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March/April 2010
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Audi R15 plus, Paul Ricard 20104.14.10* updated 4.15.10

>>This photo was taken last weekend at Paul Ricard.  It shows the underside of the Audi R15 plus' front splitter and is interesting for the appearance of the vortex generators.   The use of the VGs seems to indicate that conditions are ideal for detached flow on the underside of the Audi's splitter (asymmetrical cross section, 30 mm trailing edge thickness).  But this should be somewhat expected considering the reduced height bodywork has made the operating conditions for the splitter a little more difficult inasmuch as the flow off the trailing edge is concerned.  On the previous R15 execution a lot of work had gone into providing the front wing and flap with ample airflow allowing for maximum  pressure recovery.  That's why the covering bodywork was mounted high and shuttered.  But the lowering of the front bodywork on the R15 plus has simply made ideal pressure recovery for the splitter unachievable.

But there are whispers that the flow separation is intentional to an extent.  Certainly part of the flow separation is the simple fact of life of the the splitter's design and execution.  But we understand that there is also beneficial aspect; the separated flow has less energy and it makes picking up sand and dust and exhausting it directly into the radiators less likely, as long as it is directed to behave in such a manner.  
The VGs simply allow for this entire condition to be better controlled.

Looking back to 2008, the Audi R10 had a very similar treatment.  Was there ever any discussion of cooling issue on the R10?


Interestingly, flow detachment was less of an issue on the R15's front wing as the mainplain/flap injected high energy flow into the underside of the assembly helping the airflow stay attached.  But then again the R15 did suffer from sand pickup clogging the intercoolers at Le Mans last year. The drawback was that this setup was much more pitch sensitive.  

Every solution has its negatives.

It also comes to our attention (via RCE's Sam Collins) that the R15 plus is running on
33/68-18 Michelins at the front and 37/71-18s at the rear.  Same as the R15...same as the R10.

Furthermore, Wouter Melissen tells us the internal rear channel ducting has been completely removed.


Photo courtesy Wouter Melissen, www.ultimatecarpage.com.
Audi R15 plus, Moza testing 20104.2.10

>>Two (make that three) videos have appeared on YouTube of the Audi R15 plus testing at Monza yesterday.  They are here, here, and here.  We noticed this detail, the lower quarter of the trailing edge of the front fender is scalloped out to allow for additional venting of the front wheel well.
Audi R15 plus, Monza testing 2010The area between the front wheel and the tub appears rather opened up, especially compared to the R15.
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3.31.10

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Audi R15 plus, Sebring testing 20103.25.10* updated 3.26.10

>>More shots from Audi's R15 plus testing at Sebring (see Robon Thompson's full gallery).  We pointed out the inner fender bulge originally (3.15.10 news item), but this shot has us really wondering what's going on there.  Previously this area of the R15 was covered by the high-mounted shuttered bodywork.  This was designed to allow the wing elements below to "breath" more efficiently.  But with the bodywork lowered, the inner fender was unveiled and these bulges became necessary to cover the tire.  But it's the size of the bulges that has us scratching our head.  We're presuming Audi is going through a testing program trying out various front wheel widths.  How wide are they, as wide as the Acura ARX-02a's were last year?  Naturally we don't know, but these bulges certainly aren't merely there for bodywork clearance for the tires through steering lock.  

But as always, we reserve the right be be seeing things that aren't there.
Audi R15 plus, Sebring testing 20103.23.10

>>Audi began a 5 day test starting this past Monday in order to shakedown the updated Audi R15 plus.  In spite a significant off yesterday in Turn 17 that reduced the one and only R15 plus into jagged carbon bits, the car was back on track this morning, according to Robin Thompson.  
Audi R15 plus, Sebring testing 2010
In this rear shot we can see the new legality louvers that cover the rear tires as seen in rear elevation.  Interestingly, the regulation , Art 3.4.1 b/, states, "(the rigid bodywork masking the rear tires must...) Be designed in such a way that air passing through them is directed toward the ground at the exit."  It would appear the R15 plus' louvers direct the air up towards the rear wing at the exit.  An interesting detail is that at the outboard corners the louvers are inset to just cover the rear tires opening up an offset that allows unhindered air to vent out the rear of the fender wells.  The exhausts exit out the car similar to the standard R15.
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Peugeot 908 Paul Ricard 20103.21.10

