Nissan LMP1 Discussion

[Bandicoot17]

Originally Posted by lne937s

Tesla goes into energy recovery on liftoff to make it feel like a "normal" car, where the engine slows the car on liftoff. It is not to make the car more efficient or faster.

In racing, I assume they really don't care if it feels "normal".

Yes but it's still doing regen (charging the battery) when you come off the throttle.

I would assume for instance, that the Porsche comes off the accelerator early, regen kicks in, this slows the car down a fair bit (hence the speedtrap data) and only then are the brakes used.

[lne937s]

Originally Posted by Bandicoot17

Yes but it's still doing regen (charging the battery) when you come off the throttle.

I would assume for instance, that the Porsche comes off the accelerator early, regen kicks in, this slows the car down a fair bit (hence the speedtrap data) and only then are the brakes used.

You miss the point-- the Tesla does that intentionally for the purpose of making the car seem like a regular car. Electric cars do not have to go into regen on liftoff.

In a race car it serves no purpose-- it would make your overall lap times slower. The energy you recover would be less than the momentum you sacrifice. The energy burned to create that momentum is more than the energy you get back (as these are not perfect machines). You want to get up to speed as fast as you can and stay at that speed as long as you can before you start braking. Accelerating up to top speed (when you are combatting exponentially higher aerodynamic drag compared to lower speeds) and going into mild regen before you brake wastes time and fuel to create a slower overall lap.

If the Porsche is slowing significantly, it would likely be due to high aerodynamic drag slowing the car on liftoff.

[MoMedic9019]

Originally Posted by Acid09

And when their race week times aren't better you'll tell us that we should wait for 2016.

No. I won't. I don't expect magical things to happen this year. Unlike many on this board, I've been through a few development processes... I get how much of a headache a new car can be.

It's classical marketing BS, always moving the goal posts.

can we stop with the marketing crap? Please? It's pointless complaining.

Honest question to you: What scenario would you deem a failure for Nissan? If none of the cars make it darkness? Or make it past 6 six hours?

Or is there absolutely nothing that you wouldn't label a success for them, no matter what, simply for being there?

I'll call this car a failure if they arent challenging for podiums by LeMans next season....one race does not make or break this program. They have a significant amount of development to do.

[MoMedic9019]

Originally Posted by lne937s

You miss the point-- the Tesla does that intentionally for the purpose of making the car seem like a regular car. Electric cars do not have to go into regen on liftoff.

In a race car it serves no purpose-- it would make your overall lap times slower. The energy you recover would be less than the momentum you sacrifice. The energy burned to create that momentum is more than the energy you get back (as these are not perfect machines). You want to get up to speed as fast as you can and stay at that speed as long as you can before you start braking. Accelerating up to top speed (when you are combatting exponentially higher aerodynamic drag compared to lower speeds) and going into mild regen before you brake wastes time and fuel to create a slower overall lap.

If the Porsche is slowing significantly, it would likely be due to high aerodynamic drag slowing the car on liftoff.

You might want to ask Colin Braun how well lift and coast works.... he might have something else to say about it.

[pach233]

Any word on how the shakedown on the Bugatti circuit went today? S365 had a short blurb but nothing on weather conditions, relative paces, reliability etc.

[lne937s]

Originally Posted by MoMedic9019

You might want to ask Colin Braun how well lift and coast works.... he might have something else to say about it.

"Lift and coast" is different than "lift and regen" (which converts momentum into stored energy, slowing the car down in the process)....

Lift and coast has its benefits in terms of saving fuel.

Regen only saves fuel if you are intentionally trying to slow the car down and the kinetic energy would otherwise be wasted (i.e., braking). But you don't get more energy back than what you put in, so it provides no benefit to regen when you are trying to go fast or maintain momentum (coast).

[ger80]

Exactly, you spend a lot of fuel running at top speed due to aerodynamic drag. So if you lift a bit early, you can reduce fuel flow and not loose too much time

[Alfaholic]

Nissan's problems sorted !

[Acid09]

Originally Posted by MoMedic9019

I'll call this car a failure if they arent challenging for podiums by LeMans next season....one race does not make or break this program. They have a significant amount of development to do.

I see, so whatever happens next week you'll be labeling it a success...color me surprised

[hcl123]

Originally Posted by Bandicoot17

Yes but it's still doing regen (charging the battery) when you come off the throttle.

I would assume for instance, that the Porsche comes off the accelerator early, regen kicks in, this slows the car down a fair bit (hence the speedtrap data) and only then are the brakes used.

Not buying that at all, 'regen' doesn't have to kick in earlier when Porsche spend the all straight before the braking zone harvesting (contrary to all others)... the differences in top speed between Porsche and Nissan as example has to do with downforce and fuel strategies -> Porsche had quite a bit more downforce and quite a bit less fuel per lap

Porsche has 7,5% less fuel to spend but has terrific hybrid power... and contrary to all others does not only regen in the braking zones but also in the straights upon full throttle (exhaust generator)

[hcl123]

Originally Posted by Alfaholic

Nissan's problems sorted !

LOL ... i can't imagine!.. now they want a rear steering car ??.... i see!, Ben Bilious bag of tricks is everything that others don't have... why do i feel it wont solve any problem but turn the cars real dangerous to drive! (huge understeering at high speed, huge oversteering at low speeds)...

[ can only be a joke!... 1th April out of date... i suppose it was supposed to be serious, but everybody is starting to make fun of NIssan... ]

[Bandicoot17]

It's satire

[Adam43]

Which even Nissan can tell!

https://mobile.twitter.com/NISMO/sta...43920401899520

It seems the Nissan PR machine has a far better grasp of all this than some on here. They can take a joke and get over themselves.

