"I think when you get the F-duct working properly you have both," the Mercedes GP
"You have the downforce in the corners and then turn drag off on the straight. At the moment we are not turning off enough drag on the straight.
"As we said before, McLaren were clever enough to come up with the concept and have a lot more experience of it.
"You are seeing certain teams abandoned in Turkey and when it works properly it is a very, very powerful tool - and we are persevering with it.
"It works in a certain way with it, but not giving us the full benefit yet. We have the right compromise with what we have.
"We will be a little bit vulnerable with straightline speed but best compromise for that time and consistency on tyres."
Ross Brawn on the F duct on the Merc. I beleive Ferrari are having the same problems, not being able to refine the duct to a point where it is an asset and not a compromise.
What he says about tyres is interesting, I guess on the straights once the downforce is reduced on the rear wing with the duct, the rear grip reduces somewhat and the tyre wear may be a little more.
I say mercedes need a shark fin with a proper F duct.
They also need a baby F duct under the chin of the nose.
This way they keep the little df advantage they have with their nose, and drop the drag on the straights.