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Pete Lyons' fantastic Can-Am Cars in Detail:
March/April 2011
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All news content copyright Michael J. Fuller, unless otherwise noted
>>Sebring 2011<<
Aston Martin AMR-One I6 turbo4.30.11

>>Race Car Engineering Magazine is reporting that the Aston Martin AMR-One was barely putting out 300 hp at the Le Mans test in order to keep the engine alive.  But the 300 hp quoted doesn't seem reliable.  Simple calculations for hp absorbed given the top speed achieved by the AMR-One requires an unrealistically low drag coefficient to achieve the 187 mph trap speed the AMR-One set in the first practice session.  Calculating for hp absorbed using the 187 mph top speed and a frontal area of 1.71 m2 yields a .cd of .37 from 303 hp. A realistic LM .cd for an open top car is approaching .6 (.57-.59).  As a reference, we should expect around .5 for a closed top car.

Working the other way and solving for hp and again utilizing the 187 mph top speed, 1.71 m2, and a more representative .57 cd yields 468 hp at the wheels, about 520 hp at the dyno.  Going "high side" and using .59 gives us 484 at the wheels and 538 hp before transmission loss.  And of course all of this assumes the ACO's speed trap was at or near where the cars achieved their top speed (and that we're looking at drag and not gearing limited speeds--though we're assuming drag limited but understand that isn't accurate) and that the Aston was really and truly on it at the moment it was captured in the trap.  But a higher top speed would simply mean the Aston is putting out even more power.

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Audi R18*4.28.11 *updated 4.30.11

>>Today Audi revealed that the R18 is using a single VTG (VariableTurbine Geometry) turbo located in between 120 degree opposed cylinder banks.  The very short exhaust manifolds emerge from the inside faces of the cylinder banks to feed the 'V' located turbo.   The downside of the single, larger turbo, is that typically there is much more turbo lag though Audi claims the implementation of a variable turbine geometry turbo makes this less of a liability.

The rooof intake feeds the turbo.  The movement of the exhaust manifolds from the side of the engine to the center of the 'V' leaves the side pods less cluttered and improves internal airflow.

Audi has admitted that future implementation of a hybrid-electric system was taken into consideration in designing the R18.  Great pains have been taken to strip weight where ever possible and that is what drove the V6 configuration as well as the single turbo.  Audi says the V6 weighs 25% less than the R15's V10, but considering the V6 has 4 less cylinders and 1.8 fewer liters of engine capacity this isn't all too surprising.  The use of a single turbo means one less diesel particulate filter and ultimately less weight.
Audi R18, Le Mans test 2011>>Little is known about the R18's rear suspension configuration though this shot from the Le Mans test day seems to indicate that it is similar to the R15's. Pushrods (1) connect to torsion bars (2) residing either side of the gearbox/bellhousing with a third spring (3) bridging across to each bellcrank.  Most interestingly perhaps is that it would appear that the R18's bellhousing is entirely made from carbon fiber.  And we understand that portions of the gearcase, at least in the areas of the rear suspension pick up points, are carbon fiber as well.
Peugeot 908, Sebring 2011>>While we're discussing engines, this shot from Sebring 2011 clearly shows that the duct above the 908's cockpit feeds to the engine's twin turbos (note how it diverges to either side just after the plenum box), one each side of the engine.

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Audi R6 compared to Audi R184.27.11

>>It's often a good idea to baseline reference data.  You'll note we typically use generic figures for frontal area when calculating various aerodynamic data:  1.71 m2 for open top cars, 1.8 m2 for closed top cars.  1.71 for an open top car as it's 5% less than the closed top car, this seems a reasonable assumption.

This week Audi released a number of images including the shot here.  It's a great illustration of how small and lithe a contemporary LMP is compared to an average sized road car.  

This image seemed to be a good way to attempt to verify our frontal area figure for a closed top car using the known frontal area of the road car as reference.  Taking the image into CAD (Dassult's DraftSight) and tracing the images, a reference to the Audi A6's frontal area was found courtesy of the Internet; 2.3 m2.  Calculating the area of the A6 sketch in DraftSight gave us a figure of .1152.  Doing the same for the R18, .0895.  Thus the R18's frontal area is approximately 77.7% of the R6 and therefore 1.786 m2 using the 2.3 m2 reference.  Considering these were sketched particularly quick and with a bit of the 'ole Mk I eyeball given the image parallax, this figure is remarkably close to our generic 1.8 m2, especially considering we didn't bother sketching the R18's side mirrors.

Yoshi Suzuka4.26.11

>>Long time readers of Mulsanne's Corner will be familiar with Yoshi Suzuka.  As you'll recall, Mr. Suzuka was responsible for the aerodynamics of Nissan IMSA GTP race cars that dominated IMSA GTP in the 1980s & 90s.     

