2022 cars 'porpoising' at high speed

[DiogoBrand]

If a cut on the floor is beneficial then I don't understand:
Why did no one have it before they had issues?
Why haven't all teams tried it yet?
Why was it never done before this year's regulations?
Why has there always been so much emphasis put on sealing the edges of the floor to not allow the high pressure from over the floor to leak onto the low pressure from benath it, to the point where cars used to have skirts and were even tested with no suspension during the 80's?

All of that just goes out the window when you say that leaking high pressure air from above the floor onto the tunnels is not only non-detrimental, but actually increases performance.

Also you challenge me to provide evidence but provide none of your own.
If both of us have no knowledge to argue on this subject, then why waste time?

[godlameroso]

If a cut on the floor is beneficial then I don't understand:
Why did no one have it before they had issues?
Why haven't all teams tried it yet?
Why was it never done before this year's regulations?
Why has there always been so much emphasis put on sealing the edges of the floor to not allow the high pressure from over the floor to leak onto the low pressure from benath it, to the point where cars used to have skirts and were even tested with no suspension during the 80's?

All of that just goes out the window when you say that leaking high pressure air from above the floor onto the tunnels is not only non-detrimental, but actually increases performance.

Also you challenge me to provide evidence but provide none of your own.
If both of us have no knowledge to argue on this subject, then why waste time?

What's that then? Sure seems like over the car high pressure air going to the low pressure side, but what do I know.

[DiogoBrand]

"Why did no one have it before they had issues?"

Why would you need solutions to problems you don't know you have?

Maybe because you're saying it provides a benefit over having a sealed floor edge.
And you still didn't answer why all the time up until now everyone has put so much effort into sealing the floor rather than leaking high pressure air into it.

"Why was it never done before this year's regulations?"

Is your memory really that short, do you not remember the z cut outs in last year's cars?

You mean the cutouts teams were forced to put on their cars to reduce downforce?

https://files.catbox.moe/5324dh.jpg

What's that then? Sure seems like over the car high pressure air going to the low pressure side, but what do I know.

Maybe high pressure leaks onto low pressure because it's unavoidable unless you have skirts, not because teams desire it.

But you're clearly the aerodynamicist here so I'll stop questioning as your knowledge is beyond my understanding.

[djos]

Chaps, I really don’t think this is a big deal, the teams will learn to sort their cars to the point were it’ll be a non-event.

Indy Cars have run tunnels and regular springs and dampers for decades and you just don’t see it happening to them.

All the F1 teams will be on top of this before the season starts unless they have a fundamental design flaw in their car.

[gcdugas]

Chaps, I really don’t think this is a big deal, the teams will learn to sort their cars to the point were it’ll be a non-event.

Indy Cars have run tunnels and regular springs and dampers for decades and you just don’t see it happening to them.

All the F1 teams will be on top of this before the season starts unless they have a fundamental design flaw in their car.

Correct. GP2 cars also had tunnels. Plus the teams are dealing with stiffer low profile sidewalls. All this necessitates more movement under control of the suspension system. Who knows? Maybe McLaren is drawing on some Indy Car knowledge.

This is Day 2 of testing. Have some perspective.

[SmallSoldier]

According to Enrique Scalabroni (Car designer that worked for Dallara, Williams, Ferrari, Lotus and Peugeot) the problem is with the ratio between the inlet size and the minimum section of the Tunnels… That ratio, according to the tests done back in the day, if higher than 1.2 would create porpoising above 290 km/h

I haven’t made the math, but apparently teams like McLaren who seem to have an smaller inlet to the tunnels are suffering less from this phenomenon

It is not related to to the T-Tray shape

[101FlyingDutchman]

According to Enrique Scalabroni (Car designer that worked for Dallara, Williams, Ferrari, Lotus and Peugeot) the problem is with the ratio between the inlet size and the minimum section of the Tunnels… That ratio, according to the tests done back in the day, if higher than 1.2 would create porpoising above 290 km/h

I haven’t made the math, but apparently teams like McLaren who seem to have an smaller inlet to the tunnels are suffering less from this phenomenon

It is not related to to the T-Tray shape

Bingo

[Andi76]

What stands out on the straight here: Some of the cars are very bumpy. Especially the Williams, but also the Aston Martin and the Alpine. On the Aston, it disappears when DRS is open. Red Bull stable, right up to the braking zone. Ferrari, Merc and AlphaTauri don't bounce at all. #F1

That is very interesting. Somewhat worrying for the A522.

Sorry but that seems to be wrong regarding Mercedes. German Media, which is very well informed about things regarding Mercedes, report Mercedes indeed has the biggest problems with porpoising together with Williams.

Still i am not convinced that the sidepods could not be contributing to this problem. The "new"-longer sidepods are used to keep the front-wheel tyre wake outboard. The Williams/Mercedes sidepods are shorter, so this effect is missing or much less. Maybe that has something to do with that and thats the reason why Williams and Mercedes are suffering more than teams with longer sidepods. . If the reports are true that Williams and Mercedes are suffering more than others, i just cannot imagine that it is a coincident. On the other hand McLaren, who also have short-sidepods do not seem to have a big problem...

It was also reported that the Ferrari is one of the cars suffering less. One thing i noticed about the Ferrari is that the suspension is extremely stiff. Stiffer than any other car. Maybe Ferrari has the advantage of Rory Byrne. Rory is still advising Ferrari and he is probably the only technician left who has huge experience with ground-effect cars, as he designed such cars for Toleman in the early 80's.

[henry]

Over in the Tyres thread, I suggested that porpoising might be a problem because of the new tyres,and the restrictions on suspension components.

