Nissan LMP1 Discussion

[tyronnezx]

Originally Posted by philipp

Motorsport-total.com is reporting that the Nissan managed 68 laps over the 2 days in Sebring. Also saying that in comparison with the Audi, the Nissan is a substantially slower through the corners....

http://www.motorsport-total.com/wec/...-15030503.html

That is grim. The slowness in the corners should be expected. I've always mentioned that you aren't setting yourself up well when you choose to have a FF drive-train where turning, braking and accelerating comes from the front wheels. Nissan's only trump card will be the enormous amount of horsepower it has, which may make up for the slow cornering speeds. Surely Ben and the team had seen this and focused on other areas for improvement. just how limited these improvements will be is the real question from an engineering standpoint.

I have a feel that the other three will run circles around the Nissan

[Trebor123]

Originally Posted by TF110

You can tell the front wheel is a larger diameter in certain photos from Sebring. Enlarging the pic I posted from Sc365 you can tell. Its also in question on Mr. Fuller's facebook group page. So others have noticed the same thing.

There are lots of photos from Sebring on Flikr, This photo, taken on March 4th, shows a tyre stack in the background where the front and rears can be compared. Fronts are slightly larger in diameter.

https://www.flickr.com/photos/nissan...n/photostream/

Also more detailed photos of the Flybrid KERS

https://www.flickr.com/photos/nissan...n/photostream/

https://www.flickr.com/photos/nissan...n/photostream/

[The IC]

This is what TF110 is talking about...its definitely a larger rim size in the Sebring photo:

[Articus]

Originally Posted by The IC

This is what TF110 is talking about...its definitely a larger rim size in the Sebring photo:

In short, it's likely that they needed bigger front brakes to offset the drop in ERS category. The split between mechanical and KERS braking being the main factor on brake disc size.


It just would not add up that Porsche, Toyota were running to 6MJ with larger brakes but Nissan could get away with running smaller rotors on a 4MJ-6MJ car. I think the smaller wheel rims will come with the 8MJ system next year.

The smaller wheel rim and larger tire is also lighter so added benefit to unsprung mass. So if Porsche and Toyota could run the smaller they would too.

[Articus]

Originally Posted by philipp

Motorsport-total.com is reporting that the Nissan managed 68 laps over the 2 days in Sebring. Also saying that in comparison with the Audi, the Nissan is a substantially slower through the corners....

http://www.motorsport-total.com/wec/...-15030503.html

but also the Audi last year was mega in cornering because of the downforce package. The car was around 1-2 seconds quicker than Porsche Toyota regularly in the twisty sectors around WEC calendar.

The Nissan is a straightline rocket. Bowlby knows the weight distribution means this thing is far from the corner carving ninja that is the Audi.

[TF110]

Originally Posted by Articus

but also the Audi last year was mega in cornering because of the downforce package. The car was around 1-2 seconds quicker than Porsche Toyota regularly in the twisty sectors around WEC calendar.

The Nissan is a straightline rocket. Bowlby knows the weight distribution means this thing is far from the corner carving ninja that is the Audi.

Audi wasnt that much faster in the curvy section. You can go through the timing and see they were maybe a half second better, but usually 1-2 seconds slower combined everywhere else. Nissan won't even be close to that at the current rate. They'll have to be super in the straights to be on pace. Don't see that happening except maybe Spa Shanghai or Fuji.

[Articus]

Originally Posted by TF110

Audi wasnt that much faster in the curvy section. You can go through the timing and see they were maybe a half second better, but usually 1-2 seconds slower combined everywhere else. Nissan won't even be close to that at the current rate. They'll have to be super in the straights to be on pace. Don't see that happening except maybe Spa Shanghai or Fuji.

In race trim, they were. At places like COTA and Brazil, Audi is in another timezone in the twisty sectors. This maybe isn't so obvious just looking at qualifying times.

[TF110]

Sector 2 at Brazil during the race- Audi's best was 39.146; Porsche's best was 39.760; Toyota's best was 39.415 http://fiawec.alkamelsystems.com/

[Trebor123]

Originally Posted by Trebor123

The wheel rim diameter is the same, at 16" front and rear, but the tyre rolling diameters are different. This is because the tyre sidewall height is 71% of the tyre width but the fronts are 14" wide and the rears 9". The Michelin tyre specifications are: 31/71 R16 (front) and 20/71 R16 (rear).

http://www.tiretechnologyinternation...p?NewsID=65911

Originally Posted by wdave0

I believe the 71 is an outside diameter of the tire and if both are the same it would make the fronts about 40 profile and the rear about 60, which is pretty much what they look like. I think the apparent disparity in wheel diameter is an illusion because of this. Also, that rear tire is really tall for a modern race tire, many daily drivers are shorter.

Thanks wdave0. My novice mistake was in assuming that slick tyre size definitions followed the convention for road tyres. I've since found a thread, from 2009, covering this topic:

http://tentenths.com/forum/showthread.php?t=119929

So 71 in the racing slick specification is 71 cm = 27.935" rolling diameter, or just within the 28" maximum permitted in ART 15.2 of the regulations. As the front tyres are 14" width then it may make sense, like the other teams, to use a larger wheel rim diameter (up to a maximum of 18") and modify the suspension rather than partially relying on tyre sidewall flexure, as in F1.

[cokata]

Smaller sidewall in the front might actually improve performance. They also might need bigger front brakes then planned originally due to abandoning the rear drive train, making the car even more front biased.

[wdave0]

Where is that huge posed full side on pic from? You can read the tire sizes off the sidewalls. Both F and R are 16".

