VWs Pikes Peaks EV

[roon]

Yes, may not be worth addressing solely from an efficiency standpoint. That's what I was getting at six posts down. Aesthetically I would like to see this noise abated, though. I find the gear noise on racing EVs kind of annoying. The challenge would be in making a quieter, by necessity more efficient (sound waves have sources), spur gear.

[VARIANT | one]

Would they benefit from some sort of narrow range CVT?
I know the torque of the motor is constant, but would varying the gearing slightly help with corner exit?

Probably not worth the mass (and driveline losses). Like I said earlier, this is all about getting the most kg of downforce on the least kg of car. That's how you win this race, especially now that it's all tarmac.

Yes, may not be worth addressing solely from an efficiency standpoint. That's what I was getting at six posts down. Aesthetically I would like to see this noise abated, though. I find the gear noise on racing EVs kind of annoying. The challenge would be in making a quieter, by necessity more efficient (sound waves have sources), spur gear.

What part of 'unlimited' don't you understand? Run what you brung don't care about your musical sensibilities. Try a night at the opera, haha!

[Cold Fussion]

[Andres125sx]

Great video

[roon]

[Brake Horse Power]

Would they benefit from some sort of narrow range CVT?
I know the torque of the motor is constant, but would varying the gearing slightly help with corner exit?

Are you sure the torque is constant over a wide range of rpm? I think in most EV's the torque is maximum in the first 20 - 25% or so of the rpm range, than torque decreases but the power output stays the same to max rpm.

Suppose they need max torque the first 20% of the rpm range, and then they achieve max power. If the maximum speed on track is 200km/hour in a single gear, you would only have less than max power below 40km/hour. Which you will only drive at the starting line

[Tommy Cookers]

the (maximum) torque at each and every rpm will be whatever the designer has chosen
the designer of the EM and its drive (called a control unit by the FIA)

the specification of spending stored energy in the most battery-efficient and Pike's Peak time-efficient way is a higher task
the EM/drive design can only be as good as this specification
the Pike's Peak specification may be different to the specification for road use

[Big Tea]

Would they benefit from some sort of narrow range CVT?
I know the torque of the motor is constant, but would varying the gearing slightly help with corner exit?

Are you sure the torque is constant over a wide range of rpm? I think in most EV's the torque is maximum in the first 20 - 25% or so of the rpm range, than torque decreases but the power output stays the same to max rpm.

Suppose they need max torque the first 20% of the rpm range, and then they achieve max power. If the maximum speed on track is 200km/hour in a single gear, you would only have less than max power below 40km/hour. Which you will only drive at the starting line

TBH I do not know enough to argue it. I believed the ICE style of rpm means grunt did not transfer to an electric motor, but there obviously has to be some carry over as a motor already spinning has the flywheel effect and no need to move a stationary mass, but I totally admit to not being competent to make any sort of stance on it.

As Tommy Cookers says, they design to a spec, and I (naively?) thought a wider window would be more difficult to fill than a narrow(ish) slot.

[Brake Horse Power]

Here a tesla model S curve I am actually surprised max power isn't maintained. You can se the shape of the torque curve which is typical for these kind of motors.

[Tommy Cookers]

I would bet money that the P-P VW doesn't use an induction motor and isn't set up for road use by Joe Public

[Brake Horse Power]

I thought they took it out a laundry machine.

What I wanted to show was the shape of the torque curve, and that having a flat torque curve is actually not what you want to achieve. This idea is not to dissimilar of a road car

[Tommy Cookers]

the P-P VW has custom designed permanent magnet 'AC' motors not induction motors as Tesla

both use higher power at mid-speed than at high speed (to get the best result from their limited energy)
but the P-P (max) power curve is (I guess) rather well matched to one performance envelope - not to the general

because there is always this concept of time/motion efficiency of energy use ..
neither 'inverter' drive will support inefficient energy use eg holding full torque at full speed
but the PM motor will give a greater range of good efficiency so eg higher torque at lower speed (than the induction motor)

the induction motor and its drive (also being of course open-loop) are relatively cheap and simple
the PM motor has fancy magnetic material and talks to its drive via a closed loop

[Brake Horse Power]

Thanks Tommy, makes sense! I learned something. I tried finding the P-P car curve but I think it's not made public. Would be interesting to see what it looks like, also because there are other variables such as low speed grip, high speed drag etc. Maybe with unlocking the full low end torque potential of an electric motor it will be uncontrollable?

Offtopic: For this efficiency reason Tesla switched in the Model3 to PM motors.

[Tommy Cookers]

....... Maybe with unlocking the full low end torque potential of an electric motor it will be uncontrollable?
Offtopic: For this efficiency reason Tesla switched in the Model3 to PM motors.

the induction motor works quite well uncontrolled eg by switching the (AC) mains on or off as in the traditional vacuum cleaner
it has inherently 'soft start' ie the starting torque is low so is useless for a gearless EV
the IM works much better 'inverter-driven' - whereby the 'supply' frequency and voltage are variable (as Tesla S)
this is of course open loop
any (AC) PM motor will be more efficient than the IM and controllable in the same way
so the EV doesn't need 'closed loop control' ie feedback from the motor to its drive
though the F1 mgu-h and mgu-k have this (I'd bet)

there's EM low end torque potential if the motor's field is strong - as it will be with a permanent magnet field
such a motor isn't normally uncontrolled ie on-off - the supply voltage will be controlled to vary the torque (eg toy train set)
the mgu-k is PM so has 'LET' characteristic but is always finely controlled eg to keep torque consistent with 120 kW power limit

usually motors are in torque/rpm characteristic inherently stable (or stable by control) - important where load isn't stable
stability means in EVs as in F1 the motor torque variation as road grip falls, somewhat emulates traction control and ABS

a motor can combine wound and PM fields - eg the Tesla 3 has a PM switched reluctance motor
ie a 'stepper' (open-loop) motor - (but unlike existing hybrid steppers, which have a PM in the rotor)
https://cleantechnica.com/2018/03/11/te ... -in-depth/

[jjn9128]

Updated id.r for the Nurburgring electric lap record attempt... now in Blue (also some aero changes like the smaller rear wing which now has DRS)
https://twitter.com/volkswagenms/status ... 2054093824