First sight: Ferrari Revised Mugello Exhaust

Picture Via Russell Batchelor

On Day3 of today’s Mugello test, Ferrari appeared with a major update to their sidepodexhaust configuration.  Although at this stage it’s not clear if this set up is Ferraris definitive exhaust solution going forwards, or merely another interim set up.

What’s clear is Ferrari continue to follow their own path for exhaust and cooling flow.  With the main cooling outlets being via chimneys exiting from the flank of the sidepod, a solution popularly termed the “Acer ducts”, due to the presence of the sponsor’s logo on the launch spec bodywork.  With the launch car the exhaust exited through the rear exit of the ducts, and latterly the exhaust was moved to prevent overheating rear tyres and the duct cut away to allow more inboard location of the exhausts tailpipe.

Now the “Acer” ducts are brought more inwards and the exhaust exits over the top of the duct, periscope style.  This suggests the exhaust is not being aimed at the floor at all, simply along the centre of the top bodywork towards the beam wing and the winglet mounted atop it.  This would be less effective at creating downforce, but would be less sensitive to throttle position and have less of an effect on the rear tyre temperatures.

The floor and top body mouldings appear to new and quite large sections.  This also suggests that the bodywork is going to change. Often with interim bodywork the panels are smaller to allow different shaped sections to be added.  However the black heat shield panel around the exhaust is removable and may allow a switch to a McLaren style open-topped duct exit.

The continued presence of the vortex generator near the mirrors suggests some downwash effect is still being created, although the current spec is not really making use of it.

I will update this post as the test develops

Red Bull: Bahrain Sidepod Analysis

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 sidepodexhaust 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)

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 tyrediffuser intersection.
If the exhaust flow cannot reach the tyrediffuser 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 tyrediffuser 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.

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.

2012: Technical Regulations Published

Today the FIA published the final version of the 2012 F1 regulations. Both the Technical and Sporting regs have changes for this year, most notable are the technical changes. The two main changes were expected, being the exhaust position and nose regulations, but there are a large number of new rules concerning control systems.

Controls for the throttle, antistall and gearshift have all been clarified, such as a requirement to stay in first gear until 100kmh. I can only speculate some teams were improving their launches, by controlling the clutch off the line under the auspices of the antistall and gearshift rules. I will research this further to see if this is the case.

FIA Website

Technical Regs (PDF)

Sporting Regs (PDF)

3.7.9 Bodywork in front of the front (A-A) bulkhead must not be higher than 550mm, as outlined in my previous post

3.12.6 The manufacturing tolerance for the floor is reduced to 3mm (from 5mm)

4.2 Fixed Weight distribution confirmed for 2012 & 2013

5.5 Drivers torque demand via the accelerator pedal more tightly defined

5.8 Exhaust position confirmed as outlined in my previous post

5.19 Anti stall systems more tightly defined

8.6 All driver buttons and controls to be via dedicated input to the ECU. The Drivers use of these controls must logged for FIA inspection

8.11.1 Five additional sensors for data logging can be fitted for P1 and P2

9.2.5 Clutch control is more tightly defined

9.8.1 Clarification of multiple driver gear shift requests

9.8.2 At the race start and at pit stops, first gear must be used until the car is travelling 100kmh

9.8.4 Clarification of time allowed for shift requests to be started and completed

9.8.5 Track position cannot be used as an input the gearshift control

10.5.3 Uprights cannot extend too far inboard, similar to brake duct dimensions

12.7.3 Only tyre heating blankets may be used to warm the tyres

12.8.4 Wheel guns can only run on Air or Nitrogen, not Helium

McLaren: Suzuka upgrades and design overview

McLaren have proven to be Red Bulls nearest competitor for most of the season. While not quite having the same raw pace as the RB7, the MP4-26 is as fast on race day and arguably can be easier on its tyres. Having started with two bold concepts the “U” shapes sidepods and the mysterious “Octopus” exhaust, the design had to be compromised to ditch the complex exhaust and revert to a Red Bull style outer blown diffuser. Leaving McLaren with a large amount of space under the gearbox, that was supposed to package the exhaust. This left the car with a higher rear CofG without the benefits of the exhaust to offset it. So it’s been remarkable that McLaren have been able to morph the initial concept into a race winning, Red Bull baiting package.
The pace of development never slows, So McLaren arrived at Suzuka with a new diffuser detail and another iteration of its Silverstone short-chord rear wing.

Following a lot of the rest of the paddock , McLaren added a diffuser flap across the top edge of the diffuser exit. The flaps profile only being broken by a large gurney flap under the rear crash structure. As already discussed in the Red Bull Monza diffuser article (http://scarbsf1.wordpress.com/2011/09/22/red-bull-monza-diffuser-analysis/), this flap is an evolution of the trailing edge gurney, used to create lower pressure aft of the diffuser for more downforce. McLaren can run such a large central gurney flap as it sits in a 15cm window in the bodywork rules that allow taller bodywork. Its also beneficial as the raised rear crash structure (for the “octopus” exhaust) allows a good airflow to pass underneath it towards the gurney.

Again we saw McLaren run the short chord DRS rear wing, allowing the team to use the DRS more frequently during qualifying runs. This wing has already been detailed in the blog (http://scarbsf1.wordpress.com/2011/07/14/mclaren-new-drs-rear-wing/).

