Every year High Power Media, who publish ‘Race Engine Technology’ (RET) Magazine, produce a number of magazine format Race Technology Reports. Covering F1, Moto-GP, Nascar, Drag racing and 24-hour racing.
Just out is the current F1 Race Technology issue, covering Technical subjects from 2011 and 2012.
With the switch to Pirelli tyres, their rear tyre construction has needed a lot of care in managing degradation. This drop in tyre performance happens when the tyres drop out of their operating temperature window, and this can come from the tyres running too hot or too cold. As the preceding RenaultSport article explains managing rear temperature takes a lot of effort and understanding. McLaren have been active in understanding this problem and over the past year have developed an innovative method of controlling tyre temperature via its relationship with Brake temperatures. It’s come to light in the past two races McLaren have an adjustable brake duct set up and this can have an impact on tyre temperature.
Brake discs (red) visible inside the Brake Duct
F1 carbon brake disk temperatures can peak at over 1000-degrees centigrade. The discs being 278mm diameter inside a 305mm wheel means that there is little space between the two and heat inevitably passes from the disc into the magnesium alloy wheel. In previously years this was avoided to try to reduce heat conducting into the tyre, but McLaren have found a way to harness this.
By altering the flow of heated air coming from the periphery of the brake disc, the amount of heat passed into the wheel and tyre and can be altered. Already teams tune brake cooling with different inlets scoops, but these tend to stay fixed from qualifying onwards (wet races excepted). If the team want to alter brake and thus tyre temperatures during the race then normally there’s no path open to them. However McLaren have fitted an adjustable window in the rear brake ducts. A mechanic can adjust this in the pits to tune the brake and tyre temperature to suit conditions. Depending on the wording of the Parc Fermé rule, this could also be altered on the grid as one of the areas allowed to be changed is brake cooling blankings.
The heated flow from the brakes (arrowed) exits around the brake duct
To do this McLaren have altered their brake cooling design from most other teams. More typically the round brake drum cooling ducts exit the brake flow through the rounded outer face of the duct; this passes out through the wheel spokes. McLaren’s brake discs vent their through openings in the outside of the brake drum, with its outer face closed off from the disc. So all the heated brake flow passes between the duct and the wheel before exiting through the wheel. To accommodate this flow, McLaren’s wheel spoke arrangement has been altered. The Enkei wheel features 29 drillings around the face of the rim, with the more conventional spokes positioned inside these drillings. Brake flow is directed through these drillings and relatively little passes through ten holes between the main spokes. With this set up the heated brake flow has far more contact with the wheel, both as it passes to wards the spokes and even the spokes themselves have more surface area to absorb heat from the brake flow.
The heated brake flow passes through the outer drillings (red)
Normally teams tune the brake cooling via the inlet, taping it over or changing to a different sized inlet scoop. With the McLaren system the inlet scoop remains largely the same, but brake cooling is tuned via a threaded adjuster (Yellow in the following diagrams) moving a flap to either open or close the openings in the brake drum. This is analogous to the cars engine cooling, the inlet tends to remain the same and the outlet area is tuned for optimum cooling. A larger than required duct will create extra drag, but I suspect the operating window the adjustable duct is within quite a small range. Probably smaller range than switching to the next size brake duct inlet.
The flap (grey) is closed to cover up the cooling outlets
When the flap closes the opening, more heat is retained within the duct for hotter brakes, but cooler tyres.
The duct is open to expose more of the cooling outlet (red)
Conversely opening the flap to expose more duct exit area, brakes run cooler and more heat is passed into the tyre.
Also, see these images comparing the adjustable brake ducts of Hamiltons car (right) and the unadjustable ones on Buttons (left). via Russell Batchelor XPB.cc. The silver coated section inside the brake duct on the right, is the adjustable part. This semi cylindrical panel winds in to open up more cooling outlet area.
We have seen the adjusters fitted to the rear brakes in Bahrain, but they’ve reportedly been on the car since China and F1 insiders tell me they were used even last year. I’m also told the front brakes are adjustable too, but I’ve seen no evidence for this. One thing is clear, these are quoted as secret devices, but most rival F1 engineers know about them!
