Horsepower of the engines.

[Big Mangalhit]

If I got this right it is possible that some teams are reaching the max harvesting from K and H and maybe can have the MGU-K spending the max 120kW all the time they need in every lap of the GP and not only the initially theorised 33s?

[Frank_]

Unfortunately no. A radial inflow turbine does not act as a pump when overdriven. In fact the faster it goes - the higher the backpressure.

that makes sense and thank you (yet another up-vote if i could,ve )
i assume axial turbines are not allowed

[Cold Fussion]

If I got this right it is possible that some teams are reaching the max harvesting from K and H and maybe can have the MGU-K spending the max 120kW all the time they need in every lap of the GP and not only the initially theorised 33s?

33 seconds comes from the 4MJ/lap limit of energy transfer from the ERS to MGU-K at 120kW. The rules allow for unlimited energy transfer from the MGU-H to MGU-K so in principal you could have full time deployment of the MGU-K Whether or not the PU manufacturers are able to harvest at a rate of 120kW is cause for speculation (we have 2 massive threads on this very topic).

There is also the concept of the self sustaining mode, which is where the MGU-K is run at the harvesting power level (eg, MGU-H harvesting 95kW at time x, MGU-K deploying 95kW at time x). Now when they run in this self sustaining mode is an interesting optimisation problem because in theory the most effective deployment of energy is to deploy it at high rates over shorter time instead of lower rates over more time (120 kW for 2 seconds is better than 60 kW for 4 seconds, assuming no traction problems). This points to you always first using energy from the battery before going into self sustaining. For an example, accelerating out of a corner, the ECU/CE will probably at first deploy power from battery energy until some % of Vmax/for x time before switching into self sustaining mode. However if you can harvest around 120kW it's probably more energy efficient to send it straight to the MGU-K instead of having to go through two battery conversions. You'd have to develop a proper model to really get a proper idea of how they may be deploying though.

Unfortunately no. A radial inflow turbine does not act as a pump when overdriven. In fact the faster it goes - the higher the backpressure.

that makes sense and thank you (yet another up-vote if i could,ve )
i assume axial turbines are not allowed

AFAIK axial turbines are not explicitly forbidden but IIRC you're only allowed one turbine stage, so you'd struggle to get the correct Pr for a single stage axial turbine.

[henry]

If I got this right it is possible that some teams are reaching the max harvesting from K and H and maybe can have the MGU-K spending the max 120kW all the time they need in every lap of the GP and not only the initially theorised 33s?

Sorry for being a bit slow to respond.

As with everything to do with these PUs I don't think there is a single, one size fits all, answer to this. It varies with circuit, chassis and aerodynamic characteristics and even things like wind direction.

I've tried to work out a method to get a ballpark idea of what it would mean to achieve what you suggest.

First we need a definition of "all the time they need". One definition might be all the time they are not traction limited and running at max ICE power. I'll use that.

Second we need to look at how energy is used around the lap and through the race.

If we take a lap time we can divide the lap into three states :

1 Traction limited - part power running typically the slow medium parts of the course. The ICE is at part throttle or low revs, or both. The MGU-K is not deployed.

2 Not traction limited - full power running, typically the straights and fast corners. The ICE is at full power making as much power as it can. The MGU-K is fully deployed motoring.

3 Braking. The ICE is off. The MGU-K is generating.

There is a fourth state, lift and coast, but trying to deal with that is beyond me.

I think that using the 100 kg and 100kg/hr fuel regs and some estimates for the above it is possible to estimate the output that would be needed from the MGU-H to make it possible to run the MGU-K flat out (120 kW ) while in state 2.

I have worked on three circuits, Barcelona, Spa and Singapore. I'll use the data for Barcelona.

Barcelona runs over 66 laps with a typical lap time around 92 seconds. That makes average fuel useage 1.515 kg a lap.

Brembo give the % braking as 18%. I found a figure of 57% full throttle (52.4 secs) on the f1fanatic website.
This leaves 25 % at part power.

If we assume the full 120 kW is captured during braking the 2 mJ Is captured into the ES every lap.

The time in state 1 Is 23 secs. To calculate the fuel available to run the ICE at full power we need an estimate of the fuel usage in state 1. I assumed an average engine speed of 9000 rpm, giving a Max fuel flow of 83.6 kg/hr. I then assumed an average of 50% of this for part throttle. Arbitrary I know but necessary to get an answer.

This gives a fuel useage in state 1 of 0.275 kg/lap. Leaving 1.24 kg for full throttle state 2.

This converts to 44.6 seconds, with a consequence of needing several seconds coasting Per lap.

If the MGU-K runs at 120 kW for this time it needs 5.4 mJ. 2 come from the ES leaving the MGU-H to supply 3.4.