[miatanut]

Originally Posted by hcl123

.. now they want a rear steering car ??.... i see!, Ben Bilious bag of tricks is everything that others don't have... why do i feel it wont solve any problem but turn the cars real dangerous to drive! (huge understeering at high speed, huge oversteering at low speeds)...

But seriously....

Months ago, when I heard it was FWD and had skinny rear wheels, I was wondering if it would be rear steer. That would make the rear tires run closer to what their slip angle would naturally be when turning, reducing the load on them.

I concluded the reason a racing car would never go rear steer (if it had the tires balanced to the load on each end) is that to straighten the car out, you have to exceed the slip angle of the rear tires and they would end up sliding until they caught the rear of the car, which would be a very unsettling feeling for a driver.

In other words, if the rear tires were smaller than the fronts, at high speed it wouldn't be understeer, but it would be tough to get it straightened out again because it would be oversteer as you tried to straighten out.

Thoughts?

[Adam43]

Currently the fastest car I the world ever was rear wheel steer Different design constraints mind.

Four wheel steer (small angles on the rear) is where it is at.

[FormulaFox]

Originally Posted by Acid09

I see, so whatever happens next week you'll be labeling it a success...

I'm pretty sure that all Mo meant is that you can't label it a success unless it actually meets it's goal, but you can't call it a failure just because it doesn't meet those instantaneously.

Just because something hasn't met failure criteria doesn't mean it's a success.

[hcl123]

You got to be joking 'miatanut' !

Upon braking there is a transfer of weight front, rear steering would be irresponsive as hell, specially at high speed and strong braking, huge understeering... huge imbalances...

There is a reason for everything, many things has been tried ... leaning from ones mistakes can be called progress/evolution(quite painful sometimes)... learning from others past mistakes can be called wisdom...

Nissan is clearly in the first path, and its starting to be very painful, if they make it worst with the stance of being innovative of being 'different'... it can enter the roam of stupidity.

[MoMedic9019]

Originally Posted by Acid09

I see, so whatever happens next week you'll be labeling it a success...color me surprised

Nope. Ill simply say they tried to hit the benchmarks they were after, and have learned a ton, and acquired a proverbial mountain of data to make them better in the long term.

Also. Darren has gone on the record as of this morning, and stated that the fast trap time was set without using KERS, and the drivers were told to "stroke it" his words, not mine... As they were hitting their benchmarks, but, had to alter the workflow due to the rain. He said that it was extremely beneficial, though, dry running would have been better.

[miatanut]

Originally Posted by hcl123

You got to be joking 'miatanut' !

Upon braking there is a transfer of weight front, rear steering would be irresponsive as hell, specially at high speed and strong braking, huge understeering... huge imbalances...

There is a reason for everything, many things has been tried ... leaning from ones mistakes can be called progress/evolution(quite painful sometimes)... learning from others past mistakes can be called wisdom...

Nissan is clearly in the first path, and its starting to be very painful, if they make it worst with the stance of being innovative of being 'different'... it can enter the roam of stupidity.

Why would you be braking while turning? Decreasing radius turn, I suppose (done VERY carefully), but other than that, trail braking is to fix an understeering car, and a car with fat front tires and skinny back tires is going to be anything but.

Maybe that's a problem Nissan has been having. A bunch of drivers used to trail braking in a car that absolutely does not want that, so they have to put a rear wing on it to keep the drivers from swapping ends.

[Adam43]

Originally Posted by miatanut

Why would you be braking while turning?

Because you are Jim Clark?

It's a legitimate thing to do (well) in any car to varying degrees and Clark was a master at it. Schumacher was pretty good at it too.
You don't wait until you are completely straight on the exit of a corner before you apply the throttle, so why would you not brake and steer? It's harder, because braking is more dramatic than accelerating, but the principle is the same.

[lne937s]

Originally Posted by hcl123

You got to be joking 'miatanut' !

Upon braking there is a transfer of weight front, rear steering would be irresponsive as hell, specially at high speed and strong braking, huge understeering... huge imbalances...

There is a reason for everything, many things has been tried ... leaning from ones mistakes can be called progress/evolution(quite painful sometimes)... learning from others past mistakes can be called wisdom...

Nissan is clearly in the first path, and its starting to be very painful, if they make it worst with the stance of being innovative of being 'different'... it can enter the roam of stupidity.

Rear steer is actually a much more stable way to change the direction of a vehicle at speed. That is why some speed record cars, most monster trucks, most airplanes and most boats all use rear steering.

Effectively, you are putting a relatively small load at the rear to change the angle of attack at the front. At the front, the track becomes effectively wider, with the load distributed more equally, compared to if the front wheels were turned. Like the wings on a climbing airplane, the load is being taken on at the front, not the elevators at the rear (rear wheels), which are just changing the angle of the wings (front wheels).

The problem is it takes up more space to turn a vehicle with rear steering, making precision driving around a relatively narrow track more difficult because of the rear swinging around. Not impossible, but it would be tricky in traffic. Four wheel steering would be ideal.

[MitchZ06]

Monster trucks use 4WS to decrease the turning radius not change direction at speed. Aircraft on the ground steer with the nose wheel and use the rudder in the air because aerodynamics. Boats/ships/watercraft are rear steer for the same reasons (hydrodynamics).

The GTR-LM couldn't use RWS as the car has no space in the rear end to allow space for the wheels to move, same reason the rear wheels are so small width wise.

[TF110]

Is rear steering allowed? If it was, you would think itd be a no-brainer for Nissan.

[Adam43]

[miatanut]

Originally Posted by Adam43

I think this is fun!

Thanks all for your responses! The whole boat/plane angle hadn't even occurred to me. Wheeled vehicles seem to actually be an exception to what is otherwise "normal."