Looking back on the technical developments from Hockenheim and the Hungaroring, here’s John Beamer.
As Mark Webber said the list of accusations thrown at Red Bull is starting to look silly. First we had the trick ride height system, then illegal suspension fairings and now flexing front wings.
In the midst of all this teams were racing to copy Red Bull’s exhaust blown diffuser and next year, with the banning of double diffusers, no doubt pull-rod suspension will be flavour of the month.
The Red Bull package
2010 represents a microcosm of why, once a team has a technical advantage, it is relatively easy to keep it. While rival constructors chase their tail to try to copy and retrofit parts to their car, the team ahead is refining and optimising its aero and dreaming up the next technical leap forward. Given the regulations won’t radically change until 2013 we could be in for a period of Red Bull dominance. As Christian Horner repeatedly says its not one thing that makes the RB06 quick but the whole package.
Since the last technical review two races – Germany and Hungary – have passed and a couple of trends are clear. Red Bull is still yards ahead in raw downforce. Ferrari has usurped McLaren as the second quickest team, and Renault has also closed the gap to the Woking-based outfit. Mercedes along with many of the other teams on the grid have started to focus resources on its 2011 challenger.
The flexi-wing controversy
The pitlane scuttlebutt since Hockenheim has been about Red Bull’s (and to a less extent Ferrari’s) flexable front wing. The TV pictures are clear – under high downforce the endplates sink. There are contrasting opinions as to what is happening. Some say that the the wing is less rigid so that under high downforce conditions the tips visibly lower, which creates a ground effect under the endplate.
Yet another explanation is that Red Bull is running more rake (which means the car is inclined to the road lengthways, with the rear raised). If this was so then the back of the RB06 should be visibly higher – and although film suggests that the Red Bull is more nose down than its rivals it doesn’t appear to be running an aggressive rake.
Another is that the the front part of the floor (splitter) is somehow flexing and after Vettel’s nose dropped off in P3 at Silverstone there is suspicion that this is what Red Bull is doing. This is prohibited and the flex tests are stringent. The front splitter is subject to 200kg loadings and is only allowed to deflect 5mm. Although teams were able to circumvent this by hinging the splitter with a rear mounting and using a 200kg preloaded spring at the front (to resist the loading test) the FIA became wise to this practice in 2007 as part of the Spygate saga. In short it would be a substantial engineering feat to circumvent the rules. Even if the splitter did deflect it is likely that the underside plank would suffer more than the proscribed 1mm wear.
There was even another, more outlandish suggestion that perhaps the nose cone itself was mounted to the chassis with a spring, allowing the entire wing to operate in ground effect, but FIA checks found nothing.
Although teams are still partly in the dark about what Red Bull’s secret sauce is, the most likely explanation is that the wing is manufactured in such a way as to allow flexing under high downforce conditions. To this end after the Hungarian Grand Prix the FIA announced new deflection tests for Spa. According to article 3.17.1 the front wing is allowed to, “deflect no more that 10mm vertically when a 500N load is applied to it 800mm forward of the front wheel centre line and 795 mm from the car centre line”. The new test will double the loading and with a 20mm deflection now allowed.
This may seem a wash but it is designed to stop team building in non-linear flex whereby the wing will meet the 10mm/500N condition but then start to flex more generously at higher loadings. We’ll need to wait until Spa to see if the RB06 wing flexes as much on camera.
The advantage of flexi-wings
A flexing front-wing could be quite an advantage as it not only generates more downforce but it self-modulates so is less pitch sensitive.
Typically teams build a semi-circular channel into the footplate that is used to create and capture vortices. These help generate downforce and also seal the underside of the front wing (from being contaminated with dirty air). Under high speed the force acting on the footplate will increase, which will pull the carbon fibre down. This has two benefits: first a ground effect is created which produces more downforce and hence a larger ground effect; second the vortex inducing seal is more powerful so makes the rest of the wing work more efficiently – both are very powerful particularly through medium- and high-speed corners.
A flexing front wing also better handles stall (particularly through slow corners) as the front wing will deflect absorbing the change in load rather than transmitting the load to the suspension (which would be the case in a stiff wing car). This means the suspension can be run softer (or tyre pressures lower) for better traction in the slow corners.
Exhaust Blown Diffuser (EBD)
McLaren has slipped to third in terms of raw pace as it races to get on top of its EBD. After the Silverstone fiasco, McLaren returned to Hockenheim with a revised EBD set-up with many modifications. The most obvious were that the exhausts were moved out from under the sidepods and the cut was changed to better direct gas flow and control heat dispersion. In addition the wishbones and floor were reinforced with more heat resistant material to prevent buckling.
