2017 Tyres revealed

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henry
54
Joined: Mon Feb 23, 2004 7:49 pm
Location: England

Re: 2017 Tyres revealed

Post by henry » Mon Sep 04, 2017 10:19 am

FW17 wrote:
Mon Sep 04, 2017 7:43 am
New tyres are good but it is quiet sad that the current engines with almost a 1000 hp could not crack the 350 kph mark and nowhere close to the all time speed record of 372kph

The current tyres now seem to be limited to just 3 specs in most races with medium and hard not going to be seen again

I think for 2018 Pirelli can offer the 3 softest tyres in 2 sizes to have a range of 6 tyres. 3 types, ultra softs, supersofts and softs in 2017 sizes (305 front 405 rear) and 3 types, ultra softs, supersofts and softs in 2016 sizes (245 front 325 rear)

https://cdn-2.motorsport.com/images/mgl ... lli-ty.jpg

If they did that will the chassis be able to handle 2 different tyre sizes during the race?
The reason they don't get to such high speeds is because that's not the fastest way round the lap. Unfortunately for those who like big numbers they probably don't run max power at the end of straights but rather at the beginning. So if the PUs really do have 1000hp at max power they set up downforce and suspension to use it as soon as they can on the straights. Hence all the talk of traction differences between cars. So stickier tyres, more downforce, faster lap times, lower top speed.
Fortune favours the prepared; she has no favourites and takes no sides.

FW17
189
User avatar
Joined: Wed Jan 06, 2010 9:56 am

Re: 2017 Tyres revealed

Post by FW17 » Mon Sep 04, 2017 11:46 am

henry wrote:
Mon Sep 04, 2017 10:19 am
The reason they don't get to such high speeds is because that's not the fastest way round the lap. Unfortunately for those who like big numbers they probably don't run max power at the end of straights but rather at the beginning. So if the PUs really do have 1000hp at max power they set up downforce and suspension to use it as soon as they can on the straights. Hence all the talk of traction differences between cars. So stickier tyres, more downforce, faster lap times, lower top speed.
You can also consider reduction of Drag vs Higher grip in certain circuits

Monza with last years tyres would certainly got closer to the outright lap record than with current tyre

DaveW
242
Joined: Tue Apr 14, 2009 11:27 am

Re: 2017 Tyres revealed

Post by DaveW » Mon Sep 04, 2017 12:05 pm

Years ago, when playing with active suspension (on a road vehicle), I discovered that the lateral stiffness of a tyre could affect the stability of a suspension. Basically, the vehicle could be made to "dutch roll". The issue was more pronounced with the vehicle stationary, and the "fix" was to halve the loop gains in this condition.

Later when rig testing real vehicles (road & race), a roll input at the contact patches generated two body modes, one with the roll centre below the ground plane (i.e. mostly translation), and the other with it above (i.e. mostly roll). Initially, I discounted the first (thinking it was caused static tyres). But later, when playing with options on a touring car I discovered that as bar/spring stiffness ratio was increased, and dampers followed the springs, the vehicle could (& did) go unstable in the middle of a corner. The cure was the go back a step, increasing springs & dampers and (I think) reducing bar stiffness. Lateral tyre stiffness was important in this case, and the damping ratio of the lower roll mode was a useful parameter during a rig test.

I suspect that the instability shown in the GIF was similar to that of the touring car (but at a different axle). It shows a mixture of lateral and roll tyre deflection (and probably a lot else). The motion couples with the sprung mass (at least aft of the engine bulkhead). The patterns seen on the loaded wheel, and the wake of the unloaded one suggests that the CPL changes were large. My guess would be that this was the stability that Raikkonen complained about (hence it affected more than one team).

My thoughts are that it is unlikely it would be predicted by a full vehicle simulation, that F1 engineers have generated designs that are difficult to work with (dampers are usually non-adjustable, and springs take forever to change), and who knows what has happened to the tyres. It probably explains comments like "we were quick & don't know why", or "we lost performance unexpectedly", etc.

I could comment on the "notorious Michelin standing waves", but not right now.

hardingfv32
28
Joined: Sun Apr 03, 2011 6:42 pm

Re: 2017 Tyres revealed

Post by hardingfv32 » Mon Sep 04, 2017 6:15 pm

DaveW wrote:
Mon Sep 04, 2017 12:05 pm
My thoughts are that it is unlikely it would be predicted by a full vehicle simulation, that F1 engineers have generated designs that are difficult to work with (dampers are usually non-adjustable, and springs take forever to change), and who knows what has happened to the tyres. It probably explains comments like "we were quick & don't know why", or "we lost performance unexpectedly", etc.
1) In your opinion is the response 'we don't know why' just something that is issued at the track or could they actually have difficulties understanding the issues after spending some time at the shop/lab?

2) The difficult F1 designs you speak of: Is this an indication that in the recent past there were fewer problems that required a highly adjustable design… the designers saw no need for the adjustments in the future?

In a way we are lucky that the tires continue to add an important variable to the engineering competition we enjoy viewing.

Brian

henry
54
Joined: Mon Feb 23, 2004 7:49 pm
Location: England

Re: 2017 Tyres revealed

Post by henry » Mon Sep 04, 2017 7:36 pm

DaveW wrote:
Mon Sep 04, 2017 12:05 pm

I suspect that the instability shown in the GIF was similar to that of the touring car (but at a different axle). It shows a mixture of lateral and roll tyre deflection (and probably a lot else). The motion couples with the sprung mass (at least aft of the engine bulkhead). The patterns seen on the loaded wheel, and the wake of the unloaded one suggests that the CPL changes were large. My guess would be that this was the stability that Raikkonen complained about (hence it affected more than one team).

