Audi LMP1 Discussion

[TF110]

During the race when the E-tron pit the tires on the front looked bad. Maybe that was a one-off issue, but I remember the commentators saying the tire wear was worse than on the Ultras. Did they just speculate then?

[CTD]

Originally Posted by TF110

During the race when the E-tron pit the tires on the front looked bad. Maybe that was a one-off issue, but I remember the commentators saying the tire wear was worse than on the Ultras. Did they just speculate then?

Could be setup, if there is any tire wear difference between the E-tron and the Ultra.
We know that there was setup difficulties with the Etron

[TF110]

I'm just wondering because I thought I heard that the tire wear was questionable on their E-Tron. I could be hearing things or maybe heard wrong. If it is I doubt they'll have much trouble with it at LeMans.

[gwyllion]

According to McNish in http://www.youtube.com/watch?v=XiH6ttjB9Cs#t=1m13 the tire wear is similar between both cars.

[chernaudi]

McNish has said that in testing, tire wear between the two cars are virtually the same, and the drivers complained about a lack of heat in the front tires until late in the event due to the dryer track.

This seems to hint--intentionally or inadvertently--that the e-trons were set up maybe with a bit too much of a bias towards wet conditions, almost like the front suspension was set up a bit too soft or a bit too compliant. The Ultras may've run a stiffer set up up front, which to a slight extent may explain some of the wet weather pace difference, but why the Ultras picked up the pace as a dry line formed. And considering his wet weather F1 and LMP1 experience, that's probably what encouraged Gene to change on to slicks before everyone else.

As CTD mentioned, the Ultra may share it's tub with the e-tron and about everything else, but lacking the hybrid AWD system, those guys can rely more on the notes from 2011 if they get in a jam compared to the e-tron, which Fassler, Ben, and Allan have mentioned does drive sliglty but noticeably different until you get used to it. Both cars are different than the '11 cars with improved areo, weight distribution, and improved grip and handling, but the e-tron system does make the cars handle slightly differently when it's activated.

[gwyllion]

I am not convinced that the understeer issue has to do with the suspension settings. It could also be a weight or aero balance problem. In the ultra they have a lot of ballast weight that can be moved around freely.

In http://www.lemanslive.com/en/2012/05...llon-flat-out/ Dumas explains that "the new R18 ultra is completely different to the R18 TDI" and that he could do Raidillon flat out for the first time in an Audi prototype. The front suspension and the steering have been changed significantly since last year.

[gwyllion]

Originally Posted by gwyllion

I had a look at the timing information from Spa. The R18 e-tron quattro did 23 lap stints and the R18 ultra 24 lap stints. Last year Audi and Peugeot also did 24 lap stints at Spa.

So Audi does is suffering much less than expected from the fuel tank reduction: in 2011 65 liters and in 2012 60 liters for non-hybrid and 58 liters for hybrid.

In http://tentenths.com/forum/showthrea...43#post3070743 I calculated the average of 20% fastest race laps for the different LMP1 cars. That avearge lap time was around 2:05 for both versions of the new R18.

Out of curiosity I decided to compute the same metric on the timing data from the 2011 race.

• Audi #1: 2:08.4
• Audi #2: 2:06.8
• Audi #3: 2:07.4
• Peugeot #7: 2:06.9
• Peugeot #8: 2:07.0
• Peugeot #9: 2:06.9
• Oreca Peugeot #10: 2:09.4
• Rebellion #12: 2:10.5
• Rebellion #13: 2:11.5
• Pescarolo #16: 2:11.5

These numbers show that the Audi got quite a bit quicker this year, while still using less fuel during a stint. Of course, the weather conditions were completely different last year: around 25°C (2011) vs 8°C (2012).

[TF110]

Doesn't cooler weather allow for better engine performance? I'd like to know how the difference in temperature affects the power the engines put out. Also tire construction may be better this year? And temperature can have an affect on grip as well. But it seems that even with the smaller tanks and less power, the Audi has gained what they lost and some. I think last year with the fact the R18 was a new concept to them in terms of the car being a coupe compared to this year, they can make better gains with better understanding.

