McLaren P1 Auto Racing Aerodynamics Explained - SHAKEDOWN


Uploaded by drive on 05.10.2012

Transcript:
While the other guys of Drive go on the road, I, like you,
get inspired by their work.
Chris Harris driving the 1987 Le Mans-winning Porsche 962C.
And Mike Spinelli traveling to the Paris Auto Show reporting
on the McLaren P1 on jalopy.com and here on Drive.
And when I say "inspired," I mean I want to know more about
those cars.
Which gets me to today's Shakedown and our topic,
ground effects in race cars and road cars.
Looking at the subject through the lens of the Porsche 956
and 962 race cars, they were actually a Porsche cash cow,
as the 962 was a customer race car.
Like today's 911 GT3.
But 962 was the ultimate customer sports racing car
because it was the first to sell ground effects.
And the new McLaren P1, which is being marketed as the
ultimate road car providing race car performance for the
street because the foundation of its design is driven by
race car aerodynamics, down force, and ground effects.
Now, I'm not ignoring this weekend's racing action.
McLaren's next race is in Japan, the Suzuka F1 race.
And the Aussie V8 Supercars at the Bathurst 1,000,
celebrating his 50-year anniversary.
We'll cover them both next week.
And you'll watch them this weekend because VH Supercars
is what NASCAR should be.
And come on NASCAR, there should be at least one road
race in the Final 10 race Chase for the championship
season-ending miniseries.
And the racetrack for V8 Supercars, Mount Panorama, is
a racer's soul search of elevation
changes and blind corners.
And the V8 Supercars themselves are mega-cool.
And of course, the Aussie grid girls are some
of the best in racing.
In Japan, the championship battle for F1 stays intense
among the top six.
Alonso Ferrari fighting off the McLaren and Red Bull boys.
And Kimi's Lotus is P3.
Now, Button McLaren won last year's Suzuka race.
But he's docked five spots this race because of a gearbox
change penalty.
Alonso finished P2 last year, Vettel P3.
And we can all watch Hamilton's throw down of
attitude this year as he drives his last races for
McLaren with his eye on the future that he has with the
Mercedes team.
When we come back, we'll get down with downforce.
That sucked.
And I'll explain what this photo has to do with Chris
Harris's 962 Le Mans car and Mike Spinelli's McLaren P1.

