Archive for the ‘carbon fiber’ tag
1992 GM Ultralite concept. Photos courtesy GM Media Archives.
Performance or optimum fuel efficiency. Since the dawn of the automobile, buyers have generally had to choose one or the other. In 1992, however, GM debuted a concept car called the Ultralite that promised numbers straight out of science fiction, including fuel economy up to 100 miles per gallon and a 0-60 MPH time reportedly below eight seconds. No mere bit of rolling sculpture, the Ultralite was a fully functional automobile that may have seen limited production, had history been written with a slightly different twist.
The mission behind the Ultralite’s development was both simple and ambitious: design a four-passenger car that was capable of carrying four passengers, yet returned fuel economy of 100 MPG and produced low emissions. Performance, in the form of both acceleration and handling, was expected to equal or exceed that of Chevrolet’s conventional compact sedan, the Lumina, and such specifications called for a car that was light in weight. The final product would tip the scales at just 1,400 pounds, roughly half the weight of a Lumina sedan.
In researching carbon fiber for the Ultralite’s development, GM patented a process to reduce production costs of the exotic and expensive material. Partnering with specialist supplier Scaled Composites to produce the carbon fiber monocoque, the end result was both incredibly strong and incredibly light. The final product weighed just 420 pounds, yet was rigid enough that the Ultralite employed wide gullwing doors that lacked B-pillars for improved visibility (and, of course, enhanced style). The slippery shape of the Ultralite’s design helped to produce a drag coefficient of 0.192, revolutionary for a functional automobile in the 1990s.
With such a light structure, only a modest engine was needed. GM opted to use a 1.5-liter three-cylinder two-stroke engine rated at a surprising 111 horsepower, good enough to produce the aforementioned 0-60 MPH time of under eight seconds, along with a claimed top speed of 135 MPH. Dipping into the corporate parts bin, GM selected an electronically controlled four-speed automatic transmission from its Saturn brand, and the entire driveline was housed in a “power pod” located at the rear of the Ultralite and designed for easy removal. The thinking behind this was twofold: On the one hand, a removable drivetrain made for easy service, especially on complex repairs, while on the other hand, the power pod concept allowed for fitting different types of drivetrains. At the time of the Ultralite’s development, GM was reportedly working on a gas turbine powertrain, an electric powertrain, and a propane powertrain, though none proved viable for the application.
Because the Ultralite was a rear-engine, rear-drive automobile, handling would likely have been impressive. Further aiding this (along with the car’s aerodynamics) was an airbag suspension on all four corners that enabled variable ride height. At high speeds, the Ultralight sat low on its suspension, reducing the center of gravity (for improved handling) while cutting fuel-economy robbing drag. At more modest speeds, the Ultralite rode high enough to ensure that clearance over speed bumps and frost heaves was a non-issue.
The Ultralite’s headlamps used fiber optics to project multiple beams of light from a single source, and they accurately predicted the current trend of minimizing headlamps for aesthetic effect. Its taillamps incorporated LEDs, an idea that GM had previously reserved for high center-mounted brake lamps on its high-end products. Inside, seats were made of an open-weave mesh for ventilation and weight savings, though this design may have proven to be a hard sell in northern climes. Its most impressive feature, however, was likely the fact that the Ultralite concept was functional, not theoretical, and even received an EPA fuel economy rating of 88 MPG. GM maintained that 100 MPG was achievable at a steady 50 MPH cruise.
At one point, GM even discussed limited production of the Ultralite, though its sticker price would likely have been staggering, thanks to its extensive use of carbon fiber. Instead, with California’s zero-emission vehicle mandate looming on the horizon, GM shelved the Ultralite and began work on an all-electric car that would emerge in 1996 as the EV1, which would see limited distribution in select markets.
Though the Ultralight never entered production, its less-is-more sensibility has been embraced by contemporary automakers looking to maximize fuel economy to meet ever-stricter Corporate Average Fuel Economy standards. Carbon fiber has almost become mainstream, particularly in sports cars where cost is a secondary consideration to weight (although carbon fiber monocoque construction continues to be reserved for race cars and cost-be-damned supercars). While no current production car achieves the Ultralite’s 0.192 coefficient of drag, features like grille shutters, airdams and underbody trays are used extensively to improve aerodynamics, particularly on an automaker’s most fuel efficient models. Even the three-cylinder engine has become commonplace, with automakers like Audi, Ford, Volkswagen, Hyundai, Mitsubishi, Renault, and Opel all offering triples in their global lineup (though two-stroke engines are no longer in vogue for automotive use).
