Driving style

[mechanoit]

I’m currently having an interesting discussion with an engineer who used to work at a senior level (not at the highest level i.e not TD or similar!) at a top team. Doesn’t work in F1 currently. I don’t want to say who because the engineer is on the usual youtube, twitter etc. and most here will know if I named, but I reached out to the engineer from an account using my own name and I’d prefer to remain anonymous here.

This engineer posts quite a lot of excellent information on the cars from different teams but I was interested what this person thought about the drivers which hasn’t been mentioned by this person so far who instead has only talked about the cars and tech. Hasn’t revealed anything too juicy so far, but some things told were interesting. Said that prior to 2022 rule change, Mercedes opted to go for long wheelbase because it maximised downforce and efficiency in medium to high speed corners and while that long wheelbase had an inherent weakness in rotation in slower corners compared to short wheelbase cars, Hamilton’s ability to maximise rotation in slow corners from his driving style compensated for the rotation weakness inherent in the longer wheelbase. So if what this person is saying is accurate, the team actually designed a car that had a particular strength in an area where their driver couldn’t be the performance differentiator i.e fast corners, so it was superior there to the other cars, but had a weakness in an area where their driver could differentiate i.e slower corners.

Same engineer made the comparison to the Red Bull, which had one of the shortest wheelbases, saying that this gave the car fantastic rotation in the slower corners but compromised aero in the faster corners however Red Bull’s aero dept is so strong that even with the shorter wheelbase they designed a car that was very good in fast corners and impressively close to, but not as good as the Mercedes. However the short wheelbase also had a flaw in that it was twitchy and Verstappen’s ability and reaction times to correct a car that was twitchy at speed compensated for this weakness, while providing a car that was very easy to rotate in slower speed corners.

I also asked the engineer about the braking part, why we’ve seen Hamilton very late on the brakes in earlier seasons, notoriously late in fact, but in the last few years not as much as the Red Bulls or even the Ferraris. Is it simply just a matter of age or anything to do with the car design? The engineer said this was also due to wheelbase. That the ability to brake late hinges on three factors. One being feel for the brakes and bleeding off braking force to compensate for the exponential loss in grip as aero load comes off with reduction in speed. Two being able to hold onto the rear under hard braking and especially during the last phase of braking as steering is fed in. Three, the ability to get the car turned. Noted that Hamilton has stood out from other drivers on the first two parts, having an excellent feel for grip as aero load is shed during braking, and coping with an instable rear end as the car starts to rotate with most of the weight over the front axle. However, the engineer thinks that the long wheel base means that even with Hamilton employing trail braking and controlling the rear pivoting around the front axle, the car simply isn’t agile in the slower corners and wants to understeer if too much speed is carried in compared to the same speed in a shorter wheelbase car. Hence Hamilton is forced to take a more traditional geometric line through the corner than his preferred V which is basically a straight hard braking line late into the corner, then a short and sharp rotation, followed by a straight exit.

Very interesting to see how a driver’s qualities certainly can influence car design but also how car designs can either choose to align with a driver’s strength in aligning to the driver or go the opposite route of using the driver’s strength to compensate for a weakness in the car derived from an intentional compromise in car design towards that car weakness in order to maximise another car strength. Sorry if I have not worded all of this well or poor grammar as English is not my first language.

[johnny comelately]

I’m currently having an interesting discussion with an engineer who used to work at a senior level (not at the highest level i.e not TD or similar!) at a top team. Doesn’t work in F1 currently. I don’t want to say who because the engineer is on the usual youtube, twitter etc. and most here will know if I named, but I reached out to the engineer from an account using my own name and I’d prefer to remain anonymous here.

This engineer posts quite a lot of excellent information on the cars from different teams but I was interested what this person thought about the drivers which hasn’t been mentioned by this person so far who instead has only talked about the cars and tech. Hasn’t revealed anything too juicy so far, but some things told were interesting. Said that prior to 2022 rule change, Mercedes opted to go for long wheelbase because it maximised downforce and efficiency in medium to high speed corners and while that long wheelbase had an inherent weakness in rotation in slower corners compared to short wheelbase cars, Hamilton’s ability to maximise rotation in slow corners from his driving style compensated for the rotation weakness inherent in the longer wheelbase. So if what this person is saying is accurate, the team actually designed a car that had a particular strength in an area where their driver couldn’t be the performance differentiator i.e fast corners, so it was superior there to the other cars, but had a weakness in an area where their driver could differentiate i.e slower corners.

