2021 Engine thread

[AJI]

The plan is they loose the full lap off ERS they have now. They can deploy the 300kw on chosen parts of the track and save up several laps to have one longer stint of deployment.

But will they do that? With no fuel limits they can motor against the K to charge the ES. It all depends on the new SoC limits.

[hurril]

Sure, but if you don't use the brakes then you don't get any recovery no matter how big the generator is...
TC's point on all wheel recovery is the only way I can make the calculations work, and that is not going to happen

120kW is not using 100% of the available breaking power so a bigger generator can and will produce more power. It's important that we keep energy and power separate.

It still doesn't change the fact that the current cars cannot even recover 2MJ per lap from the rear axle under brakes with a +/-120kW K. They simply don't use the brakes enough to do it.
Yes, a bigger K will give you the ability to capture more braking energy, but if the aero is the same that lack of braking is a problem. Have they mentioned anything about ES SoC limits? With a 300kW motor 4MJ per lap isn't a problem, but that's pretty much the limit unless they start burning fuel to charge the ES.

You seem to still be missing the point. They brake away MUCH more than 2MJ. They just cannot funnel enough of that to the battery since the hose will only accept the energy at a rate of 120kW.

[AJI]

120kW is not using 100% of the available breaking power so a bigger generator can and will produce more power. It's important that we keep energy and power separate.

It still doesn't change the fact that the current cars cannot even recover 2MJ per lap from the rear axle under brakes with a +/-120kW K. They simply don't use the brakes enough to do it.
Yes, a bigger K will give you the ability to capture more braking energy, but if the aero is the same that lack of braking is a problem. Have they mentioned anything about ES SoC limits? With a 300kW motor 4MJ per lap isn't a problem, but that's pretty much the limit unless they start burning fuel to charge the ES.

You seem to still be missing the point. They brake away MUCH more than 2MJ. They just cannot funnel enough of that to the battery since the hose will only accept the energy at a rate of 120kW.

With respect hurril, I'm not missing the point.
It's a no-brainer that the cars generate much more than 2MJ of braking energy, most of which is currently turned into heat and sent into the atmosphere because, as you and I have pointed out, the current K is only allowed to recover 120kW per second.
The real question is: how much braking energy can the K recover from the rear axle with a 300kW unit? This has been discussed many times in many threads and a ton of calculations have been done using Barcelona because it's a medium track and we have the braking data.
Ignoring the fact that they aren't on the brakes long enough currently to recover 2MJ at 120kW, let's make it simple and assume that they will recover 2.5 times more energy than they currently do because the K is 2.5 times the size, so, 5MJ per lap. That's it, 5MJ under brakes is the upper limit per lap with the same aero and only rear axle recovery.
NL_Fer has pointed out that they will need to recover over multiple laps and then deploy in a strategic manner.
I suggested that the other option is to burn fuel to charge the ES.

I'm happy to be proven wrong, but the reality is; until we know the new fuel allowance, and what the new aero package is, and what the new max allowable SoC difference is, we're all just guessing.

[hurril]

You are right, I see what you're saying now. Sorry about being a bit of a dick about it.

So, have we seen any numbers on what the "available" braking power on the rear wheels are?

[AJI]

You are right, I see what you're saying now. Sorry about being a bit of a dick about it.

So, have we seen any numbers on what the "available" braking power on the rear wheels are?

That's cool.
There are numbers on available braking power in about 10 different threads, but they're all just educated guesses.
The main problem with the current formula is, as they aren't allowed to recover more than 2MJ i think they deliberately stay away from that number (while braking) for safety. It would be a delicate balancing act to suddenly lose 120kW of rear brake power when you exceed 2MJ on the entry to a fast corner... They must make up the deficit by motoring against the K.
If the 2021 rules allow unlimited K recovery then they can use the K for brakes more consistently.

[henry]

You are right, I see what you're saying now. Sorry about being a bit of a dick about it.

So, have we seen any numbers on what the "available" braking power on the rear wheels are?

