Volvo flywheel KERS

[WhiteBlue]

It's sad if the only F1 relevance is in the name. Thinking about it, KERS is a much more appropriate name for this because it is storing kinetic energy close to the point of application (ie wheel/axle). That's in contrast to F1 converting kinetic to electrical storage from the wrong end of the ICE power train.

Truer words never spoken, it would be most interesting to learn about the total efficiency of F1 KERS, probably less than 50%.
Energy is going from the wheels thru the entire drivetrain, spinning a generator to convert mechanical energy to electrical, charging a battery, then discharging electrical energy from battery to a motor to convert back to mechanical energy and finally sending the remains thru the drivetrain to the wheels. Pathetic really.

Well, the F1 KERS is obviously giving a higher power to weight ratio and superior packaging or it would not be used. It appears to me that the flywheel systems are nice for stationary and low performance systems like a bus or truck but not so useful in a racing application. Toyota's supercap system was superior to the Audi flywheel in LMP1 this year and the electric KERS was superior in F1. There isn't much more proof required that the crucial design parameters don't match well with high performance applications in racing. I think when the storage capacities are set to grow substantially next year we will see mixed systems from ion batteries and supercaps like those used by Red Bull take over in both F1 and LMP1. You get very fast loading/unloading and bigger slower energy storage from combined electric systems than from any other system.

[Richard]

I think the reason for the F1 KERS configuration is due to a number of contrived external influences. Firstly the rules say the kit has to be at the wrong end of the power train, then total power is limited which means batteries are a possibility. Finally aero is king, so packaging can swing the pendulum against pure power density.

For example significantly increasing KERS power results in a lot more weight for the electric KERS batteries (ie power/weight of batteries is linear), but I imagine only a small weight gain for flybrid. A flybrid can increase the rpm for little extra weight, and I imagine the energy storage is square or cubic in relation to adding weight to the outer perimeter of the wheel.

I also imagine the optimum solution will be different in F1 if the unit could be anywhere.

For example the Volvo system on rear wheel drive would put KERS on the front wheel, giving 4wd on the exit to corners, that’d greatly improve handling, no more undesteer! I’d expect a small flybrid would be perfect for that in preference to electric? …. Although a flybrid would put the weight up high while electric simply uses low level batteries as ballast. So we’re back to packaging overruling power/weight efficiency?


My point is, how much of the choice to use electric KERS is dictated by the rules & aero, as opposed to the optimum power/weight efficiency? So perhaps the Volvo flybrid configuration might be more efficient in terms of power/weight of its intended application?

[WhiteBlue]

I seem to remember that Williams at the time said that the system is simply too big/heavy to fit into the available space that is allocated for the energy storage in the safety cell of the chassis.
The Toyota system in LMP1 also works on the rear wheels only and they use supercaps. Audi used the flywheel and exclusively on the front wheels where more electric energy is harvested. Nevertheless Toyota's system was deemed much superior. I think it shows that the space/weight requirements are simply excessive for the highest performance racing applications. The single seater safety cell would become too bulky if they had to accommodate a flywheel system even if you allow all wheel drive and allow to harvest all of the kinetic energy they can get. At least that is my conclusion. LMP1 with the open book rules will show us what is possible next year, but you have to consider that the coupe chassis in LMP1 provides a lot more space for a flywheel than an F1 single seater. Nevertheless I don't expect the flywheel to become the dominant system there.

[xpensive]

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My point is, how much of the choice to use electric KERS is dictated by the rules & aero, as opposed to the optimum power/weight efficiency? So perhaps the Volvo flybrid configuration might be more efficient in terms of power/weight of its intended application?

While running the risk of coming across as a sucking-up, this is also my position. If the FIA was serious of this "green" image, they should start with adapting the bodywork rules to suit off-the-driveshaft power take-off, picking it up/giving it back at the other end of the drive-train is simply stooopid.

Moreover, throw-away batteries can hardly be credible neither energy- nor environmentally-wise.

[WhiteBlue]

If the FIA was serious of this "green" image, they should start with adapting the bodywork rules to suit off-the-driveshaft power take-off, picking it up/giving it back at the other end of the drive-train is simply stooopid.

Could you elaborate a bit more on that? You lost me a bit in the abstraction level. What kind of design would be better? Feeding the electric torque into the gearbox?

Moreover, throw-away batteries can hardly be credible neither energy- nor environmentally-wise.

I agree with that sentiment but it will usually be considered of secondary priority if the competing technology does not meet the requirements of the engineers in terms of weight/performance and volume/performance.

[xpensive]

If the FIA was serious of this "green" image, they should start with adapting the bodywork rules to suit off-the-driveshaft power take-off, picking it up/giving it back at the other end of the drive-train is simply stooopid.

Could you elaborate a bit more on that? You lost me a bit in the abstraction level. What kind of design would be better? Feeding the electric torque into the gearbox?
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Do I have to draw you a picture? If the aerodynamic situation/regulations did not favor Fischer-Price gearboxes, a wider bodywork at the rear would easily house the MGU-K closer to the source of energy, which happens to be the rear wheels.

[WhiteBlue]

If the aerodynamic situation/regulations did not favor Fischer-Price gearboxes, a wider bodywork at the rear would easily house the MGU-K closer to the source of energy, which happens to be the rear wheels.

Ok, I see your point but I hardly think it is the only one for F1. There is a purpose in the regulations which require complete power units to be interchangeable and do not include gearboxes. The location of the bolt studs are specified, the turbo design is specified, the exhaust port location is specified and even the rotational sense of the crankshaft is specified to make it simple for teams to swap power units from one supplier to another one. All of this is done for a purpose. So since MGUs are part of the power unit definition how can they reasonably be attached to anything but the interchangeable power unit?

[xpensive]

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All of this is done for a purpose.
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Amen.

[Edis]

It's sad if the only F1 relevance is in the name. Thinking about it, KERS is a much more appropriate name for this because it is storing kinetic energy close to the point of application (ie wheel/axle). That's in contrast to F1 converting kinetic to electrical storage from the wrong end of the ICE power train.

Truer words never spoken, it would be most interesting to learn about the total efficiency of F1 KERS, probably less than 50%.

Energy is going from the wheels thru the entire drivetrain, spinning a generator to convert mechanical energy to electrical, charging a battery, then discharging electrical energy from battery to a motor to convert back to mechanical energy and finally sending the remains thru the drivetrain to the wheels. Pathetic really.

The round trip efficiency of the battery electric systems used in F1 is probably in the 60-70% range. Flybrid have mentioned an efficiency just below 70% for their mechanical system, so no major difference.

In F1 the motorgenerator is placed in front of the engine due to a desire to keep the weight as far forward as possible. From and efficiency standpoint, it matters very little where you take the power from the drivetrain but from a packaging and weight standpoint, taking the power directly from the engine is clearly the best option.

[autogyro]

In F1 the motorgenerator is placed in front of the engine due to a desire to keep the weight as far forward as possible. From and efficiency standpoint, it matters very little where you take the power from the drivetrain but from a packaging and weight standpoint, taking the power directly from the engine is clearly the best option.

Not if the motorgenerator is also the gearbox.

[Richard]

Posts on Autogyros's gearbox have been moved here http://www.f1technical.net/forum/viewto ... 53#p444353