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

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

History: Periscope Exhausts

Following the meeting of the Technical Working Group, the FIA have agreed to mandate periscope style exhausts from 2012. This has been in an effort to rid the sport of exhaust blown diffusers, a trend that has dominated aero development in 2010 & 2011. While initially it was the FIA’s intention to move exhausts to the rear of the diffuser, the teams preferred to route the exhaust out of the top of the sidepods “periscope” style. This solution is far more aero neutral and prevents teams developing new complex exhaust routing to gain what little aero advantage there is from the rear exit. Also it benefits the engine suppliers who don’t have to retune their engines for long secondary exhaust pipe lengths.

It’s interesting to note the history of the periscope exhaust, as this was at first a retrograde step in aerodynamic development. Historically F1 cars ran their exhausts straight out of the back of the car. Only the introduction of ground affects and turbo engines forced a packaging rethink to exhausts routing through the top of the engine cover. When ground effects were banned and teams sought to find some aero gains at the rear, it was Jean Claude Migeot, who was then the head of aero at Renault, doing the exhaust blown diffuser solution in 1983. This trend continued through the late nineties, when F1 engines were normally aspirated and the V10 format became the trend, as were ever higher rev ceilings. Teams were finding the aerodynamics sensitive to throttle position and slowly they started to move the exhaust away from the diffuser kick line and towards the trailing edge to reduce this sensitivity. This necessitated quite long secondary exhaust pipe lengths (the single pipe section leading from the multipipe collector). This passed the exhaust in close proximity to the gearbox and hydraulics as well as the rear suspension, which at the time was starting to be made form carbon fibre. Back in ate nineties materials were not as advanced as they are now and heat resistant materials were not as effective.

In 1998 this forced Ferrari into a rethink of the exhaust solution. Head of Aero at Ferrari at the time was Willem Toet, he explained to ScarbsF1 how the periscope came to be. He starts with an honest explanation “I was sort of forced into the periscope exhausts at Ferrari”. At the time Ferrari were developing their 90-degree V10 engine, seeking to find higher revs to regain the power lost from the more powerful V12s. This engine developed was the catalyst for the move according to Toet “Long pipes didn’t suit the engine at all so we needed to go short”. Unable to create the long secondary pipes the traditional rear exits were unviable, however their first solution was not immediately the periscope, “We found the best solution, quite an aero gain at the time, was to exit the exhausts out of the sides of the bodywork beside and ahead of the rear tyres with an extra panel to protect the tyres from hot exhausts. That’s how the car was launched”. This solution met the initial aero and engine development targets, but was not without its problems, as Toet adds “The materials available at the time weren’t so advanced and we had mechanical grip and driver feel problems associated with the rear suspension, still steel on the Ferrari in those days, deforming under temperature. We were forced to abandon this due to the handling feel of the car”.
Again the workaround was not the periscopes “We went to a simple blown diffuser but the performance loss was “noticeable”. We then tried a short pipe leading into but not connected to a secondary pipe but had some fires due to exhaust flame outs off throttle that then caused problems”. With other solutions finally exhausted Toet shifted to an up and out exhaust solution, which we tend to call periscopes, but he terms snorkels. Toet concludes “And so the exhaust snorkels were born. Then with lots of optimisations we got them to work quite well (not as good a solution aerodynamically speaking as the side exits but not bad in the end). The solution then allowed for tighter rear bodywork which began to bring further benefits”. Looking at the rear of the 1998 Ferrari F300, the first design of periscope stood the test of time and in concept hasn’t changed much in the ten subsequent years. Ferrari of course had initial problems with the periscope design. Although the shorter exhaust bundle kept the radiated heat away from the side of the gearbox, where the suspension and hydraulics are packaged. But instead the hotter exhaust plume played over the rear bodywork of the car and critically over the suspension. Ferrari suffered suspension problems despite their early attempts at heat reflective materials being added to the upper wishbone. Detail development continued and by the end of the season Ferrari had proven the periscope was a workable solution.

F300 periscope exhaust, courtesy of Gurneyflap.com

It was a while before other teams followed the periscope solution. As their engine suppliers demanded shorter pipes, their carbon fibre suspension struggled with the heat and the throttle sensitivity upset the handling. So eventually every team switched to the up and out solution. By 2001 nearly all teams had gone this route. Leaving just Minardi and McLaren with blown diffusers. Minardi exiting their exhaust relatively high up over the trailing edge of the diffuser, at the time technical director Gabrielle Tredozi told me this was to reduce heat rejection and throttle sensitivity. However the team did trial some low exit exhausts, similar to McLarens at the high speed tracks of Indianapolis and Monza. But for 2002 the Asiatech V10 engine Minardi were to use demanded shorter exhausts and Minardi went for the periscope design with the Gabrielle Tredozi designed PS02.
Up to the 2001 MP4-16 Adrian Newey at McLaren directed his exhausts low down through the central boat tail of the diffuser. But in 2002 Newey was forced to go with periscopes, as he explained to me in my first ever interview with him in 2002 “The 2000-2001 cars had the same engine, we now have new engine, and different V angle that’s obviously changed, some of the packaging of the car the engine also has some different requirements, which is affecting us. Requests from the engine supplier Ilmor were different exhaust system requirements which meant we could no longer continue with putting the exhausts exits out through the floor so we had to go for top exits”. I pressed him if this was purely for engine demands, which he confirmed, but when asked if it was specifically for shorter pipe lengths he cautiously replied “I’d rather not go into details; we couldn’t accommodate what was wanted”.
So by 2002 every team had exploited the less sensitive, but aerodynamically inferior periscope design. It seems the effect of blowing the top rear wing or beam wing was of little advantage with the periscope design. However the trend in the 2000′s was for ever tighter sidepods, the periscope design enabled teams to go much further with the slimness of the coke bottle area as the pipes no longer needed to exit rearwards through the tail of the sidepod, they could be packaged further forwards in the sidepods. Slimmer and slimmer rear ends were developed, all to the benefit of the diffuser airflow, which in itself reaped aero gains. Initially the teams had the exhaust collector point upwards, with the short secondary pipe pointing up the turning 90 degrees to exit rearwards horizontally. As sidepod heights and widths reduced it became better to point the collector forwards and curl the secondary pipe in a “U” bend to point backwards. This placed the bulk of the exhaust system above the radiators and left very little volume to the side or behind the engine, to the benefit of the slim rear aerodynamics.
During the 2000s teams continuously varied the exit format of the exhaust. At some points during the decade an oval exit was used with a small horizontal stiffener added for strength. Also the exit varied between flush to the sidepod surface and protruding through the bodywork. Ferrari adopted a protruding exhaust, surrounded by a tall fairing that aided the extraction hot air from the sidepods. Some teams also exploited the hot exhaust for rear tyre temperature. Jordan exited their exhaust high and wide through the flip up ahead of the rear wheel. They had optional exhaust pipes that sent more of the exhaust plume over the rear tyres to increase their temperature. Renault also briefly tried a scoop that caught some of the exhaust plume and directed it over the rear wheel.
Then in 2010, it was Adrian Newey who returned the exhaust position to low down on the RB6, in order to exploit the fast moving exhausts gasses passing over and through the diffuser, the Exhaust Blown Diffuser was reborn. Several teams discarded periscopes during 2010 for low exhausts. But for the start of 2011 every team had gone for a low exit and the periscope disappeared. It appeared as though it was lost from F1. Now with its mandatory renaissance in 2012, it will be interesting to see if teams can further develop this simple concept further.