These days Yoshi is enjoying his retirement.  But he isn't sitting still.  Yoshi has been working on a Office Size scale wind tunnel.  Yes, it's about the size of a small cat carrier and accepts 1/24 scale models, and it will even measure front and rear lift forces as well as drag.  

Now some people are going to immediately scoff at this.  But watch the videos, Yoshi has made a 5 part video series that shows the model functioning and him working through a test case.  Understand that Yoshi doesn't make any claims that the data is accurate to full scale, simply that the trends are accurate.  Yoshi used 1/7 scale models for the Nissan IMSA GTP program and designed and built NPTi's wind tunnel.  According to Suzuka, he was able to achieve 2% and 4%, drag and downforce respectively, correlation to full scale with this tiny windtunnel.  This being the closest correlation to full scale in any of the 14 wind tunnels he used throughout his 35+ year career.  And the Nissan GTP program achieved results, so Suzuka must know a thing or two about what he's up to with his Office Size wind tunnel.

Part 1
Part 2
Part 3
Part 4
Part 5
  

Yoshi is looking to market this idea as well as other aerodynamics services.  Contact Suzuka Racing Services for more information.
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Pescarolo 01, Le Mans test 20114.24.11

>>Easily the most bizarre rear wing flap seen in recent years can be spied on Oak Racing's Pescarolo 01, this courtesy Race Car Engineering's Sam Collins.  The secondary flap has large "buttons" just aft the leading edge as well as an undulating gurney flap trailing edge.  We're trying to make sense of the buttons.  It's said they are in place to add energy and thus prevent flow separation.  But their placement on the top side of the flap, the high pressure side, is puzzling.  And given the typically low(er) flap angle seen at Le Mans (given the desire for less drag), problems with flow separation are even more puzzling.  So we're not sure we buy that argument.  The undulating gurney is designed to better mix the low and high pressure side airflows.
Aston Martin AMR-One, Le Mans test 2011>>Aston Martin's weekend collapsed early with multiple engine failures due to cylinder liner issues.  Could the effort be in question for Le Mans in June?

Looking in the left hand side of the engine bay we can just see the end of the inboard duct; it appears to simply empty into the engine bay.  The engine cover appears to be split in three pieces, a center piece carrying the fin and left and right hands.


See detailed analysis of all the Le Mans entries at Race Car Engineering.

 
Aston Martin AMR-One, Le Mans test 2011>>The Aston's repositioned turbo exhaust looks rather last minute.
Peugeot 908, Le Mans test 2011>>Close up of the small front fender exit duct on the Peugeot 908.
Peugeot 908, Le Mans test 2011>>We know that the equivalent duct on the Audi R18 is used to cool the car's LED headlights.

Aston Martin AMR-One, Le Mans test 20114.23.11

>>
Aston Martin has a few updates on the AMR-One for the Le Mans test weekend.  Most significantly, the rear wing mount is now of the swan neck variety.  Secondly, the turbo primary and wastegate exhaust has been moved and pokes out the right hand sidepod's shuttered louvers.

Race Car Engineering's Sam Collins is reporting to us:

  • The Lola developed Rebellion aero package is not available to customers
  • The Audi R18s apparently failed their first time through technical inspection, "...due to something on the front end."  
  • The reason for the absence of the Peugeot Hybrid4 is that it appears Peugeot are suffering through teething issues with the car
  • The Hope Racing Oreca Swiss HY Tech Hybrid is struggling to clear the ACO's hybrid inspection being carried out on the Bugatti section of the track
>>Minor Audi R18 details:
Audi R18, Sebring testing March 2011
Audi R18 Sebring testing, March 2011.  Audi ran two configurations, the debut configuration (shown here) and an updated/definitive configuration.  
Audi R18, Le Mans test 2011
We noticed this in the images that came out from Audi's testing at Sebring in March, but with closer shots and different angles available from the Le Mans test weekend it becomes a little more apparent what's going on here.  It would appear that the leading edge entry to the front diffuser is bell mouth in plan view.  The evidence of this is the vertical surface that appears to start wide and curve inboard (1).  In frontal elevation view, the transition from the outboard surfaces to the 50 mm step is less severe, but there's a new transition (2).  So assuming the split line (4) is the same, it would appear the mandatory 1000 mm wide 50 mm step area is slightly wider here (therefore more than the mandatory 1000 mm) on the R18.  Why?  More airflow to the front splitter for more consistent ride height sensitivity?

 Note the more substantial diveplane brace (3).

