Publications: F1 Race Technology Report

Every year High Power Media, who publish ‘Race Engine Technology’ (RET) Magazine, produce a number of magazine format Race Technology Reports. Covering F1, Moto-GP, Nascar, Drag racing and 24-hour racing.

Just out is the current F1 Race Technology issue, covering Technical subjects from 2011 and 2012.

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McLaren MP4-26 2011 – Fan Tail (Octopus) Exhaust

McLaren went into 2011 with an aggressive design strategy, this was a response to the poor initial form in 2010 and resulted in the dramatic “U” sidepods and a mysterious exhaust system.


It was this exhaust system that stole most of the column inches in the F1 press and the fan forums during pre season testing. One particular column fed the interest around the exhaust and christened it the “Octopus”. The article suggested the exhaust was ducted to several exits and used high temperature Glass Ceramic Carbonfibre (GCC). It went on to explain the unreliability of the exhaust solution was due to the heat making it fail.
It was true McLaren’s first tests, even from the first private shakedown runs before the public testing had started, demonstrated a problem with the initial exhaust design. But this exhaust solution was not the “Octopus” as described; in fact McLaren Technical Director Paddy Lowe explained to me at the 2012 cars launch, that “it didn’t look anything like an Octopus”. Adding “The exhaust we had was a slot, we called it a fantail”, which was a simpler, albeit still innovative solution.

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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

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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Red Bull – Preseason front wing update

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In the last pre-season test at Barcelona, Red Bull introduced their updated front wing. Like the rest of the car, this is an evolution of what has gone before. Albeit based on the complex late-2010 set up, with 3-4 elements in differing areas across the wings span. It’s the endplate and cascade that have changed the most. While the flaps take some inspiration from Renaults early 2010 shape.

Firstly the shape of the main plane remains the largely the same, While the 2 flaps also retain their extra slot on the outermost span. This creates a four element wing nearest the endplate, this section gains a gurney to help keep flow attached. Meanwhile the inboard ends of the flaps follows Renaults idea from 2010, as they are feathered. This is visible by the space created in between the wing tips, Looking at the set up intuitively, the flaps remain loaded, but their tip vortex would be broken up into two smaller less powerful trails. Which still creates downforce, but may be less disruptive to the flow along the centre of the car.

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The cascade is slightly revised, again with the two conjoined winglets. Now the larger outboard winglet is curved near the join with the endplate, creating a deeper angle of attack and correspondingly a larger vortex spilling of the wingtip to direct airflow around the tyre.

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Mounting the new cascade is a revised endplate vane, Red Bull merge this organically into the rest of the outboard wing shape, but in principle this is the same as the vanedendplate-less set up of most other teams. The vane is slightly more outboard creating a wider cascade, probably for both more downforce potential and also to move the aforementioned vortex further outboard.



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Mercedes W02 preseason side pod & exhaust update

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After a slow start to the 2011 campaign Mercedes GP brought along the long expected changes to the W02 at the last Barcelona test. We have already covered the front wing (http://scarbsf1.wordpress.com/2011/03/11/mercedes-w02-new-front-wing-analysis/). But more crucially was the revised sidepod and exhaust package. Mercedes have gone their own way with the design of the W02, with its short wheelbase set up and the resultingly bulbous mid section. Contrary to my expectations the new sidepodexhaust package was not as unconventional as expected. Which still leaves some questions over some design choices on the car or the permanence of the solution shown in Barcelona.