History: BAR Honda 2-3 Element Rear Wing

copyright: Craig Scarborough

Looking at the Ferrari Spanish GP rear wing with its literal interpretation of the slot gap separators, it brought to mind another rear wing designed to work around the rules. Back in 2004 the FIA introduced a further limit on upper rear wing elements, going down from three to just two elements, a rule that stands to this day. In 2003 teams ran with what was often called a bi-plane rear wing. That is the three elements were mounted as: a two element wing (main plane and flap) and a further element cascaded above them. When two elements were mandated, the wording in the technical regulations was vague and defined what constituted the two closed sections by defining how large a space was allowed between them. This left some opportunity for a different interpretation. Willem Toet was then the Head of Aero at BAR Honda, he and his design team found a way to make a three element wing meet the wording of the two element wing.

Credit: Willem Toet

By joining the three element wings cascade element to the flap with twisted vanes, the cross section of the assembly always met the FIA definition of a closed section. Each of the 20 vanes joind the two wing elements such that any cross section always had the upper and lower elements joned by part of a vane. This met the rules, just as the fishbone exhaust outlets in 2009 or the F-duct slots in 2010 met the closed section rule.

This high downforce wing was initially envisaged for a Monaco Debut, but was already prepared before the car was launched. BAR had planned a media launch day at Barcelona, as was often the practice back in those days, the teams reserved the track the day before for a shakedown and filming. Taking this opportunity to test the wing the team ran the 20-3 element design for several laps and then hid it away from the media arriving for the launch the next day. Un be known to the technical team, these laps were photographed and filmed for the teams official website and PR material. At one point it was said this “secret” rear wing was on the front page of the BAR Honda website! Once discovered the public images were removed, but BAR feared the secret was out. The wing was track tested at Silverstone by Anthony Davidson. I was unaware of the wing and only noticed the vanes when reviewing the photographs. Although I recalled that the team were fitting a gurney to the car at the time that had slots cut out. At the time I thought this was to allow the carbon fibre gurney to flex around a curved wing. Then my first inspection of the images made me think that a gurney with 20mm serration was being tested. Only later did I discover the 2-3 element wing was being tested and the reasoning behind it. However BAR feared a protest would be lodged if they raced the wing at Monaco so it never appeared at the principality.

Later in the season BAR innovated again with deep fences being fitted to the rear wing, both these and the 2-3 element wing prompted clarifications from the FIA on variation in aspect ratios of the rear wings cross section. Although not published, these demands probably still stand today.

Credit: Willem Toet

 

Red Bull – Monaco floor analysis

Monaco is a unique venue, not just for the layout of the circuit, but also the pit lane facilities provided to the teams. With no space for a conventional paddock and pit building, the teams park their transporters away from the small pit garages. Thus parts have to be ferried in-between the trucks and the pit, as well as parts being stored in the upper floor of the pit facility. Luckily for F1s technical observers, this presents an opportunity to see parts not normally exhibited in front of fans. Just such an opportunity presented itself to Jean Baptiste (@jeanbaptiste76) who saw Mark Webbers floor being lifted up to the mezzanine, through the crowd he was able to a quick photo of the entire assembly. From a single picture we have been to gather a lot of info on the design of Red Bulls floor. We’ve confirmed where the exhaust blows, how the trailing edge forms a flap and exclusively how the starter motor hole is blown by ducts in the upper floor. There also a wealth of detail not normally visible, although not unique to Red bull, seeing this detail is a rare treat.

Firstly we can see that this is a floor that has been run on the car, evident by the burns and dirt generated to what would otherwise be pristine black and silver floor. I suspect this is a floor assembly used for free practice, as the floor ahead of the rear tyres still sports the tyre temperature sensors. These are not typically run from qualifying onwards.

We can also see that the floor is in one complete piece, which is unusual. Normally the front t-tray splitter section is removable. Perhaps with the front splitter being lighter this season, it no longer formed of a large piece of ballast, making having a one piece floor more convenient. Plus the new more stringent splitter deflection tests are probably easier overcome with a single structural assembly, rather than two assemblies bolted to the car. Plus we can see the front bargeboards are a permanent fitment to the floor, whilst the sidepod fins are unbolted from the floor and remain attached to the sidepod fronts.

Exhaust routing

Silver coating (zircotech) and gold film provide heat shielding

We’ve seen many pictures of the Red bull exhaust system, how it curls down to pass the exhaust along the floor towards the outer 5cm of floor aside the rear tyres. Obviously no exhausts are fitted to the floor, but the general heat protection within the engine bay appears a coating applied to the carbon floor (most likely Zircotech). Additional local heat protection is provided with separate heat shields and gold reflective sheet, under the exhaust area. The exhausts then run out of the engine bay and along the floor. Again reflective coating is used on the bare floor beneath.

