Audi have just launched their latest LMP car to contest the Le Mans 24h, Now with a downsized V6 turbodiesel the chassis has been given a closed cockpit.   The chassis exploits both current thinkign and some innovations.  I’ll soon add more detail to this article, for now I just wanted to post the pictures, each with as simple summary

R18 - front diffuser

R18 - Diffuser flow out through gap between chassis and wheelpod

R18 Tail fin - working with the chamfered underfloor, the fin creates high pressure above the car to prevent blowovers when the car's sideways

R18 wing pillar, the pillar forms a structural end to the tail fin, it's swan-necked to fre the underside of the wing from obstructions

R18 two part doors - following Peugeots lead, the doors are split to meet the FIA template, only the top half is normally opened

 

R18 front vanes - in order to maintain flow 'through' the car and still obscure the mechanical parts, these vanes are used

 

R18 wheelpods - pressure build up in the wheel arches creates lift, venting the arch helps creates downforce, the size of the upper vented openings are constrained by the rules

With KERS being revived and expected to race again next year, let’s just recap what hardware’s involved and how its packaging affects the car design for 2011.

KERS (Kinetic Energy Recovery System) is a hybrid drive system that the FIA allowed to be raced as part of the 2009 major rules rewrite. It allows energy to be harvested under braking and stored, then that energy can be released to provide a power boost for around 6s per lap.
In 2009 most engine manufacturers developed their own KERS system, while Williams were the sole team developing a system independently. Albeit not every team raced with KERS and some teams dropped KERS at various races. For 2010 FOTA agreed to drop KERS, albeit it was still legal with in the rules, as a cost cutting measure it was best not to run or develop KERS any further. Even within 2009 season KERS was not a huge success, the system had a FIA cap on the amount of energy that could be re-used, only 400kJ could be stored, which when used for 6.7s per lap, the car gained some 80hp. Thus although a 0.3s boost to laptimes, the system was ultimately limited in its potential to improve laptimes. Thus no team could create a competitive advantage from a more powerful system. Then the weight of the system created issues, At a time when the wider front slick tyres demanded an extreme weight distribution of up to 49% weight on the front axle, the 25+Kg of a KERS system mounted behind the CofG handicapped teams being able to push weight forwards. Most teams dropping or not racing their system cited weight as the main reason for its loss.

What is a KERS system?
In essence a KERS systems is simple, you need a component for generating the power, one for storing it and another to control it all. Thus KERS systems have three main components: The MGU, the PCU and the batteries. They are simply laid out as in the diagram below:

In detail

MGU (Motor Generator unit)

Marelli MGU as used by Ferrari and Renault

Mounted to the front of the engine, this is driven off a gear at the front of the crankshaft. Working in two modes, the MGU both creates the power for the batteries when the car is braking, then return the power from the batteries to add power directly to the engine, when the KERS button is deployed. Running high RPM and generating a significant Dc current the unit run very hot, so teams typically oil or water cool the MGU.

Batteries

McLaren Mercedes Battery Pack complete with water cooling system

During the 2009 season only electrical batteries were used, although at least two flywheel systems were in development, but unraced. We will focus on the arrays of lithium-ion batteries that were raced. Made up of around 40 individual cells, these batteries would last two races before being recycled. In McLaren’s case these were mounted to the floor in the sidepods beneath the radiators. Other teams mounted them in a false bottom to the fuel tank area for safety in the event of a crash. Being charged and discharged repeatedly during a lap, the batteries would run very hot and needed cooling, this mainly took the form of oil or water cooling, and again McLarens example had them pack water cooled with its own pump and radiator.