I understand the brake ducts can be adjusted from a single point near the fuel filler flap, so I presume cables (Grey in the preceding diagrams) run from the threaded adjuster back to the middle of the car. At a pitstop the mechanic can adjust the brakes with a tool accordingly.
See this picture from the Spanish GP (via F1talks.pl) shows the adjustment in operation. Cables from each of the adjusters meet at the fuel flller flap and the mechanic, who is usually there to hold the car steady and clear out the airbox, can adjust the ducts with a pre-agreed number of turns on the hand tool in the adjuster. As the adjustment is done via a mechanic it is a legal change to set up, allowed once the race starts, but not during qualifying or whilst the car is in Parc Fermé. When the car is stationery at a pitstop, the system is not considered moveable aero.
Changing the brake ducting will alter the amount of brake cooling, opening the duct will allow more heat to escape and reduce brake disc temperatures and vice versa with closing the ducts. Adjusting the rear brake temperature may be the sole reason for this season. With changing tyre balance and KERS usage the rear brakes have been prone to overheating. But the more likely benefit is the effect of the brake heat altering tyre temperature. As the brake heat passes through the smaller set of drillings in the wheel, this has a greater surface area than the more usual 8-10 spoke wheel; this allows more heat to transfer into the wheel. Heating the wheel will transfer heat into the tyre; this will be useful when the driver is struggling for tyre temperature. The contrary is reducing the heat transfer into the wheel to reduce tyre temperature when the driver is struggling with heat related degradation.
Of other teams are able with their current wheel and duct arrangement to alter tyre temperatures via heat radiated from the brakes, then this will be an easy modification to make to the car. However many other F1 Engineers suggest that they find little effect of brake temperatures altering tyre temperature, making the solution unattractive to them. So it’s not clear if this is a must have solution or other teams are able to tune tyre temperatures with more conventional means. As yet I have not seen any other team run these types of brake ducts.
Sauber have proven to be one of the more progressive teams with aero development this year. The team’s have played with several different approaches to aero and exhaust positioning over the opening months of the year.
Now Sauber have produced their fourth sidepod iteration and surprisingly it is a McLaren style exhaust outlet. This goes away from the path they forged with the ramped downwash sidepod. Aiding the new exhaust position is a revised vane over the top of the sidepod.
The team also ran a revised front wing. I will cover this development in a separate post.
Sauber launched their car with a simple sidepod (above); this almost looked like a Red Bull RB5 set up, with the top exit exhaust aimed generally over the rear bodywork. This simple initial attempt was probably just for the launch pictures.
As soon after, the definitive Melbourne spec exhaust was tested. This sported a distinctive ramped section, which created a downwash that drove the top exit exiting exhaust flow downwards, then the ramped tail of the diffuser encouraged the flow to follow the sidepods line down towards the rear tyre\diffuser. This mix of downwash and coanda effect all but reproduced the EBD effect used in 2011. As the exhaust flow was directed along the bodywork, it appears to be more accurate way of directing exhaust flow towards the diffuser. However the effect lacks a path for the sidepods undercut airflow to pass through. Red Bulls Melbourne spec (V2.0) exhaust attempted to cure this with the cross over tunnel.
To aid the downwash flow over the sidepod Sauber added a horizontal vane over the front section of sidepod. This front 15cm of sidepod is free of the bodywork restrictions of the main sidepod volume. The vane points the airflow downwards, to drive greater flow over the exhaust exit. In isolation this vane actually creates lift, as is common with F1 aero this counter intuitive solution creates more global downforce because of its downstream effect, than the small loss in downforce its creates on its own.
In practice for subsequent races Sauber tried a third iteration of the exhaust, still with a top exit, but the exhaust faired-in and blow out through scalloped slot, presumably to better direct the airflow. Using similar interpretations of the exhaust\bodywork rules as McLaren exploited with their side exiting exhaust. This V3 set up wasn’t raced and will probably never race, with this fourth version now seen in testing.