The exhausts route along the floor and blow beneath the diffuser

We can then see the exhaust exits to the edge of the tyre decks 9the small section of floor between the tyre and diffuser. This area is extensively cut away and the edge of the floor is a metallic part which curls up to encourage the exhaust to pass beneath the floor and into the diffuser. We have seen from pre-season (http://scarbsf1.wordpress.com/2011/02/02/red-bull-rb7-open-fronted-exhaust-blown-diffuser/) that the exhaust curls up into the outer top half of the diffuser, further proven by the additional heat protective coating applied in this area. Recent pictures of the Ferrari being craned away in Spain, show that Ferrari do not shape the floor to encourage as exhaust flow to pass under the floor, McLaren are also more similar to Ferrari than Red bull in this regard. As of Monaco 2011, Red Bull were the only team to passing the exhaust flow under the outer edges of the floor towards the diffuser.

Trailing edge flap

On the diffusers trailing edge a flap aids downforce

Red Bull switched to a revised diffuser at the Chinese GP, this exploited a new treatment to the top trailing edge of the diffuser. Rather than a simple Gurney, the team formed a flap above the trailing edge in-between the rear wing endplates. This was not a new feature in F1, Toro Rosso launched their car with just such a flap and historically many cars have sported the detached gurneys of flaps. The Arrows cars in the 2000s sported just such devices. Completely legal, these simple aerofoil sections of bodywork, sit within the allowable area for bodywork at the rear of the car. Much like the gurney, these devices aim to use the high pressure air moving over the diffuser to create a low pressure region above the diffuser exit, to drive more flow out of the diffuser beneath. Effectively making the diffusers exit area larger than a simple exit.

Blown starter hole

Two inlets lead to ducts (yellow) that feed the Starter Motor Hole with airflow

What’s most interesting from Jean Baptistes picture are the two ducts set into the floor ahead of the diffuser. Looking closer we can see these two inlets, lead to ducts that pass inside the engine bay and either side of the starter motor tube. The starter motor hole in the boat-tail of the diffuser is a wide slot, so I believe these ducts blow the starter motor slot. Until other teams cottoned on to Newey’s exploitation of the outer 5cm of floor, most teams pointed their exhausts towards the Starter Motor Hole (SMH), as a way of using the high velocity exhaust gas, to drive more flow through the diffuser and thus create lower pressure for more downforce. With Newey’s outer blown diffuser he could not exploit the large SMH with his exhausts, so this solution allows him to exhaust-blow the diffuser and passively-blow the SMH. By passive-blowing, I mean the exhaust is not used to blow the SMH, but simply the normal airflow over the car. Of course the effect of this passive blowing is dependant on the airflow approaching the ducts inlets. The RB7 has all enclosing bodywork around the gearbox and floor. So airflow could not directly lead to the SMH. So Newey has had to duct flow to this area. It’s unlikely that the flow arriving at these ducts is that powerful, having had to pass around the sidepods and over the fairings covering the exhausts. This is likely to be a small aero gain, albeit one that other teams with similar gearbox fairings could employ. Should the engine mapping ban make the outer blown diffuser solution too sensitive to throttle position, then this duct could receive the exhaust flow to still provide a degree of blown diffuser.

Other details

The T-Tray is formed with the floor and has an opening normally covering by the plank

Away from the unique Red Bull features, the floor exhibits a lot of standard practice for contemporary F1 floors. In Red Bulls case the floor completely encloses the underneath of the car, only a small open section in the t-tray splitter is open. This opening will be enclosed when the plank is fitted to the car. There’s probably a matching section of ballast attached under the chassis that fits in the hole, allowing the ballast to sit a precious few millimetres closer the ground.

An older Red Bull floor (this floor can be purchased via F1-247.com)

With other teams more sections of the floor above the plank are open, and in some cases the base of the monocoque also forms the floor, so the removable floor section has even larger openings.

Enclosed Lower Leading: note the ECU inside the hollow section

The area forming the front lower leading edge of the floor also has to house the Side Impact Tubes (SITs). Clearly with a one piece floor like this, the floor cannot be removed with the SITs still attached to the monocoque. Many teams have the SITs removed with the floor, by unbolting them at the side of the monocoque. This would appear to be the case the RB7 floor. Although not visible in this photo, presumably the removed SITs remain with the car, so possibly this floor is being changed, rather than stored temporarily for refitting.

Such is the tight packaging of the area within the sidepods; space for electronic boxes is limited. We can see a small black box and loom within the enclosed section of floor. Just to the rear of this there appears to be a blue-grey square set into the floor. This is probably a transparent window for sensors to project through, most likely the ride height sensors. Normally three are fitted, one to the left one the right and another at the front or rear, these three ride heights can be extrapolated to provide the engineer with the cars attitude to the track.

Note the wiring for sensors passing around the floor

There is also a reasonable amount of wiring loomed around different areas of the floor. When wiring was seen dangling from Vettels front wing mounts earlier this year, people were quick to assume, this related to wing flex. But instead a lot of the car is instrumented, both for data acquisition but also troubleshooting during the race. In the case of the floor, two measurements are commonly taken, pressure and temperature. Pressure sensors log the pressure beneath the floor, should a car suffer damage in the race, the team can tell from the telemetry if a change in pressure readings are likely to cause handling problems. Equally teams have been known to fit temperature sensors the titanium fasteners holding the plank to the chassis. If these skid blocks, ground too frequently they will heat up. This delta in temperature will alert the team that the plank might be suffering undue wear and cause legality problems in scrutineering.

More pictures from @Jeanbaptiste76

http://twitpic.com/57snf2

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Trends 2011 – Exhausts and Diffusers

This year the technical talk has largely been about exhausts.  How teams have adapted to the ban on double diffusers and the added restriction on Exhaust blown diffusers. Just to aid understanding going into the new season, I have explained how these solutions work and how they look from beneath.