PCU (Power Control Unit)

McLaren Mercedes PCU

Typically mounted in the sidepod this black box of electronics served two purposes, firstly to invert & control the switching of current from the batteries to the MGU and secondly to monitor the status of the individual cells with the battery. Managing the battery is critical as the efficiency of a pack of Li-ion cells will drop if one cell starts to fail. A failing cell can overheat rapidly and cause safety issues. As with all KERS components the PCU needs cooling

Marelli prototype PCU

Ancillaries

Aside from these main components the KERS system also integrates with the FIA SECU in order to control and monitor the PCU. KERS has to be driver activated; this is achieved from a steering wheel button. Although the drive has to initiate the KERS boost, the teams set the system up such that the driver knows to engage the system out of specific corners, the system then delivers the predetermined amount of boost specific to the demands of that section of track. In practice the KERS systems is being charged and discharged to this preset map of activations. Which smoothes the balance between charging and discharging, so the system does not overcharge above the regulatory limit. Again the SECU ensures no more than the capped amount of energy is delivered each lap.

KERS in 2011
With KERS return to F1 next year, the designers are faced with the same operating requirements in terms of energy storage and discharge. But the packaging requirements of the systems have changed in the two years since its introduction. Firstly the penalty of weight distribution has eased. With narrower tyres and the move to a fixed weight distribution for the Pirelli tyres, means that 25kg KERS system no longer tip the weight balance the wrong way. Plus there will be a higher minimum weight limit for next year.
But challenging the designers will be the amount of space to package the hardware. With the ban on refuelling, teams have enlarged the fuel tank into the sidepods to create sufficient capacity, already the sidepods are full of longer narrower radiators and the gearbox oil coolers have been moved to above the gearbox to save space in the sidepods. Then the aerodynamically undercut shape of the sidepods robs yet more volume.
Given the success of McLarens sidepod mounted solution in 2009 and the safety concerns that dogged the systems introduction, means that teams will probably opt for sidepod mounting of the Batteries and PCU. Especially as to expand the fuel tank area to mount the batteries as in 2009 will create a huge bulky rear to the monocoque. There will no doubt be an aerodynamic penalty to the slightly bulkier sidepods to house the hardware and additional cooling. This needs to be less than 0.3s laptime penalty in order to offset the gain from the power boost. Even with the gains and losses in laptime with a KERS system, teams may opt to run the system simply to use it for an overtaking aid in the race. Off the line and onto long straight the boost might be enough to overtake a rival.

Hydraulic KERS

A filament wound carbon fibre Hydraulic Accumulator

A further alternative to the generation and storage of energy is to use hydraulics. This system has some limitations, but with the capped energy storage mandated within the rules the system could see a short term application. Separate to the cars other hydraulic systems, a hydraulic KERS would use a pump in place of the MGU and an accumulator in place of the batteries. Simple valving would route the fluid into the accumulator or to the pump to either generate or reapply the stored power. Hydraulic accumulators are already used in heavy industry to provide back up in the event of failure to conventional pumped systems.
Using filament wound carbon fibre casing, an accumulator of sufficient capacity could be made light enough to fit into the car (see http://www.ctgltd.co.uk/page/hydraulicaccumulators/47). They might be capped in terms of practical storage with in the confines of an F1 sized system, but McLaren had prepared just such an energy recovery system back on the late 90s, but it was banned before it could race. With the relatively low FIA cap on energy storage, just such a system could be easily packaged, the hydraulic MGU would be sited in the conventional front-of-engine position and the accumulator, given proper crash protection fitted to the sidepodfuel tank area. Saving space would be minimal control system (equivalent to the PCU) as the valving to control the system could be controlled by the cars main electro hydraulic system. McLaren have recently been quoted as saying the 2011 KERS would be more hydraulic and less electronic. Giving rise to speculation that a hydraulic storage system could be used.

