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Showing posts with label E20. Show all posts
Showing posts with label E20. Show all posts
22 Sept 2012
Gurney Trims, Tabs or Flaps and why they're important for the Diffuser in 2012

A Gurney flap is so named after Dan Gurney who first applied such a device to the trailing edge of the rear wings of his car's in the 70's. This was not a new concept however and has been used in flight applications since the early 1900's in order to make a wing create more lift to the deficit of more drag.

The Gurney is quite a blunt method of producing lift/downforce but can also help to rectify deficiencies in the wings design. It helps to trim the angle of attack of a wing thus allowing a higher angle of attack before separation occurs. In terms of flight, had a designer miscalculated the design profile of his wing adding a gurney may help to rectify the flight pattern, as such the same can be done with an F1 wing. The advantage of this in terms of motorsport is that you can continue to leverage more downforce from a wing by increasing the wings angle of attack, however by default this will create a larger proportion of drag. This is caused by the airflow on the rear of the wing being unable to sustain the same AoA and so separation occurs as the boundary layer increases at the trailing edge.

The FIA regulations mandate the height of a Gurney Flap be no more than 20mm on the Rear Wing's Top Flap but don't specify any further on how the flap be angled and indeed it's chord or design profile.

As we have seen during 2012 the teams are using Gurney's more and more with Front Wings being treated with them in order to create downforce in specific regions. It is however the area above the diffuser that see the teams utilising Gurney's the most this season with an array of different approaches.

With Exhaust Blown Diffusers having been outlawed for 2012 the teams are constantly looking for ways to further enhance the performance of their diffuser in order to extract more downforce and so this season have set about constructing more and more complex Gurney's.

Ferrari & Red Bull have lead the way with fully perforated Gurney's whilst McLaren now sport a similar design, however Ferrari & Red Bull have now added a further tier to their designs.

The perforation allows for airflow to seep through from the high pressure side into the low pressure region helping to maintain the speed of airflow to the trailing edge so the flow doesn't separate. This creates a more  co-efficient balance of downforce vs drag creating a more stable flow structure from the diffuser.

Above: Ferrari F2012 at Monza - Gurney above the Diffuser now has 2 tiers in order that more AoA can be run on both tiers

McLaren's Diffuser design has altered since Monaco......

Above: McLaren's Monaco (and previous) specification Diffuser Gurney saw the perforation extend all the way around the periphery of the Diffuser

Above: For Silverstone and Hockenheim the team simply lopped off the edges of the Gurney stopping it a few inches short either end


Above: Since Hungary McLaren have run a very similar design to both Ferrari and Red Bull with a fluted end that joins the edges of the diffuser

Other Teams have combined the usage of perforated sections with the usual blunt Gurney Tab

Above: As we can see from these 3 images Lotus, Williams & Mercedes all choose to run with a perforated central section to their Gurney.  Their approach helps in not only extracting raw downforce from the Diffuser but managing the effects of lateral tyre squirt on the diffuser channels


Above: Caterham & Toro Rosso showing that their use of Diffuser Gurneys can still be used as a blunt instrument with large vertical tabs

As shown by the leading teams this area is crucial in extracting additional performance now EBD has been banned and as the teams find further ways in which to manipulate the exhaust plume toward this area these Gurney Tabs, Trims or Flaps may become even more complex.
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16 Sept 2012
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Eddie Jordan threw Silly Season into full swing by announcing he was privy to information relating to Lewis Hamilton making a move to Mercedes. However this rumour alone has not the only impacted Lewis Hamilton, McLaren & Mercedes but it will form the lynch pin in the whole driver market.

Red Bull shrewdly moved earlier in the season to resign Mark Webber for another season and with Sebastian Vettel already on board until the end of 2014 the team can concentrate on racing rather than PR.

Ferrari have Fernando Alonso signed until 2016 further showing his status as number one driver within the team. Meanwhile Felipe Massa's seat with Ferrari has been in doubt all season, a recent climb in form may be enough to warrant his seat for 2013 whilst Sergio Perez spends another season with Sauber. Felipe struggled to come to terms with the F2012 and Pirelli tyres at the start of the season and marked Monaco as a turning point in the season claiming that he finally understood the setup required. It could be no coincidence that Felipe's struggles could be down to Ferrari's decision to run with Front Pull Rod Suspension, with Fernando Alonso being the last driver to utilise it to his advantage in his maiden year at Minardi.

McLaren are obviously at the centre of a battle between themselves and Mercedes over procuring Lewis Hamilton's services for 2013 and beyond. Lewis signed a lucrative deal with McLaren just before the economic downturn and it's understood that McLaren are no longer in a position to fund the same or better deal. Further adding to his requirements are his image rights and the relinquishing of any trophies the driver may win. McLaren have a history of insisting on their drivers being intrinsically linked to the sponsors that McLaren have onboard these image rights alone can be worth many millions if carefully managed and so XIX Entertainment will be fighting to release these from any further contracts Lewis should sign.
Jenson Button meanwhile has already been in this position last year and easily manoeuvred his negotiations whilst also being put in the frame for Red Bull & Ferrari seats. Although the team always give the impression that they favour neither driver it could be argued over the last 2 seasons their development path has been more favourable to Jenson. Could this also be a catalyst in Lewis' thoughts about a switch to Mercedes?
I've previously written about the relationship between McLaren and Mercedes which leaves us wondering are the two working on a deal that sees both parties win in the battle for Lewis' signature? http://somersf1.blogspot.co.uk/2012/09/could-lewis-merry-go-round-be-engine.html
Much has already been talked about the use of Mercedes global platform to catapult Lewis' image to a larger audience but I personally feel that if the negotiations are actually taking place he needs to decide if he is a racer or a celebrity.