Double Diffusers

Force India 2010 Double Deck Diffuser (DDD)

Since 2009 the regulations regarding the floor have been interpreted in a literal sense to allow the double deck diffuser (DDD). Indeed the very same rules were exploited to a lesser extent under the previous rules, but this only produced small extra channels in between the outer and middle diffuser tunnels. With the major cut in aerodynamic aids for 2009, several teams sought to find a way to gain more expansion ratio from the smaller diffusers. In essence the loophole exploited the definition of surfaces formed between the step and reference planes. Multiple surfaces allowed fully enclosed holes, which fed the upper diffuser deck that sat above the 175mm lower diffuser. This allowed diffuser to be significantly larger in order to create more downforce. Notably Brawn, Williams and Toyota launched 2009 cars with DDDs. Other teams soon followed suit in 2009 and last year every car exploited the same loophole. Over the winter the FIA acted to close the loophole, by enforcing a single continuous surface across a 90cm span under the floor. In a stroke this banned the double diffuser, there being no scope to create any openings in the floor to feed the upper deck.

Single Diffuser

Double Diffuser

 

Exhaust Blown Diffusers
Another approach to regain lost downforce was the re-invention in 2010 of the exhaust blown diffuser (EBD). This used high energy exhaust gasses to blow the diffuser, the faster throughput of flow under the floor increased downforce. Two methods of EBDs were used in 2010, one blowing over the diffuser and the second blowing inside the diffuser. This latter solution was more effective at driving flow through the diffuser and created more downforce. However this necessitated a hole made into the diffuser to allow the exhaust gas to enter, I‘ve termed this method an ‘open fronted diffuser‘.

2011: No openings allowed in the yellow 90cm zone, outside certain holes are permitted

A by product of the 2011 rules intended to ban the DDD, also stopped this open fronted diffuser solution. However the rules enforced the continuous surface only across a 90cm width of floor and the diffuser is allowed to be 100cm wide. Thus a 5cm window was allowed each side of the diffuser.

Outer Blown Diffuser – Solution

Red Bull Diffuser: Flow passes under the outer 5cm of floor into the diffuser

Red Bull and Ferrari appear to have found this loophole simultaneously. Recently Sam Michael pointed out this was probably the most efficient way to blow the diffuser under the new rules. As Red Bull appeared with this set up first, its often termed the Red Bull Blown diffuser.

What these teams have done is to open up the floor 5cm either side of the diffuser, then route the exhaust towards this opening. The exhaust gas gets collected by the coved section of floor and this directs the high energy gasses under the diffuser, to recover some of the losses from the more open diffuser allowed last year.

Front Exit Exhaust

Renault Front Exit Exhaust: Flow passes wide around the floor before entering the diffuser

Renault meanwhile turned the problem on its head. As the aim of the EBD is to increase flow under the car, they pointed their exhaust at the front of the floor. I’ve had it confirmed to me by two ex-Renault sources that the exhaust does indeed mainly flow under the floor.

The exhaust pipe outlet sits above the step plane just ahead of the leading edge of the floor. This is not simply blowing out horizontally and across the floor, but is ducted slightly to blow downwards and backwards, this is roughly in line the with the flow trailing off the “V” shape above the splitter. Along with the strong vortices set up by the splitter, vanes and bargeboards, this makes the floor appear wider than it is. The flow will go out beyond the floor and then curl back in and under the floor. Some flow will inevitably pass over the floor, but the most of the energy will be driving more flow under the floor to the diffuser.

McLarens Slit Exhaust

The slit above the floor is visible. Copyright: Liubomir Asenov

No conversation about exhausts this year, would be complete without some speculation about McLaren. Amongst the several exhaust systems run by McLaren over the pre-season tests was a “slit” exhaust. This appeared at the first Barcelona test, but did not seem to appear for the second Cataluña test. The exhaust collector could be seen to duct towards a double thickness section of floor ahead of the rear wheels. This section was also interesting for its longitudinal slot, this slot was not large enough to be the actual exhaust outlet, This might be a cooling slot, or to improve the flow from above to beneath the floor.  I beleive the Exhaust is actually below the floor.  As when the car ran the same floor with a conventional exhaust outlet, there appeared to be a removable section of floor ahead of the rear wheels. Being just outside of the 90mm opening rule, the floor ‘could’ be opened to allow an exhaust to blow through to underneath. If sculpted correctly, the exhaust could be ducted back inboard and blow towards the diffuser from under the floor. It’s possible that this could be in interpretation of a legal opening, assuming it met the maximum fillet radius rules.
I’d expect the resulting exhaust outlets to be a long wide slot, this wider outlet would be needed to meet the maximum radius rules and also reduce the back pressure from the tight curve of the exhaust outlet. As the exhaust would have a tortuous bend, to curl back under itself to direct the flow inboard, rather than out wide around the rear tyre.

Mac Slit: The exhaust might exit beneath the floor in a long narrow outlet

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Floors and Diffusers – The basics explained

An F1 car is a complex vehicle, a lot of emphasis is placed on the things we can see, the wings and bodywork. Sometimes we can talk about less visible items such as engine, gearboxes, suspension or even electronics. But perhaps the least visible and detailed part of the car is the underbody. The floor and diffuser, that together create nearly half the cars downforce, for almost no drag. Underbody aerodynamics have been the key to F1 car’s ever faster laptimes. All we ever see of the underbody is the exit of the diffuser and sometimes, if seen from a low angle, the step under the cars floor. To aid explanations in my other articles on underbodies, I have summarised and simplified what the underbody consists of.

Reference plane

Reference plane: Red

This is the datum for the cars dimensions and is effectively the lowest part of the cars floor. When the old flat bottom regulations, dating back to the banning of ground effects in 1983 were revised in the wake of Senna’s 1994 crash, the floor has had to have a step along its length. So we see the stepped shape of the car in frontal profile, with the reference plane sitting lowest in the middle of the car. This step cannot be wider than 50cm or narrower than 30cm, the reference plane must by flat and run continuously from behind the front wheels to the rear axle line. The Reference planes leading portion, also forms the splitter, also known as the T-Tray or Bib.

Step plane

Step Plane: Yellow

Above the reference plane is the step plane, this is effectively the underside of the sidepods. This must sit 5cm above the reference plane. Again the surface must be flat and run from the complex regulated bodywork zone around the front of the sidepods to the rear axle line. A large clearance is mandated around the rear wheel to prevent teams sealing off the floor against the rear tyres.

