World Endurance Championship 2015

[ian_s]

I wonder how badly Porsche will be hit when they recalculate the equivalence formula now, I believe that is done after the 24hrs?

[Cold Fussion]

lift and coast is probably just slowing down via the electric motors.

.... (they may not want harvesting lifting off in a corner for example).

One thing is for certain; lifting and coasting definitely includes slowing down by aero dag... That's simple laws of physics... Whether there is also some ERS harvesting as well is questionable... Your comment in brackets is the reason I think it would be linked only to use of the brake pedal (in the case of KERS).

That much is obvious. I can't see why you wouldn't implement it, it can't see slowing down purely from drag will be faster overall then slowing down purely from harvesting. On the onboards you can hear the whine of the electric motors when they lift off, but that noise is far more intense when they start braking (which i can't really explain).

[joseff]

I wonder how badly Porsche will be hit when they recalculate the equivalence formula now, I believe that is done after the 24hrs?

Could you elaborate please? I thought EoT is ICE only, so are you referring to their low fuel consumption?
What if their mileage is due to a superior hybrid system? The FIA is not likely to handicap the 8MJ class, and make 4MJ more attractive.

[ian_s]

I wonder how badly Porsche will be hit when they recalculate the equivalence formula now, I believe that is done after the 24hrs?

Could you elaborate please? I thought EoT is ICE only, so are you referring to their low fuel consumption?
What if their mileage is due to a superior hybrid system? The FIA is not likely to handicap the 8MJ class, and make 4MJ more attractive.

i've just spent a while reading up on how they do the EoT, and i had it wrong. i thought that each manufacturer had a different fuel flow rate, but really its just petrol vs diesel.
if toyota had beaten Audi i could see the petrols being pulled back a bit, but i dont think thats likely now.

[Cold Fussion]

I wonder how badly Porsche will be hit when they recalculate the equivalence formula now, I believe that is done after the 24hrs?

Could you elaborate please? I thought EoT is ICE only, so are you referring to their low fuel consumption?
What if their mileage is due to a superior hybrid system? The FIA is not likely to handicap the 8MJ class, and make 4MJ more attractive.

It's more likely I think that they'll alter the fuel tank capacity of the petrol class, or they'll re-evaluate the technology factor for the 2016 regulations. From the technical and sporting regulations, it doesn't look like the EoT can be changed mid season (other than adjusting the global performance level):

[Cold Fussion]

One thing is for certain; lifting and coasting definitely includes slowing down by aero dag... That's simple laws of physics... Whether there is also some ERS harvesting as well is questionable... Your comment in brackets is the reason I think it would be linked only to use of the brake pedal (in the case of KERS).

That much is obvious. I can't see why you wouldn't implement it, it can't see slowing down purely from drag will be faster overall then slowing down purely from harvesting. On the onboards you can hear the whine of the electric motors when they lift off, but that noise is far more intense when they start braking (which i can't really explain).

Actually I've just looked at the energy store regulations and you're only allowed two ERSA units. The 919 and R18 can only harvest from the front brakes , which would limit their ability to harvest during lift and coast as it would possibly make the rear end unstable (though only 200 kW (in the case of the R18) of braking power will probably limit the braking instability so they may still do it). Toyota have front and rear harvesting so I expect they will be harvesting under lift and coast.

[machin]

I've found no references anywhere which suggest that they start harvesting with their KERSs as soon as they lift off the throttle... every reference I've found relates to during a braking event, which to be honest makes the most sense to me... I wouldn't want the kinetic energy recovery system cutting in (i.e. braking the car) just because I lifted the throttle...

With the hybrid powertrain you really notice the difference at two points: under braking and on acceleration out of a corner. Because we harvest energy under braking, the driver gets a different sensation as soon as you step on the brake and this can take a little while to get used to

Our petrol hybrid powertrain recovers energy under braking

This power will be harvested under braking

a generator at the front axle converts kinetic energy into electricity during braking phases

[BanMeToo]

Along the same lines as what Cold Fussion was saying... In a hybrid car you recover more energy during a stop if you brake gently for a longer period of time. A hard stop has the recovery system taking as much as it can but for a shorter amount of time - the disk brakes are doing more work and rob you of some energy that could have otherwise been collected with a gentle stop.

The point is it all depends on how rapidly a KERS can recovery energy under braking. I'd be willing to bet that a 'qualifying pace' braking event into the Mulsanne chicanes recovers a little bit less energy than a slower stop that works the KERS as hard as possible for the longest amount of time. Maybe I am just ignorant but could 'lift and coast' sometimes really be more along the lines of 'brake early and gently to help the KERS action'. I realize that aero braking will robs a lot of potential energy here but still...

Also, though it doesn't make much sense for me to fly in the face of the references you found machin, could an LMP1 car not be set up with a little bit of KERS drag while off throttle, just like a hyrbid car? It would not mess the driver up if it's always there. And when are they really off throttle in a race, anyway? Right before they get on the brakes? Why not grab a sliver of energy while its there.


edit:

On the onboards you can hear the whine of the electric motors when they lift off, but that noise is far more intense when they start braking (which i can't really explain).