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Lola B10/60 Toyota, Rebellion Racing, Le Mans 2011 update4.22.11

>>Rebellion Racing released this image today, along with a press release, of their updated Lola B10/60.  The primary modification, all of which was designed and produced by Lola, is a switch to the new Michelin "wide" front tires and corresponding bodywork changes to accommodate that switch.  This amounts to wide front fenders with revised shape and detail changes to the headlights, front brake intakes, as well as revisions to the bodywork either side of the nosebox.  Essentially all bodywork forward of the front nose split line is new barring (presumably) the front splitter.  The car is also now utilizing swan neck rear wing mounts.  
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4.17.11

>>
Speed TV's John Dagys is reported from the ALMS round at Long Beach this weekend that the ACO has allowed a 1.2 mm increase in the inlet restrictor diameter for the HPD LMP2 engine.  Going back to the 2011 regulations' restrictor chart for non-cost capped turbo charged LMP2 engines, and we note the inlet size is 27.6 mm if using twin restrictors.  Thus the 1.2 mm now makes each of those inlets 28.8 mm, a 8.88% increase in inlet area.  Now we have it on good authority that the HPD engine is making about 455 hp.  A percentage change in inlet area relates 1:1 to changes in horse power, therefore the HPD motor should be seeing about 495 hp now.

But interestingly enough, when you analyse the Paul Ricard trap speeds for the RML HPD ARX-01d, power output seems suprisingly lower than the informed 455.  For this calculation we have to estimate frontal area and drag coefficient with the result being horsepower absorbed for the given speed.  At Paul Ricard the RML ARX-01d went through the traps at a 269.1 km/h average for its top 5 fastest speeds.  So using 269.1 km/h as the target top speed, estimating frontal area at 1.71 m2, and drag coefficient at .6, gives us a power output of 352 hp at the wheels (or using their high top speed, 270.1 km/h, 358 hp).  Assuming a 10% drivetrain loss, that's about 391 hp at the flywheel
(398 hp on the high side).  These numbers start to cozy up to the rumor that the HPD engine has closer to 420 than 455 hp.  
Looking at it another way, we can reason that our frontal area estimate is within the ballpark.  Admittedly we are guessing on the drag coefficient.  But there's enough body of evidence to suggest that btween .6 and .65 for an open top car in a draggy configuration is reasonable.  But one thing we're forgetting, using the ACO provided trap speeds we are assuming RML had set the car up to achieve drag-limited terminal velocity on the front straight.  But suppose the speed RML saw at Ricard was gear and not drag limited, we'd have to think the gearing limitation would put our estimate case at least within 5% of the actual drag limited top speed.  And by gear limited, we're meaning the car was over geared slightly to allow the ability to draft pass or what have you.  So using a 282.5 km/h projected top speed (105% of 269.1 km/h), and keeping everything else constant (frontal area and .cd), the true drag limited top speed needs 407 hp at the wheels to achieve the 105% top speed.  This put us at 452 hp at the flywheel.   That's within .6% of our informed 455 hp output for the HPD engine.



Of course Homer Simpson famously said,  "Oh, people can come up with statistics to prove anything, Kent (Brockman). 14% of people know that."

But we're hearing that the HPD engine won't necessarily be able to take advantage of the increase in inlet area.  We understand that it's a case of matching the inlet size to the available boost, and the HPD engine was struggling to utilize full boost as it was.  

Aston Martin AMR-One, Antonio Pannullo4.8.11

>>
Antonio Pannullo provides this graphic describing the Aston Martin AMR-One's cooling layout.  The blue arrows show airflow to the radiator.  Green to the brakes.  Red is part of the exhausted flow from the front diffuser.  The yellow arrows show the difference in the front diffuser flow that eventually is expelled at the back of the car.  This is the flow that is carried through the duct that runs down the side of the tub.

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Aston Martin AMR-One, Paul Ricard 20114.7.11

>>
A view of the rear of the Aston Martin AMR-One seems to produce the "elusive" brake ducts (1).  The diffuser strakes (2) are Peugeot-esque.
Aston Martin AMR-One, Paul Ricard 2011This would seem to be further proof that the exit just aft of the front wheel (2) is indeed fed by exhaust flow from the front diffuser (1).

Highcroft HPD ARX-01e, Sebring 20114.4.11

>>
We finally have some follow up on the Highcroft ARX-01e/ACO front end aero bit "issue."  It was initially our understanding that the ACO had hand-waived certain elements on the ARX-01e right into the dust bin of illegality and that Highcroft had competed at Sebring under a waiver of sorts.  Well turns out that wasn't the case.  Yes, there was some hand waiving, we had that much correct.  And yes, it had to do with the -01e's front end bits.  It turns out the discussion centered around Art. 3.6.2 and specifically the number of aerodynamic elements perched on the front end of the -01e.  

