2022 cars 'porpoising' at high speed

[henry]

Eau Rouge is a special case. The compression makes for a very significant increase in downforce which will inevitably reduce ride height, probably by more than anywhere else on the calendar. If the porpoising is being triggered by low ride heights then it will be most likely to be triggered there. And since it’s in the middle of a high G corner complex it might cause some problems.
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But at Spa you still have the compression pushing the car down, later it lifts a bit. So you have forces on the car. To my understanding purposing is the lack of force at some point, which can be seen as floor downforce oscillating: The car goes down and looses mayor part of the floor downforce, so it goes up. If you have additional compression or lift by the track, this will act like the DRS activation and damp the oscillating floor downforce.
I would also see the issue rather in situations where the wing is a bit bigger, not necessarily Spa or Monza. Might be an issue in Azer?

By the way: There is no more Eau Rouge. This issue will not happen there.

Good point. In my broad brush estimation the cars will have about 3G downforce as they approach Eau Rouge, 1 from the car mass and 2 from aero. On the exit of Eau Rouge where they hit the upslope they will gain 1G from the road shape. If this additional downforce triggers a loss of downforce from the floor it will depend how the combined downforce decay from this loss and the vertical road shape play out.

If they cancel out then the cars will progress to Radillon with no problems. If they don’t cancel and the car starts to porpoise then Radillon will be tricky, particularly since there is some loss of downforce over the crest.

Of course there may be no problem at all, in which case they’ll treat Eau Rouge/Radillon as a minor inconvenience in the straight. As they will many other corners on this wonderful circuit.

My understanding is that they have opened up the run off at Eau Rouge but not changed the track, am I wrong?

[mclaren111]

http://www.f1reader.com/#/news/spa-rele ... tes-306316


New pics of Eau-Rouge...

[piast9]

I am still curious if under current regulations the underbody tunnels may be shaped in a way that they do not stall even if the car is so low that it is dragging the plank hard for miles. Is it possible?

[JonoNic]

I'm trying to find an old video that I watched in the early 90s. Back then it was probably 15 years old already. The video investigated if a car with ground effects would lose downforce when driving over a bridge with a metal grid surface. Do any of you remember watching something like this?

Sent from my SM-G9910 using Tapatalk

[basti313]

Eau Rouge is a special case. The compression makes for a very significant increase in downforce which will inevitably reduce ride height, probably by more than anywhere else on the calendar. If the porpoising is being triggered by low ride heights then it will be most likely to be triggered there. And since it’s in the middle of a high G corner complex it might cause some problems.
.

But at Spa you still have the compression pushing the car down, later it lifts a bit. So you have forces on the car. To my understanding purposing is the lack of force at some point, which can be seen as floor downforce oscillating: The car goes down and looses mayor part of the floor downforce, so it goes up. If you have additional compression or lift by the track, this will act like the DRS activation and damp the oscillating floor downforce.
I would also see the issue rather in situations where the wing is a bit bigger, not necessarily Spa or Monza. Might be an issue in Azer?

By the way: There is no more Eau Rouge. This issue will not happen there.

If they cancel out then the cars will progress to Radillon with no problems. If they don’t cancel and the car starts to porpoise then Radillon will be tricky, particularly since there is some loss of downforce over the crest.
.....
My understanding is that they have opened up the run off at Eau Rouge but not changed the track, am I wrong?

Yes, sorry. Track layout stays the same as I just learned. I thought they straightened it up following the comments from Hamilton and how the picture looked like. Just the run offs are bigger.


For the lift at Radillon: I think exactly this loss of downforce helps just like the open DRS. The back of the car lifts, the porpoising ends.

So we have three points of interest:
- Compression at Eau rouge - I think the compression keeps the car down.
- Uphill section - danger of porpoising. Question is if the speed is high enough?
- Lift at Radaillon - I see no danger, as the rear lifts as under DRS.


Do you know at which speed the porpoising started? In the videos it is a rather short area before the breaking point if I see it correctly.

[Just_a_fan]

The teams are working to stop the porpoising from happening - it's bad for performance after all. Judging by some of the solutions seen at the test, it might be as simple as stiffening the outer floor - Mercedes added a tie in this area to do just that, for example. Obviously any stiffening carried out will be inherent to the structure and not rely on big metal struts out in the airflow.

Let's see what the cars are like in the coming test and see whether they have solved the issue on the straights.

[JonoNic]

I'm trying to find an old video that I watched in the early 90s. Back then it was probably 15 years old already. The video investigated if a car with ground effects would lose downforce when driving over a bridge with a metal grid surface. Do any of you remember watching something like this?

Sent from my SM-G9910 using Tapatalk

By the way. The video concluded that the car would literally jump because of the compressed springs unloading and lose control as it transitioned from road surface to metal grid.

Sent from my SM-G9910 using Tapatalk

[henry]

But at Spa you still have the compression pushing the car down, later it lifts a bit. So you have forces on the car. To my understanding purposing is the lack of force at some point, which can be seen as floor downforce oscillating: The car goes down and looses mayor part of the floor downforce, so it goes up. If you have additional compression or lift by the track, this will act like the DRS activation and damp the oscillating floor downforce.
I would also see the issue rather in situations where the wing is a bit bigger, not necessarily Spa or Monza. Might be an issue in Azer?

