This weekend we have been at Silverstone, a classic track but one that has undergone a facelift for this season with new sections on the second half of the lap.
As usual there were plenty of interesting technical updates on the cars, with teams catching up on the trends of the season and adding either exhaust blown diffusers or drag reducing F Duct rear wings, or in the case of Williams, both.
Following on from the rush of exhaust blown diffusers we saw coming onto the cars in Valencia, McLaren had been working towards Germany but fast tracked the update and brought theirs to Silverstone for testing in Friday practice. It was the main feature of a major upgrade package, along with a new front wing.
Red Bull pioneered the technology and has really maximised it. They blow the exhaust gas through a slot which energises the airflow through the diffuser. It is this slot which the Red Bull mechanics are so keen for people not to see when the car is on the grid. But this is a bit of a pointless exercise, as teams have photographers taking digital images of the cars as they drive down the pit lane!
One of Red Bull’s secrets is a setting on the Renault engine for use on the final crucial lap in qualifying, whereby the ignition is retarded on the over-run, which maintains exhaust gas pressure even when the driver lifts off the throttle. This maintains the performance of the blown diffuser and keeps the downforce up when it’s most needed. It thus avoids the main problem of an exhaust blown diffuser whereby when a driver lifts off the throttle for a corner, the downforce goes missing when you most need it and the rear stability changes.
It’s not something you can do for more than a lap or two as the temperatures go sky high, which damages the engine, but it gives that vital fraction of a second which keeps Red Bull ahead of the rest in qualifying.
But one of the problems with running the exhausts low is that the components at the back of the car get very hot. McLaren’s lower wishbone featured a wide insulating cover to prevent overheating. The side sections of the diffuser featured an upper insulating plate, and underneath and they were painted with an insulating coating. But these precautions didn’t prevent the diffuser slightly changing shape due to the high temperatures, and this caused some rear end instability. So the diffuser was dropped for this weekend and McLaren had a rush on to balance the car with the new front wing but without the rear end package.
Their performance in the race on Sunday was quite remarkable given how much work there was to do after Friday’s problems.
Red Bull Front wing
Ferrari brought an update to its rear suspension at Silverstone, to cope better with the overheating issue caused by the blown diffuser.
Increasingly the teams use Friday as a test session for new components and if they perform well they may continue on the car for the rest of the weekend, otherwise they may be taken off and used again at a subsequent event once some refinement has taken place.
On Friday, for example, Ferrari did a comparison run of the two cars with Massa using the drag reducing rear wing in the morning and Alonso using it in the afternoon. It was decided from that test to use the F Duct wing for the remainder of the weekend and Alonso managed to qualify third on the grid with it.