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Useful
links:
>>Le
Mans Weather<<
>>Le Mans Live<<
>>2015
24 Hours of Le Mans entry list<<
>>Andy
Blackmore's Le Mans 2015 Spotter's Guide<<
>>Radio Le Mans<<
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 6.15.15
>>I
brought my camera with me when I headed over to the Test, though I
didn't have much time to utilize it. But between my shots, and Sam
Collins' of Race Car Engineering, I'm pretty confident we cover most
angles. I'll be updating this page over the next few days, as the race
unfolds, etc.
>>Toyota TS040 |
 Outboard
strakes ala Toyota TS040. Toyota has a different take as they've
created a mainplane/flap arrangement utilizing two strakes that are
very much wing shaped, nested them together to create a slot gap, and
hung them vertically. |
 Having a look underneath and Toyota actually has two pairs of strakes located under there. |
 Toyota's
engine cover trailing edge appears to be particularly tall compared to
Audi and Porsche (1). The height is also raised at the outer
corners of the exit (2). |
 Toyota's
lower rear fender bodywork coke bottles inward to draw air in across
the cheese wedge and into the base area, though they eschew the
Porsche/Audi trend of opening up the leading edge of the lower bodywork
and directing air inboards with a strake. Instead, the lower
bodywork is offset inboard at the leading edge, and this has the affect
of grabbing air tumbling off the tire and directing it to the base area. |
 The TS040's rear wing endplate extension comes in the form of a trailing edge extension that comes to a point. |
 6.13.15
>>Porsche 919 |
 Perhaps
someone can make sense of what's going on here, though Porsche
thinks it's totally secret squirrel...Porsche doesn't use blue blankets
like Peugeot used to. No, being the asshats they are, they just
position people to stand in front. But these guys weren't really
paying attention to where I was versus where they were so a small
opportunity presented itself...
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 At
the base of the windscreen are two scoops either side of the car
centerline. I'm not sure what they cool, and they augment the
large cooling slot located in the leading edge of the nose.
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 It's
different in the details compared to Audi's, but at the end of the day
it's a small strake mounted to the most outboard part of the floor
behind the front wheel, so how different is it really?
However, the primary difference is the leading edge on Porsche's
strake rakes forward at the bottom to match the trailing edge line of
the tire.
In general the Porsche and Audi have different aero
philosophies, but in some of the details they are very similar.
Given personnel have crossed lines between the two programs, this
isn't too surprising. |
 I
noticed this cute little gurney attached to the center of the 919's
engine cover. I'm not sure what exits out of the opening below
it, but Porsche feels it is important enough to need some extraction.
My intuition is that the gurneys are too small to be about
downforce. |
 Porsche
does similar to Audi (and everyone else, this must be a pretty
profitable area) and allows outboard air to flow inboard via the cutout
(1), directed by the strake (2).
Also note the diffuser strakes are trimmed well short of the diffuser trailing edge. |
 Porsche's
rear wing endplate leading edge extension alters in camber as it moves
up the endplate's height, so it's trailing edge is further back lower
on the endplate |
 The very leading edge of the endplate extension is angled outboard. |
 6.12.15
>>Nissan GT-R LM
The
most technically interesting prototype this year is inarguably the
Nissan GT-R LM. I'm the first to disdain a marketing driven
program, and it's easy to think that's what's going on with the Nissan
given their openness and proactive social media campaign. But the
car, in spite of the obvious early-days issues (remember, this is
the car's first race event), has technical merit. As one Nissan
engineer put it to me, "The numbers work, they make a lot of sense."
And Nissan, Bowlby, and the gang wouldn't have gone in the
direction they went in if that wasn't the case. So while the
program appears marketing driven (a bad thing in my opinion as
marketers know shinola about race car design), in reality it is driven
by engineering first and foremost, the marketing plonks are simply
doing their job and telling us about it, warts and all. And
that's reality; racing is hard, period. In the mean time you
don't hear shit out of Toyota, Audi, and Porsche, and the question has
to be asked, what are they REALLY doing to promote the sport in the end? Blue blankets and bullshit is what. |
 The
answer to the "why." Without an engine, gearbox, or cooling
system in this area the most elegant and tidy rear end can be designed.
All for aerodynamics. The tunnels are fantastic, you can
see almost clear up to the front of the car. It was tempting to
want to crawl up into them... |
 The
Nissan's rear fender turning vanes are nothing particularly special and
it's very clear there's still a ton that can be done to optimize the
car aerodynamically. All one has to do is look at the detail work
on the competition to get an idea. I think this speaks to the, I
hate to say it, initial rushed-nature of the project. And this
really is my primary criticism of the program, it all appears to have
been pushed out about 6-9 months too soon. And this aligns with
the rumors of a 7 day, 140 hour, work week, in the extreme cases.