Step or Transition

Step: Orange

In between the reference plane and step plane, is the step itself or transition. Simplistically there must be a vertical surface in between these two planes. Any intersections of these surfaces are allowed to have a simple radius to be applied, with a 2.5cm radius on the step plane and a 5cm radius on the reference plane.

Plank

Plank: Brown

Not considered part of the floor for measurement purposes, the plank is a strip of wood placed under the car to enforce a minimum ride height. The FIA technical term for this part is the skid block, although this term is rarely applied. Holes in the plank allow the cars reference plane to sit directly on the FIA scrutineering jig, for legality checks over the course of a GP weekend. Titanium skid blocks are allowed to be fitted in certain places in the plank and their wear is measured to ensure a car is not grounding from excessively low ride heights.
The plank can be made in two parts to make removing the floor easier, bit the front section must be at least 1m long. This must be made of a material with a specific density, to prevent excessivley heavy or hard planks producing a performance benefit. Typically the plank is wood based, eiterh jabroc a laminate of beechwood, although more exotic blends of woods and resins not unlike MDF have been used. The plank is 30cm and 5mm thick, any holes made into it must conform to a FIA template.

Diffuser

Diffuser: Yellow

A purely flat floor would probably produce lift rather downforce, so the rules have allowed a diffuser to be fitted to the rear of the underbody since 1983. Before that date there were no rules demanding floor dimensions and diffusers were the full length ground effect tunnels that typified the wing cars of the late seventies and early eighties.
A diffuser creates downforce by creating a pressure differential, with low pressure beneath and higher pressure above. The larger a diffuser is, the more expansion ratio is has, thus more potential to create downforce. Diffusers were limited to a simple 100cm width, 35cm length and 17.5cm height from 2009. Then for this year the height further reduced to just 12.5cm. This massively reduces the potential of the diffuser to create downforce compared to the previous rules. Diffusers are allowed to have fences, but the fences and the diffuser itself must not form undercuts when viewed from below. Which is why we see the simple vertical fences and jelly mould curvature.

Other rules around floors
Overriding all of the above rules are broader regulations covering holes and flexibility. No unsprung part of the car can be visible from below the floor. Typically this means anything, but the suspension and additionally the wing mirrors. This means that no holes can be made into the floor to let flow in or out. The underbodies surfaces are termed bodywork within the rules, there is no term ‘diffuser’ or ‘wing’ mentioned in the rules. Just as with any bodywork in the rules, these parts are not allowed to move or flex. For the floor in comparison the wings, there are few deflection tests commonly carried out, the main one being the splitter deflection test.

Exploitation

Double Diffuser

Over the past two year these rules have been exploited by teams. Firstly the interpretation of holes in the floor and continuous surfaces. This lead to the openings that allowed double diffuser. Effectively the step formed two separate, but individually continuous surfaces, allowing airflow to pass up above the step plane into the upper deck of the diffuser. This rule has been clarified for this year and a single continuous surface must be formed under the floor.
Additionally the flexibility of the splitter has been brought into question, teams were believed to be flexing the splitter upwards, new more stringent tests were introduced in 2010 to stop this.



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Happy New Year – RedBull RB6 Illustration (Wallpaper)

I’ve been drawing this big detail – big scale illustration of the RB6 as a prelude to a prediction of the 2011 car designs.  So I’d thought I’d post the 2010 RB6 version up as a wallpaper in mono at 1280 resolution.  I’ll do larger sizes on request with or without logos (mail me).

Have a great New Year and thanks for supporting me in my first year Blogging and Tweeting.  Next year will be my tenth covering the technicalities of the sport, so I’ve got some new ideas up my sleeve.

Scarbs…

and without Logos…..

F1 2011 Technical Regulations – Detailed and Explained

Finally the FIA have published the detail of the 2011 technical regulations. There were no major surprises amongst the rules. There being rules to effectively ban: double diffusers, F-ducts & slotted rear wings. Newly introduced were the mandated weight distribution and adjustable rear wing. 

There’s a lot to cover, so I wont cover every rule change and neither can I cover them in detail. but here’s the main points (with the rule in italics).

The full FIA regulations are detailed here:  FIA F1 2011 Technical Regulations

 

Ban on connected shark fins

Another route to banning F-ducts, as well as a move to limit the ever expanding rear fin, the rule prevents any bodywork reaching the rear wing.

“3.9.1 No bodywork situated between 50mm and 330mm forward of the rear wheel centre line may be more than 730mm above the reference plane.”

Ban on slots in the beam wing

With the exception of the central 15cm, the beam wing cannot have a slot that widens internals to create a blown slot. Only Williams raced this last year, but the practice has prevented. This reinforces the fundamental rule that the lower wing should only be formed of one element

“3.10.1 Any bodywork more than 150mm behind the rear wheel centre line which is between 150mm and 730mm above the reference plane, and between 75mm and 355mm from the car centre line, must lie in an area when viewed from the side of the car that is situated between 150mm and 350mm behind the rear wheel centre line and between 300mm and 400mm above the reference plane. When viewed from the side of the car no longitudinal cross section may have more than one section in this area.
Furthermore, no part of this section in contact with the external air stream may have a local concave radius of curvature smaller than 100mm.
Once this section is defined, ‘gurney’ type trim tabs may be fitted to the trailing edge. When measured in any longitudinal cross section no dimension of any such trim tab may exceed 20mm.”

Ban on slots in the rear wing


As with the beam wing, the upper rear wing is prevented from having slots extending beyond the central 15cm. This prevent F-ducts or other blown slots, the latter which have been exploited for several years.

“3.10.2 Other than the bodywork defined in Article 3.10.9, any bodywork behind a point lying 50mm forward of the rear wheel centre line which is more than 730mm above the reference plane, and less than 355mm from the car centre line, must lie in an area when viewed from the side of the car that is situated between the rear wheel centre line and a point 350mm behind it.
With the exception of minimal parts solely associated with adjustment of the section in accordance with
Article 3.18 :
- when viewed from the side of the car, no longitudinal cross section may have more than two sections in this area, each of which must be closed.
- no part of these longitudinal cross sections in contact with the external air stream may have a local concave radius of curvature smaller than 100mm.
Once the rearmost and uppermost section is defined, ‘gurney’ type trim tabs may be fitted to the trailing edge. When measured in any longitudinal cross section no dimension of any such trim tab may exceed 20mm.
The chord of the rearmost and uppermost closed section must always be smaller than the chord of the lowermost section at the same lateral station.”