Further down the car, we can see the rear brake duct cascade. Rules allow 12cm of bodywork inboard of the rear wheels, there is no stipulation that these function as brake cooling ducts, so teams exploit this for ever larger stacks of aerofoil sections to gain downforce directly acting upon the wheels.
McLaren have also altered their exhaust system over recent races, switching from a simple oval profile tail pipes, for pipes that pinch-in to form a nozzle at their exit. Also the detailing around the floor area varies by track, with more or less floor being cutaway around the exhaust exit. This alters the amount of exhaust flow passing beneath the floor to suit differing ride heights. As one of the functions of the EBD is to act to seal the diffuser, often likened to a virtual skirt. The high energy exhaust gas, prevents other airflow entering the diffuser, thus maintaining downforce.
Its no surprise given the proximity of the brake ducts to the exhaust outlets, that the lower stack of brake duct aerofoils are heat protected. No doubt some of the exhausts energy is used to drive airflow under the ducts to create more downforce.

McLaren use a split cooling outlet set up, rather than Red Bull who tend to focus all the outlet area into the large bulged exit high up on the engine cover. McLaren’s main outlets are the exit to the sidepods coke bottle shape. With outlet area to the side of, and above the gearbox. This is aided by 3-slotted louvers on the flanks of the sidepods.

Lastly McLarens unique sidepod design is clear to understand from this angle. The “U” pods create a path for the airflow passing over the centre of the car, to reach the rear wing relative unobstructed. Typically airflow closer to the cars centreline is cleaner and has more energy. This is why designers tend to use this airflow to feed the sidepods for cooling purposes. What McLaren have done is to compromise on the cooling efficiency for greater rear wing performance. The small fin inside the channel is used to create a vortex to main the airflows energy and direction through the channel.

Red Bull – Monza Diffuser Analysis


Red Bull appeared in Monza was a further development of their diffuser. Changes largely appeared to be focussed on the treatment of the trailing edge of the bodywork. For Monza the diffuser gained a flap around almost the entire periphery of the trailing edge.

Highlighted in Yellow, RBR had a flap spanning around most of the diffusers trailing edge

This flap has been used above the diffuser since the start of the season, but the flap has been narrower, being only fitted in-between the rear wing endplates. As explained in my analysis of the floor as seen at Monaco (http://scarbsf1.wordpress.com/2011/06/08/red-bull-monaco-floor-analysis/ ).

Many pictures were taken of the flap now extending around the sides of the diffuser, which I tweeted about during the Monza GP weekend. But it was the fan video taken during the race, as Mark Webbers stricken RB7 was craned off the track that has shown the floor in greater detail. The video posted on Youtube.com by atomik153 and seen here (http://youtu.be/swoomrzECdM ). This clearly shows the floor from about 3m 40s into the clip. Obviously this must have been unpleasant for Red Bull as the floor is so clearly visible, I know that the other teams have seen this clip. Many fans having seen the detail at the back of the diffuser and suggested the slot created around the diffuser was some form of double diffuser or cooling outlet. While the pictures might suggest this, the slot is merely the gap between the aerofoil shaped flap and the diffuser.  This following illustration shows how the flap is actualy shaped.  There are two parts; the new curved side sections and the pre-existing top sections.

When exploded, you can appreciate how the new bodywork forms a flap around the diffuser

Diffuser trailing edge theory

Few ideas in F1 are new, merely older ideas reinterpreted and expanded upon. This flap is not a new idea, its merely an extension of the gurneys teams have been fitted to the trailing edge of downforce producing devices since the sixties. Gurneys have been added to the end of a diffuser to aid the low-pressure region above and behind the diffuser. This practice has been increasingly important with the limit on diffuser height and other rules banning supplementary channels such as the double diffuser. As far back as the late nineties teams replaced this gurney with an aerofoil section flap. Notably Arrows and latterly Super Aguri used flaps placed above the diffusers trailing edge.

The need for this sort of treatment at the back of the diffuser might at first be confusing. A diffuser is a part of the underfloor, by accelerating air under the floor, low pressure is created and thus downforce is generated. With so many restrictions on the geometry of the floor and diffuser, teams cannot simply enlarge the diffuser for more performance. So they are forced into working different areas of the device harder for the same effect. One area is maximise pressure ahead of the floors leading edge, the other is the lower the pressure behind the trailing edge. This helps flow out of the diffuser, to maintain mass flow under the floor. Although the rules limit the height of the diffuser, this is only the height below the tunnels to the reference plane. Teams have a small amount of space above the diffuser for bodywork and the common gurney fits into the area. Gurneys work by creating a contra rotating flow behind the upright section, this creates low pressure and helps pull airflow from beneath the wing. On a diffuser this has the same effect as a slightly higher diffuser exit.

A gurney creates low pressure by the contra rotating vortcies behind the gurney

The gurney can work above the diffuser, as teams have been paying so much attention to getting high pressure air over the top of the diffuser. This airflow is used to drive the vortices spiralling behind the gurney flap. The better the airflow over the diffuser to the gurney the more effective it can be.   However Gurneys cannot be infinitely increased in size and still maintain their effect. As the gurney gets too large the dual vortices break up and the low pressure effect is lost. Many teams have found this limit this year and have moved to the next solution which is a perforated gurney.