But I recognize that the fault probably lies elsewhere as Bowlby
has been around long enough to know what it takes to execute a project
like this. The fault more than likely simply came down to timing;
Nissan signed off when they signed off and the time plan unfolded from
that date. I can imagine things will calm down post-Le Mans with
the running of only two cars in the WEC. |
 Looking
at the turning vanes from the other direction and we can see that the
middle vane (1) actually is a extruded pontoon shape, not a simple
2-D vane.
An interesting detail is that a "shelf" (2) has been
created inboard of the rear tire. It's a small carve out that
creates a horizontal shelf. Ultimately it's probably
insignificant and has more to do with the fact that the narrow nature
of the rear tire means the inboard face of the rear wheel well doesn't
form the immediate outer wall of the diffuser. |
 Much
is being made about the car's apparent lack of performance. I
feel the first thing to understand is that the twin-flywheel hybrid
system is simply not working. So the concept has gone from 4
wheel drive, to 2 wheel, front only drive. And then following the
Test the admission was that hybrid simply wasn't being used at all.
So power was solely coming from the combustion engine, roughly
500 hp, and the times reflected that; 20 seconds down. The
emphasis has been on the loss in power from the hybrid for
acceleration, but perhaps more importantly, the GT-R LM is suffering
from a lack of braking given zero harvesting from the hybrid system.
And this appears to be an issue they've been dealing with for a
while as it is what directly led to the switch from 16" to 18" tires
at the front in order to use larger brakes. So you can imagine
the performance hit to power and
braking is significant, and all the while they still have to lug around
the hybrid system as so much expensive ballast given the rules
regarding LMP1-H. How much of their 20 second deficit revolves
around the hybrid issue? A huge chunk, thus there's a solution
once the system is sorted and only a neophyte would condemn the entire
concept considering this problem.
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 >>Audi R18 |
 So
Audi's front fender ducting is slightly revised, but starting from the
top; 1 LED light cooling duct, 2 is now closed off compared to the open
duct seen testing at Monza, 3 directs airflow into the front fender
well as a means of mitigating negative wheel well interactions with air
moving past the front wheel opening, 4 is still unidentified, 5 exhaust
exit for LED light cooling duct.
However, another theory
to 3's ultimate function might have something to do with the very
outboard turning vane (image below). Could Audi be putting more
air outboard to interact with the outboard turning vane downstream? |
 Audi's very outboard turning vane is fairly simple, however Porsche, Toyota, and Rebellion follow suit. |
 Given the outboard turning vane's (2) position relative to the front fender duct (1), it's
reasonable to think it might have influenced the use of that duct and
that they work in conjunction with one another, the duct brining more
flow volume to the turning vane. |
 The front wing adjustment mechanism. It would seem to require a simply socket headed ratchet to make flap angle changes.
Also note that the winglet elements are open on the back side. |
 The
R18's integral rear view mirrors are designed to tuck behind the front
fender trailing edge and reduce drag. Though the trailing edge of
the mirror, the point below the mirror, very much acts like a turning
vane.
At least one competitor privately indicated they felt
Audi's mirrors were outside the regulations. But having a look at
the rules there is very little that governs them so I can't see much
wiggle room for protest as it's clear Audi has met the regulation for
mirror area (100 cm^2) and has satisfied the scrutineers via the vision
test (detailed under Art 17.4.2). |
 At
the rear Audi has opted to move the mandatory BHH from the top location
to the inboard location. The shape is optimized to reduce (and
enhance) the impact these holes have on drag and downforce. |
 Rear
wing endplate extensions are making a come back this year with Audi,
Porsche, and Toyota all indulging. Audi utilizes a leading edge extension (arrow). |
 The
leading edge extension joggles into the leading edge of the
endplate. Note the extension has thickness beyond the 10 mm
constant thickness regulation that governs endplates; the extension is
considered "bodywork" and doesn't fall under endplate regulations.
Furthermore, the extension bends slightly outboard. In the
end though this is a subtle performance enhancer, "fine tuning" as some
one mentioned.
While we're here looking at the rear wing, note
the lack of gurney on the flap. I don't think I saw a flap gurney
on any of the LMP1 cars. This probably speaks to Le Mans and the
over riding concern for drag reduction. |
 Close up of the rear. Audi has opted to open up the outboard vertical surface up to 200 mm above the reference plane (1). Note the vertical strakes mounted to the top of the cheese wedge (2). We first saw this opening back in 2011 on the HPD ARX-01e LMP1. The opening and the strakes work to draw air inboard and help with base area infill. |
 For
2015 the ACO mandated a minimum 2" gap above the diffuser at the
bodywork trailing edge. The R18's is that height across the
entire width of the car. Note the proximity of the engine
exhaust. These are also regulated as to how close to the trailing
edge they can be (no less than 300 mm). |
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