Audi LMP1 Discussion

[MyNameIsNigel]

Originally Posted by deltawing

If the total height is the same, then the "bumpy" (as you call it) would be less draggy as it has smaller cross section.

But I would suspect that a smoother surface may also be advantageous in that it probably creates less turbulence around the cockpit area, which could favour a more efficient use of the rear wing and better overall aero efficiency. I am not a specialist in aerodynamics though.

Turbulence around the cockpit area would also create drag, or am I totally mistaken ?

[MitchZ06]

Totally mistaken, it's not bumpy so much as a simple step and it's not even facing into the airflow....

[MyNameIsNigel]

Originally Posted by MitchZ06

Totally mistaken, it's not bumpy so much as a simple step and it's not even facing into the airflow....

Thanks for your very nuanced comment

I am not entirely mistaken in that turbulence does generate drag, but your correct in that the "bump" on the Porsche LMP1 cockpit is probably not an issue in that respect.

[MitchZ06]

Being what appears to be a rules work around I'd have faith in Porsche thoroughly testing their solution in the windtunnel.

[Rodger Davies]

Originally Posted by CyberMotor

I'm sure that Audi would rather have recuperative braking rather than breaking! Recuperative breaking could get expensive quickly.

You sure? Couldn't it mean that the car mends itself when it breaks? I mean, that's only one step removed from Joest anyway, but will still save a few seconds...

[CyberMotor]

Originally Posted by Rodger Davies

You sure? Couldn't it mean that the car mends itself when it breaks? I mean, that's only one step removed from Joest anyway, but will still save a few seconds...

[chernaudi]

Originally Posted by JoestForEver

The shots from Motorsport.com make me notice that it's still a short tail version R18. Why are they willing to not make full use of permitted rear diffuser length? Or are they worrying about tire issues even in the new R18

Audi never did this with any of the R18 variants except for the Le Mans variant for '13. Mulsanne's Corner did explain that it's due to the ACO's rules for rear diffusers. The exit height has to be the same regardless of its length. But by having a shorter tail section, the angle of the diffuser from its start to end can be steeper, which makes more downforce (in effect, this replicates having a taller exit without having one). The difference in angle between the short tail (7.1deg) and long tail (6.5 degrees) was 6 tenths of a degree.

Much like the "seal" that Audi were looking for with the exhaust blown diffuser on the R18 last year, the "long tail" diffuser was used basically as a permanent DRS system (in this case) for Le Mans only, and one that didn't give up much if any downforce.

This matters much less in the much draggier sprint race trim, though.

And considering that I don't think that twin diveplanes will be used at Le Mans, the R18 pictured in the press photos is probably in a sprint race configuration.

[JoestForEver]

Thanks very much for the explanation. It seems that Audi will field another long tail experiment car at Spa next year?

[deltawing]

Originally Posted by MyNameIsNigel

But I would suspect that a smoother surface may also be advantageous in that it probably creates less turbulence around the cockpit area, which could favour a more efficient use of the rear wing and better overall aero efficiency. I am not a specialist in aerodynamics though.

Turbulence around the cockpit area would also create drag, or am I totally mistaken ?

What Mitch said in reply to your post....

Now, if you refer to this picture (from the latest tests in December) and look at the huge extractor they put at the top of the door (the big black piece), THAT would be so draggy!



The piece was not there for long time, so it looks like a complete afterthought. Perhaps they can't cool enough the cockpit and don't want to use AC, I don't know. But if you were to introduce a piece with such cross section and dimensions, that spot they put it on is absolutely the worst when it comes to drag. In that spot you have one one the largest cross sections of the entire car and they make it even larger.... It helps perhaps that it is vertically aligned with the duct exists, but that is like to move 5 steps backwards and then 1 step forward.

I hope this is just "trying something quickly" as it is easier to do this on a door rather than on a tub (if it is just drilling for trials), but if they plan to actually leave that piece in there for good, that would be very interesting. Perhaps their drag numbers are so, so good, they can afford to slam that piece on the roof and still get away with it. But if they are really as good as we all think they are, that piece should be gone soon and the extractor will be integrated somewhere else, in a much better ways.

