[HO] Project CARS

Had a great weekend driving the Lotus 98T Renault Turbo !

The graphics take you back to the 80's and i should have known this car would be a blinder - a fitting tribute to Ayrton Senna who made this machine dance like no other.

Well.. This car is awesome!! It is unique in so many ways and for me the most fun to drive, the most forgiving and the most rewarding.

Bologna / Imola

Graphics

I love the driver position right on top of the wheel. Crucially the screen rotates ever so slightly when the car BEGINS to slide and that really helps the drivability. There’s also a sense of dive on the brakes and turn in.

Turn In

This car really goes where you point it. I can put it all the way over the kerbs and actually feel it squirm at the rear to let me know it’s on the limit – ‘don’t push your luck’!

Braking

It stops beautifully but the fantastic thing with this Lotus is the way it punishes you if you squeeze a fraction too hard at the end of the braking zone. Very accurately, once the downforce has bled off and the tyre no longer has that support, this car starts to lock a front and / or a rear tyre. It’s magic.

And the best part is that these slides are recoverable. When a rear tyre snatches you can pulse the brakes, and the tyre responds immediately. This means you can really push the car.

Transition

The transition from grip to sliding in this car is superb.

It allows gradual on power slides: Entering the skid is quite gradual and with some help from steering feedback it would be extremely life like

It also allows off power slides when you overcook it on corner entry with too much brake (locking the rears) or just too fast. The great thing with the Lotus is that you end up very sideways, eating up the track until the speed rubs off and then back under control. Bang on.


Mid corner

The real life steering lets this car get placed wherever you like – it has really good mid corner grip and feel

Traction / corner exit

I pick up a little of the sim’s understeer on the exit of the last two corners at Imola

Most of the time the car is beautifully balanced and you can squeeze the throttle with a sense of the car gradually reacting to your input.

Overall

Just superb. The way the Lotus 98T darts around feels aggressive, and just like the real thing.

PS Ryan Caines did a sweet job to manage a 1min 18 second lap around Bologna in the Renault – would love to see the video. Smoking laptime dude!

HI ANDY / CASEY & THE PCARS TEAM

PLEASE EXCUSE MY ABSENCE FOR SO LONG I’VE BEEN BUSY WITH MR BOND LATELY!

I’M NEW TO THE TECHNOLOGY YOU GUYS ARE USING TO CREATE THIS AMAZING SIM SO PLEASE ALSO EXCUSE A LOT OF IGNORANCE ON MY PART REGARDS THE TOOLS YOU HAVE TO PLAY WITH IN DEVELOPING THE CHARACTERISTICS. YOUR ACHIEVEMENTS SO FAR HAVE BEEN SUPERB AND A GREAT EXPERIENCE TO DRIVE.

TO HELP ME CATCH UP I’VE BEEN GOING THROUGH ANDY’S POSTS AND WRITTEN UP MY THOUGHTS IN BOLD. HOPE SOME OF THESE ARE USEFUL – MY SYNOPSIS OF THE ASANO LMP, THE FORMULA A AND THE LOTUS 98T AT THE END.

AT SOME POINT IT WOULD BE GREAT TO UNDERSTAND THE DIFFERENT TYRES BEING USED ON DIFFERENT VEHICLES – HOW THEY WORK AND WHAT THEY ADDRESS. MY GUT FEELING IS THAT SOMETHING VERY ‘SOFT’ MIGHT BE ON THE LOTUS 98T?

The snap oversteer is inherent with a steady state tire model. It underestimates grip during dynamic transition in a corner. GPL had it. rF1 had it. iR OTM has it peek through their patch-ups from time to time. Even nKp used to have it. The dynamic tire models tend to not have it, such as LFS, VGP3, and maybe rF2. Based on comments, it is still very unclear what iR NTM is really doing.

