Model S to the Nürburgring Next Week!

[PhilDavid]

So I just thought of something...

Wouldn't it be absolutely bonkers if Tesla sets a EV record with the car driving on Autopilot? It would basically turn the Model S to the greatest amusement park ride.

This would highlight Tesla's Autopilot as well as performance capability.

I bet they can program Autopilot software to wring out every absolute millisecond of performance possible -- better than any human could -- by constantly monitoring all of the car's sensors and modulating ABS, throttle, and steering. Plus no other automaker will be able to match this capability as no one else is shipping cars with the hardware needed to do this.

Imagine if when you drive a Model S to the Nurburgring track, a button appears labeled:

Autopilot, around Nurburgring we go! | No, I want my mommy!​

 

[wenkan]

What I heard now is Tesla has reserved “industry pool” time of the ring. It’s something similar to the touring sessions but with manufacturer test cars only (so the traffic should be better than most of the BTG videos we see).

Although there will not be comparable lap record, it will still have at least a good BTG video for us to reference. From my opinion if Model S can do a 7:20-ish BTG, it’s still a win against Taycan considering the huge price gap.

 

[PhantomX]

So I just thought of something...

Wouldn't it be absolutely bonkers if Tesla sets a EV record with the car driving on Autopilot? It would basically turn the Model S to the greatest amusement park ride.

This would highlight Tesla's Autopilot as well as performance capability.

I bet they can program Autopilot software to wring out every absolute millisecond of performance possible -- better than any human could -- by constantly monitoring all of the car's sensors and modulating ABS, throttle, and steering. Plus no other automaker will be able to match this capability as no one else is shipping cars with the hardware needed to do this.

Imagine if when you drive a Model S to the Nurburgring track, a button appears labeled:

Autopilot, around Nurburgring we go! | No, I want my mommy!​

So this has been done before by Audi at Hockenheim, which is another famous German race track. Here is the video.

 

[PhantomX]

BTW, I would bet there is no car/machine out there, today or near term, that can drive as fast as a top driver on Nurburgring. The machine will always default to the safer approach, which means slower. Also, no car today has enough sensors with enough data fidelity to understand real time effect of tire degradation to the track surface, nor able to adjust lines to find the fastest lines to counter changes in handling behavior. There often is a very fine line between a fast lap and a crash. Unless one is willing to let the machine crash the car, it will never be able to push the car hard enough to equal that of a human.

 

[Realist]

The Ring is different to other circuits. You just can‘t go there and set a record out of the box.

Porsche does hundreds and hundreds of laps before making that final attempt. Everything has to be perfect, driver, car, conditions.

If you have never been to this track before you have no idea how fast 7:42 really is, especially in a car with more than 2 tons and only 260kph on the main straight.

 

[whitex]

I am an electrical engineer, and formerly worked at Enphase, a solar inverter company. Our inverter was bi-directional, and used in our storage product (a competitor to Tesla's power wall). One side hooked to AC, one side hooked to DC, and you could command the control circuitry to push power either direction, using the exact same transistors - just the timing was different. It could move the same number of Watts in either direction.
I have not seen schematics for Tesla's inverter, but strongly suspect it uses a similar topology. There is no reason for different power hardware for drive and regen.

You can design multi-purpose symmetric inverter/rectifier but that reverse capability does not come for free, like motor turning into a generator, it has to be designed that way (like in the case of solar power inverters). It would not make sense for Tesla to pay for extra in parts or even testing to make the inverter be able to regen at the same rate as driving (450W for performance MS). But hey, as a number of people have pointed out, the Model S going to the ring is probably not stock, so it would have any inverter they wish.

 

[TIppy]

You can design multi-purpose symmetric inverter/rectifier but that reverse capability does not come for free, like motor turning into a generator, it has to be designed that way (like in the case of solar power inverters). It would not make sense for Tesla to pay for extra in parts or even testing to make the inverter be able to regen at the same rate as driving (450W for performance MS). But hey, as a number of people have pointed out, the Model S going to the ring is probably not stock, so it would have any inverter they wish.

Did you read this?
The Magic of Tesla Roadster Regenerative Braking

It's all just a matter of how the frequency and phasing of the rotating magnetic field are set up in the inverter.