Like a hybrid street car! There is mild harvesting any time the car is coasting and it intensifies (to a certain point) when you get on the brakes.

[Cold Fussion]

Also, though it doesn't make much sense for me to fly in the face of the references you found machin, could an LMP1 car not be set up with a little bit of KERS drag while off throttle, just like a hyrbid car? It would not mess the driver up if it's always there. And when are they really off throttle in a race, anyway? Right before they get on the brakes? Why not grab a sliver of energy while its there.

While braking in a straight line on the Mulsanne straight I would agree with the lift and coast harvesting, but it isn't something I would want default on; I wouldn't want such an extreme balance when lifting off while turning.

[henra]

I'm not convinced by that argument... a KERS system only harvests when the car is braking, and a HERS recovers best when the engine is at full throttle... neither really conducive to "coasting to recover energy"... I think they were just partially coasting/not using full throttle to save a bit of fuel, knowing they could still run at close to Audi pace, but achieve an extra lap per stint AND a 3-4 second shorter fuel stop... reducing the time at full throttle would probably help a little with the reliability too....

Actually duruing the race on the long straights to the chicanes it looked as if they first started recovering shortly before hitting the Brakes. Also I doubt they are able to recover 8MJ just while braking. When we assume a 400kW electric Motor (The Porsche is said to have max ~1200HP of which 500 something would be the ICE) it would take 20s to revover 8MJ. I don't think they spend 20s on the brakes in one lap. decellerating from 300km/h to 100 at 4g will take less than 1,5s. So they will have to do some coasting or brake less firecely tha would be possible to recover the full 8MJ.

[Juzh]

I'm not convinced by that argument... a KERS system only harvests when the car is braking, and a HERS recovers best when the engine is at full throttle... neither really conducive to "coasting to recover energy"... I think they were just partially coasting/not using full throttle to save a bit of fuel, knowing they could still run at close to Audi pace, but achieve an extra lap per stint AND a 3-4 second shorter fuel stop... reducing the time at full throttle would probably help a little with the reliability too....

Actually duruing the race on the long straights to the chicanes it looked as if they first started recovering shortly before hitting the Brakes. Also I doubt they are able to recover 8MJ just while braking. When we assume a 400kW electric Motor (The Porsche is said to have max ~1200HP of which 500 something would be the ICE) it would take 20s to revover 8MJ. I don't think they spend 20s on the brakes in one lap. decellerating from 300km/h to 100 at 4g will take less than 1,5s. So they will have to do some coasting or brake less firecely tha would be possible to recover the full 8MJ.

I don't buy any of this, sorry. Contradicts logic on one front too many. Also goes directly against what alonso said about battery not being recharged sufficiently if he lifts and coasts.
By lifting you're also denying mgu-h recovery.

[machin]

Of course, if you use the following definitions:

"coasting" is "a vehicle moving without propulsive force, whilst being subjected to the retarding forces of rolling resistance and aerodynamic drag"

and

"braking" is "a vehicle undergoing deceleration by the application of an on-board mechanical or electro-mechanical system, either directly by the driver, or indirectly using a control algorithm, in addition to rolling resistance and aerodynamic drag"

...Then the intentional application of the KERS system as soon as the driver lifts off the throttle, would, according to the definitions above, constitute a "braking event" and not a "coasting event"....

To be honest... I don't really see what we're all trying to get at here... aren't we all saying the same thing?!

"The Porsche was giving up some of its one lap pace in order to have a better average pace over multiple stints, and some of that increased pace was a result of the 8MJ ERS systems onboard" ???!!!!

[machin]

Having said that.... it is worth noting that LMP1 rule 14.7.2 states that:-

In particular this [KERS] system must: Ensure a level of braking effort directly linked to the brake pedal effort.

If the system is set up so that it recovers some energy (i.e. slows or "brakes" the car) with zero brake pedal effort it would contravene that rule in my opinion since you would be moving the brake response away from the origin on a graph of brake pedal effort vs actually braking effort, and therefore not have a strict mathematical "direct" relationship between the two....

[henra]

If the system is set up so that it recovers some energy (i.e. slows or "brakes" the car) with zero brake pedal effort it would contravene that rule in my opinion since you would be moving the brake response away from the origin on a graph of brake pedal effort vs actually braking effort, and therefore not have a strict mathematical "direct" relationship between the two....

Hmm, would it really?
It only says linear to brake pedal effort not brake forces. So if brake force is not linear to pedal effort you could still recover without effectively applying Brakes. Not necessarily saying this is the case although I tend to believe they are doing something like that.

[machin]

I read that rule as saying "The braking effort [provided by the KERS system] must be directly linked to the pedal effort, [i.e. No pedal pressure = no KERS recovery]". But its only my interpretation, backed up from what the drivers and manufacturers are saying publically.

But lets say, they do activate the KERS braking system a bit when the throttle is closed... How much do we think? 50kW worth? 100kW worth?

Remember throttling down the ICE is going to save about 550kW of fuel use, so I would still wager that the biggest saving from lifting the throttle at the end of the straights comes from the direct fuel saving, rather than any modicum of KERS recovery they have during off throttle periods....