Bell and White, the men behind the Renault R25, explain their creation 01 Feb 2005
Renaults chassis and engine technical directors, Bob Bell and Rob White, explain the philosophy and development of the new Renault R25 and its RS25 engine.
Q: The new R25 is an impressive machine. Tell us a little about it?
Bob Bell: The philosophy behind the car is very much one of evolution, and we hope the R25 will be a package capable of fighting for race wins. Last year, the mechanical architecture of the car was compromised by the late change of engine angle; the new RS25 engine has a lower centre of gravity, and a much stiffer installation than we were able to achieve in 2004. Our focus has been on optimising each detail to improve stiffness, reduce weight and package the components very tightly to give our aerodynamicists as much freedom as possible.
Q: How did the regulation changes impact the design process?
BB: We allocated wind tunnel resources as soon as the regulation changes were announced last July. That decision was a risk, and it cost us performance at the end of last season, but it was undoubtedly the right one. We have made a big step forward from our initial downforce loss of approximately 25%.
Q: What are the major innovations on the R25?
BB: We have an all-new electronic system integrating the engine and chassis controllers, named Step 11. It is physically lighter, representing a quarter of the total weight saving in the new car, and brings us a concrete advantage in terms of the scope of our development: we now possess four times' greater processing power, and ten times' more data acquisition capacity, all of which will contribute to improvements in our control systems. The other new feature of the car is the 'v keel' front suspension.
Q: Why did you choose this solution for the front suspension?
BB: In recent years, we have seen two schools of thought evolve in front suspension design: the traditional single keel, with a single front lower wishbone, and the twin keel, which brings a measurable aerodynamic gain but can also have a structural penalty outweighing the benefit. We believe the v-keel is a very elegant solution to this dilemma, as it combines the virtues of both systems: we have obtained an aerodynamic advantage for minimal structural penalty, while maintaining our preferred mechanical configuration for the front suspension.
Q: Overall, what are your expectations for the car?
BB: The R25 is certainly the best-integrated car the team has produced so far. We have worked very closely with Viry to optimise the engine installation, and the aerodynamic improvements from our initial starting point are beyond what we would normally expect under stable regulations. I am confident that the numerous gains we have made will translate into a concrete step forward in competitiveness on track.
Q: You have said the RS25 is an evolutionary step: what is the crossover from last year's engine?
RW: The RS25 is a clean sheet design, and shares no major components with RS24: 98% of the parts are new. The engine maintains the 72° architecture of its predecessor, but we have included the lessons learned from RS24, and further refined the engine-chassis integration. The engine's centre of gravity is significantly lower, recovering nearly 70% of the difference relative to the previous generation of wide-angle engines. Equally, despite the doubling of life for this season, the engine has not gained in weight.
Q: The engine will be running a brand new electronic system: what benefits does this bring?
RW: We will use the Step 11 system in 2005, a combined chassis and engine controller developed with Magneti Marelli. This major programme has run in parallel with the car and engine design, and marks a further step in the integration of the two. Conceptually, the target has been to simplify the electrical and electronic installations while providing a more powerful platform for the development of engine and chassis control systems.
Q: What has been the impact of the technical regulations on performance development?
RW: We are pleased with the performance of RS25 at this stage of its development. The engine must drive cleanly through a huge rev range in modern F1, and we will therefore develop the engine's torque curve and power delivery according to the same philosophy of total vehicle performance as its predecessors. In terms of specifics, the RS25 has hit or exceeded all of its performance objectives thus far.
Q: What was the impact of the regulation changes on the engine's development?
RW: The changes arrived too late to affect the overall philosophy of the engine but in order to respond to them, we had to review every component and system, and conduct detailed risk analysis on the impact of extending engine life. Parts must now last four times longer than two years ago, and to ensure we can meet the challenge of the regulations, we must respect extremely strict quality requirements.
Q: Finally, will the new regulations bring about cost savings?
RW: The direct engine costs of running the car will be lower in 2005: the number of engines built will be substantially less and although each one is more expensive, there is a net saving. Change obviously has cost implications in terms of development, and these costs will offset the savings for the manufacturers. However, it is reasonable to expect that small teams buying engines will see real economies thanks to the regulations.