Mercedes have Nico Rosberg signed for 2013 and beyond but with them courting both Michael Schumacher for a contract extension and Lewis Hamilton to sign on for the team could he be forced to leave the team? Using Rosberg as leverage in a multi faceted driver and engine deal / compromise could see the young German line up alongside Jenson Button for McLaren. Rosberg's driving style is not dissimilar to Jenson's and so could allow McLaren to focus their design process behind the MP4-28 solely on their more conservative attributes.
Ross Brawn has already alluded to the fact that their 2013 challenger (WO4) will be an evolution of the WO3 but has instructed the team to 'try out' things toward the end of the season in order to have a better chance throughout 2013. (They did exactly this at Spa with the own DRD http://somersf1.blogspot.co.uk/2012/09/lotus-mercedes-drd-drag-reduction.html – and took a McLaren Style exhaust, DRD and other bodywork to the Young Drivers Test this week in Magny Cours - http://somersf1.blogspot.co.uk/2012/09/mercedes-wo3-updates-at-young-drivers.html )
The teams DDRS system although innovative has failed to make a huge dent in a season that has seen the teams closer than ever. Meanwhile they have been lacklustre in terms of developing the WO3 and now with only 9 races left of the season although mathematically still able to contest the Championships really find themselves battling for 4th place alongside Lotus and Sauber.
Michael Schumacher's impact since his return to F1 in 2010 has been low key, however this year has shown that the old dog still has some fight left in him. Schumacher's best chance of further glory lies in the regulation changes of 2014 at which point he will be 45. So can the German convince the board in Stuttgart he can still bring them success or is this why they are moving for Hamilton? I fear without Hamilton's signature either in place of Nico or Michael the German Marque may decide to cut their losses with their own team and re-focus their F1 aims at just being an engine manufacturer.

Lotus in my opinion made a shrewd move when signing Kimi Raikonnen although he had been out of the game for 2 years Kimi had remained competitive in 4 wheel sport. The Finn brings a certain character style that neither McLaren or Ferrari truly harnessed. Kimi's goals are not driven by the celebrity limelight that some require but instead lets his racing do the talking. He is signed with the team for 2013 that may be forced to rename as their sponsorship deal with Group Lotus expires at the end of the season. I have seen Kimi mentioned by McLaren fans as someone to return to the team should Lewis move but personally I cannot see that happening.
Romain Grosjean is undoubtedly a talent having succeeded at varying levels of open wheel racing however his F1 career is always under somewhat of a cloud. Whether it's his first attempt at F1 with the Renault team after Nelson Piquet Jnr was dismissed or his current drive with Lotus. Boullier however is sticking by Romain and although his contract expires at the end of the season I expect he'll remain with the team for 2013.

Sauber are a team on the up, typically Swiss they always seem to be the most neutral of all the F1 teams. However behind close doors they work away on relationships that allow them to keep a foothold in the sport. The use of Sergio Perez who is part of the Ferrari Academy allows the team to create a partnership with Ferrari who also supply their engines, KERS and drivetrain. Notably Checo has been able to use the Pirelli tyres to his advantage throughout 2012 bringing him to the attention of some of the top teams. As part of the Ferrari Academy Checo will undoubtedly have his career manipulated by the Ferrari team whilst Checo joins a long line of drivers drawn into the Hamilton to Mercedes battle as the Daily Mail today infer that McLaren are interested in the Mexican. Meanwhile Ferrari president Luca di Montezemolo has said that Checo is not yet ready to join Ferrari and so the temptation of a top seat with McLaren could test his mettle if offered a contract. The largest stumbling block I forsee in a move for Checo to McLaren are his ties to Telmex. Although Telmex are largely a South American concern any deals he currently has with the brand would eliminate him McLaren's radars due to their own involvement with Vodafone. As we can see from the C31 the Mexican's sponsorship is displayed on virtually every corner of the car (Telmex, Claro, Visit Mexico) with the Billionaire Russian Abromovich fronting the rest with his Chelsea logo's.
For a team like Sauber that relies heavily on funding from outside sources Checo must remain a driver for the team to continue in F1.
Kamui Kobayshi is a driver that will have warmed most people's hearts when he burst onto the scene with Toyota at Interlagos in 2009. He famously took on Jenson Button who needed to finish well at Interlagos to secure the 2009 Championship. Although Kamui has scored more points already this season than that of 2011, he has been overshadowed by Checo and I'd imagine like many others is struggling with the Pirelli rubber. Kamui is a solid driver and I see no reason for him to be replaced unless the cash strapped Sauber outfit do indeed lose Checo and need to balance the books with 2 sponsored drivers rather than one.