As a whole, the GM Ultralite is little more than a page in concept car history. Its designs and philosophy, however, continue to be relevant as the automotive industry struggles to meet tighter government regulations and ever-increasing customer expectations.
Four-Links – 360-degree collection tour, Windsor Castle concours, what-if Packard Panther, Vintech P550
* We heard this week from Bill Jones, who wanted to share something cool that he did – a 360-degree virtual tour of the private collection of Ken and Joan Austin of Newburg, Oregon. It’s like Google Street View, but inside a car museum.
* Much as we wanted to take in the Windsor Castle Concours of Elegance, we’re a little too rough around the edges to show up at the Queen’s home. Arnfinn Hushovd, however, apparently isn’t, and provided a full set of photos of the show.
* While researching the story on the Macauley Packard earlier this week, we came across Craig Hendrickson’s 1956 Packard Panther project, an attempt to build a car that Packard could have built in the luxury performance car segment to compete against the Chrysler 300B.
* Finally, our friend and frequent commenter Myron Vernis caught Jay Leno’s eye at Pebble Beach this year with the one-and-only Hoffman X-8, a car that we featured in SIA #24, way back in September of 1974.
Carbon fiber is today’s wonder material, lighter and stronger than its equivalent in metal or fiberglass. It’s no surprise that this expensive, complex substance is extensively used in race cars and ultra-performance sports cars. Lamborghini uses carbon fiber to keep the weight of its all-wheel drive, 561hp V-10-powered Gallardo LP570-4 Superleggera down to a comparably featherweight 2,954 pounds, and the Murciélago’s body is also carbon fiber-intense.
To continue to advance their understanding and use of this material, Lamborghini has set up a new Advanced Composites Research Center (ACRC) at its Sant’Agata Bolognese headquarters. This Center has two facilities and employs 30 engineers and technicians who will build prototypes and associated tools, as well as to carry out crash tests on complex carbon fiber structures and to develop optimized production technologies, such as Resin Transfer Molding.
“The consistent development of carbon-fiber technology is a key element of our strategy,” says Stephan Winkelmann, President and CEO of Automobili Lamborghini S.p.A. “The most important parameter for super sports cars is, now as in the future, the weight-to-power ratio; therefore, as there is a limit to power increase due to emission regulations, we must work on weight reduction. Extensive use of carbon fiber, even at structural level, allows Lamborghini to be at the forefront of development techniques. The real difference is in the correct use of technologies and materials to satisfy technical and financial concerns. This is what the Center is all about.”
Here’s another goody from Vermont SportsCar. For a few years, they’ve been making their own carbon fiber trim. They started with small things, but they’re getting more ambitious with time, and now make large dash pieces.
I’d always assumed that the same level of technology they use in aerospace applied to anything you’d want to make, but that turns out to be wrong. In fact, it’s very similar to fiberglass layup, although less forgiving. And the autoclave for curing? ‘Turns out you can make one on the cheap in your garage. Here’s their setup:
You form the part out of carbon cloth and resin, again similar to fiberglass. Alternating layers of cloth and resin, in different directions for stiffness, squeeze out any and all air and excess resin, simultaneously impregnating your carbon matrix. It’ll need to dry enough for handling.
Then, into your autoclave: [CORRECTION: Kiln]
Yep, it’s just exactly what it looks like: A big cardboard box lined with high-R sheathing. A tight-fitting cutout admits a quartz heater and fan, and some chunks of plywood keep it off the bottom.
Is there a little more to it than that? Sure there is, but there’s nothing to it that should discourage you from giving it a whirl–a quick Google search suggests that a yard of fabric and a resin kit won’t run you $100. VSC’s end result is good enough to fit out the absolute best rally cars in the USA. The only problem is that carbon weave seems to be in short supply right now, and if you want to get into vacuum-bagging, which they do for thing like airplanes, it gets a little more complex, though still not as bad as you might think.
We also found a nice series of introductory tutorials from Fibre Glast.
UPDATE: As a couple of commmentors at Autoblog mentioned, this isn’t an easy process; getting the weave tight and straight takes skill and practice. But so does driving.