Features - Technical
OCTOBER 24, 1999
BY PETER WRIGHT
Tolerances in the Technical Regulations are either stated in the form:
Xmm ± Ymm,
or they are implied with phrases such as:
"Émust not exceed Xmm", "Énot more than Xmm", or "Émaximum Xmm"
which imply a tolerance of: + Zero, - Free, while phrases such as:
"Émust be at least Xmm", "Émust be no less than Xmm", and "Éminimum Xmm"
imply tolerances of: + Free, - Zero.
Certain phrases, such as "Évisible from underneath..", "Évisible throughÉ", and "Évertically aboveÉ" (as used in Art.3.12), all rely on an engineering interpretation that involves perpendicular projection from a plane and appear to imply a zero tolerance. However, a tolerance is required to enable components to be manufactured, assembled and inspected, all of which are imprecise processes.
Until the Malaysian GP, the FIA had applied engineering sense in carrying out measurements, judging each case on the complexity and magnitude of the measurement, the rigidity of the components and the possibility of damage to the component. As a result it has not needed to use extensions to the FIA measurement rig in the locations in which the barge-boards lie. The judgement of the FIA scrutineers has, until now, been accepted, and any obviously unintentional discrepancies that extend beyond reasonable tolerances have been noted by the FIA, or indeed other teams, being pointed out to the offending team's engineers so that they can be corrected prior to the car running in an event.
This sensible and accepted approach worked, until the FIA was tipped off about Ferrari's barge-boards after the race in Malaysia. Because initial measurements, subsequently deemed inaccurate, indicated a 10mm discrepancy in the shadow plates, this was considered unacceptable and led to the Stewards' decision to exclude the two Ferraris. The accepted method of dealing with such oversights having been bypassed, it was inevitable that Ferrari would examine the whole subject of measurement accuracy and permitted tolerances extremely closely, ceasing to rely on accepted interpretations.
"To help overcome any possible manufacturing problems, a tolerance of ±5mm is permissible across these surfaces" (emphasis added).
While it has been accepted that this tolerance applies to the flatness of the underside of the car and has done so since flat bottoms were made mandatory in 1983, Ferrari asserted in the FIA Appeal Court hearing, that it also applied to the dimensions across the surfaces, unless otherwise bound by an implied tolerance e.g. "Émust not exceed Xmm".
McLaren (Ron Dennis) has stated that:
"Éthis rule was specifically designed to accommodate manufacturing problems with the flat bottom of the car. It did not have any relevance to the "vertical" plane."
However good the manufacturing process, it is not possible to make a perfectly flat vertical panel, nor fit it to a car such that it is perfectly vertical. Nor is it possible to measure it perfectly, however precise the measuring equipment or competent the operator. There must be a tolerance to make the manufacture, assembly and measurement of it practical. When the ±5mm tolerance is applied to a "vertical" dimension, which can be at least 600mm, it equates to less than ±0.5°. This is not an unreasonable tolerance, considering composites are still partially hand made. The components are assembled to the car, as are the surfaces to which the "vertical" is referenced for measurement purposes.
To claim that Art.3.12.6 does not apply to the vertical panels is to claim that they have a zero tolerance, as no other tolerance is defined for them in the Technical Regulations. If this were so, then all cars with straight, vertically mounted barge-boards would be illegal, unless fitted with shadow plates to accommodate any manufacturing errors. This would include the McLarens (according to Ron Dennis, knowingly!) and the Stewarts.
There must be a tolerance and, while the FIA's measurement methods and judgement in this area has been accepted for years, they were called into question following Ferrari's 1-2 in Malaysia. Art.3.12.6 is in the regulations to cater for such an eventuality, and has been applied to the letter.