The V4 sidepod discards the philosophy of the firth three completely, instead the sidepod is shorter and the coke bottle area forms a much tighter waist. Protruding from the flank of the sidepod the exhaust sits inside a small bulged fairing. This fairing mimics the McLaren with the open topped channel cut in to it, to allow the downwash to redirect the exhaust flow. The channel probably also provides a small degree of coanda effect in bending the exhaust flow downwards, but far less than with the earlier sidepod designs.
Exhaust flow exiting the duct now passes openly towards the tyre\diffuser intersection. With the coke bottle area now free of the ramped section, the undercut sidepod flow can pass towards the centre of the diffuser to use the energy in the flow to drive some downforce from the trailing edge gurney and starter motor slot.
With the change in sidepod profile and the exhaust exiting more sideways the through the top, the downwash vane has also been altered. Rather than a horizontal vane, the vanes curved around the frontal of the sidepod, to create the depression over the revised exhaust outlet position.
Sahara Force India ran a new front end in testing, with some of the distinctive features from the launch car dropped. The new set up is aimed redirecting the flow along the edges of the nose towards the floors lower leading edge. The new package consists of; a revised nose tip, front wing pylons and different turning vanes.
The team also ran a revised sidepod package with McLaren style exhaust outlets. I will cover this development in a separate post.
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From the cars launch and through the first four races, the nose tip sported a hammer-head style twin camera set up. Now the cameras have relocated to further back along the nose and the nose tip now forms a more aesthetically pleasing rounded shape. Although neutral in aero section, the camera pods are placed in a position where their shape will interact with the airflow to create some aero benefit downstream on the car.
Below this the pylons mounting the front wing have been extended and form a linger vane like shape. This was something FIF1 have worked with a lot over the past few seasons. Using this shape as part of the cars aero set up for different speed\downforce circuits. Typically longer pylons for higher downforce tracks and smaller pylons for places like Monza. Although the vanes may well create some low pressure behind the neutral front wing centre section to create load at the front axle, I expect they are more for directing the airflow along the y250 axis. This is a longitudinal line along the edge of the chassis, 250mm from the cars centre line. This is effectively as far outboard aero devices are allowed and hence where teams tend to focus on vane development. Creating different flow structures along this axis, helps creates the airflow distribution at the floors lower leading edge which is critical to diffuser efficiency.
Along similar line are the new turning vanes, on the launch car these were the popular “L” shaped hanging vanes (pictured above), mounted beneath the nose cone. Now they are a pair of curved vanes under the front suspension, a similar solution to Sauber\Renault and adopted by Red Bull last year. Again similar to these teams there is a small split in the vane to induce a stronger vortex effect along the y250 axis.
McLaren have long since followed their own path in aero development. Certainly since 2009 the car has increasingly diverged from other team’s aero concepts and the 2012 MP4-27 is no different. However the current car has a clear lineage in some of the design solutions and the whole front end is an evolution of recent cars.
Development Chronology
2009
Their first car to the current aero regulations in 2009 sported a conventional nose, front wing and cascades.
2010
The car that was launched in 2010 had a very different front end. The drooped nosed of the MP4-24 was gone replaced by a more horizontal and shallower nose cone. Beneath this was fitted large aero device, I term a “snow plough”, Williams had run a similar solution in 2009.
From a horizontal leading edge positioned between the front wing mounting pylons, the snow ploughs surface splits into left and right sections and eventually forms a pair vertical vanes protruding below the nose. This creates a “V” section mid way along its length and the twist of the airflow along with the pressure differential between the upper\lower surfaces creates vortices trailing from the rear of the vanes. This is an aggressive solution compared to the simpler turning vanes other teams use. This device probably creates some downforce in its own right, but I suspect the primary purpose is to direct the strong vortices along the Y250 axis, to drive a better airflow towards the floors lower leading edge.
Later in 2010 after a series of different iterations of endplate and cascade design, the wing substantially changed for Singapore GP. The main plane was effectively split into two; a section ahead of the front tyres and a section inboard of that. The intersection between the sections formed an upright for the main cascade winglet. While the less aggressive inboard wing span gains a simple “r” shaped vane.
2011
McLaren continued the 2010 design of snowplough nosecone and split front wing into 2011 with the MP4-26. Again later in the year, the wing was simplified for the Indian GP with similar endplates and cascades, but the complex split shape wing profile was changed to be straight across its width.
