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An electric sports car
06-08-2016, 01:00 PM, (This post was last modified: 06-21-2016, 07:39 AM by arturo.)
 arturo Junior Member Posts: 37 Threads: 7 Joined: Nov 2015
An electric sports car
I've put an electric motor into the AX2 and called the resulting file AX2-e.car... but before you get all excited, please be aware that electric cars are comparatively boring to drive. With no gears to change, the motor keeps pushing from the beginning to the end: when you get there, you are there.

Code:
```[engine] (...) max-power = 221000 torque-curve-00 = 0, 1111 torque-curve-01 = 1900, 1111```

Electric motors give a constant torque up to the regime of maximum power. You can then increase the regime, only to get a proportional reduction in torque so that power (equal to torque x rpm) remains the same.

The figures come from another project I'm playing with (if only I could find the 3d mesh ready-made): a C5 Tourer with the 300 hp engine of a Jaguar XF 3.0D... and matching electric power to the rear wheels! Admittedly, these would only push during short bursts (normally at the exit of a turn but also at top speed when needed to pass a competitor) using the energy recovered from braking. Those electric motors are the ones used here, without the internal combustion engine and hence with much larger batteries.

The maths involved are really easy to understand: the Jaguar engine produces its 221 kW at 4000 rpm, while the Citroën transmission has a final reduction ratio in 6th gear of 2.11. This means that the wheels (and the motors attached to the rear ones) are turning at 1900 rpm at top speed, which in turn means that we need 1111 Nm to achieve 221 kW.

Remember to make sure that your in-game clutch is strong enough to handle in excess of 1111 Nm. In fact, we are not simulating a clutch here but a fixed direct transmission between each motor and each rear wheel (which in theory would allow for torque vectoring around corners). Our gearbox and differential couldn’t be more simple:

Code:
```[transmission] gears = 1 gear-ratio-r = -1.0 gear-ratio-1 = 1.0 (...) [differential-rear] final-drive = 1.0```

I’ve made no other changes, only touring instead of sporting tyres given that much less grip is needed now. Top speed is 228 kph with the utterly unrealistic AX2’s drag coefficient of 0.30 (when you think that a typical closed-top LMP1 has 0.47, and even if the frontal area could be reduced from 2 to 1.7 square meters).
06-09-2016, 12:01 PM, (This post was last modified: 06-12-2016, 03:06 AM by arturo.)
 arturo Junior Member Posts: 37 Threads: 7 Joined: Nov 2015
RE: An electric sports car
OK, I've increased the drag coefficient from 0.30 to 0.40 (let's pretend that the car is in its Le Mans, low-drag aerodynamic configuration) and compensated, at least in part, by a reduction in frontal area from 2 to 1.7, which makes the top speed a bit harder to achieve but still doable.

The .car file is here: http://depositfiles.com/files/1gvuwaio6.

Code:
`http://depositfiles.com/files/1gvuwaio6`

I've been turning at 2'44" in Spa2008, while still learning the circuit.

EDIT: I had been using the original brake distribution 61/39 despite what was discussed here: http://www.vdrift.net/Forum/showthread.php?pid=15819.

Code:
`http://www.vdrift.net/Forum/showthread.php?pid=15819`

At La Source, it could even help you turn faster if done right. But I've realised that if you push the limit when braking downhill in the approach to Bruxelles, formerly Rivage, most of the time you will lose the back of your car and there is simply no human way to control it. Now I've uploaded a new file with 62/38 bias.

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