Williams acquired the services of the Venezulean driver Pastor Maldonado for 2011 and retained his services for 2012. I was recently at Williams for the FOTA forum where Sir Frank Williams lauded his driver for his dedication and skill set. I see no reason why Williams would want to replace Pastor as he brings plenty of money to the team and previously had success in GP2 with the Rapax Team.
Bruno Senna joined Williams having previously had arduous seasons behind the wheel of the HRT (2010) and replaced Nick Heidfeld for the end of the 2011 season for Renault. The Brazilian brings his own array of sponsors to the table for Williams and although going almost unsung hasn't had a dissimilar season to Pastor. Rumours are abound that he will be replaced for next season, however unless a driver of much higher talent or one that can bring much more money were to be available I see no reason for him to depart.

Force India have both of their drivers contracted for the 2013 season but have already stated they won't stand in the way of either making moves to higher teams. Both Di Resta and Hulkenberg have been linked with Felipe Massa's Ferrari seat and as possible replacements should Michael Schumacher decide to retire once more. Di Resta has more recently been linked as a replacement for Lewis Hamilton at McLaren should the latter make a switch to Mercedes. This may be fuelled by Di Resta's new management who also looks after Jenson Button.

Toro Rosso have already proven that their driver programme comes first when they ejected both Sebastian Buemi and Jaime Alguesuari from the 2012 plans. The Red Bull brand use the Toro Rosso team as a platform to find new talent for their senior team with Sebastian Vettel being the benchmark. Daniel Ricciardo jumped the queue during 2011 by being place with HRT in order to access his abilities in advance. With neither Ricciardo or Vergne showing the type of pace that Vettel did in his Toro Rosso days it will be a surprise to no-one if the team start with a fresh line up next season. This will leave the current drivers looking for drives in 2013.

Caterham have had the services of Heikki Kovaleinen throughout their various guises over the last 3 years. It does however seem that Heikki is done with his share of trying to help the team elevate through the grid and rumours have linked him to both Sauber and the seat potentially being vacated by Lewis Hamilton. Heikki has already been part of the McLaren team once in his career and so McLaren and/or himself may be reluctant to revisit the partnership. Vitaly Petrov found his way to a Caterham seat after a lacklustre performance for the Renault team. I've heard rumour that some of his sponsors are becoming disillusioned by his and Caterham's performances and may withdraw their support at the end of the year. I personally never understood why the Russian didn't find his way to a Marussia seat in the first place but he looks destined for there should the rumours hold firm.

Marussia may well be a further force throughout 2013 with their technical partnership with McLaren bearing fruit. The team have also announced they will run KERS for the first time during 2013 which will give them a much needed boost in order to chase the teams in front. Timo Glock is the lynch pin in the Marussia team and is signed on a multi year contract, however Charles Pic is rumoured to be unhappy and reports have him linked to Caterham, Force India and Sauber for 2013 drives.  Marussia could well place Max Chilton in the second seat in place of Pic (Thanks to @MarussiaF1Will for his fan perspective)

HRT the team if they are wanting to progress surely need to recruit some young talent in order to inject both life and money into the team. However De La Rosa's Spanish connection and years of technical experience inside McLaren may well see him keep his seat.  Both Dani Clos and Ma Qing Hua have connections with the HRT team and could see their way to at least one of the seats.  Meanwhile Antonio Liuzzi still has some connections to the team and could take up one of the seats again. (Thanks to @Lundo888 for an insight who is a HRT fan)

On the fringes – There are plenty of drivers out there that still either warrant a seat or warrant a shot at one but the most likely candidates would be:

Adrian Sutil – Was dispatched by the Force India team but has been touted to be talking to quite a few teams including Ferrari and a return to Force India
Jaime Alguesuari – Toro Rosso driver for 09-11 and currently keeping himself busy with the Pirelli test drivers role.
Lucas Di Grassi – Ex Virgin Racing driver and the previous Pirelli driver has now aligned himself with a test role with FormulaE (See my article on Formula E here - http://somersf1.blogspot.co.uk/2012/09/formula-e-future-of-motorsport.html )
Karun Chandhok – Ex HRT and test driver for Team Lotus in 11 Karun never really had the opportunity to show the talent he may have.
Jerome D'Ambrosio – Currently a reserve driver at Lotus and drove at Monza in place of the banned Grosjean
Sebastien Buemi – Currently a reserve driver for Red Bull Racing
Rubens Barrichello – Still wants a seat in F1 and could prove an asset to one of the younger teams.
The list of drivers that could/should step up from Feeder series like GP2/3 is huge but as Will Buxton mentioned in his recent article (http://willthef1journo.wordpress.com/2012/09/05/poisoning-the-well-f1s-underlying-problem/ ) the problem with this no longer just lies in the expectations of quality.

