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Tesla Roadster

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Re: Tesla Roadster

#681

Post by rohit2412 »

ardit33 wrote: post #17

The Tesla roadster specs are insane! No exotic carmaker will be able to match it (taking price as a consideration). (no Ferrari, or Lambo, can get that close. This is Formula 1 acceleration speeds). Plus 620 miles of range, and it is a 4 seater. Expensive as hell, but this is exotic car territory. Base Specs Acceleration 0-60 mph1.9 sec Acceleration 0-100 mph4.2 sec Acceleration 1/4 mile8.8 sec Top SpeedOver 250 mph…

> No exotic carmaker will be able to match it (taking price as a consideration). (no Ferrari, or Lambo, can get that close. This is Formula 1 acceleration speeds).

None of them will? Why? Has Tesla got some trade secret?

Re: Tesla Roadster

#682

Post by killjoywashere »

ska wrote: post #610
clarkmoody wrote: post #596

Earlier quoted context omitted.

Accelerating at 1.28g (41.25 ft/s2) for 8 seconds will get you to exactly a quarter mile. x = 0.5*a*t^2 = 0.5 * 41.25 ft/s2 * (8s)^2 = 1320 ft = 1/4 mi Under that acceleration, your final speed is 225 mph v = a*t = 41.25 ft/s2 * 8s = 330 ft/s = 225 mph

Accelerating at > 1g off the line has its own set of issues - without extra downforce from somewhere you have traction problems regardless of tires, street tires just make it worse. This is why you see so many approx 2.9s 0-60 times in higher end sports cars, it's hard for aerodynamics to affect it much over the first couple of seconds.

Correct me if I'm wrong, but isn't downforce an aerodynamic issue? There are no aerodynamics at 0 mph. You do have a torque problem, but the Tesla is actually a fairly heavy car, is it not? Also, isn't Tesla's center of mass pretty near the same height as the axles? So it's not like the rear end is going to get under the front end.

Re: Tesla Roadster

#683

Post by Zalastax »

zymhan wrote: post #674
thechao wrote: post #647

Earlier quoted context omitted.

I don't think it's altered video. I'm just describing possible things that people could see in that video, which might lead to that conclusion: 1. an odd camera motion; 2. scared spectators jerking; or, 3. altered video. I do, however, think the people downvoting me have significant reading comprehension problems. However, that's a thing they will have to reflect on, internally, and has no bearing on me.

You started off with a claim that the video was sped up (i.e. _altered_). I'm not sure anyone downvoting you has a problem reading.

He's not the one that made the claim. Look at the usernames.

Re: Tesla Roadster

#684

Post by sago »

gsnedders wrote: post #270
sago wrote: post #158

Earlier quoted context omitted.

> Chiron is traction limited for most of its run This sounds very dubious, unless it has negative aerodynamic downforce. Even then, the times for each successive mph drop off too fast for it to be traction limited. Even F1 cars are not traction limited for more than a brief spell of straight-line acceleration. Aero drag dominates very quickly. Cornering or braking, on the other hand...

From memory, I remember seeing something claiming that the Chrion's 0–60 and 60–0 times were identical.

That's doubly fishy, since it has an airbrake.

[My caveat on this, I'm not a road-car enthusiast, so I'm just deducing. But I used to work in motor racing, mostly bikes. Based on the standard of reporting I saw about stuff I did know well, I don't trust the motor press on tech claims.]

Re: Tesla Roadster

#685

Post by carry_bit »

0xbear wrote: post #609
ajnin wrote: post #458

Earlier quoted context omitted.

No, it's incorrect, physics does not mandate that battery should heat up as you expend energy. Ideally all the energy would go into kinetic energy and be dissipated by friction losses due to air or contact between the road and the tires. The battery heats up only because the process of tranferring the chemical energy from the batteries to the car motion is imperfect, and there are internal losses do to the internal r…

It does. It will heat up. To quote a physics textbook: “Power transfer between a voltage source and an external load is at its most efficient when the resistance of the load matches the internal resistance of the voltage source.” IOW in the configuration where the power transfer is at its most efficient, battery has to dissipate as much thermal energy as motor(s) are consuming. Too much internal resistance and most o…

That sentence from the textbook is poorly worded, see https://en.wikipedia.org/wiki/Maximum_power_transfer_theorem...

Yes, power is lower when efficiency is greater all other things equal, but you work around that by not making all other things equal.

Re: Tesla Roadster

#686

Post by zymhan »

Zalastax wrote: post #683
zymhan wrote: post #674

Earlier quoted context omitted.

You started off with a claim that the video was sped up (i.e. _altered_). I'm not sure anyone downvoting you has a problem reading.

He's not the one that made the claim. Look at the usernames.

oh, whoops

Re: Tesla Roadster

#687

Post by koreyb »

Unklejoe wrote: post #480

Has the 8 second quarter mile been confirmed to be done in stock trim (i.e., no special tires or other modifications)? The reason I ask is because that is EXTREMELY impressive. I tune EFI systems on race cars as a hobby, and any car in the 8 second range usually needs to run slicks or drag radials to have enough traction. Even all wheel drive cars (GTRs, DSMs, EVOs, etc.) usually run 4 slicks once they get to that sp…

Here is a gutted Model S P100D (4460 lb, 2 motors, 100kWh battery) running a 10.4 https://www.youtube.com/watch?v=dO8sXUGfjWQ

Roadster will be lighter, have a better drag coefficient, 2x the power (1500hp), 3 motors, 200 kWh battery (?).

According to Electrek's ride along the wheels are "fat" - 325mm rear/295mm front. Dodge Demon's are 315/40R18 Nitto NT05R. https://electrek.co/2017/11/17/new-tesla-roadster-halo/

Should be close!

Re: Tesla Roadster

#688

Post by scott_karana »

bwang29 wrote: post #19

I'm thinking what this means to gas car makers. Wave 1: "It's all about legacy and prestige, not speed/acceleration". Wave 2: "The track handling isn't all that good, how can drivers take that corner at full power without losing traction". Wave 3: "Alright, we will go electric too".

Wave 3 requires lighter, denser, cheaper batteries that we haven't achieved yet.

Re: Tesla Roadster

#689

Post by lafar6502 »

Sohcahtoa82 wrote: post #624
lafar6502 wrote: post #479

Earlier quoted context omitted.

I dunno. check the value of previous model of tesla roadsters and if their owners want to keep them

Yes, we should totally judge the next gen Roadster based on the first gen one. Ignore the advancements in battery tech and other lessons Tesla has learned in the nearly 10 years since the first Roadster.

They haven’t learned how to produce cars, that’s sure. And judging by the past, your car will become outdated and obsolete in 5 years.

Re: Tesla Roadster

#690

Post by jdunck »

Unklejoe wrote: post #491
8draco8 wrote: post #483

Earlier quoted context omitted.

Yes but in those cars traction control is usually off. In Tesla extremely precise traction control may work in your favour giving only as much power as tires can handle effectively allowing to near zero time loss on regaining tracktion. In quarter mile cars you don't have option, either tire will handle all that power or slip causing time loss.

Modern high-end aftermarket EFI systems (such as MoTeC) do have traction control, but it's not as effective as one would expect. The main issue I found is that street tires often just don't have the traction required, even under ideal conditions. The result is that traction control has to cut power so much that it ends up hurting the quarter mile times. It does help tremendously on consistency and safety though. Thin…

And what if the battery weight is nearer axle centerline than an ICE?
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