TECH TUESDAY: Understanding the Technical Directive on floors that will come into force at the Belgian GP


From the Belgian Grand Prix, a new extended version of the Technical Directive TD039 will be in force. This is an FIA technical guideline issued for the first time to teams in Canada regarding the measurement and monitoring of vertical forces acting on cars. This followed complaints from drivers about the physical effect of aerodynamic rebound on them.

The Technical Guidelines describe how the regulations will be applied, and as technology develops and the competitive push of teams takes development in directions that may not have been envisioned when the regulations were written, the TDs are then used by the governing body to control developments.


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In addition to measuring the force of vertical accelerations using sensors already installed in the cars and establishing a threshold beyond which they cannot roll, the FIA ​​has sought to start this process on a level playing field. stipulating the mounting method of the sub-floor board and the protection plates.

Currently, there are at least two interpretations of how to meet the regulations defining maximum board flex. From Spa, only one of them will be accepted.

George Russell’s qualifying crash in Austria gave us a glimpse of the W13 board

The board was introduced in 1994 as a means of limiting the development of floors that were so close to the ground that airflow could suddenly and dangerously become blocked there. With the plank defining how far the middle part of the floor could run, leaving a gap on either side, this danger was removed.

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The board stipulation played its part in aerodynamic development later on moving away from super low ride heights. The downforce under the floor was instead generated by running the floor at a rake angle. Prior to the 2022 aero regulations, when cars were driven with higher ride heights, the board effectively only limited the amount of rake that could be performed.


The board was introduced in 1994

Once beyond a certain degree of lean, the leading edge of the board fouled the ground. The rest of the board basically only served to protect the mechanical components above.

But with the 2022 venturi tunnel cars it becomes more advantageous to run the full length of the floor as close to the ground as possible and therefore the full length of the board becomes a limitation to that.

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Any way to delay the onset of aero porpoising by giving the board a more damped effect will allow the car to roll lower and therefore generate more downforce. The further back the board can be damped, around where the venturi tunnel stall point is, the greater the downforce can be.

Red Bull Rake.jpg

Red Bull previously favored the ‘high rake’ concept – as seen in the 2021-spec RB16B above – but on the 2022 cars it is advantageous to run the full length of the ground as close to the ground as possible.

The FIA ​​felt that it would have been unfair to stipulate the same vertical acceleration limit on two types of interpretation of the board flexibility regulations. When a car sinks and the board hits the ground, it wears out. There is a limit to the amount of wear accepted.

Thickness is measured at the mounting holes and the design of the skid block around that hole can influence what wears and doesn’t wear at the bottom of the car. The FIA ​​therefore sought to standardize this mounting method.

As always in F1, the regulation and interpretation cycle drives technology forward.