Lewis Hamilton holds the key to a driver market that will unravel when he puts pen to paper and why shouldn't he hold all the cards? Afterall he is a once in a generation driver who transcended the need to start his F1 career at a lower tier team and won a title in his second year (He should really have clinched the title in his maiden year too, although we'll let him have that one) 
You have to wonder if his desire to win races and titles can be matched by the Mercedes team. Their only win in 3 years came at a time when almost any team from 7/8 could have won a race as they all battled over understanding the Pirelli tyres. 
Lewis' decision needs to be one made from the heart of a racer and not one from the brain of a branding house.
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1 Sept 2012
Lotus & Mercedes DRD (Drag Reduction Device) you may know it as DDRS / Super DRS / F Duct / Passive F Duct

Lotus & Mercedes DRD (Drag Reduction Device)

In response to the original Mercedes DDRS, Lotus have gone on to develop a system they simply call 'the device'. I start here because most of the mainstream media are calling the Lotus version DDRS which simply isn't the case. DDRS or Double DRS is when DRS is used as a fluid switch to create a secondary function, in the case of the Mercedes DDRS this reduces drag on the Front Wing for a enhanced straight line speed. Most importantly DDRS (Secondary usage of DRS) is now banned within the 2013 regulations so calling it DDRS will only make things more confusing for the casual / less Tech driven F1 fan

The beauty of Lotus' device of which I'm coining DRD (Drag Reduction Device) is it doesn't need DRS in order to work and reduces drag at a certain threshold. This means unlike the Mercedes DDRS system it will reduce drag even when DRS isn't available during the race. 

How I believe the system works

(1)In terms of additional parts the system appears uncomplicated with the addition of the Airbox 'Ear's, (2) internal ducting (3) the engine cover cooling exhaust, (4) the periscope that leads to the rear wing with the small ejector holes and the appropriately shaped beam wing Monkey Seat (5).

1. Airbox 'Ears' Starting at the Front these little ducts serve a few purposes:

During normal conditions air is presented to the 'Ears' and air moves down the internal tubing (2) toward the periscope.

When 'Off Throttle' the main airbox receives more air than it can extract and so blocks off the entry point. This normally creates a backwash effect whereby the air stagnates in front of the airbox before counter rotating off the sides and over the engine cover at an undesirable speed. This is 'Air Spillage' and creates a turbulent airflow pattern over the engine cover but more importantly then goes on toward the rear wing.
So when the Lotus is off throttle this airflow is collected by the 'Ears' and utilized further down the device but just as importantly it doesn't impede the more ideal laminar flow heading to the Rear Wing.


2. Internal Ducting during the build up phase on Thursday Sutton Images managed to get the following image of the Lotus E20 which shows that there are clearly 2 outlets from the airbox into the engine cover.  Previously we had assumed the air was being moved en mass from both the Airbox and Airbox Ears down the engine cover to the outlet at the rear. This now shows that the airbox and ears have seperate outlets with the top one most likely the pipe from the Airbox Ear's that feeds to the periscope.


3. Engine Cover Exhaust: Usually the engine cover stops much more abruptly at the rear of the car that when the 'device' is fitted.  The additional exhaust section serves a few purposes: It allows the addition of the periscope that extends upto the rear wing but also acts as an exhaust for the airflow which exits into the beam wing Monkey Seat / Mini Diffuser.  As we can see from the great picture Sutton got during the rain hit Free Practice Session it would appear that even at the rear outlet two pipes remain in play, allowing the airflow a route to exit once the periscope is at full capacity (blockage)



4. Periscope: This is most important aspect of the whole system as it's how the air is transported to the underside of the Rear Wing in order to create the additional downforce at low speed and 'Stall' the rear wing over the speed threshold.  In the picture below Lotus had the ejector holes taped over in order to stop the device operating (due to bad weather conditions)


5. Monkey Seat / Mini Diffuser is placed / being used in order to take advantage of the situation presented by the device in general.  By adding this Diffuser shaped Monkey Seat the airflow will be pulled through the exhaust as Downforce is generated on top as seen by the stagnation of the Flow Viz paint at the trailing edges of the outer section of the Monkey Seat.


 Airflow Pattern


In the images above we can see that air consumed by the Airbox 'Ears' is transmitted along the top pipework and branches off to the Periscope.  In the enlarged image of the Periscope we can see the ejector holes that blow air tangentially across the width of the Rear Wing main plane (The image below shows the effect of this when the team used flow viz at the Hockenheim weekend), blowing the underside of the wing reduces boundary layer build up which allows for a steeper Wing AoA to be run giving a net downforce gain. The amount of rear downforce available to teams has been reduced since the regulations stopped blown diffusers. Making the amount of downforce generated at the rear wing once again imperative.

At a certain velocity the amount of air being blown isn't enough to prevent the boundary layer build up and the wing stalls. (CL Max) This reduces the amount of downforce and drag on the rear wing.
Simultaneously the air in the periscope now creates a blockage which allows the airflow to feed out toward the Monkey Seat / Mini Diffuser which will increase it's effectiveness creating downforce in this region.
The switch from downforce creation to drag reduction is aided by the use of the Monkey Seat / Mini Diffuser as it helps transition the forces involved.


