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29 Jan 2014

The season might seem a long way off for some people but with all but the Lotus and Marussia having physically broken cover (at the time of writing as the Marussia will come from under the covers shortly), McLaren have already pulled the wraps off what some may consider to be a silver bullet.

At first glance you'd be mistaken for thinking that McLaren still have a Beam Wing running horizontally across the Rear Wing structure but at second glance it's clear to see that there are 2 structures in front of the Rear Wing (Highlighted in Yellow).  Furthermore from this image alone you cannot infer depth and so it looks like the suspensions Wishbones (rear section of the upper and lower arms) have been flipped vertically.

(Click on the Images to them in full resolution)

What we can see from the top down view is that the team have simply designed a much boxier version of their Wishbones, getting thinner at the point around the Endplate.

The regulations surrounding Suspension elements that these boxier 'Wishbone Wings' circumnavigate are:
10.3.1 With the exception of minimal local changes of section for the passage of hydraulic brake lines, electrical wiring and wheel tethers or the attachment of flexures, rod ends and spherical bearings, the cross-sections of each member of every suspension component, when taken normal to a straight line between the inner and outer attachment points,must :
a) Intersect the straight line between the inner and outer attachment points.
b) Have a major axis no greater than 100mm.
c) Have an aspect ratio no greater than 3.5:1.
d) Have no dimension which exceeds 100mm.
The major axis will be defined as the largest axis of symmetry of any such cross-section. The length of the intersection of this axis with the cross-section must not be less than 95% of the maximum dimension of the section.

10.3.3 No major axis of a cross section of a suspension member, when assessed in accordance with Article 10.3.1, may subtend an angle greater than 5° to the reference plane when projected onto, and normal to, a vertical plane on the car centre line with the car set to the nominal design ride height.

If we now look back at the launch image I used to show the rear suspension we can see that the Wishbones are shaped into 2 sections,  a shorter chord at the inner section and wider profile outbound of that.  Furthermore as part of the crash structure we also find the Wishbones to be mounted within what look like aero shaped fins.  If you now re-check the images above you'll see I have marked two sections in Red.  These sections are further additions run on the car with the Wishbone Wings, allowing airflow to bleed out the central portion of the car and interact with the exhaust plume.

As we can see on the left the Wishbone Wings aren't simply flat fronted boxes but due to the aspect ratio and 5 degree rules, they can't simply be made into upturned foils/wings in full replication of the Beam Wing.

The other thing to consider here is that the wishbones are moving entities and so the gap between both elements will change based on the attitude of the car.

This is where it gets tricky as both the airspeed will change under braking and acceleration as does the gap between the profiles meaning airflow attachment could become an issue especially with sudden changes of direction.
A brilliant overhead shout of the car

I realise that Gary Anderson has already weighed in on the topic stating that if this does turn out to be a silver bullet it could be difficult for some of the other teams to implement.  I'd have to agree to some extent but if it is seen as worthwhile they will all try to integrate it, however it would undoubtedly effect the teams with enclosed driveshafts more (aka Red Bull, Mercedes & Toro Rosso) due to the way in which the geometry of their suspension etc is designed.

I look forward to seeing this development evolve as it's clearly only in the beta stages and will update the article with more images etc when they become available.

EDIT 13/01/14

As traffic is filtering back to this article I'll point out a few extra things about the Wishbone Wings that perhaps weren't present in this original article:

I looked at the Wishbone Wings in more concise detail here: 'Wishbone Wings' analysed and explained furthermore I showed a tech colleague this picture over on Twitter this morning alluding to the fact that McLaren like Toro Rosso and Williams are also utilising a structural and aerodynamic lower wing element which will further enhance the airflow structures and the way they all link together.  (See also: Bite Size Tech: McLaren MP4-29 Rear Wing Endplates that create 'upwash')

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  1. I see your articles on a much large number of websites these days. Fair play and keep up the good work! Always find your articles interesting and extremely detailed. Cheers

  2. Aren't these mile aerodynamic parts?

  3. i mean mobile aerodynamic devices...

    1. Hi

      A moveable aerodynamic device? No, as the expanded wishbones are covered by the suspension regulations rather than bodywork regulations. Furthermore the wishbones are needed and so to ban this solution would require a clarification of the regulations to force a shape change.

  4. hi Matt, I have really enjoyed reading your work recently, your explanations are very clear, do you think there is any question of legality surrounding this solution?

  5. Hi

    Thanks for the feedback I do appreciate it, as far as I'm concerned it's a clever interpretation of the regulations by McLaren. In order to stop its use would require a clarification of the regulations by the FIA.

  6. Just in terms of direct and indirect downforce generation, negating drag, is this a better, equal or worse solution then the beam wing of last year?

  7. Hi Matthew, from some of those pictures it seems like the wishbones are encapsulated with that blocking material, rather than just being built that way... they have lots of screws and gaps on it... wouldn't that put the following in place? 10.3.4 Non-structural parts of suspension members are considered bodywork.

  8. Hi Andreas

    Thanks for the comment, we have to assume that McLaren see them as suspension elements purely from the perspective that if they are not they become bodywork and are then in an illegality zone....

  9. It seems to me that the primary effect of these wishbones is to be an air dam of sorts, while deflecting air coming through the cooling systems upwards behind the main rear wing.

    I think this is primarily to increase the efficacy of the diffuser. If air moving over the top of the diffuser is moving more slowly and up and away from the diffuser, it will be both creating a higher pressure differential AND creating somewhat of a vacuum to suck even more air through the diffuser/accelerating the air through the diffuser even more.

    It will definitely come at a tradeoff of drag, but this should increase downforce considerably at the rear of the car.

    We will probably see a McLaren with a lower top speed, but that seems much more planted through medium and low speed corners (which would also help tyre wear).

  10. Hi Matt,

    Great analysis. Just a quick clarification. When you say that integrating this suspension will have more of an affect on red bull, torro rosso, and mercedes, do you mean that they have the most to gain from it or that they will have harder time integrating it

  11. I thought this looked like a very interesting interpretation of the rules. As it has been stated many times else where the loss of the rear diffusers means that teams will be trying really hard to claw back rear downforce and McLaren seem to have found it.
    How long do you think it will take other teams to copy the idea? To me this seems like a fundamental aspect of the design of the rear so a quick fix can't just be rushed out. Do you think it will be a mistake showing their cards to early?

  12. this is good upgration of this sports car and in any wheecals suspension is must to keep right.
    suspension upgrades Toowoomba


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