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Technical insight - McLaren's Goss & Lowe on the MP4-25 29 Jan 2010

Paddy Lowe (GBR) McLaren Engineering Director. Formula One World Championship, Rd 4, Bahrain Grand Prix, Qualifying Day, Bahrain International Circuit, Sakhir, Bahrain, Saturday 25 April 2009. (L to R): Jenson Button (GBR) McLaren unveils the McLaren MP4/25 with Lewis Hamilton (GBR) McLaren. McLaren MP4/25 Launch, Vodafone UK Headquarters, Newbury, England, Friday 29 January 2010. McLaren MP4/25 is unveiled. McLaren MP4/25 Launch, Vodafone UK Headquarters, Newbury, England, Friday 29 January 2010. Detail of the McLaren MP4/25. McLaren MP4/25 Launch, Vodafone UK Headquarters, Newbury, England, Friday 29 January 2010. The new McLaren MP4-25.

With regulation changes for this season far less extensive than those for 2009, you’d be forgiven for thinking McLaren’s 2010 car would bear more than a passing resemblance to its predecessor. The MP4-25, however, is a very different beast, with its distinctive dorsal fin just one of a number of major design changes. The team’s director of engineering, Paddy Lowe, and the car’s chief engineer, Tim Goss, explain...

Q: The MP4-25 looks very different from last year’s car - what are the principal changes?
Tim Goss:
Following last year’s clarification involving the interpretation of the underbody regulations, the 2010 car has been designed to take greater advantage of the aerodynamic benefits we can derive from the floor. That interpretation led us to change the layout of the rear of the car. The car is longer than last year’s car as a result of the additional fuel capacity and we’ve lowered the chassis and bodywork. Plus the removal of KERS has opened up opportunities on internal layout and weight distribution. It’s quite a different aerodynamic treatment to last year.

Q: The dorsal fin that attaches the top body to the rear wing is very striking - what does it do?
The principal knock-on effect of the larger fuel tank was the repositioning of some of the car’s internals. One of the outcomes of that was a decision to move some of the car’s cooling to sit centrally at the rear of the car. The dorsal fin is partly to accommodate the additional cooling duct and partly a logical development of the high-downforce wing we ran last year at races like Monaco, which feeds air more efficiently to the rear wing upper element. They’re both quite simple solutions, but they’re actually very neat.

Q: On a human level, what has the organisation learnt about itself over the past 12 months?
Paddy Lowe:
I think we’ve learnt that as a team we can operate effectively and we pull together both in success and in adversity. I think one of the greatest things about last year was the fact that on no single occasion throughout the whole team, whether that’s from shareholders, sponsors, team principal, management through to the night shifters, did I come across any individual blaming another That was a very encouraging situation, and spoke volumes about the degree of team spirit that exists here.

Q: Looking at the 2010 regulations, the biggest news is the banning of in-race refueling - how has that affected the packaging of the new car?
It has definitely been a big challenge fitting twice as much fuel into the car, because you don’t want to increase the chassis length by too much, and you also don’t want to compromise the aerodynamics by making the car too wide. You’ve got to fit radiators into the sidepods, so you’re limited as to how wide you can push the chassis.

Q: How did you tackle it?
In the end, we elected not to compromise the aerodynamics of the car, and, through a rethink of the cooling system layout and electrical packaging, we managed to provide space for the additional fuel capacity while maintaining our aerodynamic philosophy for the bodywork.

Q: The drivers will be carrying twice as much fuel at the start of each Grand Prix as they were last year, how will that affect the car’s handling and balance characteristics?
The biggest problem is just the sheer weight of the fuel - it obviously increases the stopping distance quite considerably. Running with high fuel puts demands on braking - and it means you have to design the brake discs and pads to overcome that. And with a narrower front tyre, you’ll lose grip, which will change the fundamental balance of the car. So we’ve looked at weight distribution, aero balance and mechanical balance in order to compensate for grip balance moving rearwards.

Q: Do you think the banning of refueling and its effect on the car’s tyres and balance will spice up racing in 2010?
could make the show significantly better, yes. Previously, you knew when everyone was going to stop and refuel, so each team based their strategy decisions on overtaking cars during the pitstops. What’s changed for this year is that we won’t know when people are going to stop. The only thing affecting drivers’ mandatory stops now is that they have to run both the Option and Prime tyre, so the strategy choices will be less predictable and will become a little more complicated. Races could be one or two stints with both early and late stops for tyres.And it will definitely make the racing more challenging and interesting - and, hopefully, it will promote more on-track overtaking and less overtaking during the pitstops.

Q: Finally, what’s on your job list going into the four crucial pre-season tests?
Initially, the most important thing is proving that the car is robust. Just about everything has changed on the car, there’s very little that hasn’t changed, so we want to make sure we’re fully reliable for the first race. At the start of 2009, there were teams who were more competitive than us, but we were still able to pick up a good number of points because we were more reliable. These tests will be about establishing the durability of the car and giving ourselves enough time to fix any issues we encounter. In addition, we also want to get a very thorough understanding the new tyre, its degradation and durability, and how to get the best out of it. Beyond that, it’ll be about performance development.