Same engineer made the comparison to the Red Bull, which had one of the shortest wheelbases, saying that this gave the car fantastic rotation in the slower corners but compromised aero in the faster corners however Red Bull’s aero dept is so strong that even with the shorter wheelbase they designed a car that was very good in fast corners and impressively close to, but not as good as the Mercedes. However the short wheelbase also had a flaw in that it was twitchy and Verstappen’s ability and reaction times to correct a car that was twitchy at speed compensated for this weakness, while providing a car that was very easy to rotate in slower speed corners.

I also asked the engineer about the braking part, why we’ve seen Hamilton very late on the brakes in earlier seasons, notoriously late in fact, but in the last few years not as much as the Red Bulls or even the Ferraris. Is it simply just a matter of age or anything to do with the car design? The engineer said this was also due to wheelbase. That the ability to brake late hinges on three factors. One being feel for the brakes and bleeding off braking force to compensate for the exponential loss in grip as aero load comes off with reduction in speed. Two being able to hold onto the rear under hard braking and especially during the last phase of braking as steering is fed in. Three, the ability to get the car turned. Noted that Hamilton has stood out from other drivers on the first two parts, having an excellent feel for grip as aero load is shed during braking, and coping with an instable rear end as the car starts to rotate with most of the weight over the front axle. However, the engineer thinks that the long wheel base means that even with Hamilton employing trail braking and controlling the rear pivoting around the front axle, the car simply isn’t agile in the slower corners and wants to understeer if too much speed is carried in compared to the same speed in a shorter wheelbase car. Hence Hamilton is forced to take a more traditional geometric line through the corner than his preferred V which is basically a straight hard braking line late into the corner, then a short and sharp rotation, followed by a straight exit.

Very interesting to see how a driver’s qualities certainly can influence car design but also how car designs can either choose to align with a driver’s strength in aligning to the driver or go the opposite route of using the driver’s strength to compensate for a weakness in the car derived from an intentional compromise in car design towards that car weakness in order to maximise another car strength. Sorry if I have not worded all of this well or poor grammar as English is not my first language.

Well put.
This brings up tracks.
What is the preponderance of various features like straights, high speed corners etc?
Design the car for that majority, with an interesting overlay of driver characteristics (which is not as hard and fast as believed IMHO)
So, with the move to more unappealing (to me) street tracks by the new american masters what does a designer do

[Tommy Cookers]

imo ....
the long wheelbase car doesn't need 'more' 'turning-in' moment (for a given acceleration in yaw) - it needs 'less'
ie in this sense it isn't less responsive - it's more responsive
(because the current LWB cars having a freakishly large WB/yawing moment arm relative to their PMI)
ok the LWB car has to turn slightly tighter eg in a tight corner

however ....
the LWB car has eg less front-to-rear 'weight' transfer with braking etc
(reducing the gains available eg from 'trail braking - and acceleration equivalent)

[mechanoit]

The longer the wheelbase, the greater the polar moment of inertia….?

[Tommy Cookers]

The longer the wheelbase, the greater the polar moment of inertia….?

on corner entry (or exit) ....
the car PMI is being accelerated in yaw by the combined yaw moments from the 4 horizontal wheel forces ....
these act at a longer moment arm with the longer wheelbase
the combined yaw moments (probably) have increased with the longer wheelbase more than the PMI has increased
(because some of the car's large-mass parts haven't been moved when the wheels were moved to longer wheelbase)

RETRO-EDIT
fwiw I think that .....
if the car length was doubled by stretching uniformly the PMI would be quadrupled - so yes response would be slower
if the wheelbase was doubled but (using zero-mass extensions) the PMI was unchanged - the response would be faster
ie by keeping much of the mass distribution unchanged the response remains good

anyway slow response can help the driver at times

a deliberately large PMI was the hot ticket for at least 25 years from 1937 (the M-B W125)

[AR3-GP]

The longer the wheelbase, the greater the polar moment of inertia….?

