|
 |
greentechZONE Products for the week of March 24, 2008
Green Lightning: A Geek’s-Eye View Of the Tesla Roadster
greentechZONE gets up-close and personal with Tesla Motors’ tree-hugging, Corvette-eating electric sports car
The Tesla Roadster is not a sensible machine, but it is an impressive one. From an engineer’s standpoint, its ability to stick your eyeballs to the back of your head as it explodes from zero to 60 mph in under four seconds is not as amazing as the team that brought the vehicle from a rough concept to a production vehicle in a little more than four years. I was disappointed that my recent visit to the Tesla Motors design and development facility in San Carlos, CA, did not include a test drive, but there are already several good road tests available (I liked the ones in Car and Driver and Road and Track) so this review can concentrate on some of the other interesting details I picked up during a very thorough tour of the company’s engineering and test areas. What I saw revealed a lot about the huge effort it has taken to create a car that not only performs well, but can also be manufactured in quantity with the finish and reliability you’d expect from a production automobile.
 Entering the nondescript industrial building that houses Tesla HQ, I found that most of its front is occupied by a well-appointed cubicle farm that, at first glance, is not too dissimilar to the ones I’ve seen in hundreds of other high-tech start-ups that populate the peninsula. A second look reveals that, instead of the usual check plots and chip shots, the office walls are decorated with CAD drawings of suspension members, differentials, and photos of the Tesla in various stages of development. Of course, the piles of auto magazines and posters of exotic cars might also be a hint that there’s something different from the run-of-the-mill Silicon Valley engineering miracles happening here.
Conversations with some of the folks that inhabit those cubicles reveals that Tesla has assembled an interesting cross-section of the engineering spectrum, with talent coming from aerospace & defense, high-power electronics, and some of the area’s best computer companies, as well as several well-seasoned veterans from the automotive industry. Besides the engineering expertise that they bring, the automotive types are essential for helping the company navigate the bewildering maze of design, testing and safety requirements that even the simplest dashboard or drive train component must meet. For those not involved in the automotive field, it’s hard to imagine the alphabet soup of standards from the SAE, AEC and various government agencies that designers must satisfy in addition to worrying about whether their product is able to survive a decade or more of neglect and abuse at the hands of the average consumer. One senior engineer noted that the project even had to go a bit further than usual because the vehicle plugs into household power to recharge, a feature that forced Tesla to get Underwriter’s Laboratory (UL) certification.
This enthusiastic mix of automotive, aerospace, and Silicon Valley design cultures is one of several factors that has allowed Tesla to go from concept to a relatively-refined (albeit Spartan), fully-certified vehicle in not much longer than it takes Detroit to update the sheet metal and trim packages on one of its popular models. In fairness, the Tesla shortened some of its design cycle by leveraging existing technology and even some COTS components from several manufacturers, the most notable being Lotus. While I was told that only about 20% of the chassis components are anywhere near stock Lotus parts, the genetic heritage of the Lotus Elise is evident throughout the roadster’s look and feel.
Tesla also takes a page from the playbook of the conventional auto industry and leverages the supply chains of many established companies to deliver as much of the car in ready-to-integrate chunks as possible. This means that the vehicle 248 shp (shaft horsepower) three-phase electric motor and its associated electric power control modules from Taiwan, the 6831-cell, 700-lb NiMH battery pack from Thailand, and the forged aluminum chassis elements from Norway meet for the first time at the Lotus plant in Hethel, (near Norwich) England. where final assembly takes place. If Tesla’s plans to produce a less-costly ($50 - $70 k) four-passenger sedan (code named White Star) come to fruition, the focus of the global supply chain will move to Albuquerque, NM where the company has announced plans to build its own final assembly facility.
Moving back to the lab area of the building, I found a miniaturized version of the R&D facilities that major car makers use, complete with assembly areas, lots of specialized test equipment, and even a heavily-armored dynamometer facility. One of the more unusual sights was a full-up breadboard of the Roadster’s electrical system, with every motor, module, sensor and control element lashed together on a large test bench. Complete with a steering wheel, dashboard, pedals and a full complement of lights, this chassis-less vehicle has logged way more virtual miles than any of its wheeled brethren as it allowed the development teams to do everything from test electronic modules to verify tweaks to the car’s firmware.
