Once upon a time the aerodynamics of a racing car were a black art. Cars
were created with shapes the designer thought would slice through the air, but without exact science to back up those ideas.
In Formula One, even with the introduction of wings in the late 1960s and
ground effects a decade later, aerodynamic design was often still a hit-or-miss operation.
These days, with high-tech wind tunnels and Computational Fluid Dynamics
(CFD) and sophisticated computers and intricate scale models of the car to
be used in the wind tunnel, aerodynamics is a true science.
"Aerodynamics has been steadily gaining importance in recent years,
accounting for roughly three quarters of the performance of a F1 car
today," said team owner Peter Sauber.
Every year, F1 designers find ways to increase the downforce of their cars
while adding the minimum of drag.
And practically every year, the FIA comes up with new rules to reduce
downforce trying to slow cars down.
In 2005, major new aerodynamic rules are part of the FIA trilogy of drastic
regulation changes to reduce speeds for safety reasons.
Parts one and two of that trilogy -- drivers limited to one engine for two
entire Grand Prix weekends, and drivers limited to a single set of tires
for qualifying and the race -- have already been covered by ESPN.com.
While the aerodynamic rule changes have not been controversial like the
other two aspects, they are still very significant.
"When we put a 2005 package on the wind tunnel model we lost nearly 30
percent [of downforce]," said Ferrari's technical director Ross Brawn.
"We're gradually getting that back. We would be pleased if we get to 15
percent of where we are now."
The basics of the new rules are as follows:
The distance between the bottom of the front wing and the ground has been
increased by 50 mm (1.97 inches).
The overhang of the rear wing has been decreased, so the wing must now be
located 100 mm (3.94 inches) closer to the back of the car.
The size of the rear diffuser (the tail edge of the floor of the car that
sculpts upwards behind the rear axle line) has been reduced.
The bodywork around the rear wheels has new restrictions.
The initial results, as Brawn pointed out, was losing nearly a third of the
downforce generated by a 2004 F1 car. That's a huge amount, and that's why
the wind tunnels at all but a couple of teams have been operating 24 hours
a day and seven days a week as the teams look to recoup those losses.
"We lost over 30 percent when we went to the new regulations," said
Williams BMW's technical director Sam Michael. "How much we get back is
the big question. It's obviously a long way away, but then so is [the 2005
season opening Grand Prix in] Melbourne. At the moment, because of the
changes to the bodywork, particularly the diffusers, there are fundamental
restrictions on how much expansion you can get, so no matter how much you
work away with it, it will be never be anywhere near what you had before."
Out on the track, the first tests the teams did were to take a 2004 spec
car and reduce the downforce level to what they thought the downforce would
be on the 2005 car. The aim of the engineers is to recoup somewhere
between 10 to 20 percent of the initial 30 percent loss.
"We can get back some of that over the winter, but we will still be about
20 percent down in downforce," Michael said. "Every 10 percent is one
second a lap."
Because the tires now have to last an entire race distance, they are
considerably harder than the compounds used in 2004. A harder tire doesn't
grip the track as well as a softer one. Couple this with having less
downforce to glue the car to the ground and a 2005 F1 reacts very
differently to a 2004 car.
"Slippery! It slides a lot," Renault's test driver Franck Montagny said
when asked what it was like to drive a 2005 spec car. "It's a different
challenge. There is much less grip, which you really notice in the
medium-speed corners. The rear of the car will also slide more readily,
which is fun for the driver, but it costs you in terms of lap-time."
Having slower lap times was, of course, just what the FIA was aiming for.
In general, F1 drivers don't want anything that slows their cars down. But
with the cars now pulling plus 5 G in some turns, reigning World Champion
Michael Schumacher said the time had come to reduce the speeds. By the end
of the Brazilian Grand Prix, run on an counterclockwise circuit compared to
the clockwise direction of most F1 tracks, the drivers were having trouble
holding their heads up because of the severe strain on their necks in the
corners.
Although the 2005 technical regulations were not finalized until October,
the designers have had a pretty good idea about the aerodynamic rules since
July. That's when the FIA presented the teams with three different rules
packages and asked them to come up with a compromise. While
arguments raged on things like the engine changes, the teams quietly went
ahead on the FIA's "package two" aerodynamic changes.
"The whole design process of the car typically takes around nine months,"
Michael said. "The early part of the design process starts off slowly and
there's a lot of work in the last three or four months of it. There are
480 people that work at Williams. Total design of a car takes around
25,000 man-hours, and the total cost is around 150 million pounds ($277
million.)"
While the basic chassis/monocoque shape has to be frozen as early as
possible in the design process, the experimenting on wings and diffusers
and other aerodynamic add-ons continues throughout the life of the car.
Sauber, for example, evaluates up to 100 variants of a front wing
two-dimensionally before roughly half a dozen of them are analyzed in
three-dimensional form. The most promising versions are subsequently built
for the 60-percent model and tested in the wind tunnel."
The other teams are doing the same thing.
"We're all doing the work and pushing very hard," Toyota's technical
director Mike Gascoyne said. "It a very key area, and it's an area where
we have been doing a lot of development."
Asked how much of the downforce he thinks Toyota will end up losing, and
hearing the Ferrari wants to get within 15 percent and Renault wants to be
within 10 percent of their 2004 figures, Gascoyne quipped: "Then I've got
to go for zero!"
A zero percent loss with such drastic aerodynamic rule changes? Now that
might take some black art ...
Dan Knutson covers Formula One for National Speed Sport News and ESPN.com.