So everybody and their mother using a steady state model has to find ways to patch it up. How I did it with rF1, given that all I had was the parameters they expose in their tbc files, was to exaggerate pneumatic trail....dramatically. Like an order of magnitude dramatically.

I do not recommend we do that, since that has side effects (thick feel and some understeer on turn in)

THE SNAP OVERSTEER IS VERY APPARENT IN THE ASANO LMP. MORE ON THAT AT THE END OF MY REPORT BECAUSE I JUST TOTALLY FELL IN LOVE WITH THE LOTUS 98T. IT IS THE UBER-MACHINE.

A) Stiffening up, as suspected, might fix wandering. But in a moddable sim, we might still want overly-accessible cars to work well (meaning with very soft tires, high optimum slip angles, little drop-off past peak alpha, etc). We also do not want drifting purposed cars to wander down straights.

I WONDER WHAT YOU MEAN BY WANDERING – I NOTICE THE 98T DOES IT SLIGHTLY BUT IT’S SO GOOD THAT’S NOT A COMPLAINT.

B) The steady state liability still exists, even though it may be minimized, and with the soft-tire parameters, it may be easier to judge non-stiffness based fixes. IOW, we have a known dragon lurking, and some high confidence ideas to slay that dragon.

C) Flat or flattening tires. A compromised tire will be soft.

D) As good as possible approximation of a dynamic model. I hope to get the true dynamic model in that I've been working on, eventually, but when that happens we'll still need a steady state approximation for AI, latency hiding, etc (due to CPU budget).

ONE DAY I HOPE TO LEARN WHAT SOME OF THIS MEANS!

Grip changes with load even without what is called "load sensitivity" (bolt on or not), since overall grip is directly related to Fz (load). "Load sensitivity" is the changing of the proportion of perfect grip (Cf * Fz) actually available, and the shifting of optimum slip angle. I do not have the code in front of me (I'm at my day job), but if the graphs are calling GetForce from the tire model directly, then they are probably missing the bolt-on load sensitivity.

INTERESTING POINT WITH LOAD! WITH THE LMP AND FORMULA A I DON’T GET THE SENSE OF THE FRONT OF THE CAR ‘LOCKING IN’ AT HIGHER SPEEDS, ESPECIALLY ON CHANGE OF DIRECTION. WHEN IT GOES INTO U/STEER IT SEEMS TO BE A MASSIVE SKID AND DABBING THE BRAKE / BLEEDING SPEED OFF DOESN’T RECOVER THE SITUATION.

THE SIM IS ALSO ACCUTELY LINE SENSITIVE – WHICH IS A GOOD THING IN MANY WAYS. I NOTICE THIS ESPECIALLY EFFECTS FRONT GRIP AND AGAIN IS VERY PUNISHING WHEN YOU OVERCOOK THE SPEED SLIGHTLY.

EXCEPT WITH THE LOTUS 98T. THAT LITTLE BEAUTY TRIES TO HELP YOU DIG YOURSELF OUT OF TROUBLE.

I also examined more closely what the tires are actually doing to wander, and like I just mentioned, they tend to take off-center 'sets' that cannot be perfectly balanced in all cases, due to the different load balances, etc. I think this is actually somewhat correct, at least qualitatively. Take out a real car or kart with very low tire pressures and see what it does....it can do exactly that. So with Mz in there, and the stiffening of the parameters, I think this particular wandering issue may 'solved' in that we understand it.

To get the kart hop (if it is like a real-life kart hop, which is the outside-rear binding up like a jack hammer) you'll also probably want to mix in some rear axle effect, thereby emulating a little more pants-feel with hands-FFB. The trick there will probably be to avoid diluting the front FFB with rear FFB when things are nominal (not hopping, etc).

KART HOP IS REALISTIC BECAUSE THERE’S NO SUSPENSION IN A KART - WHEN THE KART REALLY GRIPS, AND THEN MOMENTARILY EXCEEDS THE LIMIT OF TRACTION THERE IS A SUDDEN HOP AS THE RUBBER RE-CONFORMS, THE TAIL SKIDS AND THEN RE-GRIPS. THE FORCES ARE STRONG ENOUGH TO CRACK RIBS!