That's cool.
There are numbers on available braking power in about 10 different threads, but they're all just educated guesses.
The main problem with the current formula is, as they aren't allowed to recover more than 2MJ i think they deliberately stay away from that number (while braking) for safety. It would be a delicate balancing act to suddenly lose 120kW of rear brake power when you exceed 2MJ on the entry to a fast corner... They must make up the deficit by motoring against the K.
If the 2021 rules allow unlimited K recovery then they can use the K for brakes more consistently.

To recover 2 MJ at 120 kW at 100% efficiency requires 16.66 seconds of braking time. There are few circuits that require that much braking. Only Singapore and Monaco would likely require the precaution you mention.

[AJI]

... Only Singapore and Monaco would likely require the precaution you mention.

But you agree that it would be wise to take the precaution, yes?
It's probably less marginal since the 2017 aero rules reduced braking, but pre 2017 it would have been a concern at more tracks.

Anyway Henry, we're trying to estimate what will happen with a 300kW K, so, what are your thoughts on that?

[Tommy Cookers]

total rear axle braking power available (mechanical or electric) becomes less than 300 kW below about 100 mph
total rear axle braking power available (mechanical or electric) becomes less than 120 kW below about 50 mph

the available time/lap working at 300 kW is less than the time/lap working at 120 kW
so energy yield will be less than proportionate to the 300 kW power

various electrical factors may cause system trip out so the mechanical system margin for stand-in must be larger

[henry]

... Only Singapore and Monaco would likely require the precaution you mention.

But you agree that it would be wise to take the precaution, yes?
It's probably less marginal since the 2017 aero rules reduced braking, but pre 2017 it would have been a concern at more tracks.

Anyway Henry, we're trying to estimate what will happen with a 300kW K, so, what are your thoughts on that?

My numbers are from 2016. Brembo used to produce useful braking data sheets for each circuit then, with braking time at each corner. The equivalent now is a bit flashy and less interesting.

My theory is that for every lap they have a SOC map which says what the SOC should be at each point on the circuit, they will manage the MGU-K contribution to that map so that they don’t arrive at the last corner with no headroom. I would expect they spend some of practice refining the map and that it is adaptive to take account of track evolution, wind, etc.

If they have 300 kW rear they’ll still be able to fully utilise it but as speed falls they might not have enough downforce to harvest it all.

At 30 m/s TE needed is 10,000 N, at mu = 2.0 that’s 5000 N vertical force required.

The vertical load of an 800 kg car 55:45 static balance, 20% weight transfer, vertical mass load 2800 N. I doubt there is 2200 N aero load at 30 m/s. (65 mph, 105 kph)

So if the cars stay roughly the same in weight and aero configuration they will not be harvesting for the full braking time, particularly when braking to low speed. So maybe a max recovery of 3.5 to 4 MJ on the average circuit.

A lower CG and longer wheelbase would help by reducing weight transfer, and more rearward static balance would also help, as would a lower drag vector.

The rear physical brakes would get even smaller perhaps making an MGU-K failure terminal even for a Red Bull at Monaco.

@ Tommy Cookers beat me to it. I’ll still post this for the numbers.

[AJI]

... Only Singapore and Monaco would likely require the precaution you mention.

But you agree that it would be wise to take the precaution, yes?
It's probably less marginal since the 2017 aero rules reduced braking, but pre 2017 it would have been a concern at more tracks.

Anyway Henry, we're trying to estimate what will happen with a 300kW K, so, what are your thoughts on that?

My numbers are from 2016. Brembo used to produce useful braking data sheets for each circuit then, with braking time at each corner. The equivalent now is a bit flashy and less interesting.

My theory is that for every lap they have a SOC map which says what the SOC should be at each point on the circuit, they will manage the MGU-K contribution to that map so that they don’t arrive at the last corner with no headroom. I would expect they spend some of practice refining the map and that it is adaptive to take account of track evolution, wind, etc.

If they have 300 kW rear they’ll still be able to fully utilise it but as speed falls they might not have enough downforce to harvest it all.