The teams pushed to have the taller sidewalls which will mean, as you say, that the spring rate of these new tyre will be very similar to the 13”. Add to that the increased mass and the removal of inerters etc., which were used to help control the relatively undamped unsprung elements, and I think we might see some problems with kerb riding and maybe some porpoising.

The rules seem to have written to explicitly make the suspension less capable. For example:
In addition, the following systems or configurations are not permitted:
a. Anyresponseofthesuspensionelementstobodyaccelerationsand/orangular acceleration of the rockers (e.g. any inerters, mass dampers, acceleration-sensitive valves in the dampers).

whilst lower profile than before still have relatively tall sidewalls and are likely to still be fairly soft. @stu pointed out that the air chamber volumes are very little changed.

Looking at the Ferrari video the majority of the movement appears to be at the rear. I assume that the downforce is lost at the COP and if the stiffness at front and rear were in proportion to the load the car would bounce rather than porpoise. So I’m guessing the rear is less stiff. The rear tyres are almost certainly radially softer than the fronts and the rear suspension is probably soft to aid traction.

To reduce this effect is probably straightforward. Reduce the exciting forces, raise ride height?, and make the rear stiffer, by higher tyre pressures or stiffer springs/dampers. But the teams won’t want to do that because lap times will go up.

So round and round they’ll go revising, aero and suspension until they get to a point where they get to a balance of porpoising and lap time they’re happy with.

[west52keep64]

I wonder if the floor flexing is part of the issue. If you look at the W13, a large percentage of the floor is unsupported and could be prone to flexing. It's easy enough to fix if that is the case, a couple of stays should do the trick, assuming the stays would be legal?

EDIT: Look what I found on the Mercedes

[ojir19]

does "porpoising rate" related to wheelbase length ?

imo, longer wheelbase = longer floor, means bigger groundeffect = higher porpoising

viewtopic.php?p=1038206#p1038206

According to AMuS, the C42 is by far the shortest car in the field:

"What you don't see at first glance is the length of the car. According to information from auto motor und sport, the Alfa Romeo C42 is by far the shortest car in the field. The wheelbase, which was limited by the regulations to 3.6 metres for the first time this year, is said to have been cut by the Sauber engineers by another 9 centimetres.
The trick helps the aerodynamics and saves weight. The Alfa is said to be one of the few cars in the field that made it exactly to the limit of the maximum weight of 795 kilograms. During testing, some of the competitors were still lugging around excess weight in the double-digit kilogram range."

[Stu]

Over in the Tyres thread, I suggested that porpoising might be a problem because of the new tyres,and the restrictions on suspension components.

The teams pushed to have the taller sidewalls which will mean, as you say, that the spring rate of these new tyre will be very similar to the 13”. Add to that the increased mass and the removal of inerters etc., which were used to help control the relatively undamped unsprung elements, and I think we might see some problems with kerb riding and maybe some porpoising.

The rules seem to have written to explicitly make the suspension less capable. For example:
In addition, the following systems or configurations are not permitted:
a. Anyresponseofthesuspensionelementstobodyaccelerationsand/orangular acceleration of the rockers (e.g. any inerters, mass dampers, acceleration-sensitive valves in the dampers).

whilst lower profile than before still have relatively tall sidewalls and are likely to still be fairly soft. @stu pointed out that the air chamber volumes are very little changed.

Looking at the Ferrari video the majority of the movement appears to be at the rear. I assume that the downforce is lost at the COP and if the stiffness at front and rear were in proportion to the load the car would bounce rather than porpoise. So I’m guessing the rear is less stiff. The rear tyres are almost certainly radially softer than the fronts and the rear suspension is probably soft to aid traction.

To reduce this effect is probably straightforward. Reduce the exciting forces, raise ride height?, and make the rear stiffer, by higher tyre pressures or stiffer springs/dampers. But the teams won’t want to do that because lap times will go up.

So round and round they’ll go revising, aero and suspension until they get to a point where they get to a balance of porpoising and lap time they’re happy with.

Over the last few years we have seen some cars appearing to ‘porpoise’ quite a bit. Slo-mo shots appear to indicate that it has been caused by bumps in the track inducing reactions within the tyre carcass rather than physically ‘within’ the car/suspension. The Mercedes seemed to be particularly affected at certain tracks. Whether this was wheelbase length related or something with their inerter system not being set to remove this particular oscillation is something that only they know.

The ‘tell-tale’ struts that have appeared means that we can expect to see floors with modified lay-ups (at best) or visibly modified structures (at worst- as this will have an impact on the aero).
Either way, midnight oil will be burned & those that do not have the issue will benefit as they are not having to waste computer time and CFD runs on fixing problems, but can progress through their optimisation programs.
It will be interesting to see what changes are possible between now and the Bahrain test days.

[ME4ME]

Either way, midnight oil will be burned & those that do not have the issue will benefit as they are not having to waste computer time and CFD runs on fixing problems, but can progress through their optimisation programs.
It will be interesting to see what changes are possible between now and the Bahrain test days.

I think all teams even those not heavily affected at the moment will have to dedicate significant resources to analyze the phenomenon. No team can afford to ignore it, since it can be induced by upgrades, as reported by McLaren.

We had a couple of test items which appeared to promote it a bit more,” he said. “But then removing them reduced it, so you can fix it aerodynamically as well.

https://www.motorsport.com/f1/news/mcla ... t/8540476/

[Big Tea]

Does this have any relevance to the Slo-Mo shots we were seeing of ripples in the tyres at some corners?

I know it is a completely different thing, but something is generating the waves

[CrazyCarperF1]

The solution shouldn't be too difficult, the teams just have to figure out how much air they can squeeze under the floor before it stalls at minimum ride height.