Flywheels

A Flybrid Flywheel system, similar to that intended for the 09 Honda F1 car

As Li-ion batteries are still an expensive emerging technology, plus they have associated risks, recycling and transport problems. The attraction of flywheel KERS is obvious, however no team have raced such a system in F1. Flywheels can effectively replace the Li-ion batteries with in a typical KERS system, the flywheel being mated to a second MGU to convert the power generated by the primary MGU on the engine into the kinetic to be stored in the flywheel. Williams are believed to have just such a system. However the simper flywheel solution is connect the flywheel system via a clutched and geared mechanism. HondaF1 had developed this solution for their 2010 car. This solution was dropped as Honda pulled out and the renamed Brawn team need to focus development resources into the new car and its conversion to Mercedes power. The Flybrid made system would have sat with in the fuel tank area coupled to the crankshaft. This created a system simpler system of equal weight to a typical KERS. The main components being the flybrid flywheel and Torotrak system, plus a relatively small ECU, no additional cooling would be required. Thus the system could be far easier packaged into the chassis robbing just 13l of fuel tank space. A proposal was made to the FIA for a supply of this system to every team on the grid as a cost cutting measure. It seems the FIA did not take up this offer. So it seems this technology may be resigned to lower Formulae or non Motorsport applications.

Update:

Honda F1 Electric KERS

Although they also had a flywheel system in place, it transpires Honda also had an electric system.  ITs described in some detail in this link.

http://www.greencarcongress.com/2010/11/hondas-f1-kers-motor-60-kw-21000-rpm-7-kg.html

Linked images copyright
Generic KERS diagram – Craig Scarborough ScarbsF1.com
McLaren KERS – Racecar-engineering.com
Marelli KERS Highpowermedia.com

My Technical review from the Hungaroring is now on Automoto365.com.

With the updates on:

Flexing wings

Renaults: extreme rear wing

Williams: aero test & cooling outlet

Mercedes: diffuser regeression

Force India: blown diffuser

Torro Rosso: New Diffuser & Nose vanes

Lotus: all-carbon suspension delay

http://bit.ly/cKb90D

or

http://f1.automoto365.com/news/controller.php?lang=en&theme=default&month=8&seasonid=21&nextMode=ExclusiveNewsForm&news_id=41855

I’m up to 3500 followers on twitter, ‘follow me’ to get the latest technical updates as they happen…

This was my Tech Desk scheduled to be published after the British GP.   For various reasons it was not published and I have copied here…

Round10 of this year’s championship, see’s an unplanned return to Silverstone after the developments at Donnington the intended venue failed to progress.  Even with the short notice the famous Silverstone layout saw a major revision with a new in-field stadium section.  Despite the new section being another fiddly low speed section, much like the complex of turns ending the lap, the fast turns remain a key feature of the track.  As a result the track demands high downforce, but also a high level of aero efficiency as the teams cannot afford to lose too much speed on the straights.  With the demand on a mix of low speed grip and higher speed turns, the race saw the debut and return of several F-duct and blown diffuser solutions. Additionally several teams brought major development steps to their cars for this weekend, in expectation they will also provide gains at the forthcoming races.  Being an aero dominated track usually demands a stiff suspension set up, but the transition between the old track and the new section produced some tricky bumps and steps in the surface, especially affecting the braking areas. 

McLaren

Caption: McLarens blown diffuser placed the exhaust low and wide, making the sidepods extremely small.

McLaren brought forward their developments originally scheduled for the German GP; this consisted of a new front wing and the Exhaust blown diffuser package.  Both cars were equipped with the comprehensive package of parts that make up the blown diffuser, floor, sidepods, exhausts and heat shields were all specific to this set up.  McLaren’s iteration of the blown diffuser is similar to Ferrari and Renault solution, repackaged exhaust blow low down over the diffuser.  The effect at the diffuser exit as the exhaust passes over the gurney flap is to help extract air form under the diffuser, effectively making the diffuser think it’s bigger than it is.  In McLarens case the exhaust is placed quite far outboard from the cars centreline, this probably allows the flow to pass into the low pressure area behind the rear wheels for a reduction in drag.  With the exhaust exits now low down the large fairing that wrapped around the exhaust to aid cooling no longer exists.  With the unusually warm British weather the fitted new optional cooling outlet sin the similar position to the old exhaust outlets.  These used the Ferrari trick of slotting the louvers together to create the regulatory single exit.  Coping with the heat of the exhausts the lower wishbone was fitted with a carbon heat shield and this along with large parts of the diffuser were given a silver heat reflective Zirconium coating. 

