PlatinumZealot wrote: ↑08 Apr 2022, 16:25
As the topic says, why didn't we see porpoising on the flat bottomed cars?
Welcome to both hard engineering principles and empirical information and also thoughts, ideas opinions, but I'm more interested in the hard engineering principles and empirical info.
Thanks.
Sorry if any bubbles pop, but the answer is simple - diffusers don't rely that much on very low ride height and regulated step-plane was high enough to prevent any flow blockage. Rules were made exactly to prevent this (well, not bouncing but cars straightening high speed corners due to sudden downforce loss), so obviously there was no chance of it happening. Not that there could be any, since there were no side-skirts or any other kind of restricting geometry. Teams opting for large rakes also would have prevented this from happening, even if there was no floor step.
If we want to enter more into fluid dynamics, we can also add the fact that flat floor with diffuser is much less potent than ground effect floor. Downforce from the floor was much lower than it is now, making the whole car less suscpetible to any major negative effect (downforce loss, diffuser stall, etc) coming from the floor.
In theory, there could be significant aero bouncing even with flat floor and diffuser - but this has to be a much bigger and more potent diffuser than F1 ever allowed and there must be no floor step that prevents the car from going too low. Such diffuser would generate a significant amount of vortices (of significant strength) which would burst if the ride height got too low, leading to significant downforce loss. Once the car would get high enough again, vortices would form again, leading to increase in downforce and the circle is complete.