Products We Love: Lotus Elise

December 11th, 2009 by Steve Myers

If you hang around the MindTribe lounge long enough, in addition to becoming current on the latest Internet memes, you’ll hear passionate sales pitches from one of us to another.

You’d swear a royalty check was involved, or that we’re selling one of the thousands of products in that picture.

In actuality, great products are an inspiration to us. We know they’re the result of a talented team successfully forging it’s way through a jungle of thick vegetation, quicksand, and wild beasts conspiring to steer the team toward the Land of Mediocrity.

I wouldn’t be the first engineer to claim that the team behind the Lotus Elise successfully navigated this jungle, coming out the other side nearly unscathed. If an engineering team ever wore out their Rocky Theme Song cassingle during the traverse, it must have been this one.

To appreciate what’s the big deal with this car, you have to understand its mission: to provide extremely high performance at a relatively low price point. To pull this off, there are a host of elegant engineering solutions and optimizations, as well as some admittedly small details that simply offer up a geek-out moment in the right company.

Elise_cars

The first (right) and second (left) generation Lotus Elise

Much of the engineering challenge of the Elise was to make the car weigh as little as possible. The lighter a car, the more adept it is when the road isn’t straight, and the better it responds to both the gas and brake pedals.

The backbone of the car, or chassis, is the starting point for the rest of a car. Lightness is important here as a lighter chassis means a smaller (lighter) engine can be used, which means smaller brakes and tires can be used, and so forth.

To achieve chassis lightness, Lotus engineers came up with a novel idea for a production car: glue it together. Yep, just glue. No, not the body panels or trim—the load-bearing structure for the entire car. Why glue? The more traditional process—welding—heats metal up and weakens it, thus requiring thicker metal to compensate. Gluing enables use of the thinnest—and therefore lightest—metal structures possible.

Elise_glue

A glimpse behind the front wheel reveals orange-colored glue holding the chassis together

Another exciting aspect of the car is the extensive use of aluminum extrusions: they’re fast and cheap compared to equivalent tooling to form, stamp, and assemble traditional sheets of steel. Think of squeezing a toothpaste tube where the toothpaste is aluminum and the opening of the tube is the shape of the desired part. Engineers can quickly and inexpensively create building blocks for a car, and easily change the basic dimensions to create other vehicles.

Elise_tub

Aluminum extrusions can be seen throughout the cockpit—note the chassis side rails and structural cross-member integrated with the dash

Elise_hinge

The same extrusion process can be used for chassis rails and door hinges

To further minimize weight, the body of the car is made of thin fiberglass. It also enables creation of tighter “bends” in the surface and more complex shapes than sheet metal, which both designers and engineers are a fan of.

Elise_door

Fiberglass body panels are lightweight and enable complex shapes

Aside from minimizing mass, there are some noteworthy aerodynamic mechanisms built into the car to maximize performance.

To aid stability at speed and reduce drag, one wants air to flow as smoothly as possible beneath the car (think of the bottom of a boat moving through water). The bottom of the Elise is nearly completely flat to aid in achieving this goal.

Elise_bottom

The Elise’s flat bottom

At the rear of the car, a diffuser panel manages airflow for a clean transition out from beneath the bottom of the car to minimize flow separation—a low-pressure eddy current of air following the car around, doing its best to slow it down whenever the car is in motion.

Elise_diffuser

The rear diffuser manages airflow as it exits the bottom of the car

If you were sitting in a desk chair, and you wanted a friend to start spinning you around as fast as possible, would you hold your arms outstretched or tightly next to your body? If you held them next to your body, you would reduce your polar moment of inertia, or resistance to turning. Now what about if you were holding an engine in said chair on a twisty road? You’d want it on your lap, as close as possible to the chair’s axis of rotation. The Elise is a mid-engined design, enabling some of the heaviest parts of the car—engine, transmission, and passengers—to huddle together near the middle of the car (the “tub” design of the chassis also allows passengers to sit extremely low to the ground, which also makes for better handling dynamics).

Elise_engine

Engine and passengers sit together near the middle of the car to decrease polar moment of inertia, or resistance to turning

As for the geek-out details on the Elise, it is one of the few modern cars available without power steering, enabling a sense of feeling the road with one’s fingertips. Everything in the car that looks like metal is metal, and all the vents on the car are functional. Air for the radiator flows in through the big center opening, and out beneath the windshield. There is an oil cooler behind each of the smaller front openings, and air for the engine intake and cooling flows through the side gills.