[Trebor123]

Originally Posted by wdave0

Where is that huge posed full side on pic from? You can read the tire sizes off the sidewalls. Both F and R are 16".

I found it on the paultan.org website:

http://paultan.org/2015/02/02/nissan...e-lmp1-hybrid/

This was posted at the time of the Super Bowl commercial, on 02/02/2015, so plenty of opportunities to modify the configuration in the meantime.

Some of the photo comparisons posted could be slightly misleading, because the cars are not usually viewed side-on, so the wheels often appear elliptical and of different sizes. Also, the car is either: not the same one, or the stickers have been changed!

If the photographs have also been adjusted in Photoshop, in order to correct for geometric perspective or lens distortion, then this introduces a further variable.

[MulsanneMike]

Originally Posted by wdave0

Where is that huge posed full side on pic from? You can read the tire sizes off the sidewalls. Both F and R are 16".

Yes, the LAUNCH car certainly had 16s. But the images from testing show vastly different front wheel diameters being tested. Most certainly still 16s on the rear but probably 18s on the front. And I hinted at this back in January that there were concerns the KERS didn't provide enough braking potential.

[Maelochs]

The initial Nissan press photos and info showed 16s, but there is no way I am going to ever doubt Mulsanne Mike on anything technical.

[YorkshireLad]

Nissan-racing a Flickr account has more images of the hybrid system, engine and much more

[wdave0]

Originally Posted by Maelochs

The initial Nissan press photos and info showed 16s, but there is no way I am going to ever doubt Mulsanne Mike on anything technical.

Nor would I - just trying to figure out what's going on (pop song).

I too questioned the logic of the original tire sizes, not only for brake size but for tire deformation. I wonder how many of the initial extreme choices will end up being compromised.

[Trebor123]

Originally Posted by wdave0

Nor would I - just trying to figure out what's going on (pop song).

I too questioned the logic of the original tire sizes, not only for brake size but for tire deformation. I wonder how many of the initial extreme choices will end up being compromised.

I heard that Ben Bowlby is having a rethink, since the decision was taken to go with FWD only. The new plan is to use SuperKart Division 1 tyres for the rear wheels: 7" wide, overall diameter 11.3" on a 6" diameter rim!

There was an initial worry about tyre longevity, in this size but this was easily overcome, by mounting 3 (or 4) wheels and tyres onto a Ferris wheel type configuration, on each side of the car. This can rotate, to perform a rapid change, without any need for the car to pit!

Because the overall diameter is less than that of that of the original rear wheel and only one of the new smaller wheels is being used at a time, then this solution neatly falls within the regulations.

[YorkshireLad]

Originally Posted by Trebor123

I heard that Ben Bowlby is having a rethink, since the decision was taken to go with FWD only. The new plan is to use SuperKart Division 1 tyres for the rear wheels: 7" wide, overall diameter 11.3" on a 6" diameter rim!



There was an initial worry about tyre longevity, in this size but this was easily overcome, by mounting 3 (or 4) wheels and tyres onto a Ferris wheel type configuration, on each side of the car. This can rotate, to perform a rapid change, without any need for the car to pit!



Because the overall diameter is less than that of that of the original rear wheel and only one of the new smaller wheels is being used at a time, then this solution neatly falls within the regulations.

I thought they were struggling with small brake discs and tiny callipers.

Won't this make braking worse? Or will larger discs and callipers on the front make up for small substitutes on the rears.


Crazy car!

[miatanut]

Sarchasm alert!

[Articus]

Originally Posted by YorkshireLad

I thought they were struggling with small brake discs and tiny callipers.

Won't this make braking worse? Or will larger discs and callipers on the front make up for small substitutes on the rears.


Crazy car!

The brake system at the rear is largely unaffected. Remember that it's front engine so the weight distribution is biased towards the front. This means that due to weight distribution and load transfer during braking, the contribution to braking from the rear axle is smaller than what is normal (aka Toyota, Porsche, Audi)

[miatanut]

Originally Posted by Articus

The brake system at the rear is largely unaffected. Remember that it's front engine so the weight distribution is biased towards the front. This means that due to weight distribution and load transfer during braking, the contribution to braking from the rear axle is smaller than what is normal (aka Toyota, Porsche, Audi)

But in 8MJ class, most of the braking was coming from the energy recovery. In 2MJ, most of the braking comes from the brakes. On the 8MJ plan, the back brakes were hardly going to do anything, and the front weren't doing much. In 2MJ class, both brakes have a lot of work to do.

[miatanut]

Originally Posted by MyNameIsNigel

I suspect that this is the Flybrid unit:

LOOK! Off in the distance! Is that a couple flywheels I see, to go along with the flywheel drivetrain?

You would think that when somebody came up with that, they would decide to not even show it to their client because it is an obviously absurd solution, and the real answer was to go back to the drawing board.

[Bandicoot17]

Originally Posted by miatanut

But in 8MJ class, most of the braking was coming from the energy recovery. In 2MJ, most of the braking comes from the brakes. On the 8MJ plan, the back brakes were hardly going to do anything, and the front weren't doing much. In 2MJ class, both brakes have a lot of work to do.

Surely if they've dropped one of the flywheels they'll be planning on running in 4MJ??

[Maelochs]

Surely if they are doing major rethinks (to be followed by major redesigns and re-fabrications) a month before Spa, we can write off Le Mans.

[miatanut]

Originally Posted by Bandicoot17

Surely if they've dropped one of the flywheels they'll be planning on running in 4MJ??

I read somewhere they were doing 2MJ. With 2MJ they could retrofit a completely different system, like supercapacitors, and focus on Le Mans. The bigger energy recovery is a bigger deal on the twisty tracks.