over the conventional layout when you consider the damper, its drive arm and reaction bracket.” McQuilliam goes to on to highlight its packaging and resultant aero benefits “also the packaging is easier, without finding a volume for the damper. Akio Haga who is now alternating chief designer at Force India was laying out the rear suspension back then and we had a few different lay outs, mainly to try and keep the mechanicals out of which ever area the Aero was telling us was most important”.
With there being less parts to be splined together and less bearings in the Rotary design is also stiffer and suffers much less from slop. Jorg Zander explains “the good side of the Rotary damper is that because of the rocker integration, the system is very stiff and direct, so there is little losses due to backlash in linkages, ball joints, etc. which meant it had a good high frequency response”.

So with the damper being a constant volume design, structurally stiff, lightweight and easy to package why has it not become the norm for F1 suspensions?

There is a simplistic argument bandied about that the damping effect is the reason they do not work so well. Neither designer suggested this was the case to me, although at the time McQuilliam did suggest to me it was a factor, but corrected himself with hindsight “I think the damping was actually reasonable”. McQuilliam continues to highlight a more specific deficiency in the Rotary design, “there is a much more complicated sealing arrangement in the damper, adding stiction”. Stiction is one of the enemies of the suspension designer, a mix of terms meaning “sticky” “friction”. This is seen as initial friction, then smoother running. This non Linearity of response is hard to design out. Where as the inherent spring rate added by a gas charged damper can be considered in the overall suspension spring rate, stiction cannot. Zander also echoes this issue “However, the downside is that due to the high internal pressure, the hydraulic seals had to have reasonable preload, which induced a large amount of friction and hysteresis”. This internal pressure also lead to structural issues, the Ex Brawn designer tells me “the high internal pressures caused local deformation of the housing, as well as the vane, this lead to increased friction and pretty inconsistent damping characteristics. Initial developments started with Aluminium, then Ti and steel options to gain stiffness to reduce the issues caused due to deformation. The Midland Damper that I have appears to be titanium. This was an earlier design compared to the Sachs dampers run on the Brawn in 2009. It is possible to see the ribs machined in to the casing to reinforce the device from deformation.

Another argument quoted in the press is the small size of the damper, which results in a lack of oil or radial movement. I removed some 75cc of fluid from the damper and the damping chamber was quite large. The limited radial movement was not seen to be a major problem, being taken into account in the rocker sizing, although both designers point out it still had to be factored in. Zander explains “The angular displacement wasn’t so much of an issue in 2009 and in previous years, but with the heavier fuel loads from 2010 that should be something to be considered.” Seeing as the 2009 Brawn BGP001 was succeeded by the Mercedes W01, it’s interesting to note the latter went back to Linear dampers.

Away from the technical argument of Rotary over Linear there was one other factor which perhaps underlines the less publicised aspect of the designers’ role, budgets! But when we recall that Midland and Brawn were both teams managing a tight budget, this last issue makes sense. Both designers highlighted price as one of the major issues of the Rotary damper. McQuilliam starting by saying “They were mighty expensive, so not good value for money for the weight saving”. Zanders more recent recollection of the Brawn days provides this insight “I think a bigger argument against it for some teams, were the cost of such a Rotary damper. Depending on the specification, it was in the region of about €15.000 per piece”. With these being sealed dampers for each set up, a pair of dampers (€30,000) would be on the car and a multitude of other dampers pairs in the pits, each set up for different damping characteristics.

Conclusion
Clearly the stiction and internal stiffness issues need to be addressed with the design. Evolution via detail design has overcome similar issues with Linear dampers, so presumably the same could be resolved for Rotary dampers too.
The cost issue still remains; inherently they are a complex and high precision part. Where as turning on a lathe produces the correct finish for a Linear damper, careful milling operations are required for the damper body of the Rotary damper, which will inevitably make this an expensive part to produce. No doubt more teams using the damper would drive the price down.
It’s interesting to note that the Sachs Race Engineering website no longer details Rotary dampers as part of their range. Instead conventional Linear dampers and a Through-Rod version of the same, form the basis of their product range and their current Formula1 teams use these Linear format dampers.
Given the choice between Rotary and Linear, Zander sums up the decision well “I would at the current stage of damper technology development prefer Linear dampers over Rotary ones. The friction can be controlled in a better way and problems like cavitation are well understood and do not cause any issues in contemporary Linear damper designs. Also the flexibility with Linear damper designs is much wider, considering systems like: frequency depending damping, high & low speed damping, drop off characteristics (blow by valves, pressure relief valves)”.
Perhaps the Rotary damper will be explored in F1 again at some point, but for now the Linear damper is the sole solution in F1.

Front Anti Roll Bar Solutions

An excellent Sutton Images picture seen on F1Talks.pl, taken through the aperture on the front of the McLaren has given us a rare chance to see the set up of the front suspension.