Elise_vents

All vents have a (functional) purpose

How does everything come together on the road?

No two cars are optimized for exactly the same circumstances, so comparing them is a bit apples and oranges. But for sake of discussion, let’s park the Elise next to a couple of other small, iconic sports cars—the Mazda MX-5 Miata and Porsche 911—to see how they compare.

The 911, Miata, and Elise are similar in size (911 wheelbase 92.5″, Miata 89.2″, Elise 90.5″, whereas a BMW 3-Series Coupe is 107.3″*). Yet the Miata weighs in nearly 500 pounds more than the 1,975 pound Elise (and doesn’t include an integrated rollbar, like the Elise), while the 911 is a full 1,100 pounds heavier than the Elise (though it does include two tiny back seats and is much more comfortable and practical than the Elise).

Why does the weight matter? Take a look at acceleration times for the Porsche and Elise, which are nearly identical around 4.8 seconds for a 0-60 mph run. The Elise manages a (revised) EPA rating of 20/25/22 mpg (city/highway/combined), while the Porsche is 16/24/19. The Miata, with the same engine size as the Elise of 1.8L, is closer in fuel consumption to the Elise as you would expect at 20/26/23, but is significantly slower to 60 mph at 7.7 seconds.

Cost-wise, the price (for the base 2005 model year) of the Miata ($22,098) is roughly half of the Elise ($39,985), while the Porsche ($69,300) is about one-and-three-quarters that of the Elise. Strictly performance-wise, the Elise is a deal compared to the 911, turning in similar performance numbers. That’s not to say the Elise is the best choice given the Porsche would be significantly more practical and comfortable as a daily driver, and the Miata provides incredible bang-for-the-buck. But on purely performance-per-dollar merit, the Elise is hard to beat, which was the intended destination when the Lotus team set out through the jungle.

* All vehicle data based on 2005 model year. Vehicle data sourced from Edmunds.com, autos.aol.com, and respective vehicle manufacturers.

Poking Around with Multi-Touch: Building MindTribe’s Multi-Touch Mobile Reference Platform

July 2nd, 2009 by Alan Laursen

The iPhone was the breakthrough product that introduced multi-touch—the ability to manipulate a touch screen interface with multiple fingers at once—to the average consumer. Along with the popularity of the iPhone came the realization that this new technology could make a user interface more flexible and more intuitive than previously possible. As such, MindTribe has seen a surge in companies looking to incorporate multi-touch interfaces into their products.

While the tools needed to implement a multi-touch interface are increasing in availability, they are still not established enough to be in the hands of every company’s engineers or contract manufacturers, and product technologies and offerings are rapidly evolving from week to week.

Some of our clients see the addition of multi-touch as an avenue to differentiating themselves, some see a means of creating new user experiences, while others seek insight in determining whether multi-touch is feasible for their product.

The rush for multi-touch is on. To help our clients quickly get an intuitive feel for the possibilities and limitations of multi-touch interfaces, we built a mobile reference platform to enable quick and easy experimentation. The product of this effort, a handheld demo unit, will serve as an anchor to future client discussions on the technology.

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Mechanical Prototyping Processes: What to Use and When

June 19th, 2009 by Troy Edwards

Here at MindTribe, our product design team works with clients who have varied schedules and budgets. To best serve their individual needs, we use a variety of prototyping methods to create mechanical models for review. Sometimes the parts are used for engineering purposes, and other times the parts are purely cosmetic for interdisciplinary design reviews. Understanding the pluses and minuses of each process allows us to minimize time and budget while achieving the design objectives. Below is a short summary of the processes we use most often for small quantities of mechanical parts.

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Five Materials Worth Watching—A Distraction

October 29th, 2008 by Lori Hobson

MindTribe has an orb in the office that we need to stop watching. The orb glows red when the NASDAQ drops, glows green when it rises, and pulses when the index’s movement exceeds 4%. Lately, its perpetually pulsing red light has been making me feel as if a hooker moved in to the next row of cubicles. Ironically, the orb can’t be reconfigured to monitor something more optimistic than tech stocks because—in a true sign of the times—the Web site that supports it is now defunct.


