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13 Sept 2012

 
McLaren introduced a new rear wing for the Spa weekend and continued it's usage at the ultra low downforce Monza circuit. McLaren fans will be well aware of the who-har Lewis Hamilton made about the usage of the Wing when he presented the world an overlay of his and Jenson's qualifying data. Lewis was using the normal wing whilst Jenson went on to take pole position and the win with the new design.

Above: The famed data overlay sheet that Lewis posted on Twitter

Rear Wing design is crucial in the behaviour of these cars as it can attribute a large proportion of the cars overall downforce, intrinsically linked to this downforce however will be a large chunk of drag. The designers always aim to design the most co-efficient Rear Wing ie one that offers the most downforce for the least drag.

So what's so special about McLaren's new Rear Wing I hear you say. Well after studying the photo's there are several interesting design solutions at play with the McLaren rear wing:

Firstly the team have followed others into utilising the outer 15mm of the wing planes which has freedom to place holes (This is how Mercedes are able to utilise their DDRS system)
2/3rd's of the way up the channel of the main plane you will find a hole in the front profile, this is projected onto the rear of the main plane and so allows some of the high pressure air from the frontal region to be ejected into the low pressure region at the rear. This has a two fold effect, energising the boundary layer created by slow moving air on the rear of the wing plane allows the air to work more effectively. Secondly it helps to reduce the amount of drag induced at the outer extremities of the wing.


Next up the top flap has been totally redesigned and instead of sporting the usual up turned Wing design we are used to features a design that looks very much like one you'd expect to see on an airplane. The design is truly 3 dimensional with the outer sections slimming to a regular concaved style (from the front) whilst the central portion of the wing is convexed.

Above: In this side on image it's easy to see how convex the top flap is and you can see the Gurney tab angled at 45 degrees on the trailing edge of the flap.  The shape and orientation of the endplate louvres have also been adjusted to suit this new wing style (Endplate Louvres are used in order to bleed high pressure to lower pressure areas, reducing drag)

The team added a large Gurney Tab at Monza which is usually associated with High Downforce configurations which is obviously not the case of for the Monza Circuit.  However due to the design nature (airfoil profile) of the top flap the gurney may simply augment the adjusted aero influence.

Speculation and cause to think?

Lastly I'd like to talk about the images below, this shows the top flap from behind, initially I thought that perhaps I was seeing a reflection but after looking at a few different images it would appear that there is a gap at the trailing edge of the top flap.  This leads me to believe that the top flap is hollow, and may be being used to blow airflow increasing the efficiency of the wing. If so how are they getting the air to the wing?




We don't usually get to see a close up shot of the car motionless with DRS open so to further fuel speculation in this image I've also added an arrow to the part of the wing that remains in position when DRS is active.  This also appears to be hollow but what significance does all this have?  Without being able to rationalise how a high velocity airstream could be channeled I'm simply leaving the evidence here for others to look at whilst I try to find more.


Is it however plausible that these hollow sections attached to the Endplates act as a fluid switch elsewhere and McLaren are using DRS for a secondary function (DDRS) just as Mercedes are with their Front Wing system.....

I found it strange that McLaren although their hydraulic DRS mechanism remains unchanged (albeit a new wing design) decided they would leave access panels in the endplates.  Does this mean that the panels hide DDRS tubing? Maybe not but as a team that sometimes borders on anal in regard to aesthetics I find it remarkable the Endplates were not designed as normal for the hydraulics.  The hydraulics are usually routed through the Beam Wing via the mounting below that as you can see carries 4 pipes (2 are plumbed in and the 2 higher ones are not in place as is the cover that usually hides these pipes from sight.


I'm left at a crossroads with my thoughts and trying to find further evidence but felt I'd present my findings thus far to see if others have idea's on what McLaren could be doing with these gaps in the Rear Wing Top Flap.
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