At 30 m/s TE needed is 10,000 N, at mu = 2.0 that’s 5000 N vertical force required.

The vertical load of an 800 kg car 55:45 static balance, 20% weight transfer, vertical mass load 2800 N. I doubt there is 2200 N aero load at 30 m/s. (65 mph, 105 kph)

So if the cars stay roughly the same in weight and aero configuration they will not be harvesting for the full braking time, particularly when braking to low speed. So maybe a max recovery of 3.5 to 4 MJ on the average circuit.

A lower CG and longer wheelbase would help by reducing weight transfer, and more rearward static balance would also help, as would a lower drag vector.

The rear physical brakes would get even smaller perhaps making an MGU-K failure terminal even for a Red Bull at Monaco.

@ Tommy Cookers beat me to it. I’ll still post this for the numbers.

Thank you (and TC) for a very useful contribution to the conversation.
So, in short, we are in agreement that a 300kW K can't recover the theoretical maximum (based on simple multiplication of the current recovery) of 5MJ per lap under braking with the current aero (and weight).
Next question. What do we think the 2021 max SoC difference will be for the ES. I'm guessing 6MJ, but I'm hoping it will be unlimited.

[NL_Fer]

Unlimited ES will fire a development battle for battery cells. Without restrictions one of the f1 teams will become the worlds best battery manufacturer, surpassing Panasonic.

[Big Tea]

Unlimited ES will fire a development battle for battery cells. Without restrictions one of the f1 teams will become the worlds best battery manufacturer, surpassing Panasonic.

Or panasonic will come on board with a team.
May be a good thing if they started a battery war. As long as the cost was kept in the suppliers, not to the teams.

[wuzak]

Unlimited ES will fire a development battle for battery cells. Without restrictions one of the f1 teams will become the worlds best battery manufacturer, surpassing Panasonic.

ES will likely be a standard component, as will the K.

[henry]

But you agree that it would be wise to take the precaution, yes?
It's probably less marginal since the 2017 aero rules reduced braking, but pre 2017 it would have been a concern at more tracks.

Anyway Henry, we're trying to estimate what will happen with a 300kW K, so, what are your thoughts on that?

...

@ Tommy Cookers beat me to it. I’ll still post this for the numbers.

Thank you (and TC) for a very useful contribution to the conversation.
So, in short, we are in agreement that a 300kW K can't recover the theoretical maximum (based on simple multiplication of the current recovery) of 5MJ per lap under braking with the current aero (and weight).
Next question. What do we think the 2021 max SoC difference will be for the ES. I'm guessing 6MJ, but I'm hoping it will be unlimited.

The SOC limit is dependent on several other controllable factors. Fuel rate, fuel quantity, drive and recover MJ/lap limits.

If we assume no limits I think 8 MJ would be a ballpark figure to allow full 300 kW deployment for complete laps at almost all circuits, in qualifying.

For ballpark calcs like this I use a fictitious circuit, 60 secs WOT, 25 secs part throttle, 15 secs braking.

That puts max deployment per lap at 18 MJ.

Energy recovery 10 MJ - (Max braking recovery around 4 MJ and recovery at part throttle maybe 6 MJ ) I also assume the ICE power at 500 kW which might be high in conjunction with 300 electrical.

Limit case for continuous SOC drain is probably Baku, 22 secs WOT, 6.6 MJ.

On race laps they’d be 8 MJ short of full deployment so there would be opportunities for “save and deploy” which I’ve heard is an objective.

Unlimited ES capacity would allow saving for multi-lap deployments but would not affect qualifying above the 8 MJ I suggest.

As an aside I expect a consequence of recovering and deploying more electrical power will be a continued emphasis on low speed grip, through suspension and downforce. Top speeds will likely stay as they are or fall. If they “fix” the noise the fans will move on to top speed as the reason the cars are not as good as they used to be.

[NL_Fer]

Would they move cog to the rear, for more rear brake bias? Maybe we get more twisty rear ends this way!