Inspecting the breadboard system also gave me a chance to catch a quick look at the guts of the module that supplies power to the Roadster’s motor. About the size of a small computer table top, and 8 - 10 inches deep, it houses the goose egg-sized IGBT assemblies that feed juice to the motor, their associated drive electronics, and the DSP board (housing a TI chip) that shapes the drive waveforms. The module’s fit, finish and overall design was much closer to a design intended for moderate-volume production than a hand-built prototype although there seemed to be lots of places that hand assembly and overall parts count could be reduced once demand is sufficient to justify the tooling costs.
I also got a clear peek at the vehicle cooling and air conditioning system, driven by a single electrically-powered compressor (rumored to draw as much as 8 kW at full blast), whose primary job is to keep the drive electronics and liquid-cooled battery system within operating specs, even in 100º+ heat. With 200+ kW coursing through its tiny body, heat management is a recurring theme throughout the Roadster design. For example, the motor drive electronics are designed to limit the power it delivers if they detect an over-temperature situation in either the motor or its thermistor-encrusted battery pack. This means that doing too many burn-outs on a hot day may force the car to limit your hot-rodding for a while until it has a chance to cool itself down a bit. You may also get a hint that you’re pushing the car a tad hard when cabin A/C cuts out as its cooling capacity is diverted away from drying your sweaty brow to attend to more urgent matters under the hood.
 While comfort-oriented consumers who are accustomed to the heavily-padded luxury tanks that populate today’s highways may find the odd cooling system unacceptable, it is perfectly proper in a car like the Tesla which was put together with as much attention to minimizing both weight and volume as any spacecraft I’ve ever worked on. This same fanatic minimalism is evident throughout the Roadster’s design, giving one the impression that little, other than the padding in the seats and the steering wheel (and a few bits of sexy but unnecessary carbon fiber trim), has been included that would detract from its scorching performance.
The test-fit I was allowed to take behind the wheel of one of the prototypes confirmed the impression that I’d just slid into a vehicle whose sole purpose in life was eating up miles of twisty asphalt at an unreasonable rate of speed. Inserting oneself into the Tesla’s tight, low-slung cockpit requires some level of planning (and gymnastics), especially if you’re packing a middle-age gut as large as mine. After a couple of false starts I adopted a butt-on-seat, swing-feet-in strategy that was not particularly smooth looking but had me tucked into the car with a minimum of grunting and embarrassment. Strangely, the Tesla’s entry and seating is reported to be a big improvement over its cousin, the Lotus Elise, thanks to its narrower transmission tunnel, lower door sill and slightly larger cabin volume.
Once aboard, I found the driver seat to be a comfortable, business-like place that gives one an idea of what piloting a fighter plane might be like -- if the Air Force allowed leather-lined cockpits. All the tools of the trade are close at hand and in plain sight with a set of crisp-looking Swiss Army Watch-like gauges tucked neatly below the generous windshield. About the only give-away that you are in an unconventionally-powered craft is the two-speed transmission (plus a detent for an electric reverse) and a small LCD screen just above your left thigh whose job it is to display the battery’s state of charge, the estimated remaining range, and the status of the car’s many sub-systems. Unlike Toyota’s Prius, whose system display is located front-and center to call attention to the workings of its computerized guts, the Tesla systems monitor is positioned where it can give you the information you need without spoiling the panel’s spare, clean, looks. To see what I mean, check out the cockpit photos in Tesla’s image gallery. 
Even though I didn’t get a chance to actually take the Tesla Roadster out for a spin, the afternoon I spent around the car and the people who designed it was highly informative and provided a glimpse into a bright possible future. After looking at what’s been done by a handful of men and women in a few short years it’s easy to squint into the horizon and see a time when the lessons learned from this highly-specialized vehicle inform a new generation of ultra-efficient cars that are as practical as they are fun to drive.
The Tesla Roadster is currently sampling to selected customers, with full production slated for late 2008. Pricing is $98,000 for early adopters, not including optional ablative heat shield, drag chute, and mil-spec radar jammer.
|
|
|
|
|