2012
Again this format was brought forward to the launch and initial test version of the 2012 MP4-27. Only in the last days of Barcelona testing did the revised front end appear. Gone was the snowplough and the straight wing profile. In their place was a simpler nose cone and a pair of vanes dropping vertically from the nose. While the more complex split wing profile was reintroduced. With EBDs less powerful this year, teams are finding downforce levels are lower. We could conclude that the snowplough and straighter wing arrangement were better for downforce, so the new simpler arrangement may be a more efficient way of producing less downforce.
The other change in China was the deletion of the slots in the small cascade winglet. The slots would have reduced the strength of the vortex produced by the winglet, removing the slots will have increased them. This change will be made in order to direct a stronger airflow around the inside face of the front wheel.
As the team get to grips with the new exhaust regulations and start to develop more downforce, potentially some of these solutions could return. So any reappearance will tell us a story of development and aero load figures in 2012.
Compared to the other leading teams the Lotus appears to be quite conservative car. However performances in testing and the in particular at the Bahrain GP show the cars looks belie its pace.
E20 Overview
Unlike its rivals there isn’t a stand out feature or innovation that’s obvious on the E20. Development from the Renault R31 with its ill fated front exit exhausts (FEE) has been iterative and logical. Unlike its forebear the E20 features a simple exhaust set up, blowing over the tail of the engine for apparently less aero effect than other team’s downwashed sidepod\exhaust solutions.
Indeed the sidepods are largely conventional, the peak above and below the sidepod inlet are similar to the R31, only the vane atop the sidepod front is unusual. Within the sidepods the team have spent time with internal airflow management, the left sidepod houses a large single water radiator, the left sidepod has a split cooler set up, which appears to keep the coolers mounted clear of the floor with electronics houses below. Perhaps for the KERS power control hardware. This high mounted radiator set up reminiscent of the packaging for the FEE and also similar to McLarens 2012 cooler package.
The nose is a straightforward interpretation of the 2012 regs, with the rounded undernose profile similar to 2011. Only the presence of a slot under the nose is a distinctive feature, this smiley face shaped slot is created under the nosecone and passes through the front bulkhead into the chassis. Presumably for cooling the driver or the steering rack mounted low on the front bulkhead. One interesting point on the front of the car is the unusual hump arrangement on the top of the chassis. The usual bumps used to clear the rockers and other front suspension linkages are asymmetric. With a larger bulge on the left and a smaller one to the right. This suggests something is unusual about the suspension, Renault were known for the innovation in this area with front to rear interlinked suspension, the reactive ride height system and also running with a roll damper in place of side dampers. I suspect the bulge is to neatly incorporate the asymmetric rocker arms needed for a roll damper and hence the car runs without left and right dampers. However the front of the bulkhead is so heavily packaged with other hardware it’s impossible to see the spring\damping elements inside. Externally we can see that the torsion bar mounts allow for free rotation and even feature a rotary sensor to measure their movement. This shows that the torsion bars are not grounded to the chassis instead react against each other. This negates their spring effect in roll, so all roll stiffness is provided by the anti roll bar. This approach has been common on other cars for a few years.
The anti roll bar is mounted higher in relation to the front bulkhead compared to last year, equally the link between the torsions has been moved inside the chassis, rather than the external bracing strut seen on last year’s car.
At the rear, the gearbox shows no evidence of side dampers either, although these could be packaged inside the casing so also not visible externally. Its possible Lotus have made a step in suspension design, which makes the best use of the tyres or control of the aero platform better.
Lotus are another team to adopt OZ wheels with integral fairings added to the front rims.
At the rear, a lot has been made of the laterally diverging diffuser. All teams start the diffuser far narrower than the 1000mm allowed between the rear wheels, and then diverge the diffuser (in plan view) outwards towards the limit of the allowable area. This effectively limits the expansion that can be achieved within the regulatory diffuser volume. Lotus has effectively diverged the diffuser to the 1000mm limit far earlier, with the outermost channels effectively exiting out of the side of the diffuser. This potentially gains more theoretical volume for the diffuser, but also creates a far more aggressive sidewall to the diffuser, risking flow separation and the diffuser sidewall is shorter more open and hence may leak more. Other teams have followed this path in the past, so the potential benefit is there assuming the drawbacks of the geometry can be overcome.
