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Pete
Lyons' fantastic Can-Am Cars in Detail:
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March/April 2011
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All news content copyright Michael J. Fuller, unless
otherwise noted |
| >>Sebring 2011<< |
 |
 4.30.11
>>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.
|
|
 *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. |
 >>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. |
 >>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. |
|
 4.27.11
>>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. |
|
 4.26.11
>>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. |
|
 4.24.11
>>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'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.
|
 >>The Aston's repositioned turbo exhaust looks rather last minute. |
 >>Close up of the small front fender exit duct on the Peugeot 908. |
 >>We know that the equivalent duct on the Audi R18 is used to cool the car's LED headlights. |
|
 4.23.11
>>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 ran two configurations, the
debut configuration (shown here) and an updated/definitive
configuration. | 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). |
|
|
 4.22.11
>>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. |
|
 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.
|
|
 4.8.11
>>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. |
|
 4.7.11
>>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. |
 This
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). |
|
 4.4.11
>>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. |
 Though
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? |
>>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? |
|
 4.3.11
>>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. |
|
 4.2.11
>>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. |
>>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. |
|
 4.1.11
>>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. |
|
  3.25.11
>>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.
 |
|
 3.24.11
>>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. |
 The
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. |
 The rear wing endplates now attach to the rear bodywork and the rear wing has also been lowered. |
 The 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. |
|
 3.23.11
>>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. |
 The
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.
Below
the primary intake, and slightly recessed rewards, is a secondary
intake. This air intake is no doubtedly for cockpit
cooling.
|
 The front fender louver detail is completely different. |
| There's a exit duct of some sorts in the front fenders (1). |
The front fenders are now one piece. The outer corner of the splitter has been redesigned.
|
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.
|
|
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.
 |  | | Debut Audi R18 | Audi
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. |  |  | | Debut Audi R18 | The
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. |
|
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. |
|
 3.13.11
>>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.
|
 It
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. |
>>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?
|
 The
-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.
 |
>>Big honking fin alert. Also spied testing yesterday at Sebring, Peugeot's new 908 and Level 5's 2011 Lola-Honda LMP2 coupe. |
 |
|
 3.10.11
>>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. |
 It'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. |
 In
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. |
|
 3.4.11* 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.
|
 The
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.
|
|
 In
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. |
 Overall
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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