Despite only being denied a third victory of the season in Valencia by unreliability, Red Bull is still struggling with development of its RB8.
Normally, it is the team that sets the design direction for the rest of the grid, but this year its exhaust solution has left it trailing. Not since 2009 and the double diffuser upgrade has Red Bull had to make such major updates to the car mid-season.
For Valencia, the team had another version of its exhaust\sidepod solution. This was a return to the bridge\tunnel concept first seen on the Melbourne-specification car.
Not only did the RB8 have new sidepods for the European Grand Prix, but also revised suspension, brake ducts and other aero parts.
Red Bull's decision to test its Melbourne exhaust solution in pre-season testing backfired when the system didn't deliver the results expected. Since then, it has tested several iterations of sidepod\exhaust, even returning to the launch specification for Vettel in China.
It is this tunnel solution in the sidepod that seems to promise the results Adrian Newey's design team are looking for, but it has its problems.
New rules brought in for 2012 banned the lowline exhausts used last year to create more downforce by blowing directly into the diffuser. Teams have sought to regain this blowing effect and the most popular design appears to be McLaren's, where the exhaust exits from the side of a short sidepod through a deep duct. The exhaust plume follows the downward line of the duct and the airflow over the sidepod further presses the plume back down towards the diffuser. Having the exhaust blow along the flank of the diffuser helps to seal it which creates more downforce.
Conversely, Red Bull has its exhaust exit on the top of the sidepod and the bodywork behind the tailpipe forming a ramp, which the exhaust plume follows down towards the diffuser.
In comparison to McLaren's solution, which points the exhaust plume openly at the diffusers edge, the Red Bull ramp guides it directly to the diffuser. This design should be more accurate and suffer less loss in the exhaust plume's energy.
But this longer sidepod design prevents the airflow passing low around the sidepods from reaching the diffuser. To allow the exhaust plume and sidepod flow to crossover, Red Bull devised the tunnel set up to allow the sidepod flow to pass under the ramped bodywork. In the early versions, this 50mm high tunnel did not allow the flow to pass through it as expected. Flow appeared to be reversing back out of the tunnel at speed, and its intended benefit of blowing the centre of the diffuser was not realised. So from Bahrain, the tunnel was closed off.
The suspicion is that the tunnel was too low and its inlet had sharp edges, which combined to deter airflow from smoothly passing into it.
For Valencia, the tunnel has returned and again it's limited by the rules to a 50mm height. But its entry has a significant radius to allow more flow into the duct. This flow is then routed inside the bodywork to exit through outlets flanking the gearbox. This allows the flows to cross over and enable the exhaust to be more accurately directed at the diffuser.
Sebastian Vettel and the RB8 upgrade were the class of the field in Valencia © LAT
Further aiding the downswept flow over the sidepod are two new fins, similar to those on the McLaren, on top of the sidepod fronts. These direct airflow over the exhaust outlet to help it point downwards at the diffuser.
At the back of the car, the rear suspension has been redesigned. The upper wishbone is shorter, bringing its mounting point well inboard from the rear wheel. This change will increase the tyre's camber change as the suspension moves, which is a method of increasing the temperature of the rear Pirellis. Accompanying the new rear upright is a new fin over the top of the brake duct area and a new shaped brake drum inside the wheel. Changes have been made to the lower wishbone as well, which is shaped to fair-in the driveshaft to reduce the drag the rotating driveshaft creates.
With this solution potentially offering more downforce and less tyre wear, the prospects look good for Red Bull. As it not only improves one-lap pace in qualifying but also in the race with better tyre management.
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