So in essence with DRD the rear wing is passed more air than usual underneath the main plane allowing it to generate more downforce until such a point it stalls, allowing the car to attain a higher top speed (I'd predict anywhere from 5-10KMH)

So far all I have shown you is the Lotus variant but during Free Practice on Friday Mercedes also placed a similar device on Nico Rosberg's car.  The weather forced the team into blanking off the ejector holes and so DRD was never actually used.  However it did afford us the opportunity to see their version....


As we can see from the image above the Mercedes variant has their Airbox ducts slightly further back which allows them to be fitted with the engine cover. (Rather than be part of the Airbox structure and un-removable if the system isn't used, as we saw Kimi with the taped up over the Hockenheim and German GP weekends when not in use)
The arrangement at the rear of the car is very similar to that shown on the Lotus however one thing is yet unknown due to the weather not allowing the 'Device' to be tested.  We can see in the picture above and below that the Periscope doesn't extend to the underside of the Rear Wing Mainplane.  It may be the case that Mercedes simply ran their usual Rear Wing configuration and didn't bolt on the Deeper/Higher AoA Wing they could use in conjunction with the DRD.  The other plausible reason is that it is infact designed this way and Mercedes plan to attempt blowing a larger section of the Rear Wing to gain downforce / reduce drag.



I see absolutely no reason as to why Mercedes can't continue to use DDRS in conjunction with DRD as one will not impact the other even in terms of packaging.  As we can see below the twin pipes leaving the beam wing going through the chassis don't intefere with the placement of the Exhaust / Monkey Seat arrangement.


If you wish to understand my interpretation of the DDRS system that Mercedes use it is included in my recent Mercedes article: http://somersf1.blogspot.co.uk/2012/08/the-trouble-at-mercedes.html

In terms of others copying the Lotus design, as we have already seen Mercedes a team that is known for taking a long time to implement upgrades take up DRD I see no reason why others won't do the same.  One crucial factor however is that both Lotus and Mercedes run fairly aero neutral exhaust designs.  Whether this will factor in the design of everyone elses DRD is something I very much look forward to.  As I have previously alluded to Mercedes and Lotus (nee Renault) have good experience with Passive devices but I see no reason for the likes of McLaren and Ferrari to adopt the designs too. http://somersf1.blogspot.co.uk/2012/08/bank-holiday-monday-musings-rear-wing.html

EDIT: Additional Images of Mercedes DRD from the Young Drivers Test 10-12th September

Above: Day One, Sam Bird Tests the same configuration as Nico had fitted in Spa

Above: Day 3, Brendon Hartley Tests the configuration without the Monkey Seat straddling the engine cover exhaust (However as it was wet the system was removed)

Images used in this Article are copyright their respective owners: Mario Keszeli / Sutton Images / Xpb Images
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27 Aug 2012
Bank Holiday Monday Musings: Rear Wing Design & The Past, Present &Future of Passive Ducts, F Ducts, DDRS and Super DRS - Lotus E20

As much of the traffic to my site atthe moment centres around the Lotus DDRS/Passive F Duct system Ithought for my pre Spa Musings I'd talk a little about thepast iterations of such a system. 

We can go as far back as 2008/09 to seethe first signs of these devices emerging with both McLaren and Toyota fielding passive ducting on their cars for more co-efficient designs. 

The designs of all the systems have always centred around the premise of the central 15cm of the wing being free to allow holes. The Toyota and McLaren designs of 08/09 featured such holes in the15cm region which would increase downforce in the central portion of the wing by injecting airflow below the normal wing gaps. 

As we can see from the pictures below of the McLaren from behind at Monaco in 09 the slot gap projects the same width on the rear as it does at the frontal collection area. McLaren angled the wing fences on the wing in order to augment the airflow across the wing. The slot gap delays the onset of boundary layer separation caused by the wing being run at additional angle of attack, resulting in a downforce gain with the slot acting as a third slot gap separating the wing plane. The rear wing planes angle of attack and the size of the hole in the wing are crucial at higher speed. As the speed increases the air provided by the hole gets to a point where a blockage occurs, (ie no more air can be vented) this causes the boundary layer to separate and thus the wing stalls. 
In aerospace the term 'stall' is used in a different context to the way the F1 fraternity use it. In terms of an F1 wing a stall occurs when the angle of attack is too large (same as aerospace) whereas when an airplane wing stalls, lift is lost due to the critical AoA being exceeded and the flow separates creating drag.  This is where the major confusion occurs as principally when an F1 wing stalls just like an airplane it creates drag but essentially there is a resultant loss of downforce.   The loss of downforce makes the wing less efficient and so cancels out the drag further giving a top speed advantage of between 5-10km/h dependent on the system.

 Above: Toyota TF108 - Monaco 2008 you can see the central duct in the 15cm free zone
Above: McLaren MP4-24 - Monaco 2009 Shows the passive duct used by McLaren which was the genesis for the 2010 driver controlled F Duct

It is widely accepted that drag reduction is the desired effect of both passive and F ducts but it is entirely plausible downforce is also gained as a result of careful management of the rear wings angle of attack (AoA).