Limit on Rear wing support pylons

The number, thickness and cross-section of the rear wing support pylons are now more tightly controlled.

“3.10.9 Any horizontal section between 600mm and 730mm above the reference plane, taken through bodywork located rearward of a point lying 50mm forward of the rear wheel centre line and less than 75mm from the car centre line,
may contain no more than two closed symmetrical sections with a maximum total area of 5000mm2. The thickness of each section may not exceed 25mm when measured perpendicular to the car centre line.
Once fully defined, the section at 725mm above the reference plane may be extruded upwards to join the sections defined in Article 3.10.2. A fillet radius no greater than 10mm may be used where these sections join.”

 

Clarification of the starter motor hole


After some teams were exploiting oversized starter motor holes in the diffuser to create a slotted effect, the FIA clamped down with a clarification. This has now been written into the rule book.

“3.12.7 No bodywork which is visible from beneath the car and which lies between the rear wheel centre line and a point 350mm rearward of it may be more than 125mm above the reference plane. With the exception of the aperture described below, any intersection of the surfaces in this area with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car.
An aperture for the purpose of allowing access for the device referred to in Article 5.16 is permitted in this surface. However, no such aperture may have an area greater than 3500mm2 when projected onto the surface itself and no point on the aperture may be more than 100mm from any other point on the aperture.”

 

Ban on Double Diffusers (DDD) and Open Exhaust Blown Diffusers (EBD)

Due to a previous weakness in the rules defining the underfloor, teams were able to exploit this to create the double diffuser. Double diffusers were only possible as an opening could be created in the gap been the reference plane, step plane and the diffuser. Now the rules close this avenue off.
Additionally this opening allowed teams to open up the front of the diffuser to blow the exhaust through for an even greater blown diffuser effect. This rule also prevents this opening in all but the outer 50mm of the split between the diffuser and the floor.
One additional clarification is that the suspension must not form any of the measured point for the under floor. Previously the minimum height was exploited by some teams placing wishbones or Toe-Control arms across the top an opening in the diffuser.

“3.12.9 In an area lying 450mm or less from the car centre line, and from 450mm forward of the rear face of the cockpit entry template to 350mm rearward of the rear wheel centre line, any intersection of any bodywork visible from beneath the car with a lateral or longitudinal vertical plane should form one continuous line which is visible from beneath the car. When assessing the compliance of bodywork surfaces in this area the aperture referred to in Article 3.12.7 need not be considered.

3.12.10 In an area lying 650mm or less from the car centre line, and from 450mm forward of the rear face of the
cockpit entry template to 350mm forward of the rear wheel centre line, any intersection of any bodywork
visible from beneath the car with a lateral or longitudinal vertical plane should form one continuous line
which is visible from beneath the car.
3.12.11 Compliance with Article 3.12 must be demonstrated with the panels referred to in Articles 15.4.7 and
15.4.8 and all unsprung parts of the car removed.”

 

Driver operated F-duct

Even though the loop holes in the rear wing regulations have been closed, this additional new regulation prevents the driver influencing aerodynamics. So that other driver controlled F-duct type devices cannot be exploited other areas, such as: front wings, sidepods or diffuser.

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

 

Ban on movable splitters

As with some other rules, this is a 2010 clarification now added to the regulations. Its thought that teams were allowing their splitter to flex upwards, to allow the car to run a more raked attitude and lower front wing ride height. There are now more stringent tests and restrictions on the splitter support mechanisms.

“3.17.5 Bodywork may deflect no more than 5mm vertically when a 2000N load is applied vertically to it at three different points which lie on the car centre line and 100mm either side of it. Each of these loads will be applied in an upward direction at a point 380mm rearward of the front wheel centre line using a 50mm diameter ram in the two outer locations and a 70mm diameter ram on the car centre line. Stays or
structures between the front of the bodywork lying on the reference plane and the survival cell may be present for this test, provided they are completely rigid and have no system or mechanism which allows non-linear deflection during any part of the test.
Furthermore, the bodywork being tested in this area may not include any component which is capable of allowing more than the permitted amount of deflection under the test load (including any linear deflection above the test load), such components could include, but are not limited to :
a) Joints, bearings pivots or any other form of articulation.
b) Dampers, hydraulics or any form of time dependent component or structure.
c) Buckling members or any component or design which may have, or is suspected of having, any non-linear characteristics.
d) Any parts which may systematically or routinely exhibit permanent deformation.”

 

Driver adjustable rear wing


The driver adjustable front wing is now deleted from the rules and instead the rear wing is now driver adjustable. This is because the expected benefit of greater front wing angle never provided the driver with more grip when following another car. The front flap adjustment was much more a solution to tune the cars handling in between pitstops. The TWG found that the loss of drag from the rear wing was a more effective solution to allow the following to overtake. Now the rear wing flap can pivot near its rear most point and open the slot gap from 10-15mm to up to 50mm. Opening this gap unloads the flap and reduced both downforce and drag.
This being controlled by the timing gap to the car ahead and managed by the FIA. So there’s two ways the driver can use the system. Firstly in free practice and qualifying the rear wing is solely at the control of the driver. They can adjust the wing at any point on the track and any number of times per lap. So for the ideal lap time, as soon as the car is no longer downforce dependant (straights and fast curves) the driver can operate the wing, just as they did with the F-duct. Although a small complication to the driving process, at least their hands remain on the wheel and not on a duct to the side of the cockpit.
Then in the race the wing cannot be adjusted for two laps, then race control will send signals to the driver via the steering wheel, such that when they’re 1s or less behind another car at a designated point on the circuit, the rear wing can be trimmed out. The wing returns to the original setting as soon as the brakes are touched.

“Furthermore, the distance between adjacent sections at any longitudinal plane must lie between 10mm and 15mm at their closest position, except, in accordance with Article 3.18, when this distance must lie between 10mm and 50mm.”