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Firstly the new sidepods are formed of a completely new moulding, common to several other teams the sidepod bodywork is one piece and is not formed by add-on sections to the monocoque. Even though the general shape appears the same as the launch format, the overhead view shows the sidepod inlets are angled inboard slightly. Although the bigger visual change is the exhaust and cooling arrangement. Uniquely the exhausts are sited halfway along the sidepods, exiting where the sidepod is nearly at its widest and starts to taper in to the coke bottle shape. Unlike Red Bull and Ferrari Mercedes have not extended the exhaust towards the diffuser, instead the exhaust blows over a long length of open floor. A small vane redirects the flow inboard of the rear wheels and into a coved section that sends the exhaust flow under the diffuser to be more effective at creating downforce. To keep the bodywork safe from its close proximity the exhaust pipes numerous grilles are moulded into the sidepod. The rearmost of these are outside the exclusion zone for cooling outlets, but the larger removable grille appears to be at odds with the bodywork rules. Perhaps the low exhaust position (below the 100mm above the reference plane) allows the grille to be regarded as the opening for the exhaust. Equally these could have been precautionary fitments for overheating (which blighted the cars earlier tests) and might removed for the Australian race.
Having the exhaust so far forward does not make the exhaust act like Renaults Front-Exit-Exhaust, nor like Red Bulls ducted set up. The exhaust gas will lose energy as its merges with the freestream airflow before it reaches the diffuser. Its exactly this energy that teams want to exploit to drive more flow through the diffuser for more downforce. So why is the set up a less efficient solution? Potentially there are several reasons, last year Mercedes struggled with overheating bodywork, unable to get enough supply of the permitted Glass Ceramic Composite (GCC) material used to protect the phenolic composite of the cars floor and bodywork. When they ran their blown floor, the heat, simply melted and warped the bodywork. Its unlikely supply of the material is still an issue, but keeping the bodywork cool and the nature of the exhausts might be the problem.

All three Mercedes teams (McLaren, Mercedes GP and Force India) all had issues with sensitivity of the car when run with EBDs in 2010. McLaren found the cars balance changed significantly on and off throttle, while Mercedes found that the exhaust plume would touch differing parts of the bodywork in different sessions and even differed between cars. This suggests that the exhaust plume was less than predictable. Where-as CFD and wind tunnel tests use a simulation of the exhaust blowing, perhaps the knowledge of what the exhaust flow is actually like is missing. Strangely this seems to be a very Mercedes engine specific problem. Being too aggressive with the exhaust blowing and too specific with the heat shielding makes the car throttle-sensitive and prone to overheating bodywork. McLaren have more problems with their EBDs in pre-season testing and Force India have yet to truly shine, with an otherwise good looking design. If this is the case, then the teams either have to lose potential downforce by having to use a less aggressive EBD solution or suffer the sensitivity problem. Its hard to be clear how easy an unpredictable exhaust plume might be to solve, its not likely to be a solution teams and engine suppliers have had to look at before.

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Elsewhere on the sidepods the cars pod vanes have been enlarged from the truncated versions seen in the cars early tests. Why the team would be run stunted versions of long standing designs is again part of the confusion around the W02 debut. The pod vane features an unusual outwards bulged lower section. This mimics the shape of the short launch spec vane. I presume this is mated to the sidepods undercut to feed more flow around the sidepod and over the diffuser. Along with the new undercut the car sports new serrated bargeboards and the complex shaped under nose vanes from late last year have been revised with the more common nose cone mounted vanes.

One last unsolved conundrum is the side impact protection on the sidepods. Normally teams pass the side impact tests with two pairs of crash beams, one upper pair above the sidepod inlet and a lower pair in line with the floor. Each of these pairs are formed of one larger carbon beam and a smaller one to spread the load over a wider area of the chassis. Rules demand these parts are not exposed to the exterior airflow and must be covered by bodywork. These structures are quite heavy and unavoidably raise the cars Centre of Gravity (CofG). This years car sports something appearing very much like a side impact structure passing horizontally across the middle of the sidepod inlet. This would be beneficial as the weight is that much lower down and better for a low CofG, a high CofG was a problem that afflicted the 2010 W02. Meanwhile at floor level the structure is unusually slim, which is better for aerodynamics.
But this mid placed structure appears to be in contravention of the rules as its exposed to the airflow. The FIA have started to be stricter with teams interpretation of these structures, so its hard to understand why this set up has been accepted. Possibly the structure is covered by vestigial bodywork to bypass the rules, but this detail did again promote some of my ideas that the sidepods were to be more unconventional. If allowed this year, we can expect the FIA to stamp out this set up for future years. Of course teams cannot copy this, as crash structures are homologated for the year, and cannot be changed.