A perforated gurney can be larger as it's offset from the diffuser allowing airflow to pass under the gurney

This is a similar vertical device fitted to the diffusers trailing edge, but there is a gap between the bottom of the gurney and the diffuser. Airflows through this gap to create the distinctive contra rotating airflow behind the gurney. Again this has the same effect as creating a larger diffuser exit and hence creates more downforce.

An aeroil shaped flap can be larger and more efficient than a Gurney

While the gurney is a relatively blunt solution, Such is the quality of the airflow over the diffuser now that teams are able to fit a more conventional aerofoil shaped flap above the diffuser for a similar effect. Without the contra rotating flow of the gurney this solution can be scaled up, as long as the flow to the flap is maintained. Many teams have this solution fitted along the top edge of the diffuser. Although Red Bull are the only teams to have fitted to the side of the diffusers trailing edge. Increasingly teams are seeing the diffuser exit as a 3D shape, the diffuser not only diverges vertically at the exit , but also laterally. No doubt exhaust blowing does allow some of these devices to be effective.

In Detail: The flap on Red Bulls diffuser

We can expect its use to be expanded for next year with larger flaps above the diffuser and flaps around the entire periphery of the diffuser. A long with Rake this will be a critical design feature for 2012, as a result sidepod design will become one of the critical factors in aero design, making sure the top of the diffuser is fed with good airflow. As so few other areas provide potential gains for improving aero efficiency.

Other notes on the Red Bull Floor

Fences

Red Bull fit three fences in each side of the diffuser, these prevent different pressures regions migrating from one side of the diffuser to another. They help maintain downforce and sensitivity. Its interesting to note the fences are not triangular in side profile, I.e. that they don’t meet at the kick line between the floor and diffuser, instead they start a few centimeters behind the axle line with a rounded vertical leading edge.

Starter Motor Hole


As mentioned in the Monaco RBR floor analysis the starter motor hole is blown by ducts in the upper side of the floor. This injects some energy into the flow in the middle of the diffuser. This so called boat-tail section is where the steeped underbody merged with the higher step plane. With the lower centre section and plank, getting airflow into the area is difficult and separation can easily occur if the angle of the floor is too steep. Having the starter motor hole blown helps maintain airflow in this area.

Metal Floor

Exhaust Blown Diffuser Flow

Renaults Hungarian Sidepod Fire

The silver canister is visible towards the front lower of the sidepod - via nextgen-auto.com

Update: Lotus Renault GP, have provided me with this response from Technical Director James Alison.

Three days after the incident on Nick’s car, has the team identified the reason why it caught fire after the pitstop?
J.A.: As with most accidents, several incidents combined to cause the fire that Nick suffered in Hungary. First of all, we ran a slightly different engine mapping strategy in qualifying, which produced hotter than normal exhausts. We believe that this elevated temperature and caused a preliminary crack in the exhaust pipe. We presume that the crack then propagated during the laps to the pitstop – this was not evident to us as we believe that the failure occurred upstream of the place where we have a temperature sensor. We believe that Nick then came in with a partially failed exhaust. This pitstop took longer than normal, the engine was left at high rpm for 6.3 sec, waiting for the tyre change to be completed. Under these conditions, a lot of excess fuel always ends up in the exhausts and their temperature rises at around 100°C/sec. This temperature rise was enough to finish off the partially failed pipe and to start a moderate fire under the bodywork.

There was an explosion shortly after Nick got out of the car, on the left. What was it?
J.A.: This was caused by the air bottle which supplies the air valves in the engine. It has overheated in the fire and failed.

Will you have to modify the car before Spa and if yes, is the August factory shutdown a handicap?
J.A.: The incident was highly undesirable, as it has caused us to write off a chassis. We will take steps prior to the next race to reduce the likelihood of a further fire and to ensure that the air bottle cannot overheat. We are in touch with the FIA both to provide them with a full report of the incident and also to explain to them the actions we are taking to prevent a reoccurrence.

As Nick Heidfeld made a pit stop at the Hungarian GP, there was a problem with one of his wheel nuts. This kept the car stationery for an extra 10-12 seconds. In readiness to leave the pit, Heidfeld kept the engine pegged at maximum revs. This extra delay was enough for the exhaust to start to overheat the surrounding bodywork. Without the usual pit fans blowing air over the bodywork, the carbon fibre soon started to smoke and then caught fire. Heidfeld was then released from the pit, as the wheel nut was properly fastened. Sparks were being blown from the car as he sped down the pitlane, this was the action of the exhaust blowing the fragments of the burning carbon fibre bodywork and not electrical sparks as some have speculated. The airflow over the bodywork only fed the flames and by the time he was at the pit lane exit his sidepod was well alight. As it was the bodywork itself that was on fire, the flames were on the outside of the sidepod and looked perhaps more alarming than was actually the case. Bodywork fires are not uncommon and teams have well rehearsed drills to meet the car in the pitlane with the pit fans and a precautionary fire extinguisher. Although it’s fair to say these sorts of fires are normally prevented by detail work to the shape and heat shielding of components early in the cars testing. Particularly around the exhaust which is the greatest source of heat within the sidepod. This year’s unusually long faired-in exhausts contribute a greater risk and the Forward exhaust exit (FEE) of the Renault only adds to the proximity of the exhaust to bodywork. With more conventional exhaust blown diffusers (EBDs), the exhausts are run along the floor to ahead of the rear tyre; these are slightly easier to manage. Additionally the heat shielded ducting for the Renault FEE, also provide a route for flames to exit out of the front of the sidepod, making the flames in closer proximity to the driver. This isn’t to say the Renault FEE is inherently unsafe. Any F1 cars bodywork left to overheat will see the flames rapidly spread across the skin of the cars sidepod bodywork.

http://youtu.be/s9tF7g3CwK8

What made Heidfelds fire more concerning was the apparently explosive moment when debris and gasses were blown out from the cars sidepod as the marshals sprayed extinguisher foam over the burning bodywork.

