Wholly agree.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.
Again, this is simply not true and I cannot understand why this false information is repeated so many times. There were questions and brief discussions early last season if sidepods could indeed be the biggest problem. Even before the initial floor photos surfaced, it was clear floor was likely too aggressive, had too much raw downforce and sidepods can't be the major cause of problems.
I am quite busy, so reply just quickly. I never said there was anything about the sidepods or it was about sidepods. But he talked about why Mercedes did not see certain problems related to porpoising etc. coming. Starts at 1.06.50 and its about belt surface roughness and boundary layer. The separated sidepods he talked about were from the 1996 Ferrari designed by John Barnard. It also had massive side head protections why we called it "Armchair" back then.mechanoit wrote: ↑27 Feb 2023, 12:21I’ve watched that lecture, excellent.Andi76 wrote: ↑26 Feb 2023, 18:48I recommend Willem Toets (Ex-Benetton, Ex-Ferrari, Ex-BAR, Ex-Sauber Head of Aerodynamics) latest lecture at the University of Bolton(available at youtube) where he puts forward a theory why Mercedes might actually struggle in the wind tunnel to notice certain effects that happen in reality. It's a theory, but a very plausible one, put forward a few weeks ago by one of F1's most experienced aerodynamicists.mechanoit wrote: ↑26 Feb 2023, 17:37
Perhaps I over simplified and overstated it. Not to say that it is not important, just that the n’th degree management to maximise every last ounce from the diffuser is not as important as it was in pre-2022 regulations where the diffuser was everything regarding downforce from the floor.
Clearly front tyre wake management is important but do we really think the Mercedes doesn’t have the aerodynamic tools to model this to a high level? The most successful F1 team of all time hasn’t got its results by not having the tools to carry out basic aerodynamics. It seems to me that the floor is a different prospect altogether. New, difficult to understand, difficult to model, difficult to tune.
Mercedes understanding of side pod flow and management seems to be ok. I assume they will refine and improve in that area as they have already said so but I don’t expect very big changes. I may be of course very wrong.
In the entire duration of that almost 2 hour lecture, Willem did not mention side pods at all except for one point where he was talking about a Ferrari experience in 1980s where the side pods were separated and collected dirty air from the tyres. Then during the considerable question time, not one person asked about the Mercedes side pods. All during a lecture which specifically discussed Mercedes troubles and the porpoising.
The side pods are of course important but the challenges in solving the flow around them is much overstated in my humble opinion. The floor is the 99 percent’er in this era of venturi floor regulations.
If you watch the lecture again, you will note that Willem also explains about how the downforce increasing with reduction in ride height results in the flow choking and the porpoising occurs because the flow only reattaches back at a higher ride height than when the flow stalled. Willem also explains that the Red Bull has managed a way to introduce some air under the floor at higher speeds which effectively bleeds out this increasing downforce, keeping it all stable.
Awesome stuff about sailingHenk_v wrote: ↑28 Feb 2023, 12:13I now absolutely NOTHING about yaw and wind tunnels. I was speculating.
However I am a regatta sailor (skipper) and I know a thing or two about how wind angles change with speed and wind.
If you have a 100km/h corner (I guess that's on the high side for a slow corner) with wind, it's really simple vector calculation stuff.
If you have 100km/h winds from the side, you have 45 degrees of yaw.
For 6 degrees of yaw you need 10,5 km/h side wind. That's 5,8 knots, 2,9m/s.
Depending on location, the average wind speed is somewhere 9 -12 knots and on most locations 15+ knots is a likely circumstance.
I'd take your word 6 degrees of yaw is what they test, but to me it seems that above 6 degrees of yaw happens on track.
Like I said earlier. There is probably a difference in what yaw range you design for and the yaw range you test. Maybe one would not design anything for +6 degrees yaw, but If I was evaluating a concept, I would at least want to know nothing catastrophic happens above.
Because it is simple vector calculations, they scale linear. So at 200km/h, a 6 degree yaw means a 11,6knot sidewind.PhillipM wrote: ↑28 Feb 2023, 14:24The thing for a speed that low the car would be relying on mechanical grip for a low speed hairpin as much as aero by then anyway so it wouldn't matter too much vs the time that can be made for optimising for higher speed, lower yaw conditions.
There is a caveat to that however, these pirellis generally operate at 2-3% of slip angle, so you have yaw inherent in the car when cornering even with no wind.
When I say “quite a few”, I am not including you Vanja. In case you may be taking it personally. Instead I am referring to many news articles by journalists and pundits who see the most obvious aspect of the Mercedes, which is the side pod, and seem to lend far more weight to that than other control surfaces such as front wing and rear wing which also differ considerably between teams but somehow does not attract near as much attention by the media.Vanja #66 wrote: ↑28 Feb 2023, 11:39Again, this is simply not true and I cannot understand why this false information is repeated so many times. There were questions and brief discussions early last season if sidepods could indeed be the biggest problem. Even before the initial floor photos surfaced, it was clear floor was likely too aggressive, had too much raw downforce and sidepods can't be the major cause of problems.
However, it also became clear quickly after Barcelona floor upgrade that there is bouncing still, regardless of track surface smoothness or bumpiness, ride height settings or even after the inclusion of ice skates. If you have 10 races behind you, major floor upgrades (plural) and have tried all the possible suspension set-ups (by your own admission) and you still have bouncing, the problem simply has to be traced back to aerodynamic instability in some area. Remember Austria, both W13s ended up in the same fences after the same inexplicable understeer event.
