Technical Suspended Belief - Outsmarting the Rulebook


Rooters Reporter
McLaren's latest wheeze with their "blocker" suspension members on the rear wishbones is a stroke of genius. Like their last greatest wheeze, the so-called F-Duct, it has been thought up because someone spotted a little hole in the wording of the regulations. The F-Duct idea arose because someone realised that a hole in the side of a tube lets air out reducing the amount of air that reaches it's target. It's the kind of observation one makes when your foot pump hose splits and leaves you stranded with a flat tyre or the water pressure mysteriously drops when you're hosing the lawn because that weak spot bursts open. The key to the F-Duct was noticing that the regulation was focused on a mechanical or electrical means of activation and not covering the possibility of a drivers knee blocking a hole.

So how did the person who spotted the loophole in the suspension reg's get heads scratching along pit-lane and cause the F1 authorities to say that it is within the rules? I have a scenario that possibly explains how the boffins, whose job it is to explore the rule book for exploits, work:

Mr Boffin has been charged with the task of finding some way to compensate for the banning of exhaust blown diffusers and the lower rear beam wing. He is poring the technical rules with regard to aerodynamic surfaces, diffusers and holes. Up to this point the current understanding of an aerodynamic device puts people in mind of flowing surfaces, like wings and swooping and swept back bodywork. He reads the following:

QUOTE 10.3 Suspension members :

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) Be nominally symmetrical about its major axis.

The major axis will be defined as the largest dimension of any such cross-section.

10.3.2 Suspension members having shared attachment points will be considered by a virtual dissection into discrete members.

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.

10.3.4 Non-structural parts of suspension members are considered bodywork.

10.3.5 There may be no more than six suspension members connecting each suspension upright to the fully sprung part of the car.

Redundant suspension members are not permitted.END QUOTE from FIA

He notices that the actual cross section dimensions of the suspension members are only restricted in shape and not in size. In other words, as long as the width to height ratio (the aspect ratio) does not exceed 3.5:1 and doesn't tip at an angle greater than 5 degrees to vertical the members can be as fat as they like. In other words as long as they aren't excessively oval or wing shaped just about anything goes. So, the McLaren boffin comes up with an almost square box cross section with three rounded edges and (this is the really nice touch) a tiny up-curled lip on the back edge which is probably at less than 5 degrees just to be on the safe side! Whammee! There's an innovation that takes longer to explain than it took the boffin to visualise in his head and put onto paper!

The difficulty for the FIA is in the proof, since McLaren would have to admit that it is an aerodynamic feature, which they won't. Meanwhile, as has been noted elsewhere, the "feature" (I call it a feature as McLaren will no doubt avoid calling it a "device") does several interesting things. First and foremost it acts like the now prohibited beam wing since its flat top plane and the little lip is funnily enough, like a beam wing. Secondly it acts like an F-Duct or additional DRS because as the car runs at lower speeds with the suspension relatively uncompressed the "blockers" are blocking air flowing through the suspension struts and out the rear end, apparently (more later on that in a kind of punchline). So a flow of disturbed air is forced up and over the things behind those great big vents that channel hot air from the radiators and cooling system. Being sited only just in front of the exhaust outlet this up-wash is further increased, and lo and behold, we have that additional effect that could be described as Exhaust Blown Suspension Blocker! This adds up to increased downforce and therefore traction at lower speeds - just when you need it to corner a bit harder and accelerate out onto the straights a bit faster (than everybody else).

But wait! Now here is absolutely the best bit as alluded to a moment ago. When the car is hammering at higher speeds with good ol' downforce fully compressing the suspension a gap opens up so that air that was being up-washed is now flowing straight through the arrangement just like having your DRS flap open! Wicked!

EBSB's do not appear anywhere in the rules prohibited, allowed, restricted or otherwise since they've only just been invented. Without a full and frank explanation of their true purpose - i.e. that which I have outlined above - they are legal. It's a bit like Red Bull's floppy front wing. Everyone can see it happening but the FIA doesn't have a test to prove that that is what is happening. Even if they could they can't that it was McLaren's intention. the evidence is circumstantial, as they say. Neat.

It will be interesting to see if the device, as I now call it, withstands the inevitable protests that will come at the first race of the season. It's unlikely that it will be protested at the next test, in Bahrain, since other teams might just try out their own versions there before kicking up a storm. Of course, the FIA might just try and nip it in the bud, but for now they've been caught napping all because they forgot to constrain the cross sectional dimensions of suspension members. Excellent!
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Please note: Due to editing time running out I was unable to formally credit the extract from the FIA F1 2014 Technical Regulations, which I believe is something I should have done but forgot. So here is a formal credit just in case: The OP contains an extract from Section 10 of the FIA F1 2014 Technical Regulations .:D

Another casualty of lacking editing time was this sentence:

"Everyone can see it happening but the FIA doesn't have a test to prove that that is what is happening. Even if they could they can't that it was McLaren's intention. the evidence is circumstantial, as they say. Neat."

Which should read:

Everyone can see it happening but the FIA doesn't have a test to prove that that is what is happening. Even if they could they can't prove that it was McLaren's intention as the evidence is circumstantial, as they say. Neat.
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The way the regulations are written its clear the FIA want the teams to come up with clever tricks. If they actually wanted a non-aerodynamic suspension, the regs would read.

Rear suspension members to have 6no. oval cross sections 60x15mm and set at 0 deg angle on the plane on the car.
I think the car regulations should be as follows:

  1. All cars need a minimum of 4 wheels.
  2. Each car needs to have a driver safety cell capable of withstanding significant impacts from all sides.
  3. A form of propulsion is required to drive the wheels.
And that's it!
F1Yorkshire ... Of course if you go down that route, this is what you might get....
McLaren's rear suspension has got all the highlights but what's slipped under the radar is that Williams have a simpler solution (not involving the suspension) that is also to recover downforce lost from the beam wing. I can't find a good article that explains it (apart from a paragraph behind a pay wall) but basically there's some hole in the regulations that means they can mount two winglets down low near the diffuser. I suspect the teams will be investigating the McLaren solution but it will be the Williams solution that actually appears on other cars, at least during the first part of the season.
F1 Technical has a raft of good shots of the Williams FW36 (in their Williams forum) including some that clearly show aerodynamic wings mounted separately below the "regulation beamless" rear wing:

Regulation (that bars rear beam wing) says: "3.10.1 There must be no bodywork more than 150mm behind the rear wheel centre line which lies between 75mm and 355mm from the car centre line and between 150mm and 750mm above the reference plane." *

Boffin says: "Okay, I'll only put my beam wing somewhere between 25mm and 50mm above the reference plane. We can tweak that after trying it out at Jerez ..."

*Regulation quoted from FIA 2014 F1 Technical Regulations: item 3.10 Bodywork behind the rear wheel centre line
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