(http://www.f1talks.pl/2011/08/25/czwartek-na-spa/?pid=4590).

Typically most teams follow the same set up for the front suspension in terms of the placement of the rockers, torsion bars, dampers anti roll bars and heave elements. As unlike with rear suspension, the raised front end almost dictates a pushrod set up in order to the get the correct installation angle of the pushrod. However the McLaren antiroll bar shows there is some variation in comparison to the norm and also highlights Ferraris similar thinking in this area.

In comparison to my more recent posts, this is not a breakthrough in design, simply a chance to see the teams playing with packaging to achieve similar aims.

Typical front suspension

As an overview of the conventional of the rocker assembly in the attached diagram shows the rockers are operated by the pushrod, a lever formed by the rocker operates each of the suspension elements. Compressing the heave spring and wheel dampers, extending the inerter and twisting the torsion bars.

A typical "U" shaped ARB: Arms connect the torsion bar to the rockers via drop links

Typically teams use a “U” shape anti roll bar (ARB). In this set up the antiroll bar is connected to the rocker via drop links, and then each arm twists the torsion bar when the car is in roll. When the car is in heave (car going up and down, no roll) the ARB simply rotates in its mounts and adds no stiffness to the suspension. Different torsion bars in the anti roll bar create different roll stiffness rates for the suspension. Teams will either switch the entire ARB assembly for a different rate ARB. Red Bull have engineered their ARB for the torsion bar to be removed transversely through the side of the monocoque, in a similar fashion to removing the normal torsion bars.
However McLaren and Ferrari have gone a slightly different route.

Mclarens ARB

McLarens ARB is formed of two blades joined by a drop link

In McLarens case their ARB is a simple blade type arrangement. These blades are splined to each rocker the blades are joined at their ends by bearings and a drop link.

In roll, the blades react against each to create roll stiffness

When in roll the rockers rotate in the same direction, one blade goes down and the other goes up, the stiff drop link transfers these opposing forces and the blades flex. These opposing forces add stiffness to the front suspension in roll.

In heave, the blades move together

In heave the rockers rotate in different directions, both blades move down and the increasing gap between their ends is taken up by the drop link. So the blades do not flex and do not contribute to heave stiffness.
Different thickness blades create different roll stiffness; they must be removed from the rockers and replaced to achieve this.

Ferraris ARB

Ferraris ARB uses two blades joined by an elegant arched guide

Ferrari have used this solution at least since the late nineties, the idea has been seen on older Minardis too. I suspect the idea was taken to Minardi by Gustav Brunner, who may also be the creator of this elegant solution.
Similar to McLaren the roll stiffness is provided by blades splined to the rockers. But the connecting mechanism is instead a single bearing sliding inside an arched guide. Just as with McLaren ARB, when in roll the two ends push against each other to create the reaction force to prevent roll. When in heave the bearing slides through the arc of the guide and no force is passed into the suspension.

Summary
I don’t believe either of these solutions has a compliance benefit over the other. The McLarenFerrari systems may be take up a little less space inside the nose and may weigh a little less. But both will be a little more complex when changing the roll stiffness.

Assemblies

A legal but flexible T-Tray Splitter: The ‘See-Saw’ solution

For over a decade, the FIA have tried to reduce front wing performance by increasing its ride height. Moving the wing clear of the track for less “ground effect”, reduces the wings efficiency and handicaps downforce. When the major aero rules changes came in for 2009, the loss of the central spoon section and the smaller allowable working surfaces for the front wing, made getting downforce from it even harder.
Through out this period, teams have sought to gain front wing performance, largely by trying to make the wing closer to the ground. Either via flex or by altering the attitude of the car (i.e. rake). As has been explained before in this blog, the issue with making the front wing lower by raking the car is that the T-Tray splitter gets in the way. Teams have sought to make the splitter flexible to allow it move up and allow for a lower front wing.
to combat this the FIA have a deflection test to ensure the splitters are not flexing and that front wing ride height is maintained. In response to accusations about several teams splitters, at Monza last year the FIA doubled the test to 5mm of movement for a 2000 Newton (~200kg) load. Yet in 2011 we still see cars with a nose-down raked attitude and wings nearly scraping the ground. How can a splitter meet the FIA deflection and still flex on track? I have a theory for a splitter construction, that actually exploits the method of the FIA test to provide the splitter greater stiffness during the test.

Background
Typically teams run splitters mounted to the underside of the monocoque. The splitter is often made from metal to act as ballast, with additional carbon fibre bodywork to form the aero surfaces. Beneath the splitter runs the Skid block (plank). Made to FIA dimensions the plank features holes for measuring wear.
The splitter is bolted securely to the underside of the tub by bolts and in some cases with a small strut at the leading to aid installation stiffness. Disregarding the strut, the splitter is effectively installed in a cantilever arrangement. The protruding section of splitter will need to bend upward when grounding on track or on the FIA test rig.