In practice the blown diffuser set up complicated what appears to be stability problems for the MP4-25′s, in the corners where the old track met the new.  The car was unsettled by the bumps and steps in the road, frequently running wide on the exit of these turns.  This instability is probably not caused by the blown diffuser, but rather the stiff set up McLaren have preferred to run this year.  Regardless the blown diffuser was removed from both cars after second free practice and replaced with the normal top bodywork.

Although the diffuser was dropped the new front wing was retained for the whole weekend, it was a completely new wing and a very different philosophy from that seen before.  The wing is effectively split into two sections each side, the outer section sitting n front of the front wheel, which is split from the inner part of the wing via a fence.  Presumably McLaren are trying to boost the efficiency of the inner wing whose wake is unaffected by the front tyres, then leaving the less efficient outer portion separate.

Red Bull

A number of updates to the RB6 were tried over the weekend.  Grabbing the headlines for non technical reasons was the revised front wing, but there was a revised diffuser and a new f-duct set up was also tried on Friday.  The new front wing consisted of revised nosecone, wing mounting pylons, wing elements and endplate. While the wing itself was a similar three element to recent iterations of Red bull wings, the endplate now sported larger slot in its side to expose the two slots formed between the main plane and the flaps, this aids the airflow being directed around the front tyre.  also new was the position of the FOM camera pods, having been mounted hammer head style since the cars launch, they are now mounted almost siamesed between the front wing mounting pylons.  This places them above and behind the wings neutral centre section.  Force India tried this set up briefly but has never progressed with the idea.  What the camera position is trying to do is the negate some of the lift the neutral wing section creates, but mounting the equally neutrally shaped camera pods in a cascade with the wing; they may actually act more like a wing.  Although the nose cone is a primary crash structure and thus its design homologated for the year, team ‘skin’ retain areas of the wing allow small shape changes without having to request re-homologation.  So red bull were able to alter the camera mounts without any legality issues.

However of the two wing assemblies that were manufactured, the set up on Vettels car failed in final practice.  It appears that the pins that locate and secure the nose cone to the front of the chassis failed, allowing the wing to droop and scrape along the track.  With only one spare nose cone there became the political issue of which drivers uses the set up for qualifying.

Other developments on the car were the diffuser.   This has now gained a second slot.  This is in addition the vertical slot that allows the exhaust to blow into the upper deck of the diffuser.  This new slot is horizontal and outboard of the first one and feeds directly into the side channel of the diffuser.  By blowing more of the exhaust inside the diffuser, there is greater scope to create more downforce.  However this could possibly come at the cost of sensitivty to throttle position, so Red bull must have judged the design carefully to ensure is does not upset the balance of the car.

Also for Silverstone was a revised high pressure feed for the F-duct.  In its initial form the F-duct used a section of the main inlet snorkel above the drivers head.  This would have stolen some airflow intended for the engine, potentially costing some power on the open throttle sections of track.  so the team tried a separate inlet taken the right hand side of the roll structure, this scoops feeds the fluid switch inside the ducting, sending its flow either to the slot in the wing or the outlets placed in the tail of the engine cover, depending if the driver has the control duct covered.  In testing this new inlet, the team sprayed flow viz paint on the bodywork to track the surface airflows.

Williams

Caption: All new top bodywork brought a blown diffuser and revised F-duct, while the roll hoop oil cooler was closed off

Following on from the major front end updates seen at recent races, for Silverstone Williams brought their next batch of upgrades mainly focussed on the rear end of the car, although new front suspension geometry was also fitted.  Primarily the change has been to fit a blown diffuser, but the team have also made change to the F-duct, brake ducts and some drag reducing changes.