[chernaudi]

I wonder why Audi have been opening up a oil tanker's worth of videos and photos of the R18 before Dec. 18th. It's not like all of us need the patience of Griselda to wait until then.

[Bandicoot17]

Keeps attention away from Sebring I'd imagine

[chernaudi]

And now Mulsanne Mike at mulsannescorner.com now has some analysis of the '14 R18.

[MyNameIsNigel]

I have already posted the following on the Mulsanne's Corner Group and wanted to have your view, guys, on the matter.

Coming back to the question of the particular cockpit shape of the new Audi R18, I wonder if this shape has anything to do with the mandatory front and rear rollover structures. The rules mandate a minimum width of 300mm, at 950mm above the reference surface, for the front rollover structure and a minimum width of 400mm, at 935mm above the reference surface, for the rear rollover structure (with a minimum length of 300mm). It is apparent from the pictures that the cockpit "roofline" is substantially flat and extends above and rearward of where the driver is sitting (i.e. where the rear rollover structure is located). I suspect that the cockpit height at this location is somewhere in the region of 950mm (maybe more), as the cockpit necessarily has to comply with the front rollover structure requirements. That would mean that the cockpit area above and rearward of where the driver is sitting is possibly running "well" above (i.e. approx. 15mm) the rear rollover structure. That "could" mean that the particular cockpit shape is not as such the result of a "conservative" interpretation of the rules, but rather the result of a deliberate and specific choice, probably mainly dictated by aerodynamic choices and requirements.

(source: Mulsanne's Corner News)

Furthermore, I would be surprised that Audi's interpretation of the rules assumes that the minimum width of the rear rollover structure must be constant over the entire minimal length of 300mm. It is pretty clear to me that the 400mm width requirement (935mm above the reference surface) should only apply to the front face of the rear rollover structure (95mm behind the driver's helmet), and that the height and width of the rear rollover structure can decrease rearward of the front face. This interpretation seems to be entirely consistent with Drawing 8 of the 2014 Technical Rules:

[chernaudi]

Now it seems that Audi plans on releasing one promo video of the R18 a day until the 18th.

Of course, Audi never did this with any other of their racing cars, and I can't remember them doing this with any of their road cars, either.

They seem to think that we all need the patience of Griselda to wait until the 18th for the public launch, though it's only two days away. BTW, the phrase "patience of Griselda" goes back to a folk tale, but here's a more contemporary look at a woman called Griselda:

http://guyver.wikia.com/wiki/File:Griselda.jpg

And yes, her human counterpart certainly had needed a lot of patience to deal with a lot of the stuff that she's seen and experienced, as you can read here:

http://guyver.wikia.com/wiki/Shizu_Onuma

[MyNameIsNigel]

Originally Posted by chernaudi

They seem to think that we all need the patience of Griselda to wait until the 18th for the public launch, though it's only two days away.

Or maybe this is simply a tactic to "hold the ground" and attract media attention while Porsche try to do the same. The marketing war is in full swing I guess.

In any event, I am not going to complain about the amount of information that Audi are releasing at the moment.

[chernaudi]

Not even Porsche were constantly reminding us of the 919--they were, but they weren't releasing a promo trailer every day. They'd wait a couple days usually before sending out a new one. I'm a fan of the Twilight novels and films, and not even the promo people for that stuff posted trailers on line every day or every other day. And Toyota have been profoundly quiet about the TS040, though that car's not expected to be running until January.

As an Audi fan, I'd have no trouble if each teaser showed us or told us something new. But no new info has been leaked in any of the trailers, which just show us images that we've already seen, and equation that though from a scientific level interest me, I have to admit that I hated algebra in school, so the trailers don't to much for me unless they give out more info, which they really aren't as of now.

At least the if it was colorized, the photo of that alien-like chick would have a color pattern on her skin similar to the Audi Sport drivers' uniforms...

[MyNameIsNigel]

Originally Posted by chernaudi

Not even Porsche were constantly reminding us of the 919--they were, but they weren't releasing a promo trailer every day. They'd wait a couple days usually before sending out a new one. I'm a fan of the Twilight novels and films, and not even the promo people for that stuff posted trailers on line every day or every other day. And Toyota have been profoundly quiet about the TS040, though that car's not expected to be running until January.