The MGU-H spends 44.6 seconds generating at its max level and 23 at a lower level which I have assumed is in ratio to the fuel rate, 100 vs 43.

This gives a target MGU-H power of 3420 / (44.6 + 23 X 0.43). 62.76 kW.

I have yet to rerun the figures for a quali lap time but even using these figures and an extra 2 mJ in the ES the power required is 26 only kW.

The figures for Spa are 86 and 58 kW. For Singapore 56 and 22.

I leave everyone to make up their own minds about whether these levels are achievable or not.

In making these calculations I have noticed there is a distinct positive feedback mechanism at play. The faster you go, shorter lap time, the faster you go. This may explain some of the extent of Mercedes advantage. Just a little bit better in a few key areas makes for a big improvement.

[gruntguru]

If the total energy generated by the MGUH plus MGUK per lap is greater than needed to run the K at 120 kW during full throttle operation, the surplus energy can be used to save fuel during part load operation eg 200 kW needed at the wheels could be supplied as 120 from the K plus 80 from the ICE.

[henry]

If the total energy generated by the MGUH plus MGUK per lap is greater than needed to run the K at 120 kW during full throttle operation, the surplus energy can be used to save fuel during part load operation eg 200 kW needed at the wheels could be supplied as 120 from the K plus 80 from the ICE.

Or it could be used to motor the MGU-H with the wastegate open to make some extra power at the beginning of the straights.

Which is better would depend on which delivers the best lap time. A boost at the beginning of a straight reduces the time to cover it which reduces consumption because fuel flow is time based.

One thing I don't understand is how the deployment of electrical power is made to conform to the rules on pedal mapping. For instance when McLaren ran out of ES halfway down a straight the driver demand doesn't change but the torque goes down. If the ES isn't wholly depleted, I assume some is always held in reserve for anti lag duties, then that is a drop in torque by design, and I'm not sure why it is legal.

[wuzak]

The pedal mapping rule is there to prevent traction control software.

I don't think McLaren's case was a example of that. Certainly they got no advantage from it.

[Big Mangalhit]

Thanks everyone for the replies these engines are truly formidable. I just had one more thing to ask. While the MGU-H will slow down the turbine to harvest energy and transfer to the MGU-K->crankshaft I guess it also, in special cases like low RPM, will use some energy to accelerate the compressor and compensate the turbo lag, right? Is that energy very little to take into account, or is it being taken into account or am I understanding it poorly?

[henry]

The pedal mapping rule is there to prevent traction control software.

I don't think McLaren's case was a example of that. Certainly they got no advantage from it.

As you say, McLaren got no advantage. But what's to stop a team running the MGU-K for a couple seconds at the beginning of a straight and then turn it off to maximise energy for the next straight? I suspect there isn't anything and teams are free to use electrical power when and how they see fit.

[OO7]

The pedal mapping rule is there to prevent traction control software.

I don't think McLaren's case was a example of that. Certainly they got no advantage from it.

As you say, McLaren got no advantage. But what's to stop a team running the MGU-K for a couple seconds at the beginning of a straight and then turn it off to maximise energy for the next straight? I suspect there isn't anything and teams are free to use electrical power when and how they see fit.

Yes, that's correct.

[FW17]

Is there a rule which mentions that harvesting from MGUK can happen only when the drivers applies pressure on the brake pedal?

[ian_s]

The pedal mapping rule is there to prevent traction control software.

I don't think McLaren's case was a example of that. Certainly they got no advantage from it.

further to this, i think the rules actually state that the torque demand mustn't drop, not that the torque delivered by the PU mustn't drop.

[nevill3]

Is there a rule which mentions that harvesting from MGUK can happen only when the drivers applies pressure on the brake pedal?

I don't think so, the flashing light is activated to let following drivers know that harvesting is happening on the car in front and the lights regularly flash before a braking zone if I remember correctly

[wuzak]

Is there a rule which mentions that harvesting from MGUK can happen only when the drivers applies pressure on the brake pedal?

I don't think so, the flashing light is activated to let following drivers know that harvesting is happening on the car in front and the lights regularly flash before a braking zone if I remember correctly

I think that is because the K has stopped deploying rather than started to harvest. And specifically the H has stopped supplying the K.

[hemichromis]

The pedal mapping rule is there to prevent traction control software.

I don't think McLaren's case was a example of that. Certainly they got no advantage from it.

As you say, McLaren got no advantage. But what's to stop a team running the MGU-K for a couple seconds at the beginning of a straight and then turn it off to maximise energy for the next straight? I suspect there isn't anything and teams are free to use electrical power when and how they see fit.

But it must not be controlled by the driver, well only by the throttle pedal.
I think that's in the regs.