The F Duct systems of 2010 (Once again with McLaren at the fore, using their 2009 experience) were a development of this principle. Adding the driver as the controlling influence allowed the team to make the slots on the rear of the wing  larger meaning they could gain more downforce from an aggressive wing AoA whilst blowing the wing. When the driver covered the hole in the cockpit the airflow to the rear wing would cease and drag would be reduced.

 Above: McLaren MP4-25 - 2010 Slot gaps extend across the top plane of the rear wing

The FIA changed the rules in 2011 to stop the F Duct systems by placing a minimum radius of 100mm on the wing planes, this stops the teams from adding the slots that ran almost the length of the wing planes but the 15cm central zone still remains open to interpretation. Obviously with the allowance of DRS the FIA assumed that teams would no longer pursue this method of downforce enhancement / drag reduction. However the system that Lotus have been testing since Hockenheim uses these exact principles.

Lotus Passive Pylon Duct

With the 100mm Radius rule stopping the placement of elongated blow holes on the rear of the planes it would appear that only the original straight through style duct would be viable in order to create the F Duct effect (Like the Toyota and McLaren versions shown above).  However smartly the Lotus system takes cues from the original F Duct concepts but rather than using holes/slots in the wing planes these are placed in the pylon that connects the engine cover to the Rear Wing. The holes blow tangentially from the pylon across the wing span.

Blowing the air across the wing plane reduces the boundary layer which in combination with the steep angle of attack of the wing creates more downforce. At a certain threshold the blowholes reach a point where they can't produce enough air to stop the wing from stalling and so drag is reduced.  Careful management of the wing AoA and the size of the pylon blow holes will decide the speed threshold at which the wing loses downforce and drag.

Above: Lotus E20 - Hockenheim Showing the rear wing painted with Flo-Viz, due to the Flo-Viz you can see in the central section the airflow separating

Above: Lotus E20 Airbox 'Ears'

As I have talked about previously the 'Ears' are used as a way of recovering airflow when off throttle.  The main airbox entry blocks when off throttle and the air that usually tumbles over the side and disturbs the airflow heading towards the rear wing now enters the ear ducts.  This obviously helps by keeping the system in loop during the Braking and Turning phases generating more downforce.

Lotus placed their exhausts in a more aerodynamically neutral position than say McLaren this season and as such have a more consistent aerodynamic platform.  Realising that without EBD the downforce level is inconsistent the team have decided to achieve downforce in a more consistent way via the Rear Wing (Including the Beam Wing) and airflow en mass over the Diffuser.
The addition of the pylon for the passive F Duct required the team to have the engine cover finish further back toward the wing and so a funnel now presents itself at the Monkey Seat / Beam Wing. This Funnel and Monkey Seat act together acting as a mini diffuser atop of the beam wing creating more downforce.

In order to see how Lotus (nee Renault) came up with their current system lets quickly look back at their 2010 efforts.  The team actually used two variants of the rear wing drag reduction system back in 2010, they ran the passive style system that McLaren used in 09 and then a full blown F Duct system. Their full blown system used similar Airbox ears we now see on the LotusE20. The pylon being used as a means of carrying the air to the under side of the Rear Wing also featured in the original 2010 designs but this was structural in the 2010 versions. This however must have given the team a head start in CFD and Wind Tunnel in terms of modeling the structures involved.

 Above: Renault R30 - 2010 (Hungary) Passive System
  Above: Renault R30 - 2010 Showing the similar Airbox 'Ears' being used currently on the Lotus E20
Above: Renault R30 - 2010 F-Duct System

Something to think about?....

Before the FIA increased deflection tests and then latterly mandated the size of the slot gap teams intentionally designed the top flap to flex under load closing the gap between it and the main plane. This had the desired effect of stalling the wing and reducing downforce/drag as the AoA of both wings combined became too large.
As a parting thought on this subject I propose the use of a trailing edge Gurney that although dimensionally would be within the regulations (The Latter part of article 3.10.1: 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.) would be different to the perceived Rear Wing 'Gurney'

Above: McLaren introduced a Red Bull style Diffuser gurney in Hungary in order to aid the generation of downforce


If we take the current design of the Red Bull, Ferrari & McLaren diffuser gurneys as inspiration these Gurneys act as a method of increasing downforce through airflow injection.  Using a similar design approach at the trailing edge of the rear wing flap could produce more downforce .  Similarly it could be used in conjunction with the flap to stall the main plane by the use of flex.  The Gurney doesn't have the same deflection tests as the flap and main plane and so could be designed so that the gap is open to generate downforce and closes at higher speeds.    The 'Gurney' has no real restrictions placed on it's design and so could have a small or large chord as long as it doesn't extend beyond the 20mm mandated.  The height of the gurney and the slot gap left between it and the flap could be adjusted in order to suit the characteristics of the downforce/drag reduction required.
As usual these are my thoughts and should be taken with a pinch of salt as I haven't got access to CFD etc in order to access the general principles and most importantly the effects of DRS when the top flap is open may make the idea mute.  In my eyes the Gurney could offer a source of both additional downforce and drag reduction by lending principles from former designs. 