As an Audi fan, I'd have no trouble if each teaser showed us or told us something new. But no new info has been leaked in any of the trailers, which just show us images that we've already seen, and equation that though from a scientific level interest me, I have to admit that I hated algebra in school, so the trailers don't to much for me unless they give out more info, which they really aren't as of now.

At least the if it was colorized, the photo of that alien-like chick would have a color pattern on her skin similar to the Audi Sport drivers' uniforms...

I agree with you that the video teasers do not contain much additional information (or maybe I missed a few subliminal pictures...) and are, in that respect, mostly useless from a technical perspective. It however seems that Audi feel obliged to communicate on various themes that highlight the "complexity" of the new car and of the new rulebook. The videos teasers have so far focused on the themes of "Speed", "Performance", "Kinetic Energy" and "Power". We will surely get a couple additional video teasers until we get to the official launch on December 18th. I guess we will get one about "Efficiency", "Lightweight Design", "Exhaust Gas Energy Recovery" or the like.

Now, this whole teasing operation constantly reminds people that the official launch is just a couple of days away. Audi evidently want to attract as much media interest as possible for this upcoming launch. I've got no problem with that.

[chernaudi]

More power to Audi if that's their aim, and if it helps promote sportscar racing, again, more power to them.

But that latter point goes back to one of my complaints in the LMP1 privateer thread--car makers and OEMs do too much to promote the sport compared to the sanctioning bodies.

If Audi are doing this on their on initiative, and it seems that they are, I can't complain. My only complaint is that this gives no new info, and the stuff mentioned does seem to be cribbed from their press release that got released last week.

Even the newest "kinetic" video that got released today had an engine note soundtrack added to it, but it seemed to be from the onboard of a '13 R18.

Granted, if the '14 R18 uses basically the same engine as the '13 car--and Audi have already said that the new engine is an evolution of the previous V6 TDI--then we know kind of what it'll sound like at least.

Hopefully a pretty good trailer will be released Wed, and some new photos--aside from testing photos, Audi still haven't released many shots of what the rear of the car is supposed to look like, not that the test photos don't show everything in plain sight.

[deltawing]

Originally Posted by MyNameIsNigel

I have already posted the following on the Mulsanne's Corner Group and wanted to have your view, guys, on the matter.

Coming back to the question of the particular cockpit shape of the new Audi R18, I wonder if this shape has anything to do with the mandatory front and rear rollover structures. The rules mandate a minimum width of 300mm, at 950mm above the reference surface, for the front rollover structure and a minimum width of 400mm, at 935mm above the reference surface, for the rear rollover structure (with a minimum length of 300mm). It is apparent from the pictures that the cockpit "roofline" is substantially flat and extends above and rearward of where the driver is sitting (i.e. where the rear rollover structure is located). I suspect that the cockpit height at this location is somewhere in the region of 950mm (maybe more), as the cockpit necessarily has to comply with the front rollover structure requirements. That would mean that the cockpit area above and rearward of where the driver is sitting is possibly running "well" above (i.e. approx. 15mm) the rear rollover structure. That "could" mean that the particular cockpit shape is not as such the result of a "conservative" interpretation of the rules, but rather the result of a deliberate and specific choice, probably mainly dictated by aerodynamic choices and requirements.

(source: Mulsanne's Corner News)

Furthermore, I would be surprised that Audi's interpretation of the rules assumes that the minimum width of the rear rollover structure must be constant over the entire minimal length of 300mm. It is pretty clear to me that the 400mm width requirement (935mm above the reference surface) should only apply to the front face of the rear rollover structure (95mm behind the driver's helmet), and that the height and width of the rear rollover structure can decrease rearward of the front face. This interpretation seems to be entirely consistent with Drawing 8 of the 2014 Technical Rules:

Hi Nigel,

I believe this is not just vague or poor interpretation of the rule by the excellent Audi designers/engineers/aerodynamicists. I could be wrong, but here is the way I see it:

2014-2017 (if there are no rule changes) will be the period for downforce struggle. The common ways these cars do generate DF (downforce) have been capped and so the manufacturers have to get creative on how to get the high numbers they need to go fast around corners. If there is not much ways of creating DF, then perhaps they are looking for ways to reduce lift, which automatically results in DF gain. What Audi is perhaps doing here is a clever way of reducing the massive lift the closed cockpit generates. Here is a quick sketch that illustrates the story:




The Red line is front surface of the cockpit. The Green line is the rear surface of the cockpit. The Blue line is a straight surface (like a spacer) between the Red and Green.