What can cause this instability? Flapping floor, caused by large overhang? Yes. Is it the only explanation? No, but all other options have been practically exhausted and floor was seen flapping violently in corners in slow-mo shots all throughout the year, no matter the cable stay. This undoubtedly had major effects on floor aero. Why are the W14 sides wider at the rear? It could be structurally related, aero related, internal aero related, all together or none of it. But we can only make educated guesses and discussions based on what we see.
Could it have been mid wing vortices that caused problems with rear tyre squirt and unpredictable gains and losses of downforce? Yes. To me, it sounded too far fetched last year as I was certain Mercedes had that covered. Could it be something else, like completely hidden underfloor interactions? Yes, but we can't discuss what we don't know can we?
As you've said, top teams must be at the top of their correlation game and this isn't easy at all. On a 90s lap, 0.1s can be a pole or a fourth place even. In a race, 0.1s per lap turn to 5-6s and this can be a win or fourth place also. 0.1s is literally 0.1% performance difference and this is where you win or lose. This is the level that makes it insane and why most of us here are so in love with technical side of F1. Mercedes still has more than 0.1% overall performance gap and still lacks complete understanding of their car. This includes the sidepod concept, floor, wings, their interaction, tyre interaction, suspension interaction, aero map, all of this together etc.
To be honest, it's a given on this forum not to take too many outside pundits into account, and a few are guaranteed to be 100% wrong. Lately, more and more former F1 engineers are talking about F1 tech, each from their own angle and perspective. That's a lot better, but still everyone is speculating.mechanoit wrote: ↑28 Feb 2023, 15:14When I say “quite a few”, I am not including you Vanja. In case you may be taking it personally. Instead I am referring to many news articles by journalists and pundits who see the most obvious aspect of the Mercedes, which is the side pod, and seem to lend far more weight to that than other control surfaces such as front wing and rear wing which also differ considerably between teams but somehow does not attract near as much attention by the media.
Sides are not a magic bullet, neither before nor now, but if you get a detail very wrong it can cost you a lot of time. Absence of intricate and large bargeboards turned the task of front wheel wake management mostly to the sides, making getting them right far more important than ever.mechanoit wrote: ↑28 Feb 2023, 15:14I am not a technical expert in this field but I am a mechanical engineer with enough experience in fluid dynamics albeit not in motorsport. However I am fortunate to have some good contact with some recent ex-F1 engineers and aerodynamicists. Not one of them seems to think the side pod is a big performance influencer and certainly don’t seem to think contributed anything to the porpoising. No one is infallible and potentially anyone can be wrong regardless of experience but I personally find their views make sense to me more than some other views I read here.
It's a bit of a head scratcher, to be sure. CUDA supports double precision, same as regular CPUs. Very old GPUs had limited double precision performance (only one execution unit, from memory), but modern ones can do lots of FP64. Unless CFD solvers need multi-precision arithmetic (but that would be slow on all types of execution unit), but why not just scale the values for doubles?AR3-GP wrote: ↑26 Feb 2023, 23:36The AMD stuff is marketing. I'm actually surprised they are using CPUs rather than GPUs. GPUs are much faster.taperoo2k wrote: ↑26 Feb 2023, 23:33As for the data side of things? This article has useful information about how they use CFD, timescales etc and why the team decided to use AMD EPYC processors over other options. https://www.amd.com/en/case-studies/f1- ... g-petronas
They talk about limits of data centre space, but you'd think GPU cards would have a higher FLOPS per volume of space than CPUs too.Custom made processor was Opteron 6275, named "Fangio". This CPU has the same specifications as the 6276, except that its Floating Point unit is limited to 2 double-precision FLOPS per module. As a result of FPU capping, the maximum theoretical performance of this chip is 75 GFLOPS. Integer performance and memory throughput of the 6275 are identical to Opteron 6276.
But keep in mind that CUDA isn't used with AMD GPU's. Since AMD is the sponsor, even if they could use GPU resources, they would likely remain AMD products. And without CUDA FLOPS decrease quite a bit. Either way, for high end work I'm sure they would need some server grade CPU's to feed the GPU's.Mostlyeels wrote: ↑28 Feb 2023, 22:19It's a bit of a head scratcher, to be sure. CUDA supports double precision, same as regular CPUs. Very old GPUs had limited double precision performance (only one execution unit, from memory), but modern ones can do lots of FP64. Unless CFD solvers need multi-precision arithmetic (but that would be slow on all types of execution unit), but why not just scale the values for doubles?AR3-GP wrote: ↑26 Feb 2023, 23:36The AMD stuff is marketing. I'm actually surprised they are using CPUs rather than GPUs. GPUs are much faster.taperoo2k wrote: ↑26 Feb 2023, 23:33As for the data side of things? This article has useful information about how they use CFD, timescales etc and why the team decided to use AMD EPYC processors over other options. https://www.amd.com/en/case-studies/f1- ... g-petronas
The special Williams CPU build was interesting though: https://www.cpu-world.com/news_2012/201 ... _6275.html
They talk about limits of data centre space, but you'd think GPU cards would have a higher FLOPS per volume of space than CPUs too.Custom made processor was Opteron 6275, named "Fangio". This CPU has the same specifications as the 6276, except that its Floating Point unit is limited to 2 double-precision FLOPS per module. As a result of FPU capping, the maximum theoretical performance of this chip is 75 GFLOPS. Integer performance and memory throughput of the 6275 are identical to Opteron 6276.
What do you say is the slip angle of an F1 front tyre?