THE REALITY HERE WILL BE SIMULATING THAT AGGRESSIVE LOSS, THEN RECOVERY OR GRIP WHICH IS TAKING PLACE SEVERAL TIMES PER SECOND.

Another issue is the zero torque at zero speed, which is very unlike a real steering wheel we all know pulling out of our driveways. That is of course due to the brush model being out of its range at low speed. (side note: my dynamic model does have resistance at zero speed, naturally just falling out -- just pitching when I can ). We should be able to blend in something at near-zero speed to cover up the low speed issue, very analogous to how we have the grip point model blended in for the behavioral side.

THE STEERING TORQUE IS A FASCINATING ISSUE – IN REALITY THERE IS SO MUCH FEEL THROUGH THE STEERING WHEEL AND I WONDERED IF WE COULD DO MORE TO TAILOR THE FEEDBACK.

AT THE MOMENT THE TUGGING SENSATION WHEN YOU LOCK A WHEEL IS SUPERB WHEN YOU ARE DRIVING WITHIN THE CARS’ OPTIMUM PARAMETERS. COULD WE TRY AND BUILD IN MORE TORQUE AS THE CAR LOADS UP / GAINS GRIP ON TURN IN, AND THROUGH THE APEX, SO YOU CAN FEEL THE POINT AT WHICH YOU TAKE THE MOST GRIP FROM THE FRONT TYRES – THEN THAT TORQUE LESSENING AS YOU PICK UP UNDERSTEER OR OVERSTEER (WHICH HAS A SIMILAR FEELING BECAUSE EVERYTHING SEEMS TO GO LIGHTER AT THAT POINT) ?

THIS WOULD BE A SUPERB WAY FOR THE DRIVER TO INTERACT WITH THE CONSTANTLY CHANGING DYNAMICS OF THE CAR / TYRE THROUGH A CORNER AND ENABLE YOU TO ‘DRIVE THE HELL OUT OF IT’ WITH MORE CONTROL AND FINESSE.

DIFFERENT CARS SUCH AS THE F1, LMP (IE HIGHER DOWNFORCE MODELS) NATURALLY TEND TO EXAGGERATE THIS SENSE OF TORQUE, AND MORE ON A TRACK WITH MORE RUBBER ON THE RACING LINE. WHEN THE CAR “HOOKS UP” ITS WHEN YOU’RE ON THE RIGHT LINE AT THE RIGHT SPEED WITH THE TYRES STRETCHED TO THEIR OPTIMUM.

What I am working on at this moment, today, is the curbs.

Note that these graphs are even at zero slip, so it is not even a model-thing being too insensitive w/o any slip angle. Mz is pretty small in these particular graphs because there is no much pneumatic trail in the case. Through your current FFB, which includes rackForce, which includes mechanical trail in addition to pneumatic trail, we should be feeling substantial curb torque. But we are not. So I suspect the model is not getting the input it should.

WHEN YOU DISCUSS SLIP & SLIP ANGLE ARE YOU REFERRING TO THE RATE OF YAW THE TYRES ARE CAPABLE OF WORKING TO ? OR ACTUALLY THE ANGLE OF THE TYRE RELATIVE TO THE UPRIGHT? I’M NOT SURE I UNDERSTAND HOW YOU’RE USING THIS.

A FEW YEARS BACK I USED TO RACE ON WHAT WAS KNOWN AS CROSS-PLY TYRES AND TYRES WITH SIMILAR CHARACTERISTICS – WHICH BASICALLY MEANT A SOFTER SIDEWALL THAT GRIPPED THE ROAD WITH A GREATER ANGLE OF ATTACK (SLIDE / YAW RATHER THAN SLIP ANGLE) AND WAS ALSO OPEN TO ‘OVERDRIVING’ BECAUSE YOU COULD DRIVE THE CAR VERY SIDEWAYS BUT LOSE LAP TIME IN THE PROCESS.

