Steering angle and turning radius.

[Neo Love]

Hello Everyone,

I need to find the maximum steering angle of an F1 car's front wheels,
in order to determine the minimum curve radius the car can negotiate.
(I've wasted nearly a day of futile Googleing and found nothing useful.)

Initially the issue is simplified to a "quasi-static" low speed turn
with no consideration for slip angles et c, just depending on the car's
long axis and front wheel steering angle.

Ocular assessment of stills and race footage gives me an initial "guesstimate"
of 30-40 degrees, and I assume the actual steering angle lock is adjustable,
to some extent, within the raw design limits.

An average figure would suffice, at least for starters, and additional figures
for min/max angle settings would be even more helpful.

One source of ocular assessment:

http://www.servimg.com/image_preview.ph ... u=14795526

Thank You
// Neo

[Tim.Wright]

What do you want these values for? There are a lot of ways to estimate them but your application will determine how much accuracy is required.

If you want the minimum radius use google earth to estimate the radius of the trajectory (not the track) at the lowes hairpin at monaco or the la source hairpin at spa.

[Neo Love]

Hi Tim,

Perhaps You misunderstood the issue.

I don't need to compute the steering angle for turning a corner, or find the radius
of an existing corner (which can be estimated on Google Earth as you point out),
I need the maximum steering angle of the car to compute the minimum radius it can turn.
(It's a matter of future track design.)

Best Regards
// Neo

(PS. I already posted this follow-up once, but it seems to have dropped out somehow.)

[sosic2121]

Hi Tim,

Perhaps You misunderstood the issue.

I don't need to compute the steering angle for turning a corner, or find the radius
of an existing corner (which can be estimated on Google Earth as you point out),
I need the maximum steering angle of the car to compute the minimum radius it can turn.
(It's a matter of future track design.)

Best Regards
// Neo

(PS. I already posted this follow-up once, but it seems to have dropped out somehow.)

maybe then you should calculate radius of hockenheim hairpin

[mep]

+-15deg
Happy now?

[Neo Love]

Thanks mep,

+-15deg
Happy now?

15 deg means a raw turn radius of 17 m, assuming a long axis of 4.5 m. (Sine law)
Is that an actual figure, or did you estimate it by reverse computing an observed trajectory ?
(I ask because I have no use for estimates; I can easily compute those myself.)
If it's an actual figure: Is it the design limit or the typical lock to lock setting?

Best Regards
// Neo

[Tim.Wright]

Hi Tim,

Perhaps You misunderstood the issue.

I don't need to compute the steering angle for turning a corner, or find the radius
of an existing corner (which can be estimated on Google Earth as you point out),
I need the maximum steering angle of the car to compute the minimum radius it can turn.
(It's a matter of future track design.)

Best Regards
// Neo

(PS. I already posted this follow-up once, but it seems to have dropped out somehow.)

I understood the question. The car's are designed to negotiate the tightest corners on the calender and nothing more. As it is they already run special steering an suspension geometry at monaco to get around the lowes hairpin so you can take that as an absolute minimum.

Even if you had the precise steering angles of a car you can't calculate anything more precise than a rough estimate of its turn radius because the radius that the car can turn depends on many things over just the steer angle of the wheels. Things like tyre cornering stiffness, CG location, load transfer distribution, suspension kinematics & compliance and ackermann geometry will all have an effect on the cornering radius but are not taken into account using the kinematic model you described.

More steering lock generally means strutural compromises in the suspension and a generally bigger and heavier steering system so you can reasonably assume the minimum radius the cars can handle is the minimum one on todays calender which is probably at monaco.

[Greg Locock]

Perhaps one of you playstation kids could produce a plot of inverse radius vs latacc for Monaco on a hot lap, in iRacer or something believable.

I suggest that ignoring tire slip is throwing the baby out with the bath water.

[mep]

The topic creator could just take some satellite pictures of a track, draw a racing line through the corners and calculate the cornering radius based on that.

[Neo Love]

Hi Tim,
Thanks for the response.

I understood the question. The car's are designed to negotiate the tightest corners on the calender and nothing more. As it is they already run special steering an suspension geometry at monaco to get around the lowes hairpin so you can take that as an absolute minimum.

That hairpin has an outside radius of ~14 m, meaning a rough steering angle of almost 19 deg.
(Simple sine law, and assuming roughly 4.5 m between front and rear wheels.)
(The inside radius is ~6 m, which I can negotiate with my old Lancer, but an F1 could never.)

Even if you had the precise steering angles of a car you can't calculate anything more precise than a rough estimate of its turn radius because the radius that the car can turn depends on many things over just the steer angle of the wheels. Things like tyre cornering stiffness, CG location, load transfer distribution, suspension kinematics & compliance and ackermann geometry will all have an effect on the cornering radius but are not taken into account using the kinematic model you described.