Developments
Pre season
As one of the cars shown at the launch was a R31 rebranded and reworked to look like the E20, initial observations were hard to make. The car that commenced testing was the E20.
The first test went outwardly successfully, but problem on the first runs of the second chassis being tested at the Barcelona test showed problems with the monocoque. Subsequent checks on the first monocoque tested in Jerez, revealed the same structural problem. The tub was failing where rear leg of the top wishbone mounts. The team skipped the test to add 1kg of reinforcement to the cars.
As soon as the car recommenced testing it started to gain revisions to the floor and front wing. This included a re-profiled splitter along with its side vanes, as well as a new iteration of the front wing. The initial wing with its “R” shaped vanes and cascade winglet were nearly parallel to the cars centreline, the updated wing changed these into a more curved outswept shape. Notably the front wing pylons also house the FIA camera pods, these being mounted between the pylons and siamesed into an aerofoil shape behind the neutral centre section, to negate the lift created by this profile.
China\Bahrain update
A new aero package was prepared for China, but the team found testing inconclusive with the variable track conditions. The package was run again in practice for the Bahrain GP and adopted for both cars from qualifying onwards. The package included a revised rear wing, with new endplates sporting a squared-off lower section and mated to the diffuser with a larger vane. The floor was also revised, although the concept was largely carried over, so the changes are in the detail geometry and not the overall shape.
At the front the wing was altered for a completely new version. At first the wings appear similar aside from the vane treatment on the endplates, but the main planes leading edge dips downs more suddenly at the on with the neutral centre section, while the flaps join the same area without the coved section on the old wing. At the wing tips, the flaps fold down to form the endplate as is common in current F1, the upper flap gaining a small extra slot to aid flow through the steepest section of wing. With this endplate-less set up, the minimum surface area regulation is met by two vanes added to the footplate. These being somewhat reminiscent of Toro Rosso’s vaned set up. It’s hard to speculate on how the new package gains lap time or bring a difference in aero efficiency over the old set up.
The new package was worth a couple of tenths according to the team and the back to back tests in free practice proved its worth over the older aero package. As with the rest of the car it’s hard to pin point where the lap time comes from, For Lotus the conventional approach and iterative detail development has brought dividends over a more aggressive approach.
One wonders how much more potential there is within the car should adopt the sidepod\exhaust or DRS solutions of its rivals. If the team can successfully introduce these performance upgrades and continue to understand the tyres requirements, then there is scope for them to remain in the hunt for strong results throughout the year.
Having been slightly off the pace in the opening three races, Red Bull clearly do not have the RB8 working as they had expected. Pole position in Bahrain doesn’t prove their issues are over, but the car sports a revised sidepod set up this weekend and this has perhaps has unlocked the potential in the car. The new sidepods are a revision of the Version2 spec sidepod/exhaust set up. The Bahrain spec simplifies the sidepod, removing the complex crossover tunnel under the exhaust ramp.
Exhaust Versions
Sidepod Version1
At the cars launch the RB8 features a simple Version1 exhaust set up, aimed at being a benign solution to get the bulk of testing out of the way, without interference from complex exhaust issues. Then later in testing the focus could switch to the greater potential performance offered by the V2 set up. The V1 set up placed the exhaust in board and rearward, blowing under the top rear wishbone. The exhaust flux blew along the tail of the bodywork and under the beam wing. Despite suggestions at the time that this set up was a novel exhaust blown suspension set up; the solution was never intended for race use.
Sidepod Version2
Then on Day11 of the 12 day preseason testing schedule, the V2 sidepod\exhaust appeared. A more complex solution than either the McLaren or Sauber set up, the sidepod aimed to both direct exhaust flow at the diffuser and route the sidepods undercut flow to the centre of the diffuser. To do this the sidepod had a more outboard and rearward exhaust position.