3.18.1 The incidence of the rearmost and uppermost closed section described in Article 3.10.2 may be varied whilst the car is in motion provided :
- It comprises only one component that must be symmetrically arranged about the car centre line with a minimum width of 708mm.
- With the exception of minimal parts solely associated with adjustment of the section, no parts of the section in contact with the external airstream may be located any more than 355mm from of the car centre line.
- With the exception of any minimal parts solely associated with adjustment of the rearmost and uppermost section, two closed sections are used in the area described in Article 3.10.2.
- Any such variation of incidence maintains compliance with all of the bodywork regulations.
- When viewed from the side of the car at any longitudinal vertical cross section, the physical point of rotation of the rearmost and uppermost closed section must be fixed and located no more than 20mm below the upper extremity and no more than 20mm forward of the rear extremity of the area described in Article 3.10.2 at all times.
- The design is such that failure of the system will result in the uppermost closed section returning to the normal high incidence position.
- Any alteration of the incidence of the uppermost closed section may only be commanded by direct driver input and controlled using the control electronics specified in Article 8.2.
3.18.2 The adjustable bodywork may be activated by the driver at any time prior to the start of the race and, for the sole purpose of improving overtaking opportunities during the race, after the driver has completed a minimum of two laps after the race start or following a safety car period.
The driver may only activate the adjustable bodywork in the race when he has been notified via the control electronics (see Article 8.2) that it is enabled. It will only be enabled if the driver is less than one second behind another at any of the pre-determined positions around each circuit. The system will be disabled by the control electronics the first time the driver uses the brakes after he has activated the system.
The FIA may, after consulting all competitors, adjust the above time proximity in order to ensure the stated purpose of the adjustable bodywork is met.”

 

Mandated weight distribution

Along with the supply of Pirelli control tyres they will be matched to a mandatory weight distribution. Now the cars minimum weight is 640Kg, the specified minimum axle weights, equate to a weight distribution ranging between 45.5-46.7% on the front axle. This is a few percent behind the typical 2010 loadings.

“4.2 Weight distribution :
For 2011 only, the weight applied on the front and rear wheels must not be less than 291kg and 342kg respectively at all times during the qualifying practice session.
If, when required for checking, a car is not already fitted with dry-weather tyres, it will be weighed on a set of dry-weather tyres selected by the FIA technical delegate.”

 

Double wheel tethers

For safety a doubling of the wheel tethers has been regulated. Each tether needs to pass through a different suspension member and have its own mounting points on the upright and the chassis. There’s not expected to be any performance impact with this. But the tethers are somewhat heavier, so they and the side intrusion panel are part of the reason for the greater minimum weight limit.

“10.3.6 In order to help prevent a wheel becoming separated in the event of all suspension members connecting it to the car failing provision must be made to accommodate flexible tethers, each with a cross sectional area greater than 110mm². The sole purpose of the tethers is to prevent a wheel becoming separated from the car, they should perform no other function.
The tethers and their attachments must also be designed in order to help prevent a wheel making contact with the driver’s head during an accident.
Each wheel must be fitted with two tethers each of which exceed the requirements of 3.1.1 of Test Procedure 03/07.
Each tether must have its own separate attachments at both ends which :
- are able to withstand a tensile force of 70kN in any direction within a cone of 45° (included angle) measured from the load line of the relevant suspension member ;
- on the survival cell or gearbox are separated by at least 100mm measured between the centres of the two attachment points ;
- on each wheel/upright assembly are located on opposite sides of the vertical and horizontal wheel centre lines and are separated by at least 100mm measured between the centres of the two attachment points ;
- are able to accommodate tether end fittings with a minimum inside diameter of 15mm.
Furthermore, no suspension member may contain more than one tether.
Each tether must exceed 450mm in length and must utilise end fittings which result in a tether bend radius greater than 7.5mm.”

 

No more shaped wheel spokes

After the static front wheel fairings that abounded in 2009, were banned and the wheel design homologated, there must have been some surprise that Ferrari managed to create an aerodynamic wheel shape in 2010. This is partly limited now by the restriction on surface area for spokes and shaping. The limited only allows 13% of the wheel centre to be spoked, meaning that a ten spoke wheel has to have spokes just 16mm wide.

“12.4.6 When viewed perpendicular to the plane formed by the outer face of the wheel and between the diameters of 120mm and 270mm the wheel may have an area of no greater than 24,000mm2.”

 

Clarification of mirror positions

Again when the FIA clarify a rule or make a change for safety reasons, we don’t get to see the detail of this change until its put into the regulations. The removal of outboard mirrors was brought in early last year and now the mirrors can effectively be no more than 27.5cm from the cockpit opening

“14.3.3 All parts of the rear view mirrors, including their housings and mountings, must be situated between 250mm and 500mm from the car centre line and between 550mm and 750mm from the rear edge of the cockpit entry template.”

 

Ban on blade roll structures

Mercedes surprised many with their blade-like roll structure, reducing the obstruction to the rear wing and allowing for a much shorter inlet tract for the engine, the solution was likely to be copied. A minimum cross section forced teams to have a wider section above the drivers head, negating the fundamental benefit of the solution

“15.2.4 The principal roll structure must have a minimum enclosed structural cross section of 10000mm², in vertical projection, across a horizontal plane 50mm below its highest point. The area thus established must not exceed 200mm in length or width and may not be less than 10000mm2 below this point.”

 

Dash roll structure point maximum height

With the cockpit opening fixed at 550mm, teams have often raised the front of the chassis around the dash bulkhead to create a raised nose. In the first of several limits for both 2011 and 2013, with even more stringent plans for 2013, the height of the front of the chassis is now being controlled. The limit for this point is now 670mm, still some 120mm above the cockpit opening.

“15.2.3 The highest point of the second structure may not be more than 670mm above the reference plane and must pass a static load test details of which may be found in Article 17.3.”

 

Limit on front chassis height

As already explained teams raise the position of the front (AA) and dash (BB) bulkheads to create space under the nose for airflow to pass in between the front wheels and reach the rear of the car. The trend for “V” sections noses, introduced on the Red Bull RB5 in 2009, makes the front of the chassis even higher, often being visible above the height of the front tyres (~660mm). Now both these bulkheads need to be at 625mm, some 75mm above the cockpit opening.

“15.4.4 The maximum height of the survival cell between the lines A-A and B-B is 625mm above the reference plane.”