Art 3.6.2 states that you're only allowed 2 elements maximum (2 pairs) and it turns out the ACO had been doing some counting and had come up with the number 3, arguably 4, when they looked at the -01e.  They counted the diveplane (1), the vertical endplate that is attached to the outboard edge of the splitter (2), the vertical turning vane that attaches to the outboard face of the front fender (3), and, if the ACO wanted to really be picky, the strut that steadies the gap between the vertical endplate and the front fender (4).  Initially the really questionable element in the ACO's mind was the vertical turning vane, and questionable from a numbers standpoint, not design execution.  After some discussion, all parties agreed that the vertical turning vane was actually part of the fender and shouldn't be counted towards the total.  And with the ACO not in a nit-picking mood, the horizontal strut was ignored from the total.
Acura ARX-01c, Le Mans 2010Though the ACO's sudden interest in aero elements and numbers is a bit odd considering that the ARX-01c ran all last year with a similar setup.  Might a competitor have planted a bee in the ACO's bonnet?
Acura HPD ARX-01d >>We're dragging this one up from the bottom of the page because we want to specifically insure that the principals at RML see this.  Back on March 13 we reported on RML's Paul Ricard test, specifically focusing on RML's press release which commented on the HPD engine's apparent lack of power.  We said this in response:

RML has admittedly said the car was not in low drag configuration though we're told Paul Ricard's setup isn't too dissimilar to Le Mans'.  So it doesn't seem as clear cut as RML makes it, especially considering the high downforce set up (observing: very large front diveplanes, very large rear trailing edge body gurney).  One wonders about ride heights as well and if the car was indeed in an optimally efficient configuration.

In saying that we unfortunately overlooked provisions in the 2011 regulations stating that only two bodywork kits can be homologated;
a standard kit and a low drag kit.  But the rub is this, the low-drag kit is only allowed for Le Mans.  And the "standard" kit is the best guess average as to what the manufacturer thinks will work on most circuits.  Thus the standard kit is a compromise across the season.  And at Paul Ricard it most certainly was, but RML had no choice but to run it.  

Additionally, RML's performance was most certainly affected by running to 920 kgs, the minimum weight for non-cost capped LMP2s (vs 900 kgs for cost-capped cars).  This also means the ARX-01d was running a full 95 kgs over the car's design intent weight.  Naturally this can't help the car's handling, and this being the car that was judged by many to be the highest grip car bar none last year.

Apologies to RML, HPD, and Strakka for mucking that up.  Clearly something is amiss regarding the LMP2 restrictors.

All that being said for the HPD ARX-01d, one wonders who determines what car is or is not under the cost-capped LMP2 classification.  Could a manufacturer decide to take a loss on the car but sell it under the cost-capping classification?
Aston Martin AMR-One, Paul Ricard 20114.3.11

>>Another photo has emerged, though the picture of exactly how all the Aston Martin's ducting works still isn't completely clear.  As pointed out below (4.2.11), there's a duct that runs down the length of the tub offsetting the radiator outboard.  We suspect that all, or at least a portion of the air collected at the start of the floor (1) feeds that duct.  But note the arrow, perhaps the new duct that exits aft of the front wheel actually draws its air from the area outboard of the arrow instead of drawing off the high pressure air from the wheel well (as speculated initially)?  Both (2) and (4) clearly feeds the radiator with (3) drawing air into the brakes.  Observers note there's still a lack of evident rear brake cooling and suspect that the brakes might simply be cooled by air collected from engine bay flow through.

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Aston Martin AMR-One, Paul Ricard 20114.2.11

>>Julien Hergault produces another shot, this one with the AMR-One's radiator ducting removed.  We can see that the radiator is canted over (1) and not up against the tub.  That's interesting because there appears to be a duct (2) running down the outboard length of the tub.  We can surmise that this duct is scooping up air from the shared lower intake and depositing it past the radiator into the engine bay and eventually out the rear of the car.  We can also see the revised front wheel well airflow management (3).  This would appear to gather up high pressure air from the wheel well and deposit it just aft of the front wheel.
Aston Martin AMR-One, Paul Ricard 2011 >>Side view of AMR-One showing new wheel well exit duct (1).
>>Dailysportscar is reporting some interesting numbers from the Peugeot test that occurred at Paul Ricard just prior to the race.  According to dailysportscar.com, the 2011 Peugeot 908 was clocked at between 325 and 330 km/h on the back straight at Paul Ricard.  This compares to the 324 km/h that the Oreca entered Peugeot 908 HDi-FAP averaged (3 practice sessions, qualifying, and race trap speeds: low of 321, high of 327) last year during the race at Paul Ricard.  This got us thinking as to how the new car, with supposedly 150 hp less than last year, was able to essentially match the trap speeds from last year.