Yes, I'm well aware of that. A full model of the turn radius will be an intricate differential equation,
that requires an extensive computer program with many variables, to calculate.
Many factors will increase the radius, and rear wheel drift would decrease it,
but F1 is hardly drift racing

However, I am not modeling the turn radius of the cars for analytical purpose;
I am starting to draft a proposition to FIA regarding future track approval rules.
F.ex, several of the start incidents during 2016 can be blamed on over-tight first corners,
(in addition to occasional clumsy driving), and my proposition will include a demand that
corners should, in general, be negotiable without blocking the entire (or most of) the track.

In other words, track corners should, in general, have an inner radius no less than the
minimum turn radius of the cars. That would f.ex. mean the hairpin at Spa would need
to be rounded off (close to the current pit exit curve).

(The proposition will also address the minimum acceptable track width,
which would mean rejection of both Monaco and Suzuka in their present forms.)

More steering lock generally means strutural compromises in the suspension and a generally bigger and heavier steering system so you can reasonably assume the minimum radius the cars can handle is the minimum one on todays calender which is probably at monaco.

Yes, I understand that..
I was just wondering if any of you guys actually had the hard data from some cars rather than
estimates that we may calculate by observing de facto trajectories.

Best Regards
// Neo

[Paul]

Well, if all tracks have less tight corners, teams will design cars accordingly, with smaller steering angles. Only way I see of enforcing steering angles sufficient for sub optimal corner trajectories is if it is written in technical regulations.

[Tim.Wright]

That's pretty much what I said. The car's are designed for the track, not the other way around.

If you want some more reliable data, search for some of the Caterham telemetry traces they used to upload in high res a few years ago. You can calculate the radius from the lateral acceleration and the velocity then add half of the track width.

You know the first corners are tight to create overtaking opportunites right? If you increase their radius, the braking distance will shorten and you will see less overtaking.

[Jersey Tom]

However, I am not modeling the turn radius of the cars for analytical purpose;
I am starting to draft a proposition to FIA regarding future track approval rules.
F.ex, several of the start incidents during 2016 can be blamed on over-tight first corners,
(in addition to occasional clumsy driving), and my proposition will include a demand that
corners should, in general, be negotiable without blocking the entire (or most of) the track.

And on whose behalf are you drafting this proposition? What weight is it going to carry so that it doesn't get tossed in the bin?

I'd say there are two options for this on two ends of the spectrum. To the casual outsider just curious about the question, I'd go with Tim's approach and assume that the hairpin at Monaco is about as tight a corner as you're going to navigate.

Alternatively, if you want to be making serious safety recommendations, I'd say you need to have tremendous analytic ability going along with reams of statistical and predictive / simulation data that definitively proves your point. Answers on an internet forum are not exactly best practice there, to put it mildly. If you know a lot of people in the sport, working directly for the teams, you'd get a better answer.

Just trying to gauge where exactly you're at with this.

[Neo Love]

Well, if all tracks have less tight corners, teams will design cars accordingly, with smaller steering angles. Only way I see of enforcing steering angles sufficient for sub optimal corner trajectories is if it is written in technical regulations.

I agree.. FIA's rules need to address both car design and track design.

That's pretty much what I said. The car's are designed for the track, not the other way around.

Yes, I understand that. But can you see the vicious circle here?
FIA has done a great job of increasing the safety in this high risk sport by addressing car design.
I believe that it's now time to take a closer look at what kind of tracks are approved for the rounds.

You know the first corners are tight to create overtaking opportunites right? If you increase their radius, the braking distance will shorten and you will see less overtaking.

Well, I think there's tight.. and then there's /too/ tight..
I think it's madness to have corners like the hairpin a Spa, with a radius so tight that a
cornering car will block the entire track at corner exit.. Just review the F1 Spa start this year!
And the hairpin at Monaco..? The cars have to be rebuilt and follow the kerb along
the outside radius in single file at ~50 km/h just to get around it. Madness.
And some tracks are so narrow that (slightly exaggerated) the only way to win is
to win the pole, or hope someone in front of you crashes or makes a pit mistake.

And on whose behalf are you drafting this proposition?
What weight is it going to carry so that it doesn't get tossed in the bin?

On behalf of the sport as a whole..
Common sense can go a long way even without red tape.

If you know a lot of people in the sport, working directly for the teams, you'd get a better answer.

I wish I did, but I'm just a concerned citizen who sees madness proliferate
in one of the most dangerous sports in the world. Much as I love to watch the races,
I am concerned about the lack of common sense in some regards.

Best Regards
// Neo

[mertol]

If a team decides it is advantageous to have their cars unable to go on the inside of the thightest turns they should be allowed to do so. I'm sick of nonsensical rules as it is.