As the R31 came to rest, the driver jumped out and the fire marshals arrived from a post a few meters up the track. Two marshals tackled the blaze, running from behind the car to around the front to direct foam over the sidepods. As the first marshal carried on towards the rear of the car, the second marshal arrived at the front of the sidepods. Then there was this burst of debris and gas from the front of the sidepod. This appeared to slightly injure the marshal who limped around to the rear of the car. Renault have confirmed “he is ok. No injury. We are sending him a nice gift”. Shrapnel from the burst lay several meters away from the car in the pitlane exit lane. As we’ve seen fire’s are relatively rare in F1, oil fires being the more common and spectacular, but it’s very rare for a burning car to have this sort of violent moment.

Sidepods contain a multitude of systems; many items being solely in the left or right hand sidepods, rarely are any internals symmetrical left to right.

Typical components in this area are.

• Water radiator (LHS)

• Oil radiator (RHS)

• Hydraulic reservoir (varies)

• Nitrogen cylinder for the engine Pneumatic valve return system (varies)

• KERS battery water radiator (RHS)

• SECU, PCU, Battery, Lap time beacon (typically RHS)

• KERS PCU (RHS)

It’s important to note, sidepods do not contain the KERS batteries or the MGU. Also the gearbox oil and hydraulic fluid coolers are mounted atop the gearbox. There is very in the of little hydraulic systems being in the front of the sidepods, only the lines for the power steering passes this far forward in the car.

Seeing the explosion was not backed up with a further blaze of burning oil or steam from water radiators, its unlikely these burst in the fire. Then as most of the electronics are in the right hand sidepod, again these can be discounted. This leaves the obvious exception of the nitrogen cylinder. This is required as F1 engines do not use valve springs but instead a pneumatic pressure keeps the valves pressed open against the cam. In order to provide this pressure and as the system loses a little pressure during the race, a pressurised chamber maintains the required pressure. This comes in the form of a ~half litre aluminium cylinder. (Circled red – twitpic.com/5yycsi )

On most F1 cars and indeed Renaults all the way up to last year’s R30, teams mount these small cylinders inside the cockpit to protect them from crash or fire damage. Renaults R30 placed this on the hand side of the car, down on the small amount of floor between the driver’s seat and the side of the monocoque. But this location is not mandated by the regulations. Pictures of the R31 left-hand sidepod without bodywork, show there is an aluminium cylinder placed in the front section of sidepod. This transpires to be the nitrogen cylinder for the engine pneumatic valves. Probably because Renault had to create a slimmer monocoque to claw back the radiator volume lost to the routing of the FEE, they slimmed the monocoque and fond no space next to the driver’s seat to mount the cylinder and placed it outside on the radiator ducting instead. When this aluminium cylinder was heated in the flames and then suddenly cooled by the marshals extinguisher, the casing shattered sending the pressurised gas out in a hail of debris. This failure of a pressurised aluminium structure could also be the water radiator failing, while some rumours point to this the lack of the plume of steam ejecting from the sidepods after the initial blast, suggests to me this is unlikely. But to be clear, this wasn;t a chemical explosion, merely the failure of the casing of a pressurised vessel. as nitrogen is both intert and not liable to high rates of the thermal expansion

Comment by the team to news websites seems to back this theory up http://www.gpupdate.net/en/f1-news/265636/heidfeld-s-fire-caused-by-overheating-exhausts/ . Although I have yet to have direct confirmation from a source within Renault.

Seeing this was the first instance of such an occurrence that I can recall, I would imagine this might be examined by the FIA and technical directive issues asking teams to place this item in a more secure position to protect it and track officials from a similar incident.

More analysis of Renaults Front Exit Exhaust

http://scarbsf1.wordpress.com/category/front-exit-exhaust/

Book Review: Haynes Red Bull Racing F1 Car

When Red Bull Racing launched their new car for 2011, the event was marked by a very special press pack. The pack was formatted in the style of the well-known Haynes maintenance manuals (PDF). This in itself this was a great book, but almost unnoticed within its pages was the intended publishing of a complete Haynes style workshop manual on the RB6 car.
Now some six months later the Haynes Red Bull Racing F1 Car Owners Workshop Manual (RB6 2010) has been published. As its rare a Technical F1 book is published, not least one with insight into such a current car, I’ve decided to review the book in detail.

Summary
At 180 pages long the book has enough space to cover quite a wide range of topics and it does so. Starting with a background to the team, moving on to the cars technology, to overviews of its design and operation. With its familiar graphical style and hardback format it certainly gives the feel of a proper workshop manual. However this is somewhat skin deep and the pages within, soon revert to a more typical book on F1, although some flashes of the Haynes style do remain.