By the way: There is no more Eau Rouge. This issue will not happen there.

If they cancel out then the cars will progress to Radillon with no problems. If they don’t cancel and the car starts to porpoise then Radillon will be tricky, particularly since there is some loss of downforce over the crest.
.....
My understanding is that they have opened up the run off at Eau Rouge but not changed the track, am I wrong?

Yes, sorry. Track layout stays the same as I just learned. I thought they straightened it up following the comments from Hamilton and how the picture looked like. Just the run offs are bigger.


For the lift at Radillon: I think exactly this loss of downforce helps just like the open DRS. The back of the car lifts, the porpoising ends.

So we have three points of interest:
- Compression at Eau rouge - I think the compression keeps the car down.
- Uphill section - danger of porpoising. Question is if the speed is high enough?
- Lift at Radaillon - I see no danger, as the rear lifts as under DRS.


Do you know at which speed the porpoising started? In the videos it is a rather short area before the breaking point if I see it correctly.

From the recently released pictures the track looks the same but has a new surface.

I think the speed on entry to Eau Rouge is around 300kph, I don’t know what speeds they were doing in the videos.

I think the thing about DRS is it reduced overall downforce, keeping ride height higher, and so stopped porpoising starting as opposed to stopping it once it had started.

[henry]

The teams are working to stop the porpoising from happening - it's bad for performance after all. Judging by some of the solutions seen at the test, it might be as simple as stiffening the outer floor - Mercedes added a tie in this area to do just that, for example. Obviously any stiffening carried out will be inherent to the structure and not rely on big metal struts out in the airflow.

Let's see what the cars are like in the coming test and see whether they have solved the issue on the straights.

No doubt the teams will work hard at fixing this, but lap time comes first. A bit of porpoising on one straight at a circuit may be a price they are willing to pay.

I’m sure they’ll improve things at Bahrain but I don’t think it is one of the more difficult tracks in terms of track bumps or elevation changes. I raised Spa because I think it’s an outlier.

But as you say we will see at Bahrain what progress they’ve made, no doubt the observers will be on the lookout, more so than at Barcelona.

[Just_a_fan]

The teams are working to stop the porpoising from happening - it's bad for performance after all. Judging by some of the solutions seen at the test, it might be as simple as stiffening the outer floor - Mercedes added a tie in this area to do just that, for example. Obviously any stiffening carried out will be inherent to the structure and not rely on big metal struts out in the airflow.

Let's see what the cars are like in the coming test and see whether they have solved the issue on the straights.

No doubt the teams will work hard at fixing this, but lap time comes first. A bit of porpoising on one straight at a circuit may be a price they are willing to pay.

Porpoising affects the driver as well as the car and a driver that isn't comfortable and confident in his car won't produce lap time. They need to sort it for that reason alone, even before the hypothetical worry about particular corners at particular tracks possibly being an issue.

[henry]

The teams are working to stop the porpoising from happening - it's bad for performance after all. Judging by some of the solutions seen at the test, it might be as simple as stiffening the outer floor - Mercedes added a tie in this area to do just that, for example. Obviously any stiffening carried out will be inherent to the structure and not rely on big metal struts out in the airflow.

Let's see what the cars are like in the coming test and see whether they have solved the issue on the straights.

No doubt the teams will work hard at fixing this, but lap time comes first. A bit of porpoising on one straight at a circuit may be a price they are willing to pay.

Porpoising affects the driver as well as the car and a driver that isn't comfortable and confident in his car won't produce lap time. They need to sort it for that reason alone, even before the hypothetical worry about particular corners at particular tracks possibly being an issue.

That’s a reasonable hypothesis.

[vorticism]

Sped up another porpoising video to real time:

https://i.imgur.com/faHEbmP.mp4

[algebraist]

No doubt the teams will work hard at fixing this, but lap time comes first. A bit of porpoising on one straight at a circuit may be a price they are willing to pay.

Porpoising affects the driver as well as the car and a driver that isn't comfortable and confident in his car won't produce lap time. They need to sort it for that reason alone, even before the hypothetical worry about particular corners at particular tracks possibly being an issue.

That’s a reasonable hypothesis.

It's not a hypothesis, this is something that was found before back in Colin Chapman's day with the Lotus 80. They dumped it for the 79 because it bounced so much the drivers were getting sick.

[vorticism]

Happens to aircraft as well (feedback loop between a spring force and a lift force):



"Porpoising (runaway bounced landing) - repeated bouncing with bouncing amplitude increasing with each touchdown. This is most dangerous bounced landing type typically resulting in severe damage or destruction of airframe."

Q's: On the cars, is porpoising a pitching motion over the a particular center of pressure (f.e. tunnel waist, diffuser entry)? Is porpoising a more linear vertical motion? Is one axle affected more than the other?

[djos]

Happens to aircraft as well:

https://www.youtube.com/watch?v=x5ZzktAFJK4

"Porpoising (runaway bounced landing) - repeated bouncing with bouncing amplitude increasing with each touchdown. This is most dangerous bounced landing type typically resulting in severe damage or destruction of airframe."

Q's: Is porpoising a pitching motion over the a particular center of pressure (f.e. tunnel waist, diffuser entry)? Is porpoising a more linear vertical motion? Is one axle affected more than the other?

That pilot looks like he came in way too fast and that caused the Porpoising.