A longer wheel base also means that lateral forces generated at the front tire contact patch impart a larger moment about the center of mass.

It's like why a long wrench is easier to turn a nut than a short one.

[mechanoit]

The longer the wheelbase, the greater the polar moment of inertia….?

on corner entry (or exit) ....
the car PMI is being accelerated in yaw by the combined yaw moments from the 4 horizontal wheel forces ....
these act at a longer moment arm with the longer wheelbase
the combined yaw moments (probably) have increased with the longer wheelbase more than the PMI has increased
(because some of the car's large-mass parts haven't been moved when the wheels were moved to longer wheelbase)

RETRO-EDIT
fwiw I think that .....
if the car length was doubled by stretching uniformly the PMI would be quadrupled - so yes response would be slower
if the wheelbase was doubled but (using zero-mass extensions) the PMI was unchanged - the response would be faster
ie by keeping much of the mass distribution unchanged the response remains good

slow response can help the driver at times

I agree, if PMI remains same between shorter vs longer wheelbase then longer wheelbase easier to turn. The issue in reality though is that PMI will increase correspondingly with wheelbase and that will reduce response. The drivers themselves are clear on this and commonly note that car has better change of direction with shorter wheelbase but is twitchy. F1 engineers also infrequently weigh in on this and say the same.

[johnny comelately]

If there is a hierarchy is the wheelbase secondary to ground effect?

[mechanoit]

My discussion with the engineer was on the earlier regulations prior to 2022 hence unsure of how it relates to the ground effect cars. I suppose that the point of longer wheelbase being less agile would still apply, though probably not so much that longer wheelbase is required for better high speed aero?

[johnny comelately]

My discussion with the engineer was on the earlier regulations prior to 2022 hence unsure of how it relates to the ground effect cars. I suppose that the point of longer wheelbase being less agile would still apply, though probably not so much that longer wheelbase is required for better high speed aero?

I was thinking the longer wheelbase producing a larger floor area (I'm not an aero person)

[mechanoit]

Yes I think that’s right, that’s why Mercedes went with a longer wheelbase. But the 2022 regulations have tightened this up further so I don’t believe there are such big differences in wheelbase.

[PlatinumZealot]

Mods could merge this thread with the old one if they wish... But similar things have been discussed there with the lazier long wheels base mercedes and the sharper twitchier RedBull that their lead drivers are good at compensating for.

Alonso in the Alpine is another example. He was compensating for weaknesses that in Alline were exposed when he drove the Aston Martin.

[Gecko]

You are not taking into account the yaw damping which is the biggest contributor to long wheelbase cars being sluggish on turn-in. Basically, as yaw rate develops, the front tyres see less slip and the rears more, countering that yaw rate. Yaw damping does tend to get reduced the closer you are to the grip limit, hence why it is possible to compensate for the effect with driving style.

[PlatinumZealot]

You are not taking into account the yaw damping which is the biggest contributor to long wheelbase cars being sluggish on turn-in. Basically, as yaw rate develops, the front tyres see less slip and the rears more, countering that yaw rate. Yaw damping does tend to get reduced the closer you are to the grip limit, hence why it is possible to compensate for the effect with driving style.

The tyres generate yaw and there is a small component of cross-wind.

If you are gonna talk about damping you have to have some sort of spring-like component and vibrations.

And then we have to talk about a coordiante system for yaw. You can use a polar coordinate system with its axis vertically through the center of the car.

Now... The springs in that horizontal plane are basically the tyre side walls and the "spine" of the chassis. The damping of the tyres sidewall in yaw is extremely high compared to the "springyness" force which is acts at a very low frequency and you never really see a car wobbling in yaw.. And the tyre sidewall spring contant is the same for all cars if the pressure is the same. The other springyness in yaw would be the spine of the car (IMO). This is made as stiff as possible and is the damping doesn't need to be anything significant because it doesnt vibrate much at any high amplitude anyway...

So the yaw damping I would say is not a big difference between the teams.

Teams will want to just generate as much grip as possible and worry about the sidewall wobble during high yaw last...

You usually see the tyres start wobbling when the grip is released...