The exhaust blows down the tail of the sidepod, over a ramp made to try to attach the exhaust flow to the bodywork via a coanda effect to direct it in the correct gap between the rear tyre and diffuser. This is the same area the teams aimed their exhausts directly at last year. This area helps both seal the diffuser from flow blown laterally from the rear tyres and also the greater mass flow of the exhaust plume creates more flow through the diffuser, with both effects adding downforce. This solution follows the same path as the much applauded Sauber solution. Although the two systems were developed in parallel and RBR did not copy the Sauber after seeing it launch. The RB8 always was planned to run the V2 set up.
V2: a tunnel is created under the Exhaust ramp bodywork (yellow)
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V2: Flow from the sidepod undercut passes through the tunnel (yellow)
To keep the airflow passing over the top and centre of the diffuser, teams direct the fast moving flow from the sidepods undercut to this area. In Red Bulls case, the path of this flow is obstructed by the exhaust ramp and plume. To overcome this Red Bull have simply created a tunnel for the air to pass under the exhaust ramp and remerge towards the centre of the diffuser. This solution looks like is major aim was to direct flow to the start motor hole, an area exploited by ductwork on the 2011 RB7. Having more airflow passing into the starter motor hole, makes the hole act like a blown slot, making the airflow better up and under the middle section of diffuser for more downforce. Creating a crossover effect is somewhat like McLarens bulged exhaust fairing, that allow both the exhaust to be directed down to the diffuser edge by the downwash flow over the sidepod, but also creates a channel beneath the exhaust bulge to allow the undercut flow to reach the centre of the diffuser.
So it seems Red Bulls V2 floor make the best of the Sauber Coanda solution and the McLaren undercut solution.
What are the issues?
However this tunnel is compromised by the post-2009 area rules. Sidepod bodywork 50mm above the floor (actually 100mm above the reference plane) must meet tangential and minimum radius regulations. This means Red Bulls tunnel is limited to slightly less than 50mm in height, with a sharp top edge.
It seems it’s this crossover tunnel on the V2 sidepod that is an issue with the car. Recent flowviz tests in free practice were focussed specifically on the tunnel, as well as tests with an array of aero sensors trailing the diffuser in Bahrain. Also an insider tells me that the Red Bulls starter motor might not be creating the accelerating airflow into the steep middle section of diffuser that was envisaged. Instead the starter hole works better when blocked off. Perhaps this crossover tunnel is not flowing correctly to the centre of the diffuser and altering the accuracy of the exhaust flow towards the tyre\diffuser intersection.
If the exhaust flow cannot reach the tyre\diffuser gap accurately or perhaps more importantly consistently, then the driver will have a car that sensitive to throttle position.
Red Bull have been alleged to have clever engine mappings, cutting down to four cylinders at larger throttle openings at lower revs. This could either have the effect of a softer power delivery for better traction, of greater exhaust flow for more downforce at lower revs. Red Bull and Renault may still be finding ways to gain performance from exhaust mappings and these mapping have been investigated the FIA and shown to be within the regulations.
With several issues around the way the exhaust affects the cars handling, Red Bull said in China that the V2 sidepod was the potentially better solution, but the V1 set up gave Vettel more confidence. Horner admitted that it was possible to get the performance of the V2 with the feel of the V1. At Bahrain it appears that this is what RBR have done.
Sidepod Version 2.1
V2.1: With no tunnel the exhaust flow can pass without interference to the diffuser
These issues may explain the Bahrain sidepod upgrade. This new sidepod set up appears to be a rework of the V2 sidepod, most of the shape remains the same and the exhaust appears to be in the same position. So it looks like the moulds were altered to close off the cross over tunnel create a V2.1 sidepod.
With the tunnel closed off the issues complicating the exhaust and starter motor hole flow have been cleared up. But there still remains an issue with how the sidepod undercut flow reaches the rest of the diffuser. Sauber appear to manage this, but there still may be some potential airflow performance that is lost with this set up. Although the overall effect of an exhaust aimed accurately at the tyre\diffuser gap may be a greater gain that that loss.
However with the tunnel gone there is a less complex route for the exhaust to reach the diffuser. With the exhaust flow better managed the intended exhaust effect will more consistent resulting in a better feel for the driver at different throttle positions and car attitudes.
