Mercedes looks for DRS wing fix

Both Nico Rosberg and Michael Schumacher have been hampered in the last two events with DRS issues - where the wing does not return to its ideal downforce-producing performance for corners after it has been opened up on a straight.

Mercedes GP team principal Ross Brawn believed that alterations to the rear wing design for Malaysia had cured the issue - but ongoing problems for his drivers have shown there is more work to do.

Explaining the problem his team is facing, Brawn said: "When you activate the rear wings, when the flap goes up, effectively the flow stalls. It separates off the wing. And when the flap comes back the flow reattaches and the wing works normally.

"We are having some situations where the flap comes back and the flow doesn't reattach immediately, so it takes a little bit of time before the flow reattaches.

"We have made some modifications since Melbourne and it looked okay in most of practice. But then it [the problem] seemed to come back again during qualifying.

"In Michael's case, on his qualifying lap, there were several corners where the flow was unstable, and it happened in Nico's case as well.

"Obviously with the qualifying mode you are operating the RFA [Rear Flap Adjuster] at many points on the track, whereas in the race you are operating it one point on the straight, so it is aggravated when we get into qualifying."

Brawn said he did not yet have an explanation for why the Mercedes GP wing appeared to be so inconsistent - although he suspected that crosswinds could be to blame.

"Separation of rear wings is not a new phenomenon because we all design the rear wings to be at the limit of attachment to get the maximum performance from it.

"We have seen many times that a rear wing will work perfectly okay, but in a crosswind or unstable condition you will get some separation, so we have got this separation going on and that is what caused the difficulties in qualifying.

"We thought we had solved the problem and, if you look at the car here, you will see on the lower wing there is a thing we call the ski ramp. It is an aerodynamic device on the middle of the lower wing to reduce the pressure on the rear wing.

"It has cost us a little bit of performance but we have made the rear wing much more stable, and that is what we have been running here. And up until qualifying we were quite comfortable with it, but we had a reoccurrence in qualifying."

Brawn believes that Mercedes may need to tweak its rear wing to gain less from the straightline speed boost of the DRS.

"That is the balance you are trying to strike," he said. "Obviously our wing has been designed with an evaluation of a huge number of elements, not just downforce/drag. It is stability, it is response rate. All those things are assessed in the windtunnel.

"But you are always trying to push close to the limits, and we are trying to gain as much performance from the wing being activated as we can.

"The gain in straightline speed for our wing is quite substantial but we have this bit of instability. It is not unique. It is not new - but it caught us out at the wrong time here."