That last image, this image, was one of those Russian
Caspian "Sea Monster"--
Ekranoplan, ground effects, not an aircraft, but
definitely something.
Using air management to move about.
And this thing is the American answer, the Boeing Pelican.
500 feet of wingspan of heavy, heavy-lifting, transport
equipment-moving, ground effect aero-techie
thing that we built.
Or are building.
Where am I going with all this?
To look at downforce management in cars by
explaining as simply as possible what
ground effects is.
And I'm starting using these Sea Monsters.
Ground effects is the
interaction of a flat surface--
the ground or the water--
in close proximity to a wing.
The effect is that the ground enhances the wing's
effectiveness and reduces drag because of what the ground
does to the vortices coming off the ends of the wing and
the pressure area between the wing and the ground.
For an Ekranoplan, it creates more lift with a smaller wing.
For a car, ground effects creates downforce, the load on
the tires, by using the underbody as a reversed wing
with less drag versus the add-on wings and spoilers you
see on other cars.
Quickly.
An airplane wing creates lift by having a low pressure area
forming on the rounded surface and a high-pressure push from
the coved side.
Turn the wing over and for a car you create downforce.
The vortex spinning off the end of the wing in either case
A, tries to fill in the low pressure and thereby reduce
its effectiveness--
lift or down force-- and B, creates drag by spinning the
air behind the wing, making friction of some sort.
In the late 1960s and '70s, F1 designers started to play with
aero, downforce, and ground effects using not just wings
attached to the cars but the entire car, the undersurface.
And the first example was a guy named Tony Wright at BRM,
the Old English F1 team.
In 1968, he built this wind tunnel model.
The real race car was never built and
Wright ended up at Lotus.
Hold that thought.
Here's the March 701, with its wing-shaped fuel tanks.
And Gordon Murray at Brabham with his BT 42 and 44 race
cars, who went pyramid with the bodywork to lower the air
separation location to reduce lift.
Then put a skirt under the car to try to reduce more lift by
stopping air slipping under the car.
Instead, he discovered that he had created a low-pressure
area under the car, sealing the car.
And not just reducing lift, but
actually creating downforce.
Oh.
And small world that it is, Gordon Murray eventually found
his way to McLaren.
And besides designing the mega-winning F1 cars, did the
McLaren F1 road car, the inspiration for today's P1.
And here's the speed of technology.
Murray was God for hitting a downforce target of 160 pounds
at 150 miles an hour with the F1.
The P1 snaps up 1,300 pounds and 125 miles an hour.
And then there was Lotus F1, where Wright, the ex-BRM guy,
and that model ended up, helping Colin Chapman define
ground effects and the aerodynamic underbody tunnels.
Which gets us back to the Porsche 956, 962 cars.
1982 and beyond into the '90s they raced, 1982 through 1987
at Le Mans.
Six years, six straight wins.
Plus a seventh in 1994 when a car builder named Dauer
created a final entry for the 962 as a production car and
claimed victory one final time for this fabled Porsche.
As Porsche engineer and designer Norbert Singer said
in the Chris Harris video, the 956, 962 cars were one of the
first and certainly the most successful of the first
generation downforce sports cars.
And as a customer race car, they sold 100 or so.
962 won all over the globe.
And to get that success, Porsche worked hard to get
control of the flow of air over and under the car.
The underbody tunnel was the prime
factor to get that downforce.
But the flat-6 turbo motor that Porsche makes-- and by
the way, it was only 2.8 liters, but it generated 680
horsepower, 490 lb-ft of torque.
That was the motor in Chris's car.
But the flat-6 created aero issues, taking space that
could be used for the tunnels and blowing more air through
the diffusers.
So over the years, customers and Porsche worked to make the
tunnels bigger.
And bigger still.
This one's over the rear axle.
And if you listen to Norbert in the Harris video, he also
talks about managing the air flow on the edges, the sides
of the car, the vortices, to use them to make more
downforce and less drag.
Remember that whole Ekranoplan discussion?
Then there was Norbert Singer's mention of the rear
gurney, how it affected the front of the car.
Because the big factor in getting ground effects to work
effectively is managing the center of pressure, exactly
where the car is most planted.
And influencing and controlling that spot of the
strongest interaction of high and low pressures is a big
deal on how to get the car to feel good, how to make the
driver confident, and how the car corners.
So gurneys begat diffusers and strakes in the diffusers and
spats and aero shapes all over the car.
Anything to manage the air and the airflow.
Not just over and under the car, but
through the car as well.
Audi with their R18 race cars make a big deal about that.
And so does McLaren with their P1 road car.
These pre-Paris Auto Show teaser images tipped their
hand about airflow.
The P1 is truly the extension of everything everyone in
racing, especially McLaren, has learned over all the years
and all the designers, including Gordon Murray and
his early McLaren aero days.
Now, the first thing you notice in the P1 is the shrink
wrapping of the bodywork over the mechanicals,
just like an F1 car.
And this does two things--
smaller profile and the smallest Supercar frontal area
to pierce the wind as unobtrusively as possible.
And the front of the car is not about engine intake--
that's for the doors, of all things-- but the air
management around the front tires, through the car for
cooling, and out the hood for pressure
relief to negate lift.
Plus, check out the details of the front splitter and the
little side fences, the shapes right behind the back of the
front wheel wells.
And the back of the front wheel well as well.
Air management and managing, I think, the vortices down the
side of the car to create air fences to seal the underbody
ground effect tunnels.
P1's anticipated to have a V8 with curves that will not
intrude in the tunnel designs, making them bigger and
aggressive as ever.
And not like the fat flat-6 cylinder you'd hear on the
Porsche tunnel.
And aero knowledge evolved, so now we have the side air as a
fence, not a source of more air for the tunnel as Norbert
suggested with the 962C.
Add in the active underbody gurneys that, like the Porsche
tail gurney, to manage and control the center of
pressure, plus downforce, and you get a car, the P1, that
will make five times the downforce as the MP4-12C that
when I drove it at Spa, seemed pretty planted to me.
So this P1 should be awesome.
The rear fenders are sharp edged and, to me, look like
end plates or fences to move the air to the center of the
car for that big, active wing.
Which, by the way, is also going to have a
DRS function as well.
And the fence concept reminds me of the 1970s
McLaren Can-Am cars.
So that gets us to the rear diffuser tunnels, which F1
tech tells us is really the most critical of areas to max
out downforce inefficiency.
That P1, suitably functional looking, I'd say.
The P1 has a 0.34 drag coefficient.
And that's not bad, but it's also not
Prius brilliant either.
That's because the goal of the P1 is not
lowest drag and Vmax.
It's downforce, balance, and complete performance.
And frankly, all this race car technology becomes a very
effective, functionally effective branding exercise
for McLaren to define their performance spot in the
hypercar market.
They'd probably say, hi, we are McLaren.
We design, engineer, and build winning race cars.
Racing's not just marketing to us.
It's our cars.
It's what we do.
And we'll share all we know with you as a McLaren
owner-partner.
Now, others may race.
Others may build race cars.
But we, McLaren, give you the strongest direct connection to
our racing technology.
I just did their infomercial.
They very well may have done that with the P1 in the spirit
of the Porsche 962C and its lineage, back to Porsche aero
and turbo 6 technology.
But I know one thing that McLaren also did, is make me
want to drive the P1.
Not watch Chris or Mike do so.
So McLaren, tell me you're listening.
I'll even share the ride with Chris, Mike, or JF.
But here's the question for you guys if you've stuck
through this little classroom.
Tell me what you think about cars, road cars.
Do like this connection to race car technology?
Or do you want a car to be more aesthetically beautiful
and not be form following function?
How many of you like the McLaren P1?
How many of you like the technology?
How many of you prefer to have a beautiful road car and
really don't need all that mega-hyper-aerodynamic thing
going on for your road car?
That's the question I'm curious of.
Let me know.