The table above shows the thought process.  First we calculated the drag level it would take to achieve 324 km/h assuming 700 hp and 1.8 m^2 of frontal area.  With that in hand, we immediately knocked 150 hp keeping drag constant.  That showed a 298.9 km/h terminal velocity.  But 2011 cars have undergone extensive development and the 908 has most certainly lost drag over last year.  So taking the average of the dailysportscar.com numbers, we matched drag to that trap speed.  A 24%  reduction in drag got us the 327.5 km/h cited in the dailysportscar article.  But that's a huge amount of drag to peel out of a car with that has essentially the same frontal area compared to last year.  In fact the number simply isn't believable.  So we calculated for a 100 hp reduction over 2010 and a 10% reduction in drag over the guesstimated 2010 numbers.  That netted 318.8 km/h.  Closer, but still not 325-330 km/h.  Finally, with a further 7% reduction in drag we were able to achieve 327.5 km/h.  With a bit more tweaking my guess would be that the 908 has more than 600 at the flywheel and drag actually approaching 1000 lbs.  Naturally all of this is guess work, and it expounds from a guesstimate of the 908 HDi-FAP's drag level for Paul Ricard last year.  So it could get pretty ragged as it relates to the 2011 908, but it should give one an idea of what's involved even when we've decanted the problem into only a few simple variables.

Aston Martin AMR-One, Paul Ricard 20114.1.11

>>The first "naked" shots of the Aston Martin AMR-One are emerging, thanks to Julien Hergault and Endurance-Series.  Finally we get an idea of how the car's cooling is broken up.  And it would appear that the radiator receives most of the flow from the openings at the front (1 & 2) but for a portion going under the nose.  With another 24 hours to think about it, it would appear that the inlet poking through the front suspension (1) might be segmented with some flow going to the radiator and the rest ducting down the side of the tub and out the rear of the car (see 4.2.11 entry above).  This is further reinforced by the need for the intake above the suspension (2).  Though so far we only have this one angle to go from.

Suspension is very conventional with spring dampers and third spring. 

Audi R18 testing, Sebring, March 2011Audi R18 Evolution 2 testing, Sebring, March 20113.25.11

>>We have it on good authority the purpose of the exit duct on the side of the front fender (1).  It works in conjunction with the very tiny intake duct on the leading edge of the front fender next to the Michelin Man (below).  Audi ran a similar, but much larger, intake duct back in testing at Sebring in February.  The purpose?  To cool the LED headlights.  We're also told that the Audi R15 has similar cooling needs but utilized small cooling fans to circulate the airflow within the headlight bucket.  

And according to Audi's press release from this morning, the car currently being tested is the "Evolution 2" version of the Audi R18.  Audi has indicated the two test cars are chassis' 101 and 102.

Audi R18 Evolution 2 testing, Sebring, March 2011
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Peugeot 908 LM testing, Monza, March 20113.24.11

>>It's a tit-for-tat PR release week with images of the Peugeot 908 LM testing at Monza sneaking out.  Images copyright Motorsport Universe and 422race.com.
Peugeot 908 LM testing, Monza, March 2011The 908's front end has been completely revised with a shorter splitter/front overhang, redesigned front fenders, new detailing in the diveplane area ahead of the front wheel, 908 HDi FAP-esque bodywork either side of the nose, and revised front brake cooling intakes.  There is a very tiny exit duct just above the headlights and we suspect they are for cooling the front headlights similar to the issues Audi is having on the R18 (see 3.25.11 entry).

Looking at the rear, the brake duct scoops have been eliminated for a NACA duct in the rear fender leading edge.
Peugeot 908 LM testing, Monza, March 2011The rear wing endplates now attach to the rear bodywork and the rear wing has also been lowered.
Peugeot 908 LM testing, Monza, March 2011The rear bodywork also doesn't have the heavily cambered trailing edge of the sprint car.

Video of the test can be seen here.
>>The FIA has opened an inquiry into Peugeot's testing accidents that resulted, in both occasions, in the cars becoming airborne, this according to an article in today's Autosport.  Sources tell us that early next month the ACO will be meeting with Peugeot and Audi to discuss the situation.  

Audi R18 testing, Sebring, March 20113.23.11

>>With higher resolution images available it's becoming clear that the Audi R18 has undergone quite a few detailed changes since its debut.