[chernaudi]

I still think based on driver comments that it was probably a set up issue, and some other factors seem to be playing into this, me being as out of the loop as anyone else here. The e-trons were marginally faster than the Ultras in each practice session, but the keyword is marginally--it wasn't like the e-trons were off in another time zone, the times usually being a matter of tenths of a second a lap, and only a few tenths at that.

Also, the e-trons seemed to be faster when the track was warm, as on Friday. I wouldn't put it past Audi that they stuck to a conservative set up and strategy with the suspension settings and tire compound choices on the e-trons as those guys are racing for the drivers' title. The Ultra guys aren't running for points, so why not use them sort of as guinea pigs and let them test a slightly more aggressive set up? McNish's comments post race does seem to suggest that Audi went with the "safe" route on the e-trons as far as set up and tire selection.

But I do think that the Ultra does have a slight advantage over the e-tron right now due to it not having the hybrid system, and that's one less set up variable to deal with. The Ultra chassis wise is as different from the old R18 as the e-tron is, but it's more of an intermediate between the old R18 and the R18 e-tron. And the drivers do say that both cars are a bit different to drive and that some driving style changes are needed to get the best out of either car. So it stands to reason that even though the base setups may be nearly identical, some slight differences are likely because of the individual idiosyncrasies of both cars to optimize them due to those differences.

[MitchZ06]

Originally Posted by TF110

Doesn't cooler weather allow for better engine performance? I'd like to know how the difference in temperature affects the power the engines put out.

Cool air = denser air = more oxygen in the combustion chamber = more power.

That's why dusk is the best time to go drag racing (warm track, cool air) and early morning at Le Mans is called 'happy hour' because the track is well rubbered in, the air is still cool and there's better visibility.

[Adam43]

Originally Posted by chernaudi

McNish has said that in testing, tire wear between the two cars are virtually the same, and the drivers complained about a lack of heat in the front tires until late in the event due to the dryer track.

This seems to hint--intentionally or inadvertently--that the e-trons were set up maybe with a bit too much of a bias towards wet conditions, almost like the front suspension was set up a bit too soft or a bit too compliant. The Ultras may've run a stiffer set up up front, which to a slight extent may explain some of the wet weather pace difference, but why the Ultras picked up the pace as a dry line formed. And considering his wet weather F1 and LMP1 experience, that's probably what encouraged Gene to change on to slicks before everyone else.

As CTD mentioned, the Ultra may share it's tub with the e-tron and about everything else, but lacking the hybrid AWD system, those guys can rely more on the notes from 2011 if they get in a jam compared to the e-tron, which Fassler, Ben, and Allan have mentioned does drive sliglty but noticeably different until you get used to it. Both cars are different than the '11 cars with improved areo, weight distribution, and improved grip and handling, but the e-tron system does make the cars handle slightly differently when it's activated.

If the ultra and e-tron were set-up differently then it hints at a fundamental difference in the behaviour of the two cars.

[chernaudi]

That sort of goes against what Audi has been saying that the cars are essentially identical aside from one having a hybrid system, and the other using ballast to replicate the presence of a hybrid system.

But it is inline with the fact that all the drivers asked do say that the cars do handle differently when the hybrid system is used. Of course, that doesn't answer if the cars have to be set up differently.

I do still think that one factor may be that due to it's newness and the fact that the e-tron drivers are running for the drivers' title, that Audi went with the safe route on setups to give them a car to get a good finish with, whatever within the top 3-4 that would be. The Ultra drivers aren't running for the drivers' title, and hence, there's no need to points race or worry about that, so why not experiment if it can help out the e-tron for LM and later on?

I do think that was a purpose of the test they had on Monday, considering that there are photos of the R18s on track. I do believe that they were maybe performance testing as well as working on other normal things that they do in tests like that (pitstops, repairs, etc).

One interesting point is that the R18 e-tron may not win any straightline speed contests this year unless it's running by itself, as it does seem that the mechanical drag from the front driveshafts does seem to shave about a KM/half a MPH off of the top end speed. That would be an interesting contest as far as elapsed time down a straight--the e-tron will likely have the accelleration edge, but the Ultra might be a hair faster at the speed trap.

