I think downforce builds slower than the spring rate increases. So I don't think the rate of increase of downforce is an issue.mechanoit wrote: ↑28 Feb 2023, 10:09I wish to add that perhaps I’ve mischaracterised my posts on the side pods. It’s not to say that they are not important, but rather that they are relatively well understood. The wind tunnel and CFD tools available to the teams, and especially to the top teams, are well within their capacity to accurately model well understood aerodynamic aspects such as front wings, side pods, rear wings.
The error inducing parameter is the tyres because the deformation of the tyres with the road and interaction with the road and how combined that affects the actual aero and interaction between the tyres and other elements is of course more difficult to understand and model. However, the general front wing, barge board like structures, side pods, rear wing flow structures are not difficult to model and once the baseline is there, then errors in real world aerodynamics because of inaccuracies in the tyre model can be quite reasonably corrected for during in season development with just small adjustments to wing elements and side pod shape, especially by the top teams.
There seems to be the thought by quite a few that the side pods are the main driver of the W13’s problems and subsequent performance. I don’t think it is and instead attribute all of the porpoising on the floor design and the team’s original concept which didn’t take into account the continuous downforce build up as ride height decreases with increase in speed and the sudden stall or choke. There is no doubt that front wing, barge board, side pod etc. all influence floor performance but if there was a fundamental issue with the side pod then it does not explain the W13’s problem which is actually too much downforce. Because tyre wake issues and interaction with side pod flow structure and problems associated with that are more likely to introduce unwanted losses under the floor well before the downforce could build up. Instead, what we had with the W13 was quite an effective floor sealing where downforce built up rather too well, compressed ride height, further sealing the floor edge and drastically driving downforce higher until the floor was simply too close to the ground and the flow structure under the floor broke down.
The W13 design was completely in the wrong operating window. The aerodynamicists not accounting for this and instead designing for a window where they would get very high downforce with a very low ride height. When the porpoising revealed itself and they realised they simply could not run so low, then they had to raise the ride height but their floor design and indeed other detail design above the floor intended to seal the floor edges was poor for operating at the higher ride height so they lost significant downforce. To compensate we saw bigger rear wings and this dirty downforce was very inefficient adding much drag.
Understanding how to design the floor and build tuneability into it is the difficult challenge, where it can be run at the lowest possible, and allowed, ride height such that it achieves the potential downforce at that ride height but does not then shift into the phase where the downforce ramps up quickly overcoming the suspension stiffness and further reducing ride height into the unstable flow structure zone. An ideal scenario would be to have a type of aerodynamic “vent” where downforce builds up with speed until it reaches the maximum downforce achievable with a stable flow structure, and then the downforce levels out either by leaking in just the right amount of losses under the floor to stop the downforce from continuing to build (but not too much as to break down the flow structure) or some other vent. The floor design should also be resilient to an external ride height compressor such as a bump such that a sudden ride height compression again should not result in a sudden high downforce that generates further ride height compression and break of flow structure. An aerodynamic “vent” that can relieve any excess build up of downforce from ride height compression would be ideal.
Designing a floor that lets in certain losses from the floor edge to limit the downforce, after a certain speed and corresponding ride height, seems difficult but I think quite achievable by the teams. However this doesn’t address the external force input from a bump I mentioned previously. Such a compression is likely to overcome any of the intentionally introduced losses from the floor edge and result in a condition where the floor seals and downforce builds up uncontrollably again. If the bump is big enough, it could even compress the ride immediately into the zone where the flow structure breaks down. So I really do wonder how Red Bull have achieved this? An aerodynamic “vent” could in theory stop the build up of excess downforce. However it still doesn’t answer the problem of a bigger bump that immediately puts the floor into stall conditions. So they are able to keep their platform very stable, all the while running suspension that visually seems notably more compliant than their competition. Even with the 2021 regulation changes prohibiting hydraulic control of the suspension and further 2022 restrictions on inerters and other control mechanisms.
I don’t have any solutions to the above but I believe these broad principles drives the performance characteristics and limits of the 2022 regulations. I do believe that Red Bull have specifically solved these described challenges to a large if not the full extent.
The cars are actually slowing down in the corners!
The porpoising on the straights though, again is not a fast buildup for a suspension whose response can be measure in kilohertz.
I think it's just a matter of a balancing act... Go to close and the car just bounces. Remember the tyes are one part of the suspension that has a stiffness limit. You could use a solid steel column for springs... And the car will always bounce according to the tyre sidewalls!
This is why I would say that the bouncing has to do with just finding that balance and having the aerodynamics, as you so rightly say, work flexibly.