My thoughts are that it is unlikely it would be predicted by a full vehicle simulation, that F1 engineers have generated designs that are difficult to work with (dampers are usually non-adjustable, and springs take forever to change), and who knows what has happened to the tyres. It probably explains comments like "we were quick & don't know why", or "we lost performance unexpectedly", etc.

I could comment on the "notorious Michelin standing waves", but not right now.
I must admit that with an untrained eye I find it difficult to distinguish between the lateral and roll deflections. I do think I can see the tyres momentarily losing traction, first on the right and then on the left which would be, I assume, due to load transfer from roll. So apart from any effect on the driver stopping this loss of traction would yield lap time.

I wonder how the teams would go about understanding this behaviour, and finding a solution? I assume they have push/pull rod loads, yaw data etc. But what do they do about tyre lateral stiffness, or even without suitable insights, do they even know what they should include in their investigations and simulations. With virtually no track time to investigate and, as you say, limited options to change parameters even when do have track time simulations and rig testing need to find these behaviours. But the rigs don't have tyres and the simulations may omit models or data just because they are trying to find something they don't understand. I assume that if they did we wouldn't have seen it happening.
Fortune favours the prepared; she has no favourites and takes no sides.

henry
54
Joined: Mon Feb 23, 2004 7:49 pm
Location: England

Re: 2017 Tyres revealed

Post by henry » Mon Sep 04, 2017 7:43 pm

FW17 wrote:
Mon Sep 04, 2017 11:46 am
henry wrote:
Mon Sep 04, 2017 10:19 am
The reason they don't get to such high speeds is because that's not the fastest way round the lap. Unfortunately for those who like big numbers they probably don't run max power at the end of straights but rather at the beginning. So if the PUs really do have 1000hp at max power they set up downforce and suspension to use it as soon as they can on the straights. Hence all the talk of traction differences between cars. So stickier tyres, more downforce, faster lap times, lower top speed.
You can also consider reduction of Drag vs Higher grip in certain circuits

Monza with last years tyres would certainly got closer to the outright lap record than with current tyre
That's an interesting hypothesis.

But if that were the case why didn't everyone use the sort of ultra slim rear wing RBR brought? They would have had less drag and less downforce which would have reduced grip levels back towards those achieved with last year's tyres, and with your proposal that should have reduced drag and improved lap time.

You may be right. I think it's very difficult to do lap time estimates with these current cars because their power output varies across the lap ( amongst many other factors).

My personal model is that the most energy efficient way to lap is at constant speed, 160 + mph at Monza. The higher the speed the more energy used to overcome drag. So they will use discretionary energy, from the ES, at lower speeds. And to best use that they will run higher downforce.

In the days of 372 kph they didn't have that discretion so there was less emphasis on the downforce.
Fortune favours the prepared; she has no favourites and takes no sides.

DaveW
242
Joined: Tue Apr 14, 2009 11:27 am

Re: 2017 Tyres revealed

Post by DaveW » Tue Sep 05, 2017 8:55 am

hardingfv32 wrote:
Mon Sep 04, 2017 6:15 pm
1) In your opinion is the response 'we don't know why' just something that is issued at the track or could they actually have difficulties understanding the issues after spending some time at the shop/lab?
I don't have an opinion, but observably a good race team always has the "factory" to call upon.
.
hardingfv32 wrote:
Mon Sep 04, 2017 6:15 pm
2) The difficult F1 designs you speak of: Is this an indication that in the recent past there were fewer problems that required a highly adjustable design… the designers saw no need for the adjustments in the future?
Also observably, aerodynamics rules in F1. Little else matters, apparently.

A while ago we rig tested an F1 vehicle. I recall we made 11 suspension changes in a day & a half. I would have expected to assess over 100 changes in that time for a GP2 vehicle.
.
hardingfv32 wrote:
Mon Sep 04, 2017 6:15 pm
In a way we are lucky that the tires continue to add an important variable to the engineering competition we enjoy viewing.
Mmm... I'm not at all sure I agree with that thought. I almost missed the slo-mo because I was asleep at the time...

DaveW
242
Joined: Tue Apr 14, 2009 11:27 am

Re: 2017 Tyres revealed

Post by DaveW » Sun Sep 10, 2017 7:01 am

henry wrote:
Mon Sep 04, 2017 7:36 pm
I must admit that with an untrained eye I find it difficult to distinguish between the lateral and roll deflections. I do think I can see the tyres momentarily losing traction, first on the right and then on the left which would be, I assume, due to load transfer from roll. So apart from any effect on the driver stopping this loss of traction would yield lap time.
I think you are absolutely correct.....
.
henry wrote:
Mon Sep 04, 2017 7:36 pm
I wonder how the teams would go about understanding this behaviour, and finding a solution? I assume they have push/pull rod loads, yaw data etc. But what do they do about tyre lateral stiffness, or even without suitable insights, do they even know what they should include in their investigations and simulations. With virtually no track time to investigate and, as you say, limited options to change parameters even when do have track time simulations and rig testing need to find these behaviours. But the rigs don't have tyres and the simulations may omit models or data just because they are trying to find something they don't understand. I assume that if they did we wouldn't have seen it happening.
Again, I suspect you are correct..... The notorious Michelin issues you mentioned previously occurred because, unknown to Michelin, but not to Bridgestone/Firestone, the track had been resurfaced & grooved over the winter - changing the "grip" levels. The last suggests, perhaps, that Pirelli shares some of the "blame" in the present case.

Porsche993
0
Joined: Sun Oct 29, 2017 3:43 pm

Re: 2017 Tyres revealed

Post by Porsche993 » Sun Oct 29, 2017 3:57 pm

Why has F1 tyres such hig profile compared with e.g. LMP1 cars? Looking at an F1 running oseriösa the curbs it is obvious that they loose energi from the flexing as well as suffering with bad stability and bad handling.