[Adam43]

We shouldn't be surprised. They should behave differently, one has power going through the front wheels the other doesn't!

Not sure I get your point about safe set ups and ultras trying something for e-trons?

[gwyllion]

A huge number of pictures from the Spa test on Monday: http://www.flickr.com/photos/saarbur...7629632280764/.
The photographer is clearly employed by Audi Sport because there are no pictures of the car without body work.

Like Treluyer tweeted they did a lot of pitstop practice.

On Saturday I noticed that Audis were smoking enormously at the start grid, when the started their engine are being stationary for a long period of time. This is also visible on this picture:


On one of the pictures Oliver Jarvis has a camera on his helmet. I wonder whether the recorded video is meant for the engineers or for the PR people.


There are some good close ups of the ultra steering wheel:

[gwyllion]

Laurent Chauveau did an interview with Benoit Treluyer on Friday (so before the race): http://www.86400.fr/articles/221-ben...chaque-virageq The article contains a lot of interesting information.

Treluyer tries to explain why the ultra could match the pace of the e-tron quattro.

I confess that I am surprised at the small differential between the e-tron quattro and the ultra. I expected greater gaps, especially in the first part of this circuit with its long straight. But actually, the descent out of La Source probably helps them and in the climb the electric power only longer pushes our car.

He jokes that perhaps they should brake at the entry of Raidillon to get a hybrid boost on the climb He confirms what Dumas said: they can now take Raidillon flat, whereas with the R15 and the 2011 R18 they had to lift the throttle.

The electric boost is a plus but sometimes it can become disruptive, especially in corners with low downforce. And in Pouhon, which is nevertheless a quick double left with a lot of aero load, the actuation of electric motors slightly affect our balance because it already happens on the edge without it. The right front tire is on the limit and suddenly, it is asked a little more by forcing it to drive, so it tends to drop off slightly.

The front-rear (weight) balance is identical for both cars. However, in the ultra has a lower center of gravity because the ballast weight is placed lower than the flywheel and the electric motors. That also improves its behavior with respect to the e-tron.

The hybrid system adds more complexity for the driver.

With a conventional car, there were already a large number of available knobs. Here, we have even more ... My engineer gave me on the radio, the list of everything I had to do in my first few laps. At one point I asked him to start from scratch. I had too much info to handle .. We can manage the electrical power as much as we could already change the mapping of the engine.

Laurent was surprised that the hybrid system was activated after Pouhon, a very fast corner where the drivers do not touch the brake. Treluyer explains that at Spa the electric motors push at the exit of almost every corner.

Treluyer also reveals that they tested the e-tron quattro in the wet at Monza.

[chernaudi]

Right now it's simple as far as the "safe" set up: The drivers in the e-trons are the only ones who matter in the drivers title, as they're the only ones who Audi have entered for the full season. The drivers currently in the Ultra aren't racing for points. Right now, the e-tron drivers are out to score as many points as they can get without taking risks. The Ultra drivers aren't really factoring in the championship, and hence are more likely to be used as guinea pigs to test things for the other cars.

We all know that since Audi has made the investment for the e-tron quattro, that those cars will eventually be favored unless there's some flaw in their design that clearly makes the Ultra the superior car.

Everyone who has tested both specs say that they don't react much differently, but there are differences, but it doesn't dramatically effect tire wear or major settings and other considerations.

I do think that Audi played it safe with the e-trons in terms of drivers points, since Toyota by default have lost that title, and they knew at Sebring and Spa that barring major issues that they'd score maximum teams and manufacturers points. So why not go safe on the e-trons and and use the Ultras to test items for the e-tron? To me, that seems reasonable. After all, the e-trons were faster until the dry section of the race that proved to be the equalizer for the Ultras, and an e-tron topped each practice session (albeit marginally).

I think that between the e-trons being fairly new and the Ultra being much more of an evolution of the '11 cars, it's clear that Audi came to Spa to learn as much about the e-tron in race conditions as possible. Either they tried something for the race that didn't work, or the Ultra had something that worked better for the dry phase. That also makes sense that Audi tested all 4 cars on track Monday per the flickr photos. They're still trying to figure out exactly what works, and it could be something as simple as that the e-trons missed the set up with the change in temperature on the dry but cold track, considering that the e-trons did better in the warmer conditions earlier in the weekend--Dumas did say that the new cars provide and pick up so much feed back that minor changes in track conditions can make a huge difference in the feel of the cars now.

