Next gen Roadster

[Norbert]

Sounds great, but this brings up somewhat of a puzzling thought for me. Am I the only one who has a bit of a hard time picturing Tesla launching an aluminum intensive car line and then 3 years later ramping up a completely different model R composites manufacturing line (that can also work with the assumed bluestar aluminum)? This sounds VERY capital intensive (i do feel a sudden need for a more elaborate point besides "expensive/potentially inefficient" here).

I suppose it would be inconceivable at the same time to not use composites on the model R. I wonder if we could see tesla trying to eventually bleed the benefits of composite into their other lines (more in line with BMW i series or Aptera main tech advantages). But again, to built a state of the art aluminum line and then a state of the art composite line for a fledgeling car company just strikes me as crazy.

Well, it seems they can produce "exterior carbon fiber accents" (and a dash, but is it real carbon fiber?) for the performance version without difficulty.

Certainly that's an interesting question. Which line will the new gen Roadster use? Probably not the Model S line, and since the Bluestar line will be built for a volume of perhaps 200,000, one wonders whether it will be ready for "Model R". Will Model R be built on the same high volume line, or ... what is the alternative, a line just for itself?

[vfx]

The CF parts for the Roadster were subbed out. At first by a French manufacturer.

Tesla is big on doing things in-house. They purchased millions in massive panel stamping machines. Going to CF would be cool but no auto maker has really mastered how to do it inexpensively.

[dsm363]

It looks like Mercedes is working on carbon fiber so at least one of Tesla's partners might be able to help them.
Mercedes-Benz working on carbon fiber E-Class?

[doug]

But what about perception? Releasing a next gen roadster on the smaller platform might make some sense using the original Roadster plan of low volume high dollar car but won't critics bash them for being a rich man's car maker*? If they release the Bluestar low budget car the are not only pleasing more of the car buying public but staying closer to original plan and making fanboys happier as well.


* I am aware that the bashing will continue, regardless. Tesla has Gov loans to think about, that's all.

I think as long as Tesla eventually pays back those loans I think it's ok for them to remain a "rich man's car maker" for the time being, perhaps the wiser course even. I'll say again that the Nissan Leaf pricing was a game changer (though we still have a ways to go to see how things will pan out). It will be difficult for Tesla to compete in the low-cost/high-volume market, while at the high end they compete favorably on price and lead the industry on range and performance.

Tesla has been a catalyst for change in the industry (which also was part of the plan) and that likely has a greater societal benefit than they could provide by selling low end cars.

[vfx]

...
Tesla has been a catalyst for change in the industry (which also was part of the plan) and that likely has a greater societal benefit than they could provide by selling low end cars.

I like this, though I hope they end up being more...

[bolosky]

To deliver good times at racetracks they will probably need a transmission.
Without a transmission the acceleration at high speeds will not be sufficient and a top speed of 130mph isn't good enough to turn fast laps.

Why do you think a transmission would help at all with acceleration at high speed? With the Roadster, above about 40 mph the limit on performance is the power that the battery can deliver. Gears don't change the power at all, and acceleration depends on mass and power (and aerodynamic drag, etc.). To increase high speed acceleration, pretty much all you can do is to increase power out of the battery or reduce mass (or reduce drag through better Cd or lower frontal area).

What a transmission might help with is increased top speed, because you might redline the motor before you get to the point where all of your power is spent overcoming drag. This is not the same as acceleration, though.

[richkae]

Why do you think a transmission would help at all with acceleration at high speed? With the Roadster, above about 40 mph the limit on performance is the power that the battery can deliver. Gears don't change the power at all, and acceleration depends on mass and power (and aerodynamic drag, etc.). To increase high speed acceleration, pretty much all you can do is to increase power out of the battery or reduce mass (or reduce drag through better Cd or lower frontal area).

What a transmission might help with is increased top speed, because you might redline the motor before you get to the point where all of your power is spent overcoming drag. This is not the same as acceleration, though.

The transmission discussion comes after assumptions of doubling the battery power and reducing drag by one third from the original Roadster - discussed earlier.

[drees]

Why do you think a transmission would help at all with acceleration at high speed? With the Roadster, above about 40 mph the limit on performance is the power that the battery can deliver.

Tesla had a power chart which shows that power peaks around 8000 rpm (not sure what speed that corresponds to, ~60 mph?). Can't find the original, but found this one. I assume the battery could push 200 kW+, no?

[TEG]

Tesla had a power chart which shows that power peaks around 8000 rpm (not sure what speed that corresponds to, ~60 mph?). Can't find the original, but found this one. I assume the battery could push 200 kW+, no?

I think it is a bit abover 60mph... maybe closer to 70.
Also, I think the battery is only expected to do highest C-rate for short amounts of time to avoid long term damage.
The power drop off may (in part) be intentional to save the battery longevity.
Just 'food for thought'.

[stopcrazypp]

Why do you think a transmission would help at all with acceleration at high speed?

It might help a tiny bit, just due to the way the Roadsters' torque drops at that high end. It drops asymptotically with the center of curvature above the curve (like a skateboard ramp). That means at the same speed, the wheel torque can actually end up higher at a higher gear (starting at ~60mph the blue curve is above the red curve in the below graph). This is basically impossible in an ICE car because the torque curve of an ICE almost always drops with the center of curvature under the curve (kind of like an upside down bowl, see the source link for the original Roadster Sport torque graph to see an example).

If I had the free time, I can probably graph the entire wheel torque graph of the Veyron, 911 Turbo S, or GTR and then find out the actual target gearing and peak power a Model R would need to top it in wheel torque under 60mph (although that probably isn't completely necessary for a faster 0-60, but would basically guarantee it is faster, given ideal traction in both cases).

I made the above graph using the graph here:
http://www.teslamotors.com/roadster/technology/motor

I found the gearing and tire size here (to convert to mph and to scale the wheel torque for the 1-speed):
http://www.teslamotors.com/roadster/specs

I found the gearing for the original two speed gearbox in the 2008 Roadster here:
http://www.automobilemag.com/new_and...r/viewall.html