Steve Rendle is credited as the writer of the book and Red Bull Racing themselves have allowed close up photography of the car and its parts, as well as providing a lot of CAD images.
But clearly a lot of editing has been carried out by Red Bull Racing and the book falls short of its presentation as a manual for the RB6. Despite its confusing title, the book is probably better described as a summary of contemporary F1 technology from the past 3 years.
As the last in depth technical F1 book was the heavy weight title from Peter Wright showcasing Ferraris F1 technology from 2000, this remains a useful source of recent F1 technology.
This places the books target audience, somewhere between the complete novice and those already of a more technical mindset.

Anatomy

With forewords by Christian Horner and Adrian Newey, the opening 21 pages are a background to the team and detail of the 2010 season that brought RBR the championships. Then starts the core 100 page chapter on the cars anatomy, which opens with a pseudo cutaway of the car showing a CAD rendering of its internals.

Firstly the monocoques design and manufacture is covered, with images of the tubs moulds being laid up and CAD images of the RB4 (2008) chassis and its fuel tank location. Although little is made of the fuel tank design.
Moving on to aerodynamics, the text takes a simplistic approach to explaining aero, but there is an interesting illustration of the cars downforce distribution front to rear. This does highlight the downforce created by the wings and diffuser, but also the kick in downforce at the leading edge of the floor, but this is not adequately explained in the text. Mention is made of the front wing and the flexing that RBR deny, this is explained with a simple illustration showing the deflection test. The driver adjustable front flap, which was legal during 2009-2010 seasons, is explained, in particular that the wing was hydraulically actuated. When I understood that in 2009, only Toyota used a hydraulic mechanism over the electric motor system used by all other teams. In trying to explain the nose cone, the text and an illustration show a high nose and low nose configuration, but does not remark why one is beneficial over the other.

This section also covers very brief summaries of bargeboards, sidepods and the floor. Some nice close up photos of these parts included, but again with little explanation. An illustration at this point highlights the other FIA deflection test altered in 2010, which was aimed at Red Bulls alleged flexing T-Tray splitter. In this section the text cites Ferraris sprung floor of 2007, but not the allegation that RBR’s was flexing in 2010. A further simple graphic illustrates the venturi effect of the floor and diffuser, and then the text goes into simple explanations of both the double diffuser and the exhaust blown diffuser.
Having been one of the technical innovations of 2010 and since banned, the book is able to cover the F-Duct is some detail. A complete CAD render of the ducting is provided on page 53; this shows an additional inlet to the drivers control duct that was never visible on the car. This extra duct served the same function as the nose mounted scoop on the McLaren that introduced the F-Duct to F1.
Thus with aerodynamics covered in some 23 pages, the text moves onto suspension and the expectation of detail on the RB5-6′s trademark pullrod rear suspension. After a summary of the purpose of an F1 cars suspension, Pages 58-59 have some fantastic CAD renderings of front suspension, uprights and hub layouts. However the rear suspension rendering stops short at the pull rod and no rocker, spring, damper layouts are detailed. Hardly a secret item, so lacking this detail is let down for a book announced as an RB6 workshop manual. A lesser point, but also highlighting the censorship of some fairly key technical designs, was the lack of any reference to Inerters (Inertia or J-Dampers), The suspension rendering simply pointing to the inerter and calls it the ‘heave spring’, while naming the actual heave spring damper as simply another ‘damper’. Inerters have been in F1 since 2006, predating Renault’s mass damper. Their design and purpose is well documented and shouldn’t be considered something that needs censoring. It’s also this section that fails to showcase the RB5-6 gearbox case. Instead using a pushrod suspended RB4 (2008) gearbox, albeit one made in carbon fibre.
The steering column, rack and track rods are similarly illustrated with CAD images. This usefully shows the articulation in the column, but little of the hydraulic power assistance mechanism. Page 67 starts the section on brakes, again fantastic CAD images supply the visual reference for the upright, brake caliper and brake duct design. As well as a schematic of the brake pedal, master cylinder and brake line layout of the entire car. A nod to more typical Haynes manuals shows the removal of the brake caliper and measure of the Carbon discpad. A further CAD image shows the brake bias arrangement with both the pivot at the pedal and the ratchet control in the cockpit for the driver to alter bias.
Although not a RBR component the Renault engine is covered in the next Chapter. An overview of the complex engine rules regarding the design and the specification freeze kicks off this section and cites the tolerances and compression ratio for a typical F1 engine. Pneumatic valves, for along time an F1-only technology are explained, but even I failed to understand the schematic illustrating these on page 77. Also covered in the engine section is some more detail on the fuel, oil and cooling systems. With useful specifics, like capacity of the oil system at 4 litres and water coolant at 8 litres. Again some nice CAD images illustrate the radiators within the sidepod. Many sections have a yellow highlighted feature column; this sections feature is on the engine start up procedure, one of the mundane, but rarely talked about processes around an F1 car (other features are on the shark fin and brake wear). As KERS wasn’t used up until 2011, this topic is skipped through with a just a short explanation of the system.

