Superficially, Spa was a bit of a head-scratcher. Four weeks earlier, in Hungary, McLaren were 1.3 seconds off the pace of Red Bull.
How was the Woking-based outfit able to more than claw back that deficit at Belgium – despite having had a mandatory two-week factory shut down between the races?
As a circuit Spa is the antithesis of the Hungaroring. Take a look at a map of the Budapest track and you’ll see lots of corners and few straights (which is why there is always so little overtaking). Many of its bends are fourth and fifth gear turns and, as downforce squares with speed, it plays to the RB6’s strengths.
Ah, you might say, but why wasn’t the RB6 pulling out half a second in Spa’s sector two where there are several quick corners? As Red Bull never fails to remind us it has a power deficit to McLaren and Ferrari and, in Belgium, significant overtaking opportunities is into the bus stop in sector three and up the hill after Eau Rouge in sector one.
Therefore high-speed / low drag is order of the day. In order to keep the silver cars at bay Red Bull took a significant amount of wing off, which compromised grip in the twisty middle sector.
Spa also saw the introduction of a more stringent test to try to reduce flex in front wings.
Although Christian Horner denied having to alter the front wing for Spa he is no position to claim otherwise or he would be admitting rival teams had successfully identified one of their advantages.
McLaren analysts were reportedly much happier with the reduced amount of flex on Red Bull’s wing. However, Red Bull did bring a different wing to Spa – it had a smaller cascades for reduced drag (and downforce), so it might be the lower downforce that is causing it to flex less.
With the next race, Monza, being another ultra-low downforce track, and with the advent of a new floor deflection test, it won’t be until Singapore that we know whether the new load tests have had cut Red Bull’s performance advantage.
Although the mystery of the flexing front wing is no closer to being solved, it seems as though the most plausible theory is that Red Bull lay the carbon fibre composite in a specific (and different) manner that leads to non-linear deflection (in other words the degree of deflection varies to some power of downforce) as well as fiddling with the front splitter and floor to allow the front section to dive.
The onboard video of the Button/Vettel crash from the Red Bull shows the front wing moving as the RB6 pulls out of Button’s wake. The endplates move visibly as the higher airflow affects the wing causing a roll moment. There is a belief among some in the paddock that the flex wing could have contributed to the accident.
McLaren’s struggles with its blown floor seem to have been mostly resolved. On its introduction in Silverstone it had to be replaced with the so-called T2 (old) floor. In Germany, with modifications, the floor seemed to work better, but was still obviously problematic.
It is only with a couple more weeks of development that the kinks have been ironed out.
Surprisingly, Ferrari were not on the leaders’ pace in Spa.
Ferrari ran two different rear wings: Fernando Alonso preferred an older, higher-downforce design whereas Felipe Massa went for a new version with no blown slot, a shallower main plane and three curved gills in the end plates. Alonso was banking on more rain on race day where more downforce makes the car faster on a slippery surface.
Ferrari also introduced a revised diffuser with a larger top deck that integrates more with the rear wing (a la McLaren). Looking from a 45 degree angle, from the rear of the car it is clear that the upper diffuser exit is significantly larger.
There are two longitudinal fences running either side of the car centre line (four in total) supporting this open-vented structure and to act as turning vane for air under the floor. As McLaren has discovered having a over-sized diffuser exit can result in super-sensitive ride heights. Keep an eye out for whether Ferrari run such an open diffuser on the bumps of Singapore or Brazil.
There were few obvious changes to the MP4-25 at Spa. The cascade on the front wing was truncated to the inward vertical fence (rather than extending further inwards to the car centre line), and there also an additional inlet carved into the endplate. The smaller cascade cuts drag and allows the car to attain a higher top speed through sectors one and three. The endplate changes were most likely to optimise the airflow around the tyres and to the sidepods, which in turn has a knock-on effect to the floor and diffuser.
McLaren continues to tweak its exhaust-blown diffuser. Unfortunately many of its changes can’t be picked out in photographs (the performance of the car speaks for itself) although it was possible to spot a second slot in the floor in front of the rear tyres. This allows high energy air to seep under the car and around the tyre. This, in theory, keeps airflow attached behind the tyres increasing the efficiency of the entire floor.
It also appears that McLaren has been playing with its engine mapping settings to try to replicate Red Bull’s over-drive setting. Through the corners the engine on both McLarens sound rougher. This is probably a result of altering the settings to burn air/fuel mixture in the exhaust to maintain a (more constant) flow of exhaust gas to the diffuser. Red Bull allegedly only runs this setting in qualifying whereas the McLaren engine sounded rough for the whole race.
Hamilton reverted to an earlier version of the front wing (top image) having run the new one on practice (adjacent images).
Renault brought its much trumpeted F-duct to Spa. It is actually the second generation F-duct, the first having been canned before it reached production after initial tests showed it wasn’t particularly effective.
It was a good decision as Renault was immediately competitive at Spa despite having an alleged horsepower deficit due to its engine. The team claims the F-duct was worth 0.5s a lap and Kubica’s second row starting position backed up that claim – he might have started on the front row without his fuel feed problem in Q3.
The solution itself is innovative. The F-duct is like a fluid transistor which requires the driver to manually switch it on (by manipulating air pressure). Usually teams route the duct through a hole in the monocoque to the driver’s hand. When the driver places his hand over the switch is ‘on’ and air from the F-duct disrupts the standard rear wing airflow, which is what causes downforce (and drag) to drop away.
The problem for teams like Renault, who are trying to retro-fit an F-duct to a car that was designed without one, is their chassis was homologated at the start of the year. They have to think laterally to design in the F-duct because they can’t cut a new hole in the chassis.
Renault has two inlets either side of the airbox to suck in air and stall the rear wing. When the duct is ‘on’ air takes the upper route and there is an outlet feeding the main plane (rather the the flap, which is Red Bull and Ferrari’s preference). When ‘off’ the air blows harmlessly between the beam and rear wing.
To switch the f-duct on a driver activated control duct is required and this weaves from from the drivers headrest and into the cockpit to exit by the steering wheel. By placing his hand over the control duct the air pressure in the switch changes moving the duct to ‘on’ and stalling the rear wing.
As discussed above Red Bull ran a revised front wing which, like McLaren’s, had modified cascades for reduced drag.
The Milton Keynes-based outfit ran a low drag beam wing in practice but it was discarded for qualifying and the race. There were also reports that Red Bull altered the fixing for the brake ducts.
In my last technical review I gave a short primer about how installing an EBD involved complex re-routing of the exhausts to make sure the pressure waves exiting the exhausts were maximised engine power. I made mention that designers would need to tune the length of each exhaust leading into the collector to optimise this pressure distribution. Unfortunately, as a couple of readers pointed out, that isn’t right.
Variable length exhausts are of course illegal in F1. However, in implementing the EBD teams do definitely take a lot of care re-routing the exhaust structure to make sure the pressure wave behind the exhaust is optimised for engine torque and peak power – they just can’t use variable length exhausts to do so. Apologies for the error.
And now on to to Monza where top speed is all that matters. Based on what we saw at Spa expect McLaren to be quick. Ferrari should be competitive too, but, as at Spa, Red Bull may struggle a little.
The issue is that engine power rather than driveability is the key factor (Mercedes power trumps Renault driveability) and Monza is perhaps the least important for driveability.
Also the RB6 is a downforce machine and you want as little as possible, within reason, at Monza. The theory is that Red Bull can’t lose downforce fast enough and will struggle. Expect the Italian Grand Prix to be only the second time this year when a Newey machine isn’t on pole.
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