McLarens pre season has been thwarted by unreliability and apparently aerodynamic problems. The team have run a succession of exhaust designs (at least 4 so far) and time has been spent mapping the cars aerodynamics with sensor arrays\flowviz. While the exhaust solution has yet to be finalised (I have a forthcoming post on this), The last days of the Barcelona test allowed the team to introduce some new parts around the back of the car and a new front wing.
Their new rear wing sports vanes along its lower edge. These are legal as they sit in a small 5cm loophole zone in the bodywork regulations. This area has been exploited before by Red Bull on the RB5 and subsequently Toyota and Williams in 2009. Sauber also have much smaller solution on their current car. Having bodywork in this area effectively extends the diffuser sidewalls by some 30cm, which helps maximise the expansion ratio of the diffuser for more downforce. Such is the shape of the flow out of the diffuser, the bodywork needs to be vaned to allow the flow to expand. McLaren have formed four vanes into the allowable area. For the test, the rear-pointing exhausts were lined up with these vanes, thus the exhaust flow (red) will be routed by these vanes, accelerating flow inside the diffuser for even more downforce.
McLarens problems also delayed the testing of their DRS (Drag Reduction System) adjustable rear wing. To feed the hydraulics to the actuator mounted inside the middle of the rear wing, the team have routed a non-structural pylon up from the gearbox to the wing. This houses the hydraulic cables & sensor wiring and does little to support the upper rear wing.
With the weather warming a little during the relatively cold Spanish tests, the team were able to reduce the size of the engine hot air outlet for the last test. In the middle of this outlet is the oval gearbox oil \hydraulic cooler outlet. Leaving the rest of the outlet for general sidepod cooling
Scarbsf1's Blog 
Where is the explanation? This is my team. Tell me something positive.
Will you elaborate on these updates later on? Because I really wonder what the three little fins at the end of the rear wing are good for.
no explaination?
explanation*
I much prefer some words to explain the features of the excellent drawings 🙂
Check the twitter feed – literally next to this comment. You will see he wrote this on his iPad which seemingly lost all his words for him. Should of bought a ‘Droid based platform…:-)
He doesn’t know and no one knows apart from McLaren.
Scarbs, you were wrong about the possible front exhaust exits on the side pods. You give a lot of the guys a hard on at f1tech.net over this nonsense, please be clear that you are just guessing, like everyone else.
You’ve answered yourself there. I said I was looking at what Mclaren were possibly doing with exhausts and giving supporting evidence. There’s even a question mark in the posts title! I don’t know what they’re doing, they are doing several things with exhausts, often different things in the same day. There may have been front exits tried, there may have been the complex octopus tried.
Enough McG. Scarbs talks with F1 engineers, goes to F1 races, and analyzes pictures of F1 cars using his F1 experience. Furthermore, he provides explanations and analysis that can be understood quite easily. And he does this at a cost of 0 dollars and 0 cents to his readers.
Get a life.
…Can’t wait for the start and see whose innovations worked
nice article, now i know a lot more on the McLaren diffuser and especially those vanes at the bottom on the rear wing.
One question: see text below.
“With the weather warming a little during the relatively cold Spanish tests, the team were able to reduce the size of the engine hot air outlet for the last test.”
Do I miss something but when the weather becomes hotter, than there must be extra colling right. But here it states: it’s the other way around. Hotter weather less cooling. Can someone explain it to me.