With a typical splitter, wear will occur only at the leading edge of the plank

With a car in a raked attitude, when on track the splitter will exhibit a classic wear pattern, the tip of the splitter will wear away in a wedge shape roughly equivalent to the rake angle of the car. During normal running, for cars with high rake angles its likely no other wear may take place along the length of the plank. If the car runs a front ride height that’s too low, the splitter will wear away leading to exclusion at post race scrutineering.

See-Saw Solution

A pivot half way along the splitter creates a 'see saw' effect

Rather than run a cantilever mounted splitter, my theory would be to run the splitter mounted on a pivot. Taking the length of the removable section of splitter, the pivot woudl need to be half way along its length. Which would be roughly inline with the heel of the monocoque. Not having any significant mount at the rear of the removable section of splitter would allow the splitter to pivot like a ‘see saw’.

With the 'see saw' splitter, grounding on track will bend the plank & create two wear spots.

Now when the splitter grounds on track, the leading edge will tilt up and the trailing edge tilt down. This ‘See-Saw’ effect, will allow a slightly lower front ride height as the splitter will be deflecting upwards. To achieve this the plank will need to flex, as the front section of plank must now be a minimum of 1m long, far longer than the splitter. The drooping trailing edge of the splitter will now make the plank contact the ground, leading to a distinctive wear pattern. Now having plank wear in two placed, beneath the splitters leading edge and the trailing edge. This will also have the benefit of spreading the wear over a larger area of plank and reducing the likely hood that the front inspection hole will be excessively worn. The fulcrum point need not be the overtly obvious pivot I have drawn and the entire exterior of the splitter could be covered in bodywork, which will have enough strength to keep the splitter in place when stationery, but deform enough to allow the splitter to ‘see-saw’. But in this guise the splitter will not have the strength to meet the 200kg load from the FIA test.  so how will it pass the test?

The current format of the FIA test, actually aids the pivoted splitter.

The FIA test is carried out on the multi functional rig that is used for the other regulatory checks. The car is driven up onto the rig and then steel pins protruding up from the rig, locate in corresponding holes in the plank. The sections of floor under the wheel are dropped away and the cars ~580kg (640Kg less driver) weight sits on its belly (the plankreference plane floor).
Then a hydraulic strut with load and displacement sensors extends upwards beneath the front splitter. The 2000n load is applied and the deflection measured.

With a typical splitter the FIA load bends the splitter like a cantilever

For a cantilever splitter, the test tries to bend the splitter upwards straining on the bolts at its tail end.

For a 'see saw' splitter, the weight of the car is on one side of the fulcrum, making it harder to deflect the other end upwards

Where as for the ‘see-saw’ splitter the test tries rock the splitter, effectively trying to bend the splitter like beam about its fulcrum. But the cars weight is sitting on the tail end of the splitter, preventing the splitter tilting upwards. As long as the splitters beam strength is enough to meet the test, then it will pass. Being a long metal structure, it should not be hard to make the splitter strong enough.
So as the FIA tests the cars weight sat down on the splitter, it actually aids the splitters ability to beat the test. If the test were to apply the load to the splitter, when the car is supported on its own wheels and not its floor, then the car would surely fail the test.

Interpretations
The biggest flaw is this theory is the wording of article 3.17.5 which describes the test and the mounting of the splitter. But typically the FIA rules are both vague and overly specific at the same time. The regulation states that mounting between the “front of the bodywork on the reference plane” and the “survival cell” (Monocoque) must be not be capable of deflection. The definition of “front of the bodywork” might mean its leading edge, but might not incorporate stays further back along the car. Equally the design of the fulcrum need not be the pivot I drew, but a simpler solid but flexible part, that is not suspected to deflect.
As with all borderline legal parts, this would need to be carefully assessed against the wording of the rules. But where’s there’s ambiguity, there’s a chance to exploit.

The legal interpretation of the regulations not withstanding, this is a feasible solution.  The biggest risk to running it, is if the FIA change the test process without notice.  This could catch the team out, although normal FIA process is to warn the team and ask for the design to be altered and pass the test at the next event.  Thus unlikely to cause an exclusion or  ban.

 

Footnote: A team have asked the FIA for clarification on the use of this splitter construction with a view to using it themselves.  Charlie Whiting has made it clear it would not be and added that the deflection may now be altered to ensure the rules and test are not being exploited.

Pitstop set up adjustments during the race

During most races we see the mechanics make adjustments to the car during pitstops. During each stint radio communications between the driver and his race engineer will discuss the cars balance. Whether the car tends to oversteer or understeer. Since the ban on active technologies there’s little the teams can do to alter the car during the race. Currently only front wing adjustment, rear wing gurney removal and tyre pressures are easily changed during the hectic 3-4s pitstops.