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3 Aug 2012
Lotus E20 Passive F-Duct System (DDRS/Super DRS) – Part 2


You may well have already read my previous article on my feelings regarding the Lotus DDRS system http://somersf1.blogspot.co.uk/2012/07/lotus-e20-ddrs-hockenheim.html, as always the problem with not being able to see these items in the flesh leaves doubt over their actual purpose. As more images have become available it's become clearer that my original thoughts on the system although perfectly valid and usable are actually flawed. The trouble with fluidic switching systems is that there are so many ways in which you can move air from one location to another that the waters muddy.

Compounding this, Lotus had already stated that their system utilises the same loophole that the Mercedes DDRS system works within (ie using the DRS movement as a part of the flow adjustment for another device). It is plausible that is a Red Herring with the addition of the periscope simply acting as it's own device reducing drag by blowing the underside of the Rear Wing's main plane reducing drag passively above a certain speed threshold and then when DRS is activated it simply augments the DRS effect. I'll explain this first and then go on to explain how both this theory and my original one could be combined.



As we can see in the images above small slots in the periscope blow the central section of the main plane reducing drag in that region of the wing. (Flow Viz is splayed in this region denoting the reduction in drag) This concept mimics the original F Duct principles in how drag is reduced on the rear wing but falls short of being as powerful. The original F Ducts had much larger slots on the rear wing plane in order for the drag to be reduced over a larger area. The original F Duct also required the driver to act as a switch effectively turning on or off the rear wing, this was outlawed as part of the regulation change back in 2011. The Lotus system is instead tuned to reduce drag at a certain speed by specifically designing the engine cooling outlet. At lower speeds the air consumed by the airbox inlet and ear ducts can escape through the engine cover cooling exit. As the car reaches higher speeds the air consumed becomes more than can be effectively exhausted from the cooling exit and so air spills up the periscope toward the rear wing reducing drag on the lower wing plane.
The rules were amended at the end of 2010 to stop the interaction of shark fin engine covers with the wing planes and DRS was introduced in response to the teams drive to reduce drag and increase overtaking. With DRS now moving the whole top element creating a union with the engine cover would obviously be very difficult anyway.  The periscope however doesn't join to the wing frontally but on the underside and so circumnavigates this rule.

Using the periscope to blow the bottom wing plane allows a dual drag reduction system with the lower plane being blown as soon as the car reaches a pre determined speed and DRS obviously adding the larger drag reduction element as and when it's activated. Passive F Ducting to the rear wing will provide a marginal advantage during qualifying where DRS is unlimited simply boosting the DRS effect but it's during the race where the system should give Lotus the largest advantage. On circuits like Spa and Monza they will be able to increase their wing angle of attack creating more downforce during cornering and have less drag on the straights than their counterparts where DRS is unavailable.


The addition of the Airbox Ear ducts are as I mentioned in my previous article paramount in terms of balancing the system due to Airbox Spillage. As the driver comes off throttle airflow is impeded in the airbox entry and so tumbles off the sides of the airbox down the engine cover creating a turbulent airflow toward the rear of the car and most importantly disturbs the airflow around the rear wing. The ears that Lotus have employed capture this airflow in order to keep the airflow heading toward the rear wing with a laminar flow which in turn will help create downforce more effectively in the braking and turning phase (Credit Gordon Mccabe - http://mccabism.blogspot.co.uk/2011/10/airbox-spillage-and-fluidics.html)

Pit Falls & Problems

Although McLaren were the first to introduce the F Duct in 2010 it's widely regarded that once integrated that the Renault team (now Lotus) had the most effective F Duct system. This obviously puts them in great stead in terms of understanding how best to utilise such devices. The problem with a passive system over a controlled system (like the original F Duct) is that the system is very much dependent on airspeed through the airbox. This may cause problems in the form of tunabilty especially when we consider the difference between the ability of a car during qualifying with a low fuel load and that of a car full of fuel. We also have to consider the high speed nature of circuits like Spa and Monza have corners with high speed exits and so reducing drag on corner exit as the passive duct inadvertly activates could be catastophic. This means that the Periscope Duct needs to be tuned to activate at a relatively high speed and as such won't have the same drag reduction capability the older F Duct did.

Combination of the above with my original theory

If we take the team at their word that the system employs the DRS as a lever to leverage another element in the system I believe that both variants of my thoughts could be in play. The problem with this is that we are yet to see a close image of the DRS open in order to establish if the wing covers any holes in the wing plane.

This would work by exhausting the airflow from the airbox inlet through the cooling hole and as it the exit becomes too small for the airflow exiting the air moves up the periscope and reduces the drag on a portion of the lower wing plane. When DRS is activated and a hole is opened on the rear wing plane a more positive draw would be created on the airflow from the airbox inlet drawing more air up the periscope and out of the slots. This would increase the effectiveness of drag reduction on this region giving a more positive DRS effect. I believe this offers the more balanced effect with a transition phase of drag reduction from both avenues.

