Profile – Renault R26

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Fernando Alonso drove this chassis in every race of 2006, on his way to double world championships for Renault. We analyse the attributes which made it a multiple winner 

The 2006 world title-winning Renault R26 stands as the team’s crowning achievement. Although Renault entered the season as reigning world champions, the new car faced some very significant new challenges.

For one, there had been the first major formula change in 11 years: the 3-litre V10 engines gave way to 2.4-litre V8s. For another, it had already been announced that the team’s champion driver Fernando Alonso would be leaving at the end of the season to join McLaren, potentially affecting the close working relationship between driver and team in their final year together. Then there was the return to tyre changes after a season in which a single set of tyres had to last the whole race. Not insignificantly, the ’06 tyre rule played into the hands of Ferrari and Michael Schumacher, a combination that in 2005 had effectively been taken out of the equation by Bridgestone’s inability to supply a tyre that combined the pace and durability of the Renault’s Michelins. Without the endurance requirement, the Bridgestone/Ferrari combination was right back in the thick of things in 2006. Yet despite all these new threats the R26 came through, Alonso winning seven races and securing the team their second consecutive Drivers’ and Constructors’ world titles. 

Remarkably, Alonso achieved this feat using the same chassis – number three – throughout the season. Because he never damaged the car, and because there was no loss of rigidity each time it was checked, there was no reason to change it. It is this chassis which you see in our pictures.  

Despite it racing in an era where F1 cars look very much alike, the R26 was designed to a technical philosophy rather different to that of any rival. Like its immediate forebears, it featured a more rearward-biased weight distribution, and this had significant implications.  

Team pedigree

Renault bought the Benetton team early in 2000, though it wasn’t re-branded as Renault until 2002. The R26 was the joint creation of the chassis group based in the old Benetton factory in Enstone, Oxfordshire and the Renault Sport engine department in Viry-Chatillon, near Paris. A weekly shuttle plane runs between the two facilities to aid communication.  

It is a beautifully balanced team of engineers, without the role of visionary star designer seen elsewhere. In its place is a highly integrated system with many layers of expertise, and group consensus, making it relatively immune to the departure of any single person. This was notably evident back in 2002 when the team lost its technical director Mike Gascoyne and its engine chief Jean-Jacques His, yet the progress of the team as a whole continued unabated.

The R26 was the work of a group of people shepherded by technical director Bob Bell. Chief of engineering Pat Symonds fulfilled a dual role, at Enstone and at the track. Chief chassis designer was Tim Densham, chief aero-dynamicist Dino Toso. Rob White, a 20-year veteran of Cosworth, who joined Renault in 2004, oversaw the Viry Chatillon engine operation where the RS26 V8 design was project led by Léon Taillieu. 

Technical philosophy

It is believed that the R26 never ran with more than 45 per cent of its weight on the front axle line (there is scope to vary the distribution from track to track with ballast). Most rival designs could go to 48 per cent and beyond. 

This more rearward bias has been a feature of Renault designs for several years and can be traced back to the Benetton B201 of 2001. That car was fitted with what was originally a very light 111-degree V10 engine. But by the time it was beefed up to make it reliable, it was very heavy, and it had completely changed the car’s weight distribution. The limitations brought about by that engine’s relatively great weight and restricted upper rev range led the team in a direction that ultimately proved very fruitful.

The rearward weight bias brought traction benefits and also made it easier to find an aerodynamic balance at a time when the regulations made frontal downforce gains very difficult to achieve (see ‘aerodynamics’ below). The restriction in revs brought about by the mechanical imbalance of the vee angle led to very useful gains being made in the useable torque curve. This in turn helped improve the economy and lower the heat rejection of the engine – both extremely important considerations when it comes to the car’s race performance.

Ironically, the work put into minimising the flaws of the B201 design led to a development path that resulted in the world title-winning R25 and R26 designs. 

Engine/gearbox

The new 2.4-litre formula was highly prescriptive. The regulations specified the number of cylinders (eight), the angle of the vee (90-degree), the maximum cylinder bore (98mm), minimum gap between the cylinders (106.5mm), minimum total weight (95kg), the centre of gravity height (165mm above the lower edge of the oil sump), the C of G position (plus or minus 50mm of the engine’s geometric centre), minimum crankshaft height (58mm above reference plane) and maximum fuel pressure (100 bar). Variable inlet and exhaust geometries were banned, as was variable valve timing. Only one injector per cylinder was permitted, the fuel pump had to be a mechanical type and the engine could only use titanium and aluminium alloys. 

Yet even within such tightly defined parameters, the RS26 engine displayed a superb combination of performance, economy, driveability and heat rejection. In comparison to the competition it displayed much the same advantages as had the previous 72-deg V10 designed to a much freer set of regulations. There were four performance upgrades during the year and in ‘E’ specification it was believed to produce circa 775bhp at circa 20,500rpm. In original Bahrain form these figures were more like 725bhp at 19,200rpm. 

The change to V8 from V10 brought an increase in external vibrations – although internal vibrations were reduced. This made it easier to make the internals reliable but meant some external parts needed to be strengthened.