THE RADIAL TYRES TIGHTENED UP THAT TREND BUT EVEN SO IT’S POSSIBLE TO SLIDE ON THEM AND TO SOME EXTENT THERE’S NEARLY ALWAYS AN ELEMENT OF DRIFT FROM THE BACK END FROM APE THROUGHG EXIT AS THE CAR BALANCES ON POWER. IN MODERN CARS IT’S JUST VERY SUBTLE AND YOU HARDLY NOTICE THE DRIVER PLAYING THE STEERING WHEEL, BUT HE IS.

KERBS

I’VE BEEN SMASHING THE KERBS AT IMOLA AND THE CAR IS REALLY GOOD ON THEM. IN REALITY WHAT YOU TEND TO GET ON SOME OF THEM (LIKE THE LAST 2 CORNERS AT IMOLA) IS AN INCREASE IN FRONT GRIP AS IT PICKS UP THE INSIDE OF THE CAR AND FORCES ADDITIONAL LOAD ONTO THE LOADED FRONT TYRE, AND OFF THE INSIDE REAR. THAT’S WHERE IT WOULD BE NICE TO SEE A LITTLE MORE RESPONSE THROUGH THE APEXES WITH THE REAR SQUIRMING A TOUCH.

ON THE BIGGER KERBS LIKE THE TOP OF THE HILL AT IMOLA, THERE CAN BE A VARIETY OF CONSEQUENCES IF YOU GET GREEDY. THE INSIDE WHEELS GO AIRBORNE, IF TOO MUCH THEN YOU LOSE FORWARD MOMENTUM (SPEED) AND GET BUMPED WIDE – THEN IF YOU TRY AND DIG YOURSELF OUT WITH THE THROTTLE IT WILL USUALLY OVERSTEER. AT THE MOMENT THE PENALTY IS MOSTLY U/STEER.

OH – AND THE LOVELY SOUND OF CARBON AND WOOD GOING BANG, STRAIGHT INTO YOUR SPINE – ALSO WORTH PUTTING SOME KICK THROUGH THE STEERING AS YOU DO FEEL THE KERBS PULLING WHEN YOU RIDE THEM AND YOU HAVE TO MANHANDLE THE STEERING.

CARS Feedback Jan 6 2013

Version 377

Asano LMP

Spa & Imola

Been a while since I took the LMP out. By comparison to the Formula A now it feels a touch behind in terms of feel, though I still enjoy it.

Graphics

I think I was told previously that you could move the driver’s POV further forward in the cockpit – but I’ve forgotten how to do that!

In the standard config the driver is too far back with a bit too much view of the cockpit and not quite enough of track. Compared to the F1 and the 98T I don’t get as much feel of the car diving on the brakes and reckon this would help too.

Turn-In / Mid corner

The main issue in the LMP is turn-in. The modern cars are much more ‘pointy’ on corner entry and you can really push the nose in. The LMP should dart towards the apex more. At the apex it really washes out with too much understeer – some of my comments regards Torque feedback would really help with this but essentially it’s a balance thing.

I tried both ends of the spectrum on setup (super stiff / soft – high / low downforce) to no avail and died countless times on the track. My pride is in ashes..

Traction & sound

Coming out of corners the Rear goes into a slide with too little warning. I find myself listening for any sign of tyre squeal or a shift in yaw (translated through the forward field of vision rotating) to try and detect when the tail will start spinning.

I think sound effects could be helpful but essentially the rate of slide is too fast and in reality the transition from grip (u/steer in the case of LMP) to o/steer is more gradual and controllable.

*NB the Lotus 98T is more gradual – it’s superb. Also there are more visual cues as to when the car is beginning to yaw and you realise you’re on thin ice.