In Summary

Until further evidence presents itself the exact operation of the device is speculation but it's application is something I'm sure the other teams will be looking closely at as in a year where the grid is so close even the smallest advantage could play a large hand in the results of the latter races. McLaren have already hinted that they haven't ruled out the possibility of such a system before the end of the season. One thing is however clear that systems linked to DRS won't be prevalent in 2013 as the teams have unanimously voted to outlaw them. This will be passed to the technical working group (TWG) who will work with the FIA in order to constrain such usage by adjustment of the regulations.  This however doesn't prevent the usage of the passive element of the system via the pylon being exploited.

Credit to Nick McDowell for the image pointing out the slots in the periscope


Original Images Copyright Sutton Images (www.suttonimages.com)
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20 Jul 2012
Lotus E20 DDRS (Double/Super DRS/F-Duct) -  (Hockenheim)


Lotus had come to Hockenheim already stating they had 'interesting' upgrades to test. The interesting upgrade centres around a DDRS system. Lotus race pace this season has been amongst the best but due to a lack of raw pace during qualifying and some unfortunate luck they have been found slightly adrift on race day. In an attempt to bring their car closer to the front in qualifying a DDRS system should add more pace throughout qualifying where DRS is unlimited in its usage and maybe add a small increase in performance during the race.

Unlike the complicated Mercedes DDRS system that employs tubes from the Front to Rear wings the Lotus system echoes the original F Duct principles:

The two ducts either side of the airbox inlet feed air down the engine cover toward ayet unspecified source as soon as more information is available I'll post it. However I'd hazard a guess at either the starter hole or due to the central portion of the Diffuser Gurney having a slot the air exits out the bottom section of the engine covers cooling exit. Either of these will effectively help the diffuser and increase rear end downforce. 


As we can see in the picture below a small feed (Periscope) is also present as the exchanger between the bottom wing element and the collector at the beam wing. This acts as the switch and is actuated by the DRS flap above being opened (Much like the Mercedes variant, although again without the necessary close up shots of that area I can't be 100% accurate) When DRS is active the air usually feeding the lower section of the engine cover or starter hole is then drawn upward and exits out of the rear of the engine cover, the addition of a cleverly shaped cover / monkey seat helps to keep the flow managed without disrupting the flow as it exits from the rear of the car.


To break it down here is a couple of quick pictures I mocked up in MSPaint in order to show the flow pattern when DRS is active and inactive
Above: DRS is inactive and so the air being scavenged by the ducts next to the airbox inlet is sent to the lower exit (Possibly the Starter hole or the lower cooling exit)
Above: With DRS active holes hidden under the Rear Wings Main Plane act use the air to re-divert the air from the airbox inlets and exit it out of the engine cover cooling hole (which is now extended by the addition of the shapely Monkey Seat)

Above: Showing the system from the rear the engine cover now extends close to the appropriately shaped monkey seat which extends the engine covers reach past the beam wing.  On top of the engine cover you can see the periscope tubing which connects the cover to rear wing plane and acts as part of the fluid switch

Above: Slotted Diffuser Gurney as mentioned above the airflow is most likely exiting from the lower portion of the engine cover and having the slot in the Gurney here will intensify the effect of the diffuser in central portion

Above In this image you can see where the lower portion of the engine cover exits (Circled in Red) and does so in the same region of the diffuser gurney slot aft of it

Above: Basic Diagram showing the predicted airflow pattern of the Lotus System: Yellow indicates the airflow entering the ducts next to the airbox which when DRS is inactive exits lower in the cooling exit (light blue) in order to boost the diffusers effectiveness. When DRS is active a hole in the lower rear wing plane is uncovered and air interacts via the periscope duct (Green) and acts much like the old F Duct system moving the airflow to the top exit of the engine cover and through the Monkey Seat (Red)

Other side effects of the Airbox Ear Ducts

The other interesting aspect behind the utilisation of such ducts around the airbox is for 'air spillage', over recent seasons this hasn't been a problem as the engine has been continually consuming air (Off Throttle Diffuser Blowing).  However now the use of off throttle blowing has been curtailed when the driver lifts out of the throttle the required amount of air entering the airbox inlet isn't so large.  This effectively creates a blockage and so the airflow stagnates (builds up) and then cascades over the sides of the engine cover.  This type of airflow is disruptive and effects the bodywork aft of the airbox.  As this occurs during the braking and turning in phase it's quite an undesirable effect as it reduces the effectiveness of the Rear Wing aswell as any residual effect on downforce the exhaust plume may have.  The ducts added to the sides of the airbox inlet act as catchment devices for the airflow during these off throttle moments.  This helps to keep airflow heading toward the rear wing uniform resulting in a downforce gain during braking/cornering.  During normal driving conditions the ducts simply carry additional airflow to the rear of the car.

In summary the Lotus system should boost downforce performance whilst the DRS is inactive and lift the effect when DRS is in use.  Ideal for Lotus' quest for a better qualifying performance and will help with additional downforce during the race


03/08/12 I have added a new article in regard to Lotus using the system for drag reduction via a passive duct system: http://somersf1.blogspot.co.uk/2012/08/lotus-e20-passive-f-duct-system.html

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