Legality of skirts on Lotus Type 77 and 78

[matt21]

I just read a book about the Lotus Type 77 and 78.

I was wondering the whole time how the managed to get the moving skirt passed by the scrutineers.
In my opinion they had to be regarded as aerodynamic device, which weren´t not allowed to be moveable relative to the bodywork since the late sixties.
Were they regarded as bodywork?

Also, I would like to see pictures or drawing from the board-in-a-box skirts. Especially from the installed mylar film.

So, if anybody has some sources I would appreciate to see them posted here.

[munudeges]

Yes, the interpretation that the skirts were a moveable aerodynamic device and bodywork is certainly a valid one. I suppose the answer is that scrutineers did then what they have always done when faced with something new - do nothing until there are some new regulations.

[MIKEY_!]

Maybe the fact that they did not change the airflow as they moved had something to do with it. In theory (having not read the relevant regs) it could be argued that the whole car is a movable aerodynamic device since it moves around on its suspension. Changes in height from ground and such effect the aerodynamic properties and performance.

[matt21]

The car is an "legal" aerodynamic device as it is completely fixed to the sprung part.

An aerodynamic device is defined as an part which has influence to the airflow and the skirts prevented leakage to the undertray.

So, to be honest, I´m really asking myself how they could have been legal.

[hardingfv32]

"In my opinion they had to be regarded as aerodynamic device"

In the "opinion" of the stewards, scrutineers, and competitors at that time they were not regarded as aerodynamic devices. Interpretations and opinions of rules can change over time.

Brian

[strad]

Wasn't illegal then....was it?

[gridwalker]

If you inspect some of the early skirts, many of them were composed of bristles (like a very long and thin brush running down the edge of the car). Today, the layman fan may be able to look at their positioning and determine that it is an aero appendage, but the underlying principles weren't commonly understood in the 70s.

Why do people understand these principles now? Because they have been used, analysed, copied, banned and discussed : it has all been laid bare in numerous books and magazine articles that wouldn't have existed when these skirts first appeared.

What we see as self-evident comes with the benefit of hindsight. If you hadn't already learned about aerodynamic principles and the purpose of skirts, would you be able to look at the bristles lining the sides of the car and think "AHA : I know what they're up to"? I very much doubt it.