Steering Feedback

Mentioned above but it would really help the LMP especially for the steering to go more heavy to indicate grip, looser for sliding. I think this would also add something in the braking areas.

Braking

When you are right in the zone where the car wants to be in – the braking has a balance to it and you can sense a lock up via the steering feedback. When you’re out of that zone and brake too late / hard – there’s too much front skid.

The Lotus 98 has this magic quality under braking where it throws some snap oversteer at you if you overdo it. This is very realistic, especially at the end of braking when the downforce has come off.

Ideally I think the LMP should benefit from more load / grip when you first hit the brakes, then it becomes possible to lock the front or rear tyres a little and scrabble into the corner.

Formula A

Imola (Bologna)

Graphics

Phenomenal. The clarity of the circuit and the position of the driver is awesome.

Braking

The Formula A is superb on the brakes and very realistically takes the speed off.

Turn In

The rate of turn in the F1 feel more positive in that you can take a bit more of a line over the kerbs than is possible in the LMP. Still I would love to see a much more aggressive turn in from the F1, to the point of possible turn-in oversteer.

Traction

My remains are scattered across the countryside from over enthusiasm on power. Similar to the LMP the transition from grip to death is quite abrupt.

Similar feedbacks in the steering would help, as would sound. At the moment the sound of wheelspin, which I’m sure is real, doesn’t indicate when the car will spin. That seems to be another lateral function in the tyre model and I’ve found it hard to ride the limit.

Engine Power

I’ve been thinking hard about traction and power for the F1. Somerhow I think it would benefit from more acceleration power, especially when you first apply the throttle. By that I mean: is there a way to make the throttle more sensitive and to have more power attached to it so that you have to apply it a bit more gradually?

This would only work if we can add in some compliance in the way the rear tyres break traction but I just feel we are a touch down in terms of punchy acceleration out of corners compared to the real thing.

Lotus 98T Renault Turbo - Bologna

This car is awesome!! It is unique in so many ways and for me the most fun to drive, the most forgiving and the most rewarding.

Graphics

I love the driver position right on top of the wheel. Crucially the screen rotates ever so slightly when the car BEGINS to slide and that really helps the drivability. There’s also a sense of dive on the brakes and turn in.

Turn In

This car really goes where you point it. I can put it all the way over the kerbs and actually feel it squirm at the rear to let me know it’s on the limit – ‘don’t push your luck’!

Braking

It stops beautifully but the fantastic thing with this Lotus is the way it punishes you if you squeeze a fraction too hard at the end of the braking zone. Very accurately, once the downforce has bled off and the tyre no longer has that support, this car starts to lock a front and / or a rear tyre. It’s magic.

And the best part is that these slides are recoverable. When a rear tyre snatches you can pulse the brakes, and the tyre responds immediately. This means you can really push the car.

Transition

The transition from grip to sliding in this car is superb.

It allows gradual on power slides: Entering the skid is quite gradual and with some help from steering feedback it would be extremely life like

It also allows off power slides when you overcook it on corner entry with too much brake (locking the rears) or just too fast. The great thing with the Lotus is that you end up very sideways, eating up the track until the speed rubs off and then back under control. Bang on.


Mid corner

The real life steering lets this car get placed wherever you like – it has really good mid corner grip and feel

Traction / corner exit

I pick up a little of the sim’s understeer on the exit of the last two corners at Imola

Most of the time the car is beautifully balanced and you can squeeze the throttle with a sense of the car gradually reacting to your input.

Overall

Just superb. The way the Lotus 98T darts around feels aggressive, and just like the real thing.

PS Ryan Caines did a sweet job to manage a 1min 18 second lap around Bologna in the Renault – would love to see the video. Smoking laptime dude!

BUG: I noticed that if you take a slightly wide line on the exit at Piratella is flips the car onto its roof – I also noticed my competitors having similar trouble on the start finish straight when they were left of the ideal line.