>>Julien over at endurance-series.com sent this over last week.  In one shot we have a comparison of the Peugeot 908's two available front diffusers.  The top diffuser is the Le Mans low-downforce variant that was raced only at Le Mans last year.  The bottom diffuser is the sprint version and was raced everywhere barring Le Mans.  Arrows denote the differences.  Surprisingly these differences are ultimately minor (but for one major exception); a radius inboard is sharper on the Le Mans version, the shape going outboard is flatter on the sprint version, and the camber of the turning vanes is more aggressive on the sprint version.  Naturally the one major difference is that air blows through the front suspension and directly onto the sprint version's trailing edge (30 mm thick by the way, per regulations given the asymmetrical wing section being used on the 908) while on the Le Mans version air goes over the top of the bodywork. 

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Audi R15 plus3.20.10

>>An additional image has been released by Audi of the R15 plus.  This view reveals the side profile and shows that the rear fender profile has been completely changed with the leading edge shape extending much further forward and the trailing edge shape being less aggressive.  We're now only lacking a shot of the rear of the car.  The turbo intake has also changed though appears an iteration (at least in the "style" of...) of the 2009 Le Mans intake but larger and repositioned.  Furthermore, the rear wing position has shifted yet again.  When the R15 initially appeared last year the rear wing endplates extended past the rear bodywork.  At Le Mans this was revised and the wing was shifted forward and the endplates were in line with the rear bodywork (noted by the more extreme "question mark" shape of the mounts as the rear wing was shifted forward and thus positioned more directly above the mounting location).  This revision carried on from Le Mans through the rest of the season.  Looking at the R15 plus and noting the angle at which the mounts visually appear to intersect the top of the fender profile it's pretty clear that they have been designed to scoot the rear wing rearwards.  Naturally looking at the endplates gives us the additional (and more obvious) clue as it is now extending past the rear bodywork again.  This is in a further effort to shift downforce rearward compensating for the major revisions there (and see additional comments below, 3.15.10, regarding the changes to the front designed to rebalance the car aerodynamically).

Lola B09/80 Sebring 20103.17.10

>>Images from Sebring testing are trickling in.  Mike Callahan sends these along.  Here we see the first rear shot of the updated for 2010 Lola.  The area just behind the tires is now covered and louvered (though the louvers aim downwards in compliance with the regulations) and the outboard area of the fender now is sealed all the way down to the legality plate (yellow arrow).  The rear trailing edge body gurney is of huge proportions though similar to last year given the rear wing span reductions and the desire to recoup as much lost downforce as possible.
Lola B09/80 Sebring 2010At the front the Drayson Lola's central brake duct has been closed off with a plate and the older brake inlets brought back into service.
Peugeot 908 Sebring 2010The Peugeot 908 also has its huge gurney from last year as well as the two cute little gurneys we saw at Petit last year attached to the outboard ends of the fender.  The 908 does look smart in its new livery.

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Audi R15 plus3.15.10* updated 3.17.10

>>This just in...Audi releases image of the R15 plus.
Audi R15 plusThe nose vent is gone revealing the raw crash structures.  This seems to speak to a particularly functional design execution that took into account the desire to not have to re-test the nose crash structure.  Therefore the crash structures were left alone and modifications made around them.  The vent's inset leading edge (located between the two crash structure cones) now has a different shape (we can see a bonded on panel).  The changes effected here really are in response to the large changes at the rear and an effort to rebalance the car.  We're told the impact of the nose vent was minimal compared to the elimination of the rear channel concept.

Also note the riveted/bonded panels on the inboard face of the front fender to allow for wheel movement.  This area was previously covered up by the large louver panels that used to cascade over the top of the nose.
Audi R15 plusNow on either side of the nose reside new wing sections.  Note that the bodywork between the fenders has been substantially lowered.   We understand that ultimately this causes issues with airflow beneath these bodywork elements; the height here is critical and the lower these elements are, the slower the circulating airflow is in this area (hence why the R15 was designed the way it was with the cascading panels high up on the car in this area allowing flow to pass through them and helping pressure recovery of the wing elements below them).  But it would make sense that lowering them would shift downforce rearwards and reduce drag overall.  The front splitter/wing element has been redesigned as well.  This was an area of contention given the symmetrical wing elements that made up the R15's device and effectively created a front wing mainplane and flap.  From what we can see in this image, the flap is gone but the mainplane remains and it now has a variable length trailing edge.  The wing mounts are rather inelegant, amounting to little more than rounded posts.
Audi R15 plusAt the rear the large duct that allowed air to blow around the gearbox and through the rear suspension has been eliminated.  This was a primary source of internal controversy at Audi and contributed to the car's relatively high drag at Le Mans.  But then of course the R15 was carrying a lot more downforce than it's rivals (though this appeared to have cause issues with the Michelin's).  The twin channel concept came about through a different method of deriving the car's aero target.  In the past the the drag level was set and the package was developed by adjusting the target L/D.  But the new method of thinking set a target range of downforce and again L/D was adjusted as needed with drag being what it was for the given L/D.  But the problem was the amount of drag that the rear channel concept contributed, even it it was efficient from a downforce standpoint.  And if Le Mans was your goal this wasn't really the route you'd head in.  Now on the other hand, if you were interested in racing at venues such as your typical ALMS track, then you'd tend to want to have a look at the channel concept as it was very efficient if only considering very high downforce setups.  But as downforce was taken off it became less and less efficient, thus at the opposite end of the spectrum this aspect of the R15's design concept couldn't "pay" for it's ride at all.