 

Limit on shaped Rear Impact Structures


Since the 2009 aero rules, teams have been shaping the rear impact structures into ever more curved shapes to lift it clear of the diffuser and pass it underneath the beam wing. The tail of this structure must be centred at 300mm high, to prevent extreme banana shaped structures, this rule forces the structure to vary by no more 275mm.

“Furthermore, when viewed from the side, the lowest and highest points of the impact absorbing structure between its rear face and 50mm aft of the rear wheel centre line may not be separated vertically by more than 275 mm.”

Spring-Less Rear Suspension – A Quiet Revolution

In the latter part of the year suggestions were that teams were discarding the rear side springs to allow very soft rear ends.   This has proved to be the case, in the past few years teams have been removing their rear torsion bars to gain greater control of suspension set up.  This revolution has been quietly spreading as many teams have gone this route.

An early sign springs were being removed was  the I-Racing game, which accurately modeled the FW31 with the Williams teams assistance, the game provided no scope for rear springs.   Equally comments made by Anthony Davidson over the Abu Dhabi Grand Prix weekend suggested that McLaren’s extreme stiff frontsoft rear was due to this set up. Leading to Buttons problems locking up the inside wheel under braking. Closer investigation with technical people close to the sport prove this to be case and the practice is widespread amongst several teams, already McLaren and Williams are highlighted as adopting this practice, but Toyota and red bull are sporting this set up, by virtue of their gearbox supply this suggests that force India and Toro Rosso have the option too. Although this seems to be a relevantly recent practice as most teams first designed this into the 2009 cars, albeit it may have been tested or raced before then.

Suspension on F1 cars has the joint purpose to control the cars attitude both for aerodynamics and tyre dynamics. These often contradictory requirements have lead to compromises, largely against tyre performance and more to the benefit of aero control. Aerodynamicists want the car to run flat (or raked) with little change in roll or ride height. For mechanical grip the car needs softer attitude control. This has lead F1 cars to run quite stiff front ends and softer rear ends, both in roll and heave. A soft rear ARB creates more mechanical grip, which then in turns needs to be controlled by a stiff front anti roll bar. For aerodynamics reasons the front wing and splitter like to be flat to the track surface to gain most downforce, thus this also tends to require a stiff anti roll bar.
At the extreme end of this set up characteristic this has been exhibited most clearly in McLarens handling. The car gains traction from the soft rear anti roll bar, but the stiff front roll bar means that the rear heavy car tends to roll at the rear and this picks up the inside front wheel going into turns.
On a side point although McLaren run what has been called a stiff front axle, their apparent problem with grip over bumps going into turns is not necessarily a reflection of this set up, more that the cars aero requires tight ride height control, it is possible to run stiff anti roll bar and still have a compliance for coping with bumps.

Heave is when the car moves vertically, thus both wheels are rising or falling together
In a typical rear suspension the effect of heave is that the heave spring (blue) and each side spring (yellow) is providing stiffness. The dampers (Red) damp the motion.

Roll is when the car tilts, thus one wheel is rising and one is falling
In a typical rear suspension the effect of Roll is the ARB (orange) and the side springs provide the stiffness. Again, the Dampers (Red) damp the motion

Single wheel bump, which tends to be for riding kerbs or bumps in the track is a secondary requirement to heave and roll control, spring rates are not normally tuned for this requirement, instead the cars dampers allow freer suspension movement when the wheel suddenly rises up at a greater rate than normal, the damper has different rates for the wheel rising at different speeds, known as low speed (the cars chassis moving slowly i.e. pitch roll) high speed (bumps) and often a tertiary setting known as ‘blow off’ where the damper will provide a far lower damper rate for extreme wheel speeds such as kerbing.

Hence in both heave and roll the side springs are providing additional stiffness to the effective spring rate, thus both roll and have are coupled to the rate of the side springs. If we can do away with the side springs then both roll and have can be totally independent and controlled by their relevant springs. If you need a softer ARB rate, then the side springs are the limiting factor.


When you do away with the side springs, the heave and roll bar rates are higher in order to replace the spring rate added by the side spring. As long as each of these devices has a wide enough range of springs then there is no loss in control.


It’s noteworthy that both rear dampers are used, in the nineties we saw monoshock front ends, which utilised both a single spring and single dampers. But monoshocks only have one damper so the control of roll is undamped. With a side spring-less set up there’s two dampers, controlling roll motion. Which is an obvious improvement in vehicle control over Monoshocks.
Although there are some set backs with a side spring-less set up, some suspension designers want a non linear rate to the heave and wheel rates and sometimes different rising rate curve for each of these elements. This is achieved by the linkage (pushrod or pullrod) and the rocker geometry, going for side spring-less set up prevents having differing wheel and heave spring rising rates. In some engineers opinions, this is the removal of a needless layer of complexity.
A heave element not only supports the rear axle heave motion, but the element provides a non linear rate. Ground clearance is used up through downforce compressing the suspension as speed increases. The heave element has a range of free movement, this is taken up as ride height lowers until the then the heave spring itself (or Belleville stacks or bump rubbers) come into effect and add considerable rate to the heave motion. This prevents grounding or choking the underfloor through low ground clearance.
Equally making set up changes is both simplified and complicated. Engineers can now change either roll or heave rates independently, before changing a changing torsion bar effectively altered both. But changing a torsion bar, while not a quick task was the switch of an isolated component. Now teams will need to change the entire heave spring or ARB assembly.
An additional benefit is if a team wants to commit fully to the side spring-less set up, the packaging of the suspension becomes far easier, no longer having to package long torsion bars. This is perhaps a reason why Red Bull were able to effectively package the pullrod set up, as the pivot for the rocker is near vertical, fitting a torsion bar in this position would have been be tricky.

With the design of next years car leading towards a widespread adoption of pullrod, the option to adopt side spring-less will be attractive to aid packaging. Although the side spring-less pushrod set up will also allow dampers and rockers more freedom to be packaged at the front of the gearbox casing. Adoption at the front of the car is possible too, there is lesser need as the front roll rate is higher and the torsion bars can add to the effective rate. But simpler packaging and tuning may still be attractive for a designer.