Red Bull Racing designer Adrian Newey has admitted that the latest set of Formula One regulations allowed him to exercise his abilities, albeit not to excess.

Discussing the creation of the RB5, the team's 2009 challenger built to a rulebook that limits aerodynamic influence via revised front and rear wing dimensions and the elimination of extraneous aero devices, reintroduces slick tyres and allows the use of KERS technology - amongst other changes - Newey admitted that the team could start with a clean sheet of paper in most areas.

"2009 arguably sees the biggest rule change since flat bottoms were introduced in 1983, a very major change," he explains, "We have taken a clean sheet, 'blue sky' approach [to the design], looking at the implications of these rules and how to interpret them, while not changing things simply for the sake of it. However, apart from the gearbox internals, there is hardly any carry over from the RB4."

The revised aero package mandated by the rules has provoked the most debate, with enlarged front and reduced rear wings giving the cars a somewhat unusual appearance.

"The front wing is oddly proportioned!" Newey admits, "It's lower and wider and, to my eye, looks like an indoor go-kart.

"The idea is that the centre of the front wing is most susceptible to disturbance and this solution makes the centre very neutral, while the tips of the wide-span wing are heavily loaded.

"The lack of appendages such as winglets, barge boards and so on causes a loss of downforce, but they don't affect the fundamental behaviour of the car. However, the behaviour will be different, because of the front wing and the diffuser, which is now moved further back and is higher. Being alongside the rear wheels, instead of in front of them, it now works in a different way."

The return of slick tyres after years of running with grooves is less of a challenge for the designers.

"The main area of change with going back to slicks tyres was in terms of weight distribution, as it will put greater strain on the rear tyres. So, at the design stage, we moved the weight distribution forward a bit."

Technical director Geoff Willis confirms that the balance between stress on front and rear rubber will change dramatically in 2009.

"The conversion from grooved to slick tyres of the same dimensions has led to a substantial mismatch with the front tyres too strong for the rears," he reveals, "However, there was some resistance to changing this since the new aerodynamic regulations had been developed around the existing tyre sizes.

"This leaves a big challenge for the teams to match the cars' weight distribution to suit the tyre characteristics, as well as a challenge for the drivers to deal with the rear tyres going off faster than the fronts.

"We'll only have four compounds to choose from this year and we won't have two adjacent compounds in terms of their characteristics, so we will either have compounds one and three, or compounds two and four, on a sliding scale of soft to hard.

"The new regulations have hit both downforce and aero efficiency. While the gains from the tyres will make up for this, it will be interesting to see how close to 2008 levels the teams can get."

Although KERS is not mandatory for 2009, Red Bull has pressed ahead with its system, although Newey admits that packaging it was a challenge.

"We use a battery storage system [as opposed to Williams' flywheel system], which is heavy and therefore affects the weight distribution on the car. After everything is packaged in the usual manner - driver, fuel cell, engine, gearbox - you then have to find somewhere for KERS, while maintaining fuel tank capacity and achieving the weight distribution target. As a result, the RB5 carried its KERS in the base of the fuel tank."

RBR did not join the likes of BMW Sauber and McLaren in running a KERS-equipped test hack during the early winter tests, but Willis is not concerned that that, or the safety of the controversial technology, will be a problem.

"KERS is a big engineering challenge but, looking at the extent of the changes to the car design required, we made the decision not to test a KERS 'mule' car at the end of the 2008 season but to test it only on the new '09 car," he confirms.

"The high-power, high-voltage motors and batteries are new technologies to F1 and much lab testing has been needed to understand the technology and develop a safe and reliable solution. While there have been some safety concerns in early testing by a few teams, fundamentally safe operation is dependent on good design and proper procedures.

"F1 has learned to deal safely with a lot of potentially dangerous systems - this is just a new technology to learn to deal with. The additional challenges for KERS are to minimise the detrimental effects to chassis performance resulting from the additional weight, compromised braking stability and increased cooling requirements. The teams will judge where and when to use KERS by balancing these chassis performance penalties with the obvious gains."

The new aero rules also only allow holes at the rear of the bodywork for the exhausts, which reduces cooling capacity - a potential handicap given Newey's penchant for tightly packing components under the bodywork.

"Apart from the little gap around the exhausts, all the cooling air has to come out the back of the car, which is a more difficult solution," he admits, "It means you have to make the back of the car bigger, while the situation is further complicated by KERS, which increases cooling requirement by ten per cent."

Willis admits that tempering the car to the varied conditions that it will have to face during the season will not be as easy in 2009 as it was in recent seasons.

"The new regulations regarding bodywork and wings mean the cars definitely look different this year but I think we will soon get used to the changes," he concludes, "But, while the cars look cleaner without the majority of add-on aerodynamic elements, the aerodynamic concepts resulting from the new regulations will prove a challenge
to understand and optimise. Car set-up will be as important as ever.

"Up until now, it's always been fairly easy to modify cooling by fitting top panels with gills or having other ventilated panels, but now we can only vary cooling by changing the rear exit of the bodywork. This clearly places the emphasis on the teams getting their cooling calculations right first time.

"Given that the early races are usually hot, some teams may find themselves struggling to engineer their way out of an under-cooled car."