See Fortitude's gallery (500+ images) here.
Audi R18 testing, Sebring, March 2011The lower portion of the front fender trailing edge detail is now smaller (1).  There's a hatch of sorts in the rear fender leading edge (2).  Also note the exit just aft of the intake (3).

The intake is raised and the exits appear to allow air to blow freely past.
Audi R18

Below the primary intake, and slightly recessed rewards, is a secondary intake.  This air intake is no doubtedly for cockpit cooling.
Audi R18


Audi R18 testing, Sebring, March 2011The front fender louver detail is completely different.
Audi R18 testing, Sebring, March 2011There's a exit duct of some sorts in the front fenders (1).
Audi R18 testing, Sebring, March 2011Audi R18 testing, Sebring, March 2011
The front fenders are now one piece.  The outer corner of the splitter has been redesigned.
Audi R18 testing, Sebring, March 2011Audi R18 debut
Confirmation that the rear wing mount has been raised, so too the top edge of the shark fin.  The engine cover has also been revised.   The rear wing endplates are slightly longer at the bottom.  Note the louvers in the engine cover.  The rear wing mount trailing edge triangle appears to have a pointier shape.

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3.21.11

>>Shots are trickling out of the Audi test at Sebring.  Credit to George Achorn at fortitude.com for the top right image.

Audi R18 debutAudi R18 Sebring testing March 2011
Debut Audi R18Audi R18 as of March 21, 2011.  The big honking fin appears to now be parallel to the reference plane and ultimately it would also appear that the rear wing mount is raised accordingly.  Interestingly it doesn't appear that the rear wing's position has moved, just that the mount has increased in height above it following the big honking fin.  The lower portion of the front fender trailing edge also has been revised.
Audi R18 Sebring 2011Audi R18 Sebring 2011
Debut Audi R18The primary difference is that the bodywork between the front fender and the nose has been completely changed and it is now one piece and has an outboard undulation.  The front diveplanes are also much larger.  The intake on top of the cockpit also appears rounder in front view.
3.18.11

>>Race Car Engineering has pictures and video of the new, South African derived, Bailey LMP2.  Link here.

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3.17.11

>>The Aston Martin AMR-One was shaken down at Snetterton yesterday.  See photos here and here with video of engine warmup here.  Also ran at Goodwood press day, that can be seen here.
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Acura ARX-01e3.13.11

>>Highcroft tested their new ARX-01e at Sebring yesterday.  According to the drivers, the car was initially in Le Mans aero specification and they noted a higher terminal speed given the lower drag from the -01e and the larger inlet restrictor the 3.4 liter Honda V8 is using this year.  Says Marino Franchitt, "Last year you would accelerate along the striaght and hit a virtual wall, but this year the car seems to be accelerating all the way to the end."  As the track gets more rubber and the team gets through their testing program, they will add more appropriate downforce levels.
Acura ARX-01eIt would appear that the lower portion of the front fender, with its extruded plan profile, is primarily designed to move air around (in plan view) the front fender. Considering the integrated turning vane and the vertical endfence are  designed to work in conjunction with each other, this isn't surprising.  The primary purpose of these devices seems to be to reduce and control the front bow wake in an effort to reduce drag, with the more than likely added effect of more efficient front downforce generation.

See the shakedown video.
Acura HPD ARX-01d >>On the same day, RML AD Group Racing were shaking down their upgraded HPD ARX-01d LMP2 at Paul Ricard.  This car utilizes the new 2.8 liter, twin-turbo, V6, Honda LMP2 engine.

RML's pres release spoke of a concern about the speed differential between the new, lower power LMP2s and top GT cars and the Formula Le Mans cars, noting, "The HPD appears to have suffered even more under the new regulations than the rest, and the speed trap figures cannot hide the fact that the car is significantly disadvantaged along the straights."

RML has admittedly said the car was not in low drag configuration though we're told Paul Ricard's setup isn't too dissimilar to Le Mans'.  So it doesn't seem as clear cut as RML makes it, especially considering the high downforce set up (observing: very large front diveplanes, very large rear trailing edge body gurney).  One wonders about ride heights as well and if the car was indeed in an optimally efficient configuration.

RML did indicate the ARX-01d was not in low-drag configuration at the Paul Ricard test last month.  But recall starting this season, LMP2s are allowed only two bodywork configurations; a standard kit and a low drag kit.  But the rub is this, the low-drag kit is only allowed for Le Mans.  And the "standard" kit is the best guess average as to what the manufacturer thinks will work on most circuits.  Thus the standard kit is a compromise across the season.  
But additionally, the ARX-01ds are racing to 920 kgs compared to 900 kgs as they are running outside the cost-capped LMP2 classification.  And remember, the LMP2s ran at 825 kgs last year, so 920 kgs is a full 95 kgs over design intent weight of the -01d.  

