3 ms·

I don't think there's a problem with cable weight with electric motors. Production EV's today have ridiculous amounts of torque and don't require prohibitively

I don't think there's a problem with cable weight with electric motors. Production EV's today have ridiculous amounts of torque and don't require prohibitively heavy cables. The issue with acceleration using wheels is gravity. You are limited to 1g, the downforce on the wheels, which you use for traction to push the vehicle forward. Spoilers increase the downforce on the vehicle beyond 1g, but the energy required to do that is proportional to the drag on the spoiler. Short of a rocket engine, the way to accelerate beyond 1g with a wheeled vehicle is to have a downforce fan. That can be powered by combustion or by electricity. I don't know which would offer the highest power to weight ratio.

deleted 4y ago
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lazide 4y ago
I’m not sure having a ‘reverse Helicopter’ on the back of your vehicle really qualifies as ‘ground vehicle’ at that point. Especially if it’s providing enough force to literally drive upside down on a ceiling somewhere.
- stefs 4y ago
  it's as ground as can be, short of a tunneling machine maybe.
- sacrosancty 4y ago
- et2o 4y ago
  This was the basis of a very famous F1 car in the 1970s. It was ultimately banned.
- benj111 4y ago
  What's the down force for an F1 car? Are they not ground vehicles?
solidr53 4y ago
BEV used to have around 80kg of copper [1], nowadays, manufacturers are moving towards 800V architecture attempting to cut the weight in half. I also feel like 800V cars also maintain their maximum power better on lower SoC than 400V systems. [1] https://www.copper.org/publications/pub_list/pdf/A6192_ElectricVehicles-Infographic.pdf https://www.copper.org/publications/pub_list/pdf/A6192_Elect...
mannykannot 4y ago
> Short of a rocket engine, the way to accelerate beyond 1g with a wheeled vehicle is to have a downforce fan. This electric vehicle is accelerating to 100kph (~28 m/s) in less than 1.5 seconds, which is an average acceleration of about 2g, if I am not mistaken. Looking around, I have seen 4.0 given as a representative friction coefficient for drag racing tires, which would imply a corresponding peak acceleration of 4g without aerodynamic assistance (again, if I am not mistaken.)
usrusr 4y ago
If we are already what-if-ing with wired power delivery, just skip the pantograph and look at what wire-guided missiles do: they have their data lines on a spool, unrolling as they go. For power you certainly wasn't thicker wires, and while you're at it, you'll certainly power the unrolling of the spool instead of just dragging it to spin up. Then if the spool unrolling is for some reason faster than the wheels, the wire will serve as reaction mass, pushing the vehicle. Now we have what's essentially a copper rocket that isn't constrained by downforce and tire grip at all.

deleted 4y ago

[deleted]

lazide 4y ago

I’m not sure having a ‘reverse Helicopter’ on the back of your vehicle really qualifies as ‘ground vehicle’ at that point. Especially if it’s providing enough force to literally drive upside down on a ceiling somewhere.

stefs 4y ago
it's as ground as can be, short of a tunneling machine maybe.
sacrosancty 4y ago
et2o 4y ago
This was the basis of a very famous F1 car in the 1970s. It was ultimately banned.
benj111 4y ago
What's the down force for an F1 car? Are they not ground vehicles?

solidr53 4y ago

BEV used to have around 80kg of copper [1], nowadays, manufacturers are moving towards 800V architecture attempting to cut the weight in half. I also feel like 800V cars also maintain their maximum power better on lower SoC than 400V systems. [1] https://www.copper.org/publications/pub_list/pdf/A6192_ElectricVehicles-Infographic.pdf https://www.copper.org/publications/pub_list/pdf/A6192_Elect...

mannykannot 4y ago

> Short of a rocket engine, the way to accelerate beyond 1g with a wheeled vehicle is to have a downforce fan. This electric vehicle is accelerating to 100kph (~28 m/s) in less than 1.5 seconds, which is an average acceleration of about 2g, if I am not mistaken. Looking around, I have seen 4.0 given as a representative friction coefficient for drag racing tires, which would imply a corresponding peak acceleration of 4g without aerodynamic assistance (again, if I am not mistaken.)

usrusr 4y ago

If we are already what-if-ing with wired power delivery, just skip the pantograph and look at what wire-guided missiles do: they have their data lines on a spool, unrolling as they go. For power you certainly wasn't thicker wires, and while you're at it, you'll certainly power the unrolling of the spool instead of just dragging it to spin up. Then if the spool unrolling is for some reason faster than the wheels, the wire will serve as reaction mass, pushing the vehicle. Now we have what's essentially a copper rocket that isn't constrained by downforce and tire grip at all.