6 replies to this topic

[Nelson]

I quote directly from report of the 1986 San Marino GP in the 1987 FOCA Yearbook.

"Out on the circuit, on what was meant to be THE quick one, the Lotus looked remarkably twitchy as Senna slid it over the kerbs. He locked up his brakes, hit traffic, the car darted nervously from corner to corner. It was dramatic - but alarmingly so. This is Lotus's ground effect qualifying car, reserved for Senna only. It alarms other engineers: what is FISA's ruling on its ground effect, 30 per cent more than that of conventional cars? It alarms Professor Watkins: what effect does its hard springs have on its driver? It alarms other drivers: what will happen should it lose ground effect?"

Anyone have any clue what this is all about? I mean, how does a supposedly flat-bottomed car with no skirts produce ground effect?

Regards,
Nelson

[Todd]

A flat bottom car produces ground effects by running an extremely low ride height and using a rear diffuser to accelerate air exiting at the back of the car's floor. That produced a lower pressure area underneath the car. The stiff springs used in '86 to facilitate the minimal ride height were replaced with active ride on the 99T in 1987 and the pattern was set for the Williams-Renaults that carried the concepts to their highest legal evolution.

[Rogue]

In theory, you could have ground effect even without the diffuser, on a completely flat bottom car. As long as the air travelling over the top is moving faster and therefore exerting greater pressure than that moving under the car you have ground effect. Diffusers and such just accentuate it enourmously.



------------------
Rogue
f-1@ihug.com.au

[desmo]

Lest anyone pay heed to Rogue's post, to create downforce the air under the car must be moving faster not slower than the air above the car.

[Rogue]

Apologies - brain thinking one thing, fingers doing another...



------------------
Rogue
f-1@ihug.com.au

[desmo]

I know the feeling, Rogue!

[JohanPretorius]

Correct Desmo.

Think of an aircraft wing -
flat at the bottom and curved on top.
the airflow over the wing is faster i.v.o. the curvature which in turn produces positive lift. Turn this same wing upside down and you have negative lift.
i.e. if you shape the car in general layout ignoring youre other aero devices such as wings in the upsidedown wing format ; youre car will produce negative lift or downforce.



------------------
Johan Pretorius
'keep the passion!'