The three phase h-bridge can convert dc to ac or rectify ac to dc.

 

[Xenoilphobe]

I’m in Germany this week. Can you buy tickets to Nurburgring?

Never mind, just checked it’s 90 minutes away and you can actually Rent a car for a run.

Nürburgring - Touristenfahrten - Fahraction

 

[Magellan55]

Given how cautiously and unconfidently my car navigates a cloverleaf today on NoA, I just can't see it doing anywhere near the speed of even an amateur race driver around a race course. It's not just slow, it reminds me of my teen driver, speeding up, slowing down, bouncing a bit from one side to the other of the curve as it feels it's way around.

That Audi video was impressive, but how much custom programming and non-stock sensors and computing power was added to do that demo? It reminded me of a high tech version of those toy cars I grew up with that you insert a shaped cam into that the steering follows so you can make the car do a figure eight or whatever on the street. I doubt you can take that car to any other racetrack and have it repeat, without tuning it for that racetrack too.

IMO even more impressive would be to show up at a racetrack in a stock car and have it do any kind of lap time on it's own, having never been there before, no site-specific programming, no high-def map for the computer to follow. And then have the car get faster on each successive lap, as it learns the track on it's own. Heck throw in a rain shower and watch the car adapt. That to me is true autonomous driving.

 

[dark cloud]

The Ring is different to other circuits. You just can‘t go there and set a record out of the box.

Porsche does hundreds and hundreds of laps before making that final attempt. Everything has to be perfect, driver, car, conditions.

If you have never been to this track before you have no idea how fast 7:42 really is, especially in a car with more than 2 tons and only 260kph on the main straight.

They can adjust the top speed with software; not sure how high it can go "safely", but maybe they will bring one with an extra gear ratio. The weight is actually an advantage: less aero and downforce needed for the corners = higher top speed on the straights.

Edit: oh, and maybe they will bring an extra "turbo"

 

[PhantomX]

They can adjust the top speed with software; not sure how high it can go "safely", but maybe they will bring one with an extra gear ratio. The weight is actually an advantage: less aero and downforce needed for the corners = higher top speed on the straights.

Weight is never the same as downforce, because downforce never changes and is always pushing the car down. Weight is inertial loads, which is mass x acceleration. When pulling high g in turns, the mass is actually pushing the car outward (mass x centrifugal acceleration), and this is not good for tire traction. The same challenge comes in at deceleration as well. The braking g force will increase the forces tires need to hold to slow down the car. And the mass adds to the kinetic energy the brake needs to dissipate when slowing down. This is is why race car is always built as light as possible and with as much downforce as possible.

 

[TIppy]

with as much downforce as possible.

It seems like there would be a trade off here. You don't get downforce for free; it increases aerodynamic drag and rolling resistance.

 

[Dangerous Fish]

You would need massive spoilers on a road car to gain a significant benefit from downforce.
Spoilers on a road car are usually there for stability not downforce.
Getting a car like the Model S through corners fast is all about mechanical grip.

 

[dk10438]

They can adjust the top speed with software; not sure how high it can go "safely", but maybe they will bring one with an extra gear ratio. The weight is actually an advantage: less aero and downforce needed for the corners = higher top speed on the straights.

Edit: oh, and maybe they will bring an extra "turbo"

disagree
weight is always a disadvantage at the track.... You need more energy to stop, more energy to accelerate, more friction to corner. So nothing but negatives. The one area where it might help is traction for straight-line acceleration. Really wondering how the Tesla brakes will hold up with such a heavy car. My GTR had 390 mm 6 pot front brakes and they were prone to overheating at the track and it's over 1000 lbs lighter. When I look at my MS brakes they like downright puny

 

[dark cloud]

Weight is never the same as downforce, because downforce never changes and is always pushing the car down. Weight is inertial loads, which is mass x acceleration. When pulling high g in turns, the mass is actually pushing the car outward (mass x centrifugal acceleration), and this is not good for tire traction. The same challenge comes in at deceleration as well. The braking g force will increase the forces tires need to hold to slow down the car. And the mass adds to the kinetic energy the brake needs to dissipate when slowing down. This is is why race car is always built as light as possible and with as much downforce as possible.

Well as someone with a physics degree I am just going to say centripetal; not centrifugal. But yes; more mass = more resistant to change direction and more resistant to slow down: more braking force needed to reduce speed.