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McLaren preseason rear end update

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McLarens pre season has been thwarted by unreliability and apparently aerodynamic problems. The team have run a succession of exhaust designs (at least 4 so far) and time has been spent mapping the cars aerodynamics with sensor arraysflowviz. While the exhaust solution has yet to be finalised (I have a forthcoming post on this), The last days of the Barcelona test allowed the team to introduce some new parts around the back of the car and a new front wing.

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Their new rear wing sports vanes along its lower edge. These are legal as they sit in a small 5cm loophole zone in the bodywork regulations. This area has been exploited before by Red Bull on the RB5 and subsequently Toyota and Williams in 2009. Sauber also have much smaller solution on their current car. Having bodywork in this area effectively extends the diffuser sidewalls by some 30cm, which helps maximise the expansion ratio of the diffuser for more downforce. Such is the shape of the flow out of the diffuser, the bodywork needs to be vaned to allow the flow to expand. McLaren have formed four vanes into the allowable area. For the test, the rear-pointing exhausts were lined up with these vanes, thus the exhaust flow (red) will be routed by these vanes, accelerating flow inside the diffuser for even more downforce.

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McLarens problems also delayed the testing of their DRS (Drag Reduction System) adjustable rear wing. To feed the hydraulics to the actuator mounted inside the middle of the rear wing, the team have routed a non-structural pylon up from the gearbox to the wing. This houses the hydraulic cables & sensor wiring and does little to support the upper rear wing.

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With the weather warming a little during the relatively cold Spanish tests, the team were able to reduce the size of the engine hot air outlet for the last test. In the middle of this outlet is the oval gearbox oil hydraulic cooler outlet. Leaving the rest of the outlet for general sidepod cooling



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Ferrari F150 – final pre-season update analysis

For the final test at Barcelona, Ferrari brought the long awaited revisions to the F150 (although the cars name has frequently changed, I’ll continue to use this title). This consisted of a revised wings, new sidepods and new exhausts. It was Ferraris assertion at its launch that the car would have evolved aero and specifically different exhausts before the first race. So despite some people suggesting the changes are copying their rivals, it’s more likely that different teams have converged on the same ideas.

The front wing pylons have been lengthened to form turning vanes

At the front the main changes are to the front wing and its supporting pylons. These pylons have been extended in a similar manner to Renaults ideas from 2009-2010. Since 2009 the rules on vanes and bargeboards around the front of the car have been severely restricted. The rules mandate a limit on the cross sectional area for the front wing mounts, Ferrari have therefore extended their wing mounts, but also narrowed them. Thus meeting the rules and still providing the car with some aero advantage.

3.7.2 Any horizontal section taken through bodywork located forward of a point lying 450mm forward of the front wheel centre line, less than 250mm from the car centre line, and between 125mm and 200mm above the reference plane, may only contain 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.

A shapelier endplate has been added to the cascade

Details of the front wing have also changed, in particular the endplates, these now feature a more sculpted vane on the footplate. As well as the endplate fro the main front wing, the inner endplate for the small cascade mounted to it is also now shapelier. The small endplate now having a distinctly flared shape, aimed at redirecting flow inside the front wing.

New sidepod inlets and a blown diffuser are the main changes to the F150

Along the middle section of car, Ferrari have produced a new sidepod, initially similar to the launch specification. But the main radiator inlet is now reshaped, being much more of a “U” shape and smaller with it. The sidepod inlet retains the distinctive protruding upper lip. I was told by Nick Tombasis that this was an aero feature and not a structural one (i.e. side impact crash protection). Curiously this lip features a removable panel to allow for cooling. Being so far forward of the radiators its hard to understand how heated radiator flow could be ducted into the small exit, or perhaps some electronics of KERS components are sited within this hollow section.