Red and Green are identical (for this example) in shape in the short and long scenario.

The Red-Green solution (adopted for example by Porsche) is going to be less draggy, but is going to create massive lift.

The Red-Blue-Green solution is going to disrupt a lot of the lift, but it is going to be draggier. Imagine here a cross section of an airplane wing that got interrupted in the middle with a "straight spacer".

In the way I see it, Audi is going for very aggressive car (DF-wise) with the hope that they are going to take anyone by brute force. Porsche on the other hand has created a car that is not going to win the DF context, but is going to have perhaps very low drag numbers, which is going to help them to be very efficient. There was a hint sometime ago from them, along the lines of "You don't have to be the one with most HP or the fastest car to win".

It will be very interesting to see how the rear of the cockpits change in the next few months. And it will be very interesting to see which direction Toyota is going to take (I suspect is going to be more towards efficiency rather than DF).

[MyNameIsNigel]

Thanks for your analysis deltawing.

This analysis assumes that most of the air flow would run over the cockpit, but what about the air flow around the cockpit sides ?

I tend to believe that the whole aerodynamic concept (but this is pure guess as I am in no way an aero specialist) of the Audi R18 (RP4) may be to possibly channel most of the airflow to the cockpit sides, rather than over it. The substantially flat upper portion of the cockpit may possibly help in that respect. I don't know. The whole front end of the car also appears to be designed to channel the air flow to the cockpit sides.

I further note that the rear wing is located very high, probably at or close to the maximum allowable height of 965mm above the reference plane. Combined with the flat upper portion of the cockpit which should be located at a height of approximately 950mm above the reference plane (or maybe slightly more), this could possibly allow the rear wing to work more efficiently as it is less affected by the turbulence generated by the cockpit area. This is possibly more critical than before as the rear wing now has to exhibit a constant cross-section.

I would love to see a CFD model of this car.

[chernaudi]

The entire concept of the front fenders on all recent LMP1s is modeled on a concept of channeling air around them rather than over them. This predated the fender holes and was first used on the 2003 Lister Storm LMP900, but was resurrected in 2009 by the Audi R15 and Acura ARX-02.

This is based in part on a concept that actually goes back to the Nissan GTP ZX-Turbo IMSA GTP car, and perhaps earlier than that, where dive planes weren't really used to make downforce in and of themselves, but as flow conditioners for air down the side of the cars.

I'm not sure how that would work for the cockpit, especially since the engine intake is on the roof.

[JoestForEver]

I believe the new R18 revived the idea of guiding air 'through and around' the car from R15 and DTM A4 (R14), the latter of which was a great success while the former is not really so.

[manthey]

after Allan's retirement, audi official squad for 2014 will be unveiled tomorrow?

maybe someone from DTM?

[Starfish Primer]

Originally Posted by manthey

after Allan's retirement, audi official squad for 2014 will be unveiled tomorrow?

maybe someone from DTM?

They have plenty of candidates, Jarvis, Di Grassi, Bonanomi and Nico Muller was linked to Audi months ago.

[chernaudi]

Now we know why there were the Muller recruitment rumors--he'd be replacing someone. I'd have thought that it was Tom, because of his age (he's a couple of years older than Allan), and he'll probably soon will be showing signs of the effects of the DTM accident from '07. There were also some rumors of TK heading to Porsche.

Instead, Allan has elected to retire from driving prototypes for Audi, aside from possibly testing. There were rumors of a driver shake up at Audi due to one of their older drivers retiring or scaling back, didn't expect it to be Allan, though. But he has a young family, and he's probably accomplished everything that he ever wanted to achieve in sportscar racing.

LM grid won't be the same without Allan, even if he's in the TV booth--he's got a real talent for that--or if he's there with Audi, but not slated to race.