Also McLaren changed the shaping aft of the exhaust outlet – there is now a small inlet that allows some of the exhaust gasses to pass into the outer diffuser channel to boost downforce. Unlike the RB06 which was designed with the EBD diffuser in mind the McLaren solution feels more compromised and definitely works less efficiently.
More teams continue to bring EBD to the grid, with Force India being the latest. Similar to other teams, Force India lowered the exhausts to the floor and reprofiled the sidepods. The team ran the device simply to gather data with no real intention to race it. Expect both cars to feature EBD at Spa.
Ferrari, Renault, Williams and Mercedes continue to optimise their EBD. For Hockenheim the Scuderia’s exhaust was lower and more forward allowing the exhaust gas to act on a larger volume. Similar to McLaren the exhaust is cut at an angle and heat shielding on the floor and around the wishbones has been bolstered.
After Hungary, Renault announced that its latest EBD saw the team overcome the initial drop in engine power it experienced. This phenomenon is worth discussing in more detail. Designers make the exhaust exits from each cylinder a different length to produce a series of sequential resonant frequencies (the resonant frequency of the exhaust depends on length). These then feed into a tail pipe (two – one for each four-cylinder block) which produces a secondary resonant frequency. Correctly tuning the exhaust pipes allows engineers to better manage the pressure distribution at the exhaust outlets to evacuate the hot gasses. Failure to do this will result in reduced engine power as the exhaust is less efficient at escaping from the cylinders.
Williams and Mercedes both introduced big updates to their blown floor and started to experiment with blowing the exhausts into the diffusers rather than just above them. Williams introduced a large inlet (almost an open fronted diffuser) by the exhaust to allow the hot gasses to feed the floor. These gasses will add energy to the airflow in the outer channel increasing downforce. Mercedes had a similar solution albeit with a much restricted inlet.
Both Renault and Mercedes introduced significant changes to their rear wings. In preparation for the launch of its F-duct at Spa, Renault introduced a new front wing with a sharp ‘V’ cutaway in the centre and a couple of additional inlets closer to the endplate to help equalise air pressure. Similarly Mercedes added two bulbous inlets to its rear wing – the effect of this and the Renault ‘V’ are the same.
The intent is to create a virtual third rear wing element (a blown rear wing). Air enters the inlet on the upper side of the rear wing and then exits through a very thinly etched slot on the underside. This is akin to adding a flap with a very small slot gap and allows the wing to be run at a steeper angle without stall. Superficially this solution may seem illegal but careful position of the slots and the fact that the etched slot on the underside of the car doesn’t run across the entire width of the wing means that the rear wing still conforms to the ‘two closed sections’ rule.
McLaren has run a similar system for most of the season but is harder to spot with the fluorescent orange paint scheme – unlike Mercedes’ unwieldy copycat.
All the major teams continued to tweak their front wing designs but with no major overhauls. At Hungary Ferrari wavered on whether to run its new (Silverstone edition) triple element front wing. The three element version provides more consistent performance without necessarily increasing downforce (unless the wing is run at a steeper angle, which then costs drag).
While the flex-wing controversy was going on Red Bull continued to evolve its front wing, which for Hungary sported a duct in the footplate to allow air to bleed through, which stops air from separating.
A few of the smaller teams introduced new front wings. Sauber copied the Force India/Red Bull camera mounts and now place them in between the nose pylons. This adds a little downforce to the central front section of the car where the FIA has specified the flat central wing section. Toro Rosso also introduced some updates with a revised endplate which helps direct air around the front tyre and also Red Bull style vanes under the nose to reduce turbulence under the chassis.
After the break
Although the RB06 is supreme everywhere the upcoming tracks should allow both Ferrari and McLaren to challenge so don’t expect the championship to be a foregone conclusion. McLaren’s prodigious straight line speed should be enough to keep it in contention in Spa (although it will lose time in the high downforce middle sector), while in Monza the McLaren should also shine through as pace rather than aero matters. Singapore is a twisty bumpy circuit much like Monaco where the pitch sensitive MP4/25 will likely struggle badly. The F10 should do well. Korea is an unknown and Japan, with its fast corners, should be a Red Bull flush. While McLaren will probably struggle over the bumps of Interlagos expect Red Bull and Ferrari to be strong both there and at the season finale in Abu Dhabi.
Also the technical themes in the last third of the season won’t be too different to the first two-thirds. The leading teams will continue to refine and optimise their EBDs, the flexi-wing brouhaha will continue to rumble, and all teams will continue to tinker across their cars. Also don’t be too surprised to see another tech fissure (no doubt Red Bull linked) to break before the end of the season. Watch this space.
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