V2.1: Slots in the floor aid the effect in sealing the diffuser
It’s notable that Red Bull have also reintroduced the slots in the floor ahead of the rear tyres, these haven’t been seen for a couple of years, their function is to inject some higher energy airflow into the gap between the tyre and diffuse. This, like the exhaust blown diffuser, offsets the sidewash (known as ‘Squirt’) created by the rear tyres impinging into the diffuser. Again this will all result in greater rear downforce.
If this is the first solution for Red Bulls woes, then it will be interesting how the team develop from the V2.1 sidepod. Perhaps the tunnel will reappear in revised form or a McLaren style solution will be tried.
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 cylinder\piston 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.
I’ve recently made a few of my regular appearances on TheFlyingLap Webcast, talking at length about the technical developments including Mercedes F-duct, Exhaust and Sidepod design, as well as Nose Design.
This is also available via ITunes and YouTube
Update on how it links to the Front wing
Something often said of banned developments in F1, is that once understood no solution can be unlearnt. So while the FIA fights to ban technologies that they feel aren’t suited to F1, the teams will always try to apply that solution in a different way.
McLaren understood how to stall a wing by blowing a slot perpendicular the wings surface. This knowledge lead to the F-duct in 2010, as you will recall the FIA moved to ban slots in the rear wing and direct driver interaction with the cars aero. But the knowledge of blown slots to stall wings has remained and it’s been Mercedes who have been busy trying to apply it in other ways. This culminated with the tests of an F-Duct front wing late last year. Rumours continue to fly about the teams use of the F-Duct front wing (FDFW) in 2012. I understand the 2012 Mercedes AMG W03 does have an F-Duct front wing and this is operated by the rear wings DRS. Based on information I have from the sources around the team, and from looking at the cars performance and construction mean I can speculate how and why Mercedes might be using the FDFW.
As detailed in two articles last year, Mercedes are believed to have run blown slots under the front wing to stall the wing at higher speeds. Three reasons came up as to why this would be used; reducing drag, managing wing ride height and managing the cars aero balance. With nothing official being said by Mercedes, we were left unsure as to exactly why a passive FDFW would benefit the car.
https://scarbsf1.wordpress.com/2011/10/21/mercedes-f-duct-front-wing/
https://scarbsf1.wordpress.com/2011/10/24/update-mercedes-f-duct-front-wing/
Some observations from the Mercedes team last year might aid us in putting a picture together of how the 2012 solution might benefit. Mercedes were the first team to really exploit more of the open DRS effect and use a short chord flap. The open DRS boosted Mercedes top speed and could be used through the lap in qualifying. Despite this benefit the teams did struggle in qualifying, their race performances latterly became better than qualifying suggested. It was clear for Michael Schumacher at Least, that the cars handling wasn’t ideal and the team sought to resolve the cars nervousness.
Bearing these points in mind, the potential benefits of a FDFW become more apparent. Mercedes need more qualifying pace; they can exploit their DRS more frequently during qualifying, but in higher speed turns the cars lacks the balance for the drivers to fully commit through the turn.
If they can cure these issues, then they will further up in qualifying and able to take the fight to the leading teams. I now believe the FDFW works to manage the cars balance in high speed turns when the DRS is activated. As DRS reduces both rear drag and downforce, the car becomes unbalanced in downforce front-to-rear. In other words pointy or oversteering. Which in high speed turns in qualifying is hard to handle. At higher speeds even with DRS reducing rear wing downforce, the car has enough downforce to make it around corner, the problem is how to make the car more balanced front-to-rear when DRS is activated.
The FDFW we saw last year appeared to be passive, this uses nothing other than airspeed to trigger the slot to blow enough to stall the front wing. If matched to the speed DRS would be used at (in qualifying), the passive FDFW would help balance the car, by reducing front downforce to match that of the rear. However the front wing would always stall at these speeds, whether DRS was in use or not, so outside of qualifying the wing would stall and the car would understeer. With Parc Fermé rules in force, the team cannot change the FDFW between qualifying and the race.
Another issue with the passive FDFW, is that under braking as air speed reduced, the wing would need time to start working again. But this early phase of braking is just when the driver needs the most downforce. What the FDFW ideally needs is a method to link its activation to that of DRS, in other words an active F-duct.