Moving rearward to the transmission system, the old RB4 gearbox makes a reappearance. Again this disappoints, as some quite common F1 technology does not get covered. Page88 shows some close up photos of a gear cluster, but this is not a seamless shift gearbox. In fact seamless shift isn’t mentioned, even though it made its RBR debut in 2008, the year of the gearbox showcased in the book. I know many will highlight that this might be a secret technology. But most teams sport a dual gear selector barrel, each selector looking after alternate gears to provide the rapid shift required to be competitive in F1. So I think this is another technology that could be explained but hasn’t been.
Tyres, Wheel and Wheel nuts get a short section, before the text moves onto electronics. A large part of the electronic system on a current F1 car is now standardised by the Single ECU (SECU) and the peripherals that are designed to support it. So this section is unusually detailed in pointing out the hardware and where it’s fitted to the car. From the tiny battery to the critical SECU itself. Other electronic systems are briefly described from the Radio, drivers drink system to the rain light.
Of critical importance to the modern F1 car are hydraulics, which are detailed on p105. As with the other sections, CAD images and some photos of the items themselves explain the hydraulic system, although there isn’t a complete overview of how it all fits together.
Rounding off the anatomy chapter is the section of safety items and the cockpit. The steering wheel and pedals are well illustrated with CAD drawings and keys to the buttons on the wheel itself and on the switch panel inside the cockpit.

While I have pointed that the hardware shown in the anatomy chapter isn’t necessarily of the RB6, what is on show is obviously genuine and recent RBR. So for those not so familiar with the cars constituent parts, there isn’t a better source of this available in print today. Even web resources will fail to have such a comprehensive breakdown of an F1 car.

The Designers view

Moving away from the Haynes format of a workshop manual, the book then moves into a chapter on the cars design, with comments from Adrian Newey. It details the Design Team structure and some of the key individuals are listed. The text then covers the key design parameters; centre of the gravity and the centre of pressure (downforce). Plus the design solutions used to understand them; CFD, Wind Tunnels and other simulation techniques. Each being briefly covered, before similar short sections on testing and development close this chapter.
Although the text makes reference to creating ‘the package’, something Newey excels at. This section doesn’t provide the insight into the overall design philosophy, which one might have hoped for.

The Race Engineers view
Where as the Designers view chapter was limited, the race Engineers section was a little more insightful into the rarely talked about discipline of getting the car to perform on track. The process of setting up the car is covered; from the understanding of the data, to the set up variables that the race engineer can tune; suspension, aero, ballast, gearing brakes and even engine. Usefully the grand prix weekend is broken down onto the key events from scrutineering, to running the car and the post race debrief. Feature columns in this chapter include; Vettels pre race preparation and the countdown to the race start.

The Drivers view
Ending the book is an interview style chapter on the driver’s time in the car, mainly the driver’s perspective from within the cockpit when driving the car on the limit and the mindset for a qualifying lap. A simplistic telemetry trace of a lap around Silverstone is illustrated, although there is little written to explain the traces (brakes, speed and gear), this is accompanied by Mark Webbers breakdown of a lap around the new Silverstone circuit.

In conclusion
When I first got this book, I was constantly asked if it was worth the purchase or if I’d recommend it. If my review is critical at points, it’s mainly because some technology that could have been covered wasn’t. Or, that the content falls short of the books title suggesting it was a manual for the RB6.
Those points aside, I have learnt things from this book. Like details of the F-duct system, the Front Flap Adjuster and a wealth of smaller facts. There isn’t a better book on the contemporary F1 car. In particular the CAD drawings and close-up photos, just simply aren’t in the public domain. From the pictures we got over the race weekends, we never get to see half the hardware and design work that’s pictured in this book. So I’ll keep this book on hand for reference for several seasons to come.

Overall I’d recommend this book to anyone with a technical interest in F1.

Many thanks to Haynes Publishing who have allowed me to use their Images and PDFs to illustrate this article

This book is available from Haynes

10% rule: Full analysis

UPDATE: As with many of these issues arising over a GP weekend, its a rapidly developing story.  The position given to me by the teams ast night, has since changed, as Charlie whiting considered the situation overnight.  For the balance of the British GP, Mercedes engined cars (McLaren, Mercedes GP, Force India) will be able to use their fired-overrun.  As this was pre-agreed with the FIA for reliability reasons.  However Renault Sports request for their larger overrun throttle opening was requested after the event had started.  Thus Chalrie Whiting decided that, as the technical regulations for the event need to be agreed before the event, Renaults request was inadmissible for this event.   Thus they have to meet the original technical directive on throttle opening and not the 50% they had lobbied for.  This leaves Renault having to run a mapping which is not optimal for reliability and Mercedes can run their mapping.

After much expectation on the effect of the 10% off-throttle limit, what transpired over the opening practice sessions brought more confusion than clarification. As practice got under way it transpires that the expected 10% limit was in fact not applied to all teams, nor was the dispensation to the different engine manufacturers communicated clearly to all the others. This brought much confusion to fans and media alike, as well as bringing a heated debate between Martin Whitmarsh and Christian Horner in the Friday press conference. Its been reported that Renault engines have been dispensation to run at up to 50% throttle when the driver is off the throttle pedal, and slightly less well reported that Mercedes engined teams are able to run a fired overrun.