Apologies to HPD, RML, and Strakka for mucking that up.  Clearly something is amiss regarding the LMP2 restrictors.

All that being said for the HPD ARX-01d, one wonders who determines what car is or is not under the cost-capped LMP2 classification.  Could a manufacturer decide to take a loss on the car but sell it under the cost-capping classification?
Acura HPD ARX-01dThe -01d upgrades amount to turbo inlets for the engine and slightly revised outboard rear bodywork.  Note the very tall rear trailing edge body gurney.  

Note the -01d has the same lower cutout in the rear bodywork seen on the -01e.

HPD ARX-01d
Peugeot 908 >>Big honking fin alert.  Also spied testing yesterday at Sebring, Peugeot's new 908 and Level 5's 2011 Lola-Honda LMP2 coupe.
Lola Honda Coupe

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Acura ARX-01e3.10.11

>>It's hard to believe that Acura has taken a car introduced in 2007 and upgraded it yet again.  And each development hangs off of what is a Courage LC75 monocoque which can be further traced back to 2006 (LC70).  For 2011, the Acura ARX-01e further upgrades the ARX-01c to LMP1 specification.  The primary change is an overall increase in tire widths (and subsequent suspension redesign to accommodate said), front and rear.  Fronts go from 30 cm wide to 33 cm (30/65-R18 vs 33/68-R18) with rears increasing from 31 cm wide to 37 cm (31/71-R18 vs. 37/71-R18).  Engine is the same 3.4 liter  HPD LM-V8 as last year's LMP2 but breathing through a larger restrictor.  Power is transmitted through a new gearbox case.
Acura ARX-01eIt's interesting that Wirth Research hasn't adopted the wide fronts trend that they themselves started with the ARX-02a in 2009 (and that Audi, Peugeot, and Aston Martin have adopted for their new LMPs).  But considering the ARX-01e isn't a ground up bespoke chassis as the -02a was this isn't surprising.  One of the keys to making wide fronts work is the ability to place weight forward where it can load the front tires, and a purpose designed chassis would allow that freedom.

The front end carrys over features first seen on the ARX-01c, namely the outboard turning vane that is integrated into the leading edge of the front fender.  There is also a very prominent and deliberately shaped vertical end fence on the front splitter.  On the very outboard edge of the splitter is the now familiar "omega" shaped endplate foot.
Acura ARX-01eIn side elevation view, the leading edge shape of the front fender appears to be nearly vertical leading up to the headlight cover.  The front fender is also much further forward than on previous iterations.  The car's middle section appears to essentially be unchanged and there are subtle detail changes at the rear.  Specifically the rear wing endplate's forward blend onto the engine cover and the sheer vertical face of the rear outboard bodywork.  Though note the cutout in the surface just above the mandatory cheese wedge: Art 3.4.1 c/ states:

All bodywork behind the rear wheel centerline and more than 200mm above the reference plane must form a smooth, continuous, unbroken surface without cuts, and be visible from above the car with the rear wing removed. Vertical surfaces are allowed so long as their entire top edge is visible from above.

Thus the top edge of the cutout corresponds with the start of that 200 mm demarcation.

Of note is the missing big honking fin, Nick Wirth tells us that as the ARX-01e is a development of the previously homologated ARX-01 series it is exempted.

3.9.11

>>Word from Highcroft today is that the ARX-01e was loaded up and is heading to Sebring in an incomplete state.  No worries, car was fired the other day (here and here) and Wirth Research has en route the final missing body work.  The car will be completed at the track.

2011 Aston Martin AMR-One3.4.11* updated

Also posted at dailysportscar.com

>>Aston Martin has presented their new AMR-One LMP designed to contest Le Mans and the International Le Mans Cup. By appearances we have an open top LMP utilizing a bespoke carbon fiber monocoque, designed by Prodrive-run Aston Martin Racing. Aerodynamics are CFD-derived, with Totalsim doing the number crunching. We're told, thanks to Race Car Engineering's Sam Collins, the Chief Designer is Ian Ludgate.  

Bolted to the rear of the tub is a 2.0 liter, gasoline fueled, direct injected, turbocharged and intercooled inline 6-cylinder. The engine is load bearing but also makes use of a steel subframe to further transfer loads. When’s the last time an inline-6 engine has been used at this level of sportscar competition? A very quick looks brings back Sauber’s use of a BMW straight-6 in the very early 80s, might there be something more recent (have at it anoraks!)? Inline six’s have the benefit of being balanced, generating less vibrations than V or flat-6s. And Aston's George Howard-Chappell has indicated that there aren’t any packaging draw backs for the long 6-cylinder given the car’s wheel base (2930 mm) and the current LMP regulations and there actually are benefits from a cooling standpoint.  We're also told the engine is positively tiny, and easily lifted by one person.