As we’ve already mentioned, driver activation is not allowed, as are any other moving parts to directly alter the airflow. This brings up the Designers favourite interpretation in the rule book, primary and secondary purpose. Any part on the car can be for a primary purpose; sometimes any secondary purpose is banned or restricted. However in most cases the rules are vague and Designers are free to find secondary uses for a solution on the car. Examples of this are the cooling fans on the Brabham Fan car, the engine blowing off throttle for blown diffusers or brake torque altering ride height on the Lotus Reactive Ride Height system. In each case the first element was legal as its primary purpose was as stated, but a secondary purpose was able to be exploited.
The DRS rules are quite clear that the flap must not be shaped to allow other aerodynamic benefits. In fact this wording affects only a portion of the flap and additionally the endplate is excluded from this wording. If the team could find a way to blow into the front wing a duct when DRS is activated, then the FDFW could work synchronously with the DRS.
The hingeplate the flap mounts to, closes a hole when DRS is closed. When DRS is open the duct is revealed and the F-duct stalls the front wing
I believe Mercedes have found a way, by creating a duct through the endplate. When DRS is closed, the flap and the plate it attaches to is in a nearly vertical position. When DRS opens, the area the flap initially covered is exposed. If this area featured an opening that lead into a duct inside the endplate, when DRS opened the high pressure above the wing would force flow through the duct. With this duct then routed through the car to the front wing, when DRS is open the FDFW would be blown and stall in unison with the rear wing. Clearly when DRS closes the duct would be closed off and the duct would stop blowing the FDFW, restoring front and rear downforce.
When DRS is open, the duct passes into the beam wing and through the car. Eventually reaching the front wing slot to stall the wing.
Some evidence around the rear wing of the W03 shows this could be possible. We have to be careful to pinpoint every feature on the rear wing as being FDFW related as the DRS mechanism is hidden inside the endplate as well. Some access panels on the wing could be for DRS, FDFW or other purposes, some might be for both. In my research I’ve yet to see a clear high resolution shot of the Mercedes with DRS open, this is unusual as most other teams have been seen with the DRS in effect. Equally clear pictures of the inside of the endplate, where the flap meets the endplate, are in short supply. With this lack of material I can propose a solution, although the actual parts may diffuser is location and appearance. Its expected at this weekend Australian GP the rear wing duct will be exposed as the car uses DRS on the straights. We will need photographers with a big lens and steady hand to catch sharp pictures of the inside face of the endplate, when DRS is activated.
Evidence of the duct can be seen on the car, when the car is not moving. Clearly the W03 rear wing endplate is quite thick, an access panel that houses the DRS actuator is outboard of the flap\endplate intersection, plus there is another panel in line with the beams wings intersection with the endplate. I’d suggest the duct is opened by the flap and hinge plate, the duct then routes through the double skinned endplate down into the beam wing. This then exits through the duct that mounts the beam wing to the gearbox. There’s a tortuous route for the duct through the car to reach the front wing, but this isn’t that dissimilar to the 2010 F-Duct routing. As with McLaren in 2010, the trick is to design the duct into the car at an early stage to minimise losses through the ductwork. This usefully makes it harder, but not impossible to copy. To copy this set up the monocoque needs to be altered and the nose cone needs the apertures into the front wing mounting pylons to feed the airflow into the front wing itself. This requires time to redesign and potentially re-crash test any changes.
But, can this set up be legal? The act of stalling a front wing through a blown slot is legal, although F-ducts are banned, it’s only via the slot in the rear wing that this was achieved. Direct driver intervention is banned, but the driver is allowed to operate the DRS, so any secondary aerodynamic effect of that is not prohibited in the rules.
Although the rules allow this, it’s possible the FIA could issue a Technical Directive on the matter, that any overt secondary effect of using DRS is not allowed and the whole solution could be banned in a stroke.
With a tight and competitive season in prospect qualifying performance will be critical. Notwithstanding the potential structural work to allow the duct to pass through the car, the DRS activated F-duct Front wing is an attractive option for the other leading teams.
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