Further back along the sidepods, the new exhaust system is routed along the floor and into an open section of floor in the outboard 5cm section of diffuser. This is the same solution as Red Bull has come up with, as already explained this was an obvious area in the 2011 rules for exploitation, as I even proposed this location in my pre-season trends and solutions article. Ferrari route the flattened exhaust inside heat shielding along the floor. The blowing effect of the exhaust passes under the floor for a more effective method of blowing the diffuser. Ferrari wanted to produce the exhaust in glass ceramic composite (such as Pyrosic), but this request was denied by Charlie whiting who clarified the exhaust must be made of materials on the permitted materials list. Such composites, while allowed to be used in some exceptions, are not allowed to be the actual material of the exhaust pipe.

Also the middle of the car gained revised wing mirror pods.  these appear to be split into upper and lower mouldings. Presumably to allow sensors or electronics to be fitted inside the pods during testing or free practice.

Lastly the rear wing has also been modified with a smaller flap. Several teams have switched their rear wing to smaller flaps, at first this is counter intuitive to the exploitation of the Drag reduction system (DRS) also termed the adjustable rear wing. As one would initially deduce that adjusting a larger flap would reduce drag by a greater amount. However, shallower flaps effectively flatten out when the leading edge is moved 50mm from the trailing edge of the main plane (50mm is the maximum slot gap allowed for the DRS). Thus they produce very little load and therefore little drag.



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Mercedes W02 – New front wing analysis

After three tests Mercedes produced their updated front wing at Barcelona today.  Elements of this wing have been seen on the Launch specification wing, such as the extra slot made in the main plane.  The wing (main plain and flap) itself is largely similar to the launch spec wing, while the endplate and cascades have been changed.  Mercedes front wing design harks back to the Brawn BGP001 of 2009.  The BGP001 pioneered the idea of the endplate-less wing.  With the wider wings for that season sitting as far out as the width of the tyres, the contemporary endplates before that time, no longer worked to direct  flow inside the front wheel.  Brawns aerodynamicists reshaped the wing to best redirect flow around the front wheel and effectively removed the vertical endplate and replaced it with vanes. These vanes are there to both redirect airflow and to meet the minimum bodywork rules.  To aid downforce in the area inboard of the front tyres, Brawns designers added a free standing winglet, known as a cascade.  Through out 2009 and 2010 BrawnMercedes developed the wing, but retained the two element layout.  The new wing retains all of these features to some extent.

Mercedes W02 launch spec front wing

The free standing cascade has been retained, but this is now aided by a small additional winglet inboard of the main winglet.  The split between the two winglets is inline with the inner face of the front tyre. This is not coincidence, as the two winglets seek to create tip vortices trailing both inside and outside the front wheel to set up  the airflow structures dividing either side of the front wheel.

Detail changes to the endplate include a small cut out in the trailing edge and a complex leading edge.  The raised section of footplate (the horizontal outboard section of endplate) cleverly features a tiny vane inside.  this vane curves outwards and was a feature of Mercedes 2010 wing.

Mercedes have not gone as far as a full three element wing, across its full width.  Instead they have divided the wing into three sections across its width.  Near the endplate, the wings leading edge rises, this reduces the angle of attack and amount of load this area of the wing creates.  This is because the area in front of the tyre is not a good location for creating downforce, as the tyre sits directly downstream of the wing.  The inner span of the wing nearest the cars centreline is also much reduced in chord length and angle of attack, again downforce does not want to be created here, as the wake will upset airflow over the middle of the car.  Thus the middle of the wing span, which sits both away from the tyre and the centre of the car, is the area where most load is created on the wing.  We can see this section has both the greatest flap size and angle of attack.  To keep the airflow attached to the wing with its more aggressive geometry, Mercedes have moulded a slot into the main plane.  Higher pressure air above the wing enters the slots and helps keep the flow attached to the wings underside.  This section of wing is therefore a termed a three element (two slot) wing.  This creates downforce where its most efficient to do so, maximising downforce for the minimum drag and downstream disruption.



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