Of all the teams adopting the blown diffuser, Williams have been the only team to closely follow Red Bulls design.  The shape and position of the low exhaust exits closely mimic the RB6 design, admit technical director Sam Michael “Ours is most like the Red Bull when you look at the exhaust exits and how we are working the diffuser”.  However what’s not clear so far is if the exhaust flow enters the diffuser via the small window or simply flows over the diffuser.  unlike McLaren Williams retained their low exhausts fro the race, the team having to make some changes to the car to keep parts cool and in position, the additional heat shielding and bodywork stays cost the team a half a tenth in pace according to Sam Michael, but he felt this would recouped by the time the car was revised for Germany.  The team also hope that cosworth will be able to develop a reliable Q-mapping, again similar to the Red Bull solution, where the engine mapping alters under braking to keep exhaust gasses flowing over the diffuser.

Along with the new top bodywork to accommodate the low exhausts, the F-duct was altered, unlike other teams this is a low pressure solution, there being no high pressure feed from the airbox inlet.  Also the airbox area has been tidied up, with the distinctive secondary inlet for the oil cooler, being closed off for this race, as a drag reduction measure.

Ferrari

Returning with their exhaust blown diffuser in slightly revised form, Ferrari’s major development was a new front wing.  This new wing sports three profiles, over the two favoured by Ferrari all season.  Additionally the profile of the main plane kicks upwards far more aggressively where it meets the endplate, although the endplate philosophy remained the conventional endplate and vane arrangement first seen on 2009.  As Alonso has completed his fourth GP with the same gearbox, he was able to upgrade tot he same specification as Massa first used in Valencia.  This new casing repositions the lower wishbones to suit the lower exhaust position.  Both the exhaust outlet and the heat shielding were subtly revised for Silverstone, the exhaust outlet being chamfered slightly and the Heat shield on the floor directly behind it now being a separate item to allow some protective cooling flow between the floor and the shielding.

Lotus

Caption: Lightweight bodywork, was both slimmer and covered a package of lightweight internal parts

As announced by the team, Lotus arrived with a major update package to the T127.  Visually this largely consists of new sidepods, although more importantly it also incorporated a new diffuser and a host of weight saving measures.  Firstly the new sidepod package keeps the same internals, but the top body has been considerably slimmed, especially to the coke bottle shape near the exhaust outlets.  Also benefiting the more aerodynamically efficient bodywork the top bodywork section is now in one piece and lighter than the multi piece solution used up until this point.  Mike Gascoyne also confirmed that further weight savings’ come from the radiators “The same rad’s can be fitted but we are also running a lightweight radiator package this weekend” adding “We are running lightweight bodywork, rad’s, uprights, chin etc”.  This weight saving is critical as it allows the car to run more ballast to tune the mechanical set up of the car.  This weight saving is in itself difficult as the team run a fixed specification; engine and gearbox, as well as homologated monocoque and crash structures.  Looking forward the team have already stated their focus will be on the 2011 car now, but there remain some updates in the pipeline, as outlined by Gascoyne “we still have Titanium wishbones, composite ones will come in 2 races” then ”There will be final aero updates for Spa and further lightweight parts”.

Virgin 

Caption: virgin brought an all new front wing, with Red Bull-like endplates and low mounted camera pods

Having had to devote time earlier in the season to resolving the fuel tank issue, Virgin have taken some time to reach their first major performance developments to the car.  For the British GP, the team brought lightweight parts, a new front wing and turning vane changes.  Much like Lotus, the parts designed to go on the car for the early part of the season, have now been reviewed and lightened. Creating more opportunity to lower the centre of Gravity and weight distribution, via the addition of ballast.  Their front wing is a very different solution to their launch wing, being vaguely Red Bull-like, with a full size endplate aided by two slots.  Even the inner edge of the endplate gains a tiny aerofoil as Red Bull has run for two years. 

Then taking a cue from Mercedes, the team have placed their FOM camera pods low down behind the front wing to gain additional aero effect.

My technical review is now online at automoto365.com http://bit.ly/cLh8Er.  Detail of the workings of Red Bulls f-duct plus other developments from Red Bull, Ferrari, Force india and the others.

http://f1.automoto365.com/news/controller.php?lang=en&theme=default&month=6&seasonid=21&nextMode=ExclusiveNewsForm&news_id=40907