However, the situation was explained to me by several key technical staff in the Silverstone pit lane. The communication and political issues notwithstanding, the status is at least technically clear.

Firstly I gained detail of what the proposed 10% rule actually consisted of. In order to prevent teams using off-throttle engine maps to continue to drive airflow over the diffuser for aerodynamic benefit, the FIA proposed a pair of changes to what’s allowed when the driver comes off the throttle pedal. Firstly the well known 10% limit on the throttle opening, but secondly a ban on injecting fuel into the engine when off the throttle. The intention of this pair of changes was to ban both hot and cold blown engine maps.

Of course this was the FIA proposal; the original date of the Spanish GP was delayed while the teams lobbied their cases to the FIA, giving their reasons why such changes were unworkable given the timescales and restrictions on development.

Now we need to understand what goes on within the engine when a driver lifts off the throttle and the subsequent effect that has on other aspects of the car. Unlike in road cars the driver in an F1 car doesn’t leisurely lift off the throttle and delay the braking phase. Instead the driver may be at near maximum revs, when he will simultaneously lift off the throttle pedal completely and hit the brake pedal hard for the initial downforce aided braking event. During the braking event the gears will be sequentially selected, further peaking revs as the car slows. This sudden closing of the throttles blocks off the inlet to the combustion chamber, but the cylinder will continue to pump up and down at a great rate. This creates huge stresses inside the combustion chamber and the vacuum created will suck air past the piston rings. This will rapidly slow the engine, creating too much engine braking effect, which in turns creates downstream stresses in the drive train and over-brakes the engine. The excessive engine braking effect will make the car nervous on throttle lift off, regardless of any subsequent aerodynamic effect.

So engine manufacturers find different solutions to ease the stresses and braking effect of the driver lifting off the throttle. In the seasons before EBDs there were several different strategies in place, the driver was able to alter overrun setting to tunes the cars handling, and driver switching between teams found the change in overrun settings needed some adjustment to both their driving style and sometimes with the engines settings. So overrun settings were already an issue before EBDs, and many strategies were already outside the intentions f the 10% rule.

Renault have been open and said their engine already runs open throttles on the overrun, this both eases the blow-by and stress issues, it also usefully cooled the exhaust valve, an alternative to using excess fuel to cool the back of the valve. This year the Renault sport are believed to be running as much as 90% open throttle on the overrun. This is what’s best known as cold-blown mapping. Earlier this season and through out free practice at Silverstone, the three Renault engined teams, had a distinctive loud overrun note, which continues briefly as the drivers picked up the throttle out of slow turns. As the throttles are open more than other teams, the induction noise is far greater.

Mercedes HPE, equally have their solution, this is the so called fired-overrun. When the driver lifts off, fuel continues to be injected into the engine and sparked within the combustion chamber. This offsets the engine braking effect created by the engine, giving a smoother transition from on throttle to the overrun when off it. As a result this means there is less engine braking effect. This gives Mercedes the freedom to define braking bias and KERS charging, without having to account for engine braking. Effectively decoupling the engine braking effect from the actual action of the braking system. As with Renault’s pre-EBD mapping Mercedes solution is analogous to the hot blowing mapping. At Silverstone the Mercedes engined teams had a particularly clean overrun sound. Where as Ferrari had far more cracks and pops as the engine slowed.

With both engine manufacturers having long established overrun strategies that have critical impacts on the basic engine design or the braking system, it will be hard to rapidly switch to a very strict overrun mapping as demanded by the 10% rule. Both manufacturers lobbied the FIA to be allowed to retain elements of these old overrun strategies, while still emasculating their current strategies. The FIA have been able to see the mappings used in 2009 through to the current day, as the code is held by the FIA since the advent of the single ECU (SECU). They’ve been able to see the engines have had these long established mappings, but also how they have become more aggressive since the EBD has been developed.
So the FIA relented and although we will commonly call this the 10% rule, the actual throttle will allowed up to 50% and some fuel can still be injected and burnt in the engine. This sounds like a climb down by the FIA and unfair to different engine manufacturers. But the unreported events at Silverstone this afternoon are fairer than the picture being painted by the teams and the media. Its true that Renault were given their greater throttle opening, but also Mercedes were given their fired-overrun, but these dispensations have been given to every engine manufacturer, so Ferrari could have more throttle opening or Cosworth could develop a fired overrun. As I understand you can one but not both of these options, so no 50%-open with a fired-overrun.
Although the communication and timing of these clarifications appears to be wanting, the final rules clarification meets the basic needs of individual engine suppliers, but still maintains parity between the four parties involved. There is no doubt this allows some secondary benefit of greater flow through the diffuser on the overrun, but this is still greatly reduced over what’s been raced already this year. So there will be reduced aero effect and no further arms race in developing these aggressive strategies. After the furore dies we have been left with w reasonable compromise on reducing engine effect on aerodynamics, before the fuller bans comes into effect with periscope exhausts next year.

Valencia: Ban on engine map changes

A matter of days before the first practice at the European GP, there was surprising news that there will be a further restriction on engine mapping for this race. Ahead of the more stringent ban coming at the next round in Britain, in Valencia teams we have to start the race with the same engine map as used in qualifying. As with many of these FIA clarifications there is little information and even the teams have been hard pushed to provide full responses to my questions on the matter. With what limited information we have I will try to explain the impact of this change.