The smaller capacity combined with the ban on variable inlet devices forced the design team finally to abandon a six-speed gearbox – as used since 2001 – in favour of a seven-speed. This at last brought it into line with everyone else. The closer ratios increased the duty cycle of the engine, as did the greater use of full throttle prompted by the reduction in capacity. Therefore care had to be taken to ensure the motor still met the two-race endurance rules. 

The engine’s relatively friendly torque curve, in combination with the rearward weight bias, helped the car to the best startline getaways of all, something of a Renault tradition in recent years. 

Aerodynamics

Matching up weight distribution with the centre of aerodynamic pressure is a key endeavour for any F1 design team. It gives the car a wider operating band in that there is greater correlation between low- and high-speed handling characteristics – correcting excessive low-speed understeer need not involve worsening high-speed oversteer, for example. 

Which for the Renault team over the years has meant matching up the rearward weight distribution with a similar downforce distribution. The way the regulations have continuously sought to restrict frontal downforce over the years – mainly through wing height – has therefore worked in Renault’s favour. The aero distribution demanded by the weight distribution has been more easily and efficiently accomplished for them than for other teams with a more conventional weight distribution. 

There have been downsides to this approach, however. With rear tyres that are deliberately under-dimensioned for their workload by the regulations, it has sometimes led Renaults to over-use their rear tyres. This was noticeable in 2005 when tyre changes were not permitted: then the R25 was often slower than the more forward-biased McLaren MP4-20. The reintroduction of tyre changes for 2006 moved the regulations back in favour of Renault’s approach and away from McLaren’s. But it was a double-edged sword, because as well as helping Renault see off McLaren, the new regs brought Ferrari back into the equation. In effect, it simply changed the identity of Renault’s prime rival. 

Helping retain the rearward weight distribution, the R26 featured a fairly long wheelbase of 3100mm. This had aero benefits too, in that it allowed more space between the front wheels and the sidepods, thereby giving the airflow along the body a better chance of staying attached as it had a greater length in which to change direction. 

At the front, the R26’s lower suspension wishbone was attached to the tub via a ‘vee keel’ that dropped down from the high nose. Unlike the rival twin or zero keels, this allowed an adequate distance between the lower and upper wishbones to give some adjustability of camber to aid set-up. But compared to the traditional solid single keel, it still offered the airflow a clear passage through to the underbody. 

Keeping this passage uncluttered also played its part in determining the shape of the front wing. It used a twin-plane design – as opposed to the triple-plane seen on the McLaren MP4-21 – to give a single-slot gap. The size of the slot gap can be changed to tune out any airflow separation. Above the connected twin-planes are upper winglets. These are aerofoil shaped at the outer ends to give downforce but then change to a more neutral profile in the middle, so as not to block the flow to the underbody. The design of the endplates is quite intricate and is a major influence on the car’s behaviour in transient conditions – as it changes direction. This also plays an important part in maintaining adequate airflow to the radiators when the wheels are turned. 

The fins atop the front bodywork are flow conditioners which take airflow from the front and channel it to the rear wing. They effectively convert front downforce to rear, and the shortfall in the front is then compensated for by increasing the flap angle. The advantage of doing this is that front downforce costs far less drag than downforce derived from increasing the angle of the rear wing.

The low heat rejection figures of the engine allowed very small radiators. This in turn allowed the aero team to viciously undercut the lower part of the sidepods. This created a low-pressure area that the airflow rushed to fill, thereby increasing the speed of the flow towards the rear beam wing, which in turn increased downforce. 

The shorter dimensions of the engine compared to the V10, within the same wheelbase, meant that the engine could be mounted further forward in the car, thus creating more space at the rear for downforce generation. It allowed the designers to enhance the ‘coke bottle’ profile of the lower bodywork. This worked in concert with the sidepod undercuts to speed up the airflow over the rear beam wing.  

The rear wing is supported by a central pillar rather than the R25’s endplate mounting system. Freed of structural requirements, the endplates could be shaped more aggressively to scavenge the outer channels of the diffuser, so speeding up underbody airflow – a detail inspired by the 2005 Toyota.

With a narrower section in the middle than at the ends, the rear wing is highly unusual. The wing ends are usually where the greatest downforce can be created, but it is usually inefficient in that there is a greater cost in drag. The Renault wing appeared to get around the drag increase with a highly intricate wing/endplate arrangement. It is believed this design also kept downforce more consistent as the car changed direction.

Another detail unique to the Renault is the very low positioning of the lower rear wishbone. This was introduced on the R25 and required a completely new gearbox casing, but it allowed the wishbone to work in aerodynamic unison with the diffuser and lower beam wing. 

Mass dampers

The R26 ran with front and rear mass dampers from the start of the season until the devices were banned prior to the German GP. These simple devices were sprung weights that opposed the pitching and bouncing of the car. That at the front comprised a weight of up to 9kg that was tuned to counter pitch. The rear one was smaller and countered bounce. The aim was to even out the load variations on

the tyres, which on an F1 car with its stiff suspension but low-pressure tyres are very considerable. In this way the mass dampers effectively increased the usable grip of the tyres. 

They were controversially banned by the FIA after objections from other teams that they could construean aerodynamic advantage.  

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