Inertia wants to keep doing what it is doing. (Thank you Isaac Newton)

But the most important thing is not power but getting power to the ground.

I am not disagreeing with anything you are saying, but I will explain my point with a formula one car: It has twice the force towards the tarmac; that is twice the weight at speeds above 100mph due to its ground effects (aero). yes, that means it can drive upside down in a tunnel at high speeds. It actually accelerates quicker from 100-200 than it does from 0-100 because of this added "weight" . Weight (force of gravity) is traction. (as well as coefficient of friction between hot rubber and asphalt)

so if there is a huge amount of downforce which essentially turns a 740 kg racecar into essentially a 1600 kg car at higher speeds, is that not the same as having to turn a 1600 kg car in the corners and slow it down?

The reason they want a light weight on a racecar is really for acceleration ( estimate 7 lbs = 1 hp); to which the electric vehicle has no issue with.

 

[PhantomX]

It seems like there would be a trade off here. You don't get downforce for free; it increases aerodynamic drag and rolling resistance.

That's correct. Everything is a trade off. For a F1, which is the extreme case, the car gets 1G of braking force just from drag.

There are different way to get downforce, including using ground effect. That's more efficient than using wing, but it still increases rolling resistance. And a poorly design ground effect can be sensitive to car pitch changes, and cause undesirable instability.

 

[PhantomX]

You would need massive spoilers on a road car to gain a significant benefit from downforce.
Spoilers on a road car are usually there for stability not downforce.
Getting a car like the Model S through corners fast is all about mechanical grip.

I am sure the spoiler on the Taycan does generate meaningful downforce at speed, especially the high speed sections of the Ring. It won't be like the GT3 cars, but many of the high performance cars these days with active aero devices do generate useful downforce.

But yes, mechanical grip is still very important, which is why the car needs as much tires as possible and the suspension geometry and weight balance are extremely important.

 

[tga]

so if there is a huge amount of downforce which essentially turns a 740 kg racecar into essentially a 1600 kg car at higher speeds, is that not the same as having to turn a 1600 kg car in the corners and slow it down?

No, because when braking the 1600kg car, you have to overcome the inertia of 1600kg. On a 740kg car with 860 kg of downforce, you only have to deal with 740kg worth of inertia. Same thing with cornering.

Even if that weren't the case, the reduction in "weight" as the car slows and downforce drops would make braking/cornering easy. You aren't cornering at the same speeds that you reach on the straights.

 

[dark cloud]

No, because when braking the 1600kg car, you have to overcome the inertia of 1600kg. On a 740kg car with 860 kg of downforce, you only have to deal with 740kg worth of inertia. Same thing with cornering.

Ah, yes you are correct. And now it is forever in print. You are more awake than I am this morning. I am humbled.

Even if that weren't the case, the reduction in "weight" as the car slows and downforce drops would make braking/cornering easy. You aren't cornering at the same speeds that you reach on the straights.

True. Another direction I was going with this was that with a lack of downforce and the lack of drag at high speed a car with high weight will go faster more easily than a lighter one with plenty of aero wings. But again the Tesla may be top speed limited.

disagree
weight is always a disadvantage at the track....

Again, this is true in most instances but just to point out a caveat: typically one gets larger tires for racing, which are heavier than skinny ones. In this instance the tradeoff for increased weight is trumped by greater traction.

 

[tga]

Ah, yes you are correct. And now it is forever in print. You are more awake than I am this morning. I am humbled.

Well, remember, it's still early on a Sunday morning on the west coast - I've got an extra 3 hours of wake/caffeine consumption time. Is your post edit window still open? You can delete the evidence!

True. Another direction I was going with this was that with a lack of downforce and the lack of drag at high speed a car with high weight will go faster more easily than a lighter one with plenty of aero wings. But again the Tesla may be top speed limited.

Agreed - but it's easy to increase horsepower (at least in a ICE) to offset increased drag from wings/ground effects, etc.

Again, this is true in most instances but just to point out a caveat: typically one gets larger tires for racing, which are heavier than skinny ones. In this instance the tradeoff for increased weight is greater traction.

Which also increases unsprung weight and causes handling issues. As you say, lots of tradeoffs.