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FW27 Design |
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Explaining the developments of
the FW27, Technical Director Sam Michael said, “This car reflects a
philosophy of concentrating on the fundamentals. Our focus throughout the
design cycle has been built around simple variables that affect performance,
such as reducing weight and friction while increasing stiffness. As a
consequence of focusing on these fundamentals, we have reverted to a single
keel configuration for the front suspension geometry. We have also been
aggressive with our cooling, as witnessed by the extremely low engine
bodywork and the large sidepod undercuts. Reliability is the final area we
have been determined to pursue, and we have made significant progress,
specifically with the gearbox which has been running on-track since November
2004 without problems.” |
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Michael went on
to explain the implications of the new rules which have influenced the
design of the FW27. “The changes to the rules devised by the F1 Technical
Working Group have fundamentally limited the expansion ratio of the air in
the diffuser and reduced the ground effect of the front wing, the net result
of which is a reduction of around 30% of downforce without reduction in
drag. We have worked hard to recover as much lost downforce as possible,
primarily via predictive means.”
“Prediction, using computational fluid dynamics (CFD) was our main tool to
assess the implications of the new rules, and to consider a wide range of
potential solutions. Together with our partners at HP, we have scaled up our
computational resource by a factor of three times, which means we are
operating with a facility that ranks in the top 500 globally, and in the top
40 in the UK. We augmented our in-house capability with the use of HP’s
Bristol Laboratories computer farm, which allows us to run computations
using external resource at peak load times, such as during the new car
design phase,” explained Michael.
“As a consequence of all of this additional capability,” continues Michael,
“We ran almost 100% more aerodynamic models in CFD this year to investigate
the optimal solutions under the new regs. Considering that each model
contains around half a billion points of information, we have processed the
equivalent of 70,000 volumes of the Encyclopaedia Britannica’s simply to
assess the aerodynamics of the FW27. We reduced our turnaround times, with
post-processing times reduced to minutes as well as improving our accuracy.
The CFD outcomes have allowed us to optimise solutions for front and rear
wings, brake ducts and radiator ducts without fabrication or tunnel testing.
It has been a major advantage in coping with the demands of the new rules.”
“The computational resource has also significantly enhanced our structural
analysis process, which used to be highly reliant on manual calculations and
testing validation. Now we can model these highly complex parameters and
integrate the design of crash structures in the car with the aerodynamic
demands”, he adds. |
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Michael
continued, “The consequence of the application of advanced modelling
together with a streamlining of tunnel experimentation has resulted in a
distinctive profile to the FW27. “As the front wing has been lifted by 50mm,
it has become more important to utilise the drooped wing section in the
centre of the car. Additionally, as the rear wing has moved forward relative
to the lower diffuser, the other devices around the rear wing must be
optimised to ensure they are all working in harmony.”
Tyre restrictions
The other area of regulation change that has been significant is the
restriction to one set of tyres to complete both qualifying and the race.
Michael outlined the implications of this rule in the design of the FW27.
“The BMW WilliamsF1 Team has won more races on Michelin tyres than any other
team since their return to the sport, so we have worked closely on the
implications of the new rules. Essentially, aerodynamics, weight transfer,
mechanical balance and traction control are all slaves working to improve
tyre performance. We have to find grip without destroying the tyres, and
that challenge has become harder because of the new rules, but we are
confident that we have made good headway over the winter,” says Michael.
A single engine for two race weekends
Rule changes have also fundamentally affected the engine design and BMW have
been tasked with ensuring the P84/5 lasts for 1,500km, while spanning a
variety of different tasks, including practice, qualifying and racing, all
of which make their own specific demands on engine performance. Mario
Theissen, the Director of BMW Motorsport explained the implications of the
rules. “Now there is a tactical need to save engine life as far as possible.
We have two options, by running for fewer laps or decreasing engine speed.
The first option is not desirable, so during free practice, when the team is
undertaking setup work and selecting tyres, we will limit the maximum engine
speed.” |
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Engines,
however, will have to deliver maximum power for the qualifying session, and
after the race, will still have to endure another full Grand Prix weekend
before the unit can be replaced. “The penalty for an engine fault will be
considerably tougher than for any other component,” says Theissen.
“Replacing the engine before first qualifying will result in a ten place
demotion on the grid, and after qualifying, it is demotion to the back of
the grid. Only if the driver fails to finish the race can the engine be
replaced without penalty, so the environment will be very demanding in 2005.
There is also a question mark in the new rules, as a driver may deliberately
fail to finish a race in order to have the advantage of a new engine for the
next GP,” he says.
In order to prepare for the demanding new rules, BMW have concentrated on
engine unit stability, minimising performance losses and making good any
identified performance losses during the season development process. “The
critical components are the moving parts that endure a high mechanical and
thermal load, particularly the crankshaft drive and valve gear. Each of
these has been redesigned for a double life span, which normally means a
bigger and heavier engine, costing speed and power. We have been meticulous
to try and minimise these losses,” says Theissen.
Reflecting on the rule changes, Theissen said, “In principle we support
cost-cutting measures. But this was a radical and late change to the rules,
which has caused significant extra development costs, rather than save
money,” he concluded. |
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