Front wing adjustment

Front Flap Adjuster (arrowed)

This is the most flexible and simplest adjustment, during the stop the mechanics can raise or lower the front flap, via threaded adjusters in the mountings. Known as FFA (front flap angle), a greater angle will reduce aero induced understeer and less FFA similarly reduces oversteer. The race engineer will call for the mechanics to make so many ‘turns’ of wing. A ‘turn’ is quite simple a 360-degree rotation of the adjuster screw. One teams ‘turn’ will not necessarily be the same as another teams, as the wingadjuster geometry will be different for every team.
Teams have historically used a cranked handled wrench for this purpose, although teams have recently been using cordless drill type adjusters. The collar of the drill modified to quickly deliver a specific number of turns, which are pre-set into the collar mechanism.
Between 2009 & 2010 drivers had the option to use the adjustable front wing flap mechanism. Allowed in the rules in 2009 as a pre-DRS overtaking aid. Although the idea did not really aid overtaking, teams did use it for the driver to alter balance during practice and in race stints.

Rear wing adjustment

A 'taped-on'Gurney flap (arrowed)

Although common in US single seat racing, rear wing adjustments are not common in F1. No team runs a threaded flap angle adjustment mechanism, preferring multiple ‘holes’ in the endplate to screw the flap into or machined inserts providing similar adjustment. In rear wing parlance, a ‘hole’ is also one unit of wing adjustment, similar to a turn of FFA. Clearly unfastening, repositioning and re-fastening a rear flap is impractical in a pit stop. However rear downforce is also tuned via the gurney flap, an “L” shaped strip along the trailing edge of the rear wing. By switching the gurney for a taller or wider strip, downforce can be increased. These strips are attached simply by tape, so are quickly removed. However fitting one does take time, requiring the wing surface to be clean and often heat guns are used to ensure the adhesive tape is sticking properly. Due to this, in the race teams are largely faced with the only option of removing a gurney and not adding one. Typically teams will add a more powerful gurney for a wet race, if the race dries then the teams will remove it. Less gurney will also decrease drag slightly and hence boost top speed.  Removing a gurney is a relaiutrvely simple process, as the strip is taped to the wing only via its leading edge.  The mechanic standing behind the wing pushes the gurney forwards and then rip sits off at an angle, taking the tape with it.
In the 2011 Suzuka Grand prix Felipe Massa was reporting understeer and his race engineer Rob Smedley radioed “Ok, we will do that rear wing thing”. At Massas subsequent pitstop, the rear wing gurney was removed. Reducing rear downforce to balance the car.

http://www.f1talks.pl/?p=11461&pid=5892

A Ferrari mechanic attaching a gurney with tape (via F1talks.pl & sutton images.com)

Tyre pressure adjustment

Wing adjustments are largely affecting medium to fast turn performance, at lower speeds the wings are less influential and the mechanical grip needs to be altered. Since the 1994 ban on active technologies, the drivers have no ability to alter the cars suspension. Before that drivers typically had the option to alter anti roll bar stiffness from levers in the cockpit.
So now the teams are left with just the option to alter tyre pressures in the race. Just as with wing adjustments, tyre pressure changes at the front or the rear alter balance. Again ahead of the pitstop the driver and race engineer will agree the change and the new set of tyres will be prepared in advance, pressurised to the right PSI.
During the 2005 season with no tyre changes teams had the mechanics with back pack mounted nitrogen cylinders, as the car stopped for refuelling, the mechanics would rapidly alter the tyre pressures to change the balance of the car.

Other changes during the race
While major balance changes are possible with wing and tyre pressure changed only at the pitstops, the driver does have some other methods to alter the cars balance, from the cockpit. Brake bias is a common adjustment allowing the driver to alter the brake bias front to rear. This can alter the turn-in to corners, as well as tune brake temperatures and locking wheels.
KERS harvesting (charging the batteries under braking) will also have a similar effect as brake bias. Drivers can alter this setting from the steering wheel.
More influential is the differential; this will alter the car at all three points in a turn; entrymidexit. A tighter differential will aid traction out of turns, but induce understeer going into them. Drivers will be altering each of the three settings to get the correct, mechanical set up to balance the car.
One area that’s been much talked about this year is the engines overrun settings. But these settings have been used for much longer to manage corner entry balance. How the engine behaves when the driver is off the throttle going into turns affects the rear tyre grip. A stronger overrun setting will create more engine braking, dragging the rear axle slightly on turn in. Which can make an oversteering the car more stable. Conversely softer overrun setting will suit an understeering car.
Lastly throttle and engine maps will affect the car on corner exit. Intuitively fiercer maps will make a car want to oversteer out of turns, offsetting understeer.