I think that the on-track testing was probably some form of performance test to try setup changes on the cars, though it does seem that they ran in much the same condition that they were at the end of the race at Spa. That being said as far as the sate of the cars, I don't think it was an endurance test in any real form.

And it seems on the garage area photos that Audi may have a new composites supplier other than Gerg:

http://www.flickr.com/photos/saarbur...57629632280764

[chernaudi]

More things to speculate on from Audi: according to illustrations from the Panullo blog the 2012 R18s--irregardless of variant--seem to feature extra ducting inboard of the front wheels with the nose removed. It is hybrid cooling or (more likely?) extra fixed front brake ducts to overcome brake cooling issues from last year? Main brake ducts seem similar to last year's cars:

http://lemansprototypes.over-blog.it/

[Adam43]

Originally Posted by chernaudi

Right now it's simple as far as the "safe" set up: The drivers in the e-trons are the only ones who matter in the drivers title, as they're the only ones who Audi have entered for the full season. The drivers currently in the Ultra aren't racing for points. Right now, the e-tron drivers are out to score as many points as they can get without taking risks. The Ultra drivers aren't really factoring in the championship, and hence are more likely to be used as guinea pigs to test things for the other cars.
[/url]

It was the Ultras testing more risky set ups for the e-trons I didn't understand. Surely this is unlikely to help as they are, well, different?
Naturally running a safe set up I did get. Although I think it is pointless. They had no challengers they could take a little risk and they had a lot of practice, including a wet warm up. It is unlikely they would make the thing unsafe! Unless you don't rate the drivers?

[gwyllion]

Originally Posted by Adam43

I wonder what it is like to drive. Is it as simple as accelerating out of a corner at, sat 100km/h and then bang an extra 80hp when you get to 120. A bit like a turbo kicking in, but on different wheels (on the Audi). Then a bit later down the straight the energy is spent and away it goes again. It must be quite odd?

Fassler also compared with a turbo (of 200 hp) kicking in for around 3 seconds: http://www.youtube.com/watch?v=37ExC1HusGo#t=1m26

[Simmi]

I think that, as much as I expect LM to be an Audi whitewash, it is going to be very intriguing to see the inter-team battle and the complexities of this e-tron system. Specifically how that effects strategy over 24 hours.

I expect the gaps between the cars to be bigger this year towards the back end of the race. But that's just a personal hunch.

[gwyllion]

http://www.lemanslive.com/en/2012/05...partner-teams/ confirms that Audi mainly trained their pit crew on Monday.

All four Audis, the JRM-run HPD-ARX03a, Rebellion Racing’s two Lola-Toyotas and the OAK Racing cars spent much of Monday lapping at Spa where the weather was just as poor as it was last weekend.

Audi used the day to perfect its pit-stop routine, simulate problem scenarios and practice changing different parts on its cars. The objective for JRM and Rebellion was to evaluate a selection of suspension and aero set-ups for Le Mans where they stand to earn double WEC points.

[Tim the Grey]

Hopefully JRM have worked out where they went wrong in the set up! I saw it off the road twice... And missed most of the incidents.
Audi will be working to establish the e-Tron baseline for set up. And they WILL be set up very differently to the Ultras. As said above, on the limit cannot be fun, if the system kicks in on a steering axle! Instant, possibly terminal, understeer... They will need to work out how to minimise weight transfer changes as power appears, and disappears, for the front wheels.
I cannot remember one thing. Do they have driveshafts, or are the motors integrated into the front hubs?

[gwyllion]

Originally Posted by gwyllion

Laurent Chauveau did an interview with Benoit Treluyer on Friday (so before the race): http://www.86400.fr/articles/221-ben...chaque-virageq The article contains a lot of interesting information.