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Audi R15 plus3.12.10

>>Today Audi released this teaser image of what we're told is the "interim" R15 plus (effectively it is the definitive car but for a few details that are as yet to be hammered out prior to Le Mans) as it was loaded onto a transport, presumably on it's way to Sebring.  No, not for the 12 Hour race next weekend; Audi has decided to sit this one out and instead will test in the days following the race. 
Audi R15 PlusHere we can see a close up of some of the detail changes.  It seems evident that the louvered side pods are gone.  At very least the louvers are gone from the outboard vertical face of the side pod.  Additionally, the trailing edge of the front fender pontoon has been revised and the outboard plate that extended back to the rear of the car and blended into the rear channel duct is gone.  From this angle it also appears that indeed the rear duct itself is gone, thus too the channel aspect of the R15 design.  It is our understanding that early on in the initial development of the R15 a more conventional design was considered.  It would appear the R15 plus has adopted some of those details and done away with some of the more interesting, though controversial, elements.
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Acura ARX-01c, Algrave Portugal Testing 20103.11.10

>>Last month Strakka  Racing shook their Acura ("HPD") down at Algrave in Portugal.  But this past weekend was the Le Mans Series test at Paul Ricard and Strakka Racing debuted a closer-to-specification ARX-01c.  The car that was seen at Algrave was effectively the ARX-01b but for the revised rear wing (image right).   But the -01c as seen at Ricard (image below) had a number of new details.  Nick Wirth has indicated all modifications for the -01c were developed exclusively in CFD.  But more importantly, "The ARX-01c run in Paul Ricard is as much of an update aerodynamically as the -01a was to the -01b."
Acura ARX-01c, Paul Ricard Testing 2010 Acura ARX-01c, Paul Ricard Testing 2010One of the more interesting details is the new turning vane on the leading outboard face of the fender.  This is very similar to a device on the Zytek LMP (image below).  Interestingly the front diveplane appears to have been designed to work in conjunction with this turning vane.  It was always our understanding that the turning vane was a device to shed drag to gain efficiency.  Going way back, the Reynard 2KQ utilized a similar device, called a truck vane, to reduce the initial iteration's high drag.  The flush front fender louvers appear to be molded into fender, there doesn't seem to be a separate changeable louver panel.  Less significantly, the headlight bucket/bezle also appears to have been changed leading one to wonder if indeed the entire front fender shape has been massaged.  When asked, Wirth deferred specifics only stating that, "There are many new parts on the car front and back, and it is a big step forward aerodynamically from the 01b."
Zytek LMP
Acura ARX-01c, Paul Ricard Testing 2010 Acura ARX-01c, Paul Ricard Testing 2010On the ARX-01c the fender trailing edge bodywork is similar to the original Courage LC75.  It also extends back further terminating in line with the rear wing.  Note also that the rear legality structure is different with a convex leading edge ramp as compared back to the -01b (image right).  The rear brake intake has moved from the lower position up to on top of the side pod ahead of the rear fender leading edge as similar to the ARX-02a.  Finally, note the solid endplate without the trailing edge notch.  Wirth also indicated that we should, "Expect further variants to appear both in Europe and the USA this year..."  Naturally then we should see detail differences between the ALMS-based Highcroft and LMS-based Strakka cars.  Wirth has indicated mechanical changes also accompany the -01c though he would not elaborate what those changes actually are.
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ęCopyright 2010, Michael J. Fuller