Currently teams are free to alter engine mapping settings between qualifying and the race, as these parameters are not part of the Parc Fermé regulations. Thus with the advent of hot & cold blown diffusers teams are able to run a much more aggressive map for their qualifying laps for more downforce and of course faster laptimes. Unable to run these maps through out the race, due to the fuel consumption penalty and the heat generated in the engineexhausts, after qualifying teams plug in a laptop and revert the engine map to a softer race strategy. These qualifying maps give a considerable laptime gain, some reports suggest over 0.5-0.8s per lap. This is also one of the reasons for Red Bulls superior qualifying pace relative to their race pace, as I reported last year http://scarbsf1.wordpress.com/2010/07/10/red-bull-map-q-the-secret-to-the-teams-q3-pace/.

Clearly Charlie Whiting is still unhappy that the engine is being used for aerodynamic advantage, he has brought in a restriction on the maps being changed after qualifying. I asked the teams what has been introduced. McLaren told me “same engine map from Q1 until the start of the race”. A fact also confirmed by Lotus and Renault. Therefore no specific engine maps are being banned, merely the teams have to make the judgement call, on whether they can run the first stint on an aggressive map or qualify on a softer map.

But this appears to only the basic principle of the rule revision, clearly there’s a lot more to it than that. It leaves the question of what can the driver change and when can he do it, as well how is this to be enforced. Again McLaren were able to explain some more “I think the intention is that you can’t alter the map – it would take too long to change it during a pitstop as you’d need to plug a laptop into the car”. So while we are used to seeing the drivers altering engine settings from the steering wheel, there is a limit to what he is able to achieve. Renault also were able to confirm “Some parameters are adjustable from the steering wheel, but not all. In Valencia, you can officially change your exhaust setting during the first pitstop, but you would need to plug a computer to the car, so it would take ages”. So it’s clear the driver is either not able or not allowed to make the changes from the Qualifying to the end of the first stint.

From what I’ve learnt, there is a difference between what we define as an engine map. There’s the settings the driver commonly makes via the steering wheel to fuelignitingrev settings, to either increase power or lower fuel consumptionpreserve the engine. But there’s also a level above that, to which the driver has no access to via the steering wheel. The engines parameters are managed via the Standard ECU (SECU), which also includes peripheral items such as the steering wheel interface. Thus to make changes to the main map the team need to plug a laptop into the car and makes changes via the software interface.

Its been suggested the team could code a control on the steering wheel to alter the map between aggressive and soft and simply switch in the first stint, however the FIA have access to the data off the SECU which controls these parameter and could detect if this change had been made, which would be in contravention of the rule.

However its likely that the driver can still make changes to setting on the main map, during the first stint from the steering wheel, but not to the extent where it will go from full aggressive to soft. But simply to find a tactical short term boost or fuel consumption saving, as they normally would during a race.

Equally people have suggested the teams could develop a quicker method for altering the map at the first stop, rather than plugging a laptop in. I guess this is a possibility, assuming the SECU supports any alternative method. But it should be pointed out that the aim of this rule is to stop the aggressive hot blown qualifying maps, which will be restricted to the point of ineffectiveness at the next race (Silverstone), so it’s unlikely any teams would risk any literal interpretation of this rule. If indeed there isn’t already any additional info available to the teams or direction form Charlie Whiting that isn’t public that prohibits this.

If a team were able to run the first stint with an engine and fuel tank that could cope with the load from the aggressive map, the laptime gain might offset the time lost at the first pitstop. This RiskReward scenario might be played out in Valencia, but I’d doubt any of the top teams with these aggressive maps would take such a risk without weeks of testing and pitstop practice with the laptop. The short notice of this rule change no doubt aided the FIA in circumventing these sorts of workarounds.

Another workaround suggested has been set a lap fast lap on an aggressive strategy, pit, then change maps and run a lap on the race strategy. But the FIA are already beating this trick in two ways. Firstly the same map must be from used Q1, therefore all qualifying laps will have to be made with the same mapping as for the race start. This will further add to the deterrent of teams using aggressive maps, as this accounts for several extra laps in Q, as well as the first stint. This will be hard on the engines life and the fuel consumption. Secondly just as with tyres, it’s the set up on which the cars fastest lap is set that becomes the set up to start the race. It seems there are few workarounds to the rules.

The impact of this rule is teams will have to reign in their qualifying maps, this will cost them laptime and obviously any teams with an overly aggressive map will suffer more. The introduction at Valencia is significant as blown diffusers give the car more low speed downforce, although Valencia is not the slowest track on the calendar these maps will provide a big chunk of laptime at this circuit. Paddock rumour places Red Bull towards the top of the list of Q-Map users, so we could expect a smaller gap between them and FerrariMcLaren, but I doubt this would account for all of the laptime difference. McLaren are also a team with a well developed Q-map, where as Ferrari are still believed to be immature in this area of development. Further down the field the other Renault engined teams and the Cosworth teams are likely to suffer less. Which should bring the tailenders a few tenths closer to the P1 time in Q1 reducing the fear exclusion on the 107% rule.

Going forwards this rule change is likely to be retained; further reducing the special qualifying set ups that the FIA have spent the last ten years restricting. It seems now there is very little the teams can do to alter the car between a qualifying and race set up.

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