The 6-speed gearbox comes via X-trac and utilizes pneumatic semi-automatic shifting. According to the press release, the car's suspension is double A-arm, pushrod to spring/dampers (thus it would appear Aston has eschewed torsion bars), third spring/damper, and anti-roll bars, both front and rear.

2011 Aston Martin AMR-OneThe AMR-One features a very high nose, with a forward boat prow shape projecting downward from near the nose's leading edge. The prow diverts airflow either side of the monocoque. The splitter leads the entire ensemble and is “suspended” by two mounts offset to either side of the boat prow. Their angle of attack relative to car centerline seems to suggest air diverting functions additional to their structural functions. Given the front geometry and the intentional attitude of the splitter mounts, one wonders if there are provisions to remove the prow shape and related lower bodywork at higher downforce circuits unmasking additional splitter area?


The wide front tires are evident by the disproportionally wide, but now de rigueur, front fenders. Michelin says the 2011 “wide” front now has the benefit of a bespoke rubber compound and is no longer merely a rear-stuck-on-the-front-with-associated-drawbacks. The front suspension is covered by bodywork that allows air to flow under and presumably across the trailing edge of the front splitter (and then into the sidepod). Air that continues over the top of the suspension is grabbed by a second inlet downstream. We're currently unsure of the disposition of the radiators and intercooler and the exacting inflow and, more importantly exit flow, but presumably air continues into the side pods, through appropriate radiators, and exits out the louvered ducting ahead of the rear wheels. The provided PR images allowed a view into the side pods through the louvered panels from the rear ¾ image, but it would appear the photo car was sans radiators as the only thing that was apparent was empty side pod space given the visual echos and reflections. The other possibility is that after flowing over the trailing edge of the splitter, the lower airflow is segregated and ushered into the sidepod and out the car through said louvered ducts. And that cooling flow for the radiators is exclusively gathered by the second top duct and guided directly to the coolers. But the area of the louvered exit duct would seem to indicate that all the air drawn in by the front ducts actually uses this as a common exit.

2011 Aston Martin AMR-OneIn side elevation it's noted that the AMR-One has a very high belt line. Gut instinct has us thinking about methods of reducing drag, if only small amounts Peeling drag out of the same approximate package that everyone else is dragging around has always been a chore. So it's about the little bits here and there culminating into something useful. With the reduced power LMP1 regulations drag is more important, but we're understanding that the net effects isn't so much on downforce (don't get us wrong, downforce is down, but not as much as anticipated we're told), but on drag levels, and there's talk of higher efficiencies.  But having said that, the car's open top in general is contradictory to the overall desire towards lower drag.

Moving rearward on the Aston, streamline, blade-type roll over structures clean up flow to the rear wing. Parallel with the roll over structures is an intake on car centerline that blends into the ACO mandated shark fin. We're currently unsure of its function, though the inlet area suggests cooling for engine ancillaries. The inline-6’s turbo intake is on driver’s right, square on the leading edge of the rear fender. The turbo’s exhaust pokes out of the top of the bodywork towards the trailing edge of the engine cover. The trailing edge of the engine cover again tells us something of the overall aero concept of the Aston being geared towards lower drag given it maintains very little camber. But contradictory to that is the overall height of the local bodywork.  So while there's less camber to the bodywork's shape, its height runs counter to the low drag concept.  It also “smells” of CFD, lacking the intricacies of Audi and Peugeot LMP's variable height trailing edge—programs that benefit from CFD and scale wind tunnel testing. The AMR-One's rear fender shape is rather rectilinear, and in rear elevation they maintain their square shape. The mandatory shark fin is open to cooling exhaust flow and blends into a black anodized aluminum and carbon clad single rear wing mount. The rear wing mount is the conventional bottom mount type but on a single point with the outboard endplates carrying their share of the load.

2011 Aston Martin AMR-OneOverall the AMR-One lacks the detailing we see on the Audi, and, to an extent on the Peugeot. But for a while we've understood Audi was working from a power deficit relative to Peugeot and were pursuing gains through aero and regulations, hence their relatively “radical” approach. Peugeot, on the other hand, has had a very strong engine program and went with a more conservative design, aero and chassis. Naturally we don't know where Aston Martin falls in any category, but the initial reaction is that the AMR-One is very conservative. The car's broad shapes and few surface breaks certainly reflect this. Though it should be interesting to see how the inline-6 slots into the regulations and fairs against the diesels.  That's easily the biggest surprise of Aston's LMP effort.
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