A legal but flexible T-Tray Splitter: The ‘See-Saw’ solution

For over a decade, the FIA have tried to reduce front wing performance by increasing its ride height. Moving the wing clear of the track for less “ground effect”, reduces the wings efficiency and handicaps downforce. When the major aero rules changes came in for 2009, the loss of the central spoon section and the smaller allowable working surfaces for the front wing, made getting downforce from it even harder.
Through out this period, teams have sought to gain front wing performance, largely by trying to make the wing closer to the ground. Either via flex or by altering the attitude of the car (i.e. rake). As has been explained before in this blog, the issue with making the front wing lower by raking the car is that the T-Tray splitter gets in the way. Teams have sought to make the splitter flexible to allow it move up and allow for a lower front wing.
to combat this the FIA have a deflection test to ensure the splitters are not flexing and that front wing ride height is maintained. In response to accusations about several teams splitters, at Monza last year the FIA doubled the test to 5mm of movement for a 2000 Newton (~200kg) load. Yet in 2011 we still see cars with a nose-down raked attitude and wings nearly scraping the ground. How can a splitter meet the FIA deflection and still flex on track? I have a theory for a splitter construction, that actually exploits the method of the FIA test to provide the splitter greater stiffness during the test.

Background
Typically teams run splitters mounted to the underside of the monocoque. The splitter is often made from metal to act as ballast, with additional carbon fibre bodywork to form the aero surfaces. Beneath the splitter runs the Skid block (plank). Made to FIA dimensions the plank features holes for measuring wear.
The splitter is bolted securely to the underside of the tub by bolts and in some cases with a small strut at the leading to aid installation stiffness. Disregarding the strut, the splitter is effectively installed in a cantilever arrangement. The protruding section of splitter will need to bend upward when grounding on track or on the FIA test rig.

With a typical splitter, wear will occur only at the leading edge of the plank

With a car in a raked attitude, when on track the splitter will exhibit a classic wear pattern, the tip of the splitter will wear away in a wedge shape roughly equivalent to the rake angle of the car. During normal running, for cars with high rake angles its likely no other wear may take place along the length of the plank. If the car runs a front ride height that’s too low, the splitter will wear away leading to exclusion at post race scrutineering.

See-Saw Solution

A pivot half way along the splitter creates a 'see saw' effect

Rather than run a cantilever mounted splitter, my theory would be to run the splitter mounted on a pivot. Taking the length of the removable section of splitter, the pivot woudl need to be half way along its length. Which would be roughly inline with the heel of the monocoque. Not having any significant mount at the rear of the removable section of splitter would allow the splitter to pivot like a ‘see saw’.

With the 'see saw' splitter, grounding on track will bend the plank & create two wear spots.

Now when the splitter grounds on track, the leading edge will tilt up and the trailing edge tilt down. This ‘See-Saw’ effect, will allow a slightly lower front ride height as the splitter will be deflecting upwards. To achieve this the plank will need to flex, as the front section of plank must now be a minimum of 1m long, far longer than the splitter. The drooping trailing edge of the splitter will now make the plank contact the ground, leading to a distinctive wear pattern. Now having plank wear in two placed, beneath the splitters leading edge and the trailing edge. This will also have the benefit of spreading the wear over a larger area of plank and reducing the likely hood that the front inspection hole will be excessively worn. The fulcrum point need not be the overtly obvious pivot I have drawn and the entire exterior of the splitter could be covered in bodywork, which will have enough strength to keep the splitter in place when stationery, but deform enough to allow the splitter to ‘see-saw’. But in this guise the splitter will not have the strength to meet the 200kg load from the FIA test.  so how will it pass the test?

The current format of the FIA test, actually aids the pivoted splitter.

The FIA test is carried out on the multi functional rig that is used for the other regulatory checks. The car is driven up onto the rig and then steel pins protruding up from the rig, locate in corresponding holes in the plank. The sections of floor under the wheel are dropped away and the cars ~580kg (640Kg less driver) weight sits on its belly (the plank\reference plane floor).
Then a hydraulic strut with load and displacement sensors extends upwards beneath the front splitter. The 2000n load is applied and the deflection measured.

With a typical splitter the FIA load bends the splitter like a cantilever

For a cantilever splitter, the test tries to bend the splitter upwards straining on the bolts at its tail end.

For a 'see saw' splitter, the weight of the car is on one side of the fulcrum, making it harder to deflect the other end upwards

Where as for the ‘see-saw’ splitter the test tries rock the splitter, effectively trying to bend the splitter like beam about its fulcrum. But the cars weight is sitting on the tail end of the splitter, preventing the splitter tilting upwards. As long as the splitters beam strength is enough to meet the test, then it will pass. Being a long metal structure, it should not be hard to make the splitter strong enough.
So as the FIA tests the cars weight sat down on the splitter, it actually aids the splitters ability to beat the test. If the test were to apply the load to the splitter, when the car is supported on its own wheels and not its floor, then the car would surely fail the test.

Interpretations
The biggest flaw is this theory is the wording of article 3.17.5 which describes the test and the mounting of the splitter. But typically the FIA rules are both vague and overly specific at the same time. The regulation states that mounting between the “front of the bodywork on the reference plane” and the “survival cell” (Monocoque) must be not be capable of deflection. The definition of “front of the bodywork” might mean its leading edge, but might not incorporate stays further back along the car. Equally the design of the fulcrum need not be the pivot I drew, but a simpler solid but flexible part, that is not suspected to deflect.
As with all borderline legal parts, this would need to be carefully assessed against the wording of the rules. But where’s there’s ambiguity, there’s a chance to exploit.

The legal interpretation of the regulations not withstanding, this is a feasible solution.  The biggest risk to running it, is if the FIA change the test process without notice.  This could catch the team out, although normal FIA process is to warn the team and ask for the design to be altered and pass the test at the next event.  Thus unlikely to cause an exclusion or  ban.

 

Footnote: A team have asked the FIA for clarification on the use of this splitter construction with a view to using it themselves.  Charlie Whiting has made it clear it would not be and added that the deflection may now be altered to ensure the rules and test are not being exploited.