Another great interview from Laurent, this time with Ralf Jüttner: http://www.86400.fr/articles/222-ral...ntage-au-mansq

According to Jüttner the performance difference between the ultra and the e-tron quattro depends on the track. On some track the ultra has an advantage, while on other track the e-tron quattro is in front. He gives the following explanation:

You must understand that to make our hybrid version competitive, we lightened all components of the R18 in order to compensate the excess weight created by this system. Since the R18 ultra and R18 e-tron quattro share a very large number of parts, the first has benefited. To remain above the prescribed weight, it is ballasted and this weight is placed better than in the hybrid. Its center of gravity is lower, so its dynamics in curves is better. Moreover, it is now a very accomplished car, an evolution of the car which has proven its value at Le Mans last year. The e-tron quattro is still in its infancy and can not claim of such maturity.

Audi's simulations show that the e-tron quattro will have an advantage at Le Mans, because the track is very favorable for hybrids with its long straights and hard braking. However, the ultras still have a chance because if the electric system fails on the hybrid car it becomes dead weight, which is placed less ideally than on the ultra.

Surprisingly, Audi has (officially) only done one 30 hour simulation (split in two because they were not allowed to drive at night) and another one is planned before Le Mans. Jüttner motivates that they can afford a bit less testing than in the past because their computer simulations and bench testing are more relevant and refined.

For now, both versions of the R18 are using the same front tires. Potentially this could cause tire wear problems on the hybrid because the front tires are not only used to stop and steer the car but also to propel it. Sometimes the tires are propelled while they are steering, which results in higher stress. In the future, Audi might decide to develop special tires for the e-tron quattro.

They still have to determine the energy management strategy by Le Mans. The activation of the hybrid system can be configured by the driver; according to Tréluyer the knob on the steering wheel can take 8 positions. For instance if they can do 10.9 laps on a full tank, they could turn down the power of the combustion engine to do another lap. Of course this only makes sense if the drop in lap time is worth it.

Jüttner explains that in Spa the hybrid system is activated at three locations on the track, that have been defined by the ACO. This contradicts Tréluyer who said that it is active after every corner. Laurent observes that the rules only state that the hybrid system can be activated when braking exceeds 2G for more than 1 second, and he reasons that these requirements might apply to these three locations.

[gwyllion]

Originally Posted by Tim the Grey

Hopefully JRM have worked out where they went wrong in the set up! I saw it off the road twice... And missed most of the incidents.

Chandhok tweeted that they found out why they lacked pace on Saturday.

Originally Posted by Tim the Grey

Audi will be working to establish the e-Tron baseline for set up. And they WILL be set up very differently to the Ultras. As said above, on the limit cannot be fun, if the system kicks in on a steering axle! Instant, possibly terminal, understeer... They will need to work out how to minimise weight transfer changes as power appears, and disappears, for the front wheels.

Funny that the hybrid R18 is suffering from the same understeer problem that their high performance road cars are notorious for. They have made a proper quattro car

Perhaps unpredictable behaviour is a consequence of the 120 km/h rule. It is tricky for the driver to know when the hybrid system will kick in exactly and how long the electric boost will last.

More development can probably address some of the issues. The system can take into account the steering angle and maybe even an (estimated) position on the track. Torque vectoring is also an option because the two electric motors can be driven independently; this feature is present on the hybrid 911.

The electric motors act independently on each wheel and allow for torque vectoring. The exact amount is determined by the driver via two yellow knobs on the steering wheel. Regenerative braking can vector the torque as well, so the system can drastically change how the car behaves on corner entry as well as exit. Works driver Joerg Bergmeister says he likes being able to adjust the car’s driving attitude without having to enter the pits.

source: http://www.roadandtrack.com/racing/m...3-r-hybrid-2.0

Originally Posted by Tim the Grey

I cannot remember one thing. Do they have driveshafts, or are the motors integrated into the front hubs?

Drive shafts. See http://www.racecar-engineering.com/c...-tron-quattro/ for a picture.

[gwyllion]

Blog entry by McNish on Spa: http://auto-racing.speedtv.com/artic...cnish-spa-wec/

Audio interviews with Treluyer (pre race), Jarvis (post race) and Duval (post race). The one with Jarvis is nice.

Treluyer is complaining that the hybrid car is though to drive because they do not know when the electric boost will kick in. He points out that the fender hole cause more spray in the rain.