Racing goes electric: At the track with Formula E, the first e-racing series • Hacker News Board

Re: Racing goes electric: At the track with Formula E, the first e-racing series

#81

Post by TheLoneWolfling » Mon, Mar 30, 2015, 2:50 PM UTC

Already__Taken wrote: post #80

TheLoneWolfling wrote: post #65

Earlier quoted context omitted.

It's rather difficult to do that and keep some semblance of safety. Ultimately I think the simplest way to keep things sane would be to do something along the lines of "you have amount of MJ worth of for the race" (which would then spawn all sorts of related rules about what exactly counts as fuel, but meh. Such is life.).

Those are basically WEC rules then.

WEC is endurance based - this would be a much shorter race.

Also, WEC imposes lots of other limits (numbers of tires allowed, etc, etc.)

Imagine something more along the lines of Group C.

Re: Racing goes electric: At the track with Formula E, the first e-racing series

#82

Post by TheLoneWolfling » Mon, Mar 30, 2015, 2:58 PM UTC

andrewchambers wrote: post #76

TheLoneWolfling wrote: post #49

Earlier quoted context omitted.

It would be interesting to do remote control. I.e. nobody in the car. Two classes: one with restrictions (i.e. driver must be in control - no assists / etc. May be tricky to define.), one without (want to go fully computer-controlled? Sure!).

Remote control means you can tweak the scale of the cars/races.

Yep.

Although it would be interesting to go "you must have a space where a person can fit, and if you ever kill the dummy inside you lose the race" (defined a little more precisely, of course).

Remember: you probably want to keep the scale vaguely car-size. That way you'll get the most applicable innovation coming out of it. And also that way it'll tend to be the most interesting to spectators.

Re: Racing goes electric: At the track with Formula E, the first e-racing series

#83

Post by TheLoneWolfling » Mon, Mar 30, 2015, 2:59 PM UTC

andrewchambers wrote: post #76

TheLoneWolfling wrote: post #49

Earlier quoted context omitted.

It would be interesting to do remote control. I.e. nobody in the car. Two classes: one with restrictions (i.e. driver must be in control - no assists / etc. May be tricky to define.), one without (want to go fully computer-controlled? Sure!).

Remote control means you can tweak the scale of the cars/races.

Yep.

Although it would be interesting to go "you must have a space where a person can fit, and if you ever kill the dummy inside you lose the race" (defined a little more precisely, of course).

Remember: you probably want to keep the scale vaguely car-size. That way you'll get the most applicable innovation coming out of it. And also that way it'll tend to be the most interesting to spectators.

Re: Racing goes electric: At the track with Formula E, the first e-racing series

#84

Post by barrkel » Mon, Mar 30, 2015, 10:13 PM UTC

aetherspawn wrote: post #50

daphreak wrote: post #20

Earlier quoted context omitted.

Electric motors do have a constant power region and its ideal to operate there. I would expect teams to modify their transmissions to better fit their motor as more parts of the car are opened up for modification.

The engines do have a fairly flat torque curve however, so you can get away with a constant speed reduction, which gives a decrease in weight (like the Tesla). One reason they might run a transmission is so that they constantly run the engine in the most energy efficient zone, giving them a longer battery life.

A flat torque curve means you get more power at higher revs. Power = torque x revs.

If torque is the same at 5k revs vs 10k (to pick numbers from thin air), when you downgear 10k 2:1, you double the effective torque over 5k at 1:1, for the same output revs.

Re: Racing goes electric: At the track with Formula E, the first e-racing series

#85

Post by aetherspawn » Tue, Mar 31, 2015, 12:07 PM UTC

barrkel wrote: post #84

aetherspawn wrote: post #50

Earlier quoted context omitted.

The engines do have a fairly flat torque curve however, so you can get away with a constant speed reduction, which gives a decrease in weight (like the Tesla). One reason they might run a transmission is so that they constantly run the engine in the most energy efficient zone, giving them a longer battery life.

A flat torque curve means you get more power at higher revs. Power = torque x revs. If torque is the same at 5k revs vs 10k (to pick numbers from thin air), when you downgear 10k 2:1, you double the effective torque over 5k at 1:1, for the same output revs.

It does not work like that. To run twice the speed, you run twice the voltage so you run half the amps. Torque scales almost linearly with amps. With the same power input, the power output is all about the motors limits versus your conversion efficiency.

The battery layout and chemistry will limit the actual power that can be delivered to the powertrain (discharge rate). A faster electric car is not one geared higher, but one which converts the most of this energy into motion.