The Orb Glows Red When the Market Is Down – Lately, We’ve Needed a
Distraction from Its Bad News
(photo credit: MindTribe)

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The Secret Link to Marketing Breakthrough Products

July 22nd, 2008 by Lori Hobson

Silicon Valley’s Coolest Invention May Be Its Design Community

“Designed by Apple in California,” it reads. It’s July 11, and I am coddling a new iPhone.

It’s not designed in America. Not designed in the US. It’s Designed in California. What is it about the Bay Area and our product design community? It’s not just Apple. We have attracted a startlingly disproportionate number of the world’s best industrial design and product development (ID/PD) people to our little pocket of shoreline. Perhaps history will recognize this West Coast Design community as more influential than the mass media or academic institutions appear to notice. Sometimes we can’t get our clients to acknowledge our role at all, let alone put it on their product label. Still most of the successful companies here recognize that this community plays an instrumental role in bringing their technology innovations to market.


iPhone’s label highlights ”Designed by Apple in California”

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MindTribe’s Interactive Exhibit

June 5th, 2008 by Jerry Ryle

What Engineers Do If You Give Them a Dial Tone

Someday, MindTribe’s headquarters will be made of interactive masonry. Each brick will be molded from recycled consumer electronics and in-mold decorated with a high-resolution OLED display. Thousands of bricks will cooperate with distributed intelligence to celebrate your importance as you pass by. Depending upon your mood—as determined by your expression, posture, gait, and temperature—our building might inform you of your portfolio performance, challenge you to improve your mixed martial arts, or lift your spirits with kittens that frolic after your shoelaces. Someday. To tide ourselves over until that day, we’ve installed a 65″ plasma television in our front window and have written an interactive game you can play with your cell phone.

Playing Games at 119 University Ave.
MindTribe’s New Interactive Exhibition on University Avenue

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Early Evidence the Designers Accord Is Working

April 21st, 2008 by Lori Hobson

A Question of In Mold Decoration and Recyclability

Skeptics beware. Last week, MindTribe encountered direct evidence that the Designers Accord is actually having an impact. An engineer and I were meeting with a vendor. I won’t lie. Our primary focus was in exploring some issues that might help achieve the design intent of our client’s ID team, not any altruism for the environment. Late in the discussion I asked, “So how recyclable is this stuff?”

The fascinating part of the vendor’s answer was not that he didn’t know – he didn’t. The part that was stunning is what this veteran sales rep said. He shot me a glance and said, “That is only the second time that I have been asked that. The first time was yesterday.”

The rep was an in-mold decoration (IMD) supplier who is well known and well liked within our ID/PD community. The people with whom he had met the previous day were industrial designers in San Francisco that MindTribe knows (and loves).

IMD on our HP notebook
IMD used by HP to achieve a pattern on a notebook

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A Drool-Worthy Process for Rapid Prototyping of Metal Parts

March 13th, 2008 by Lori Hobson

Direct Metal Laser Sintering Meets Formula-1 – Next Up Product Prototypes?

At my house, it’s not enough to love great products and every detail of how they were made. That fact is obvious to anyone who’s seen my less-than-interested daughter hold her ears and run out of the room screaming at the first peep of conversations involving “machining” or “part line.” Product design infatuation was clearly part of our marriage vows, along with brewing strong coffee, making soufflé, and having and holding until the end. But those who know my situation best know that a keen love of motorsport was also part of the pre-nup. So when Formula 1 starts using a new method of rapid prototyping in metal, well, the pairing of the two topics—racing + product—seems almost cause for a celebration where I live, or at least a multi-hour discussion of the method’s potential over dinner with our equally obsessive friends.

Bed of Parts

Real Metal Parts from an Astonishing Prototyping Process
(photo courtesy of 3T RPD)

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Mini-USB is dead. Long live Micro-USB!

February 14th, 2008 by Jerry Ryle

While digging through one of our many boxes of miscellany, we recently stumbled across a perplexing cable that seems to connect 1975 to 2000. Perhaps the ferrite bolus actually houses a small flux capacitor that reduces conducted tachyon emissions.

Cable that connects 1975 to 2000

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As a Matter of Fat

January 11th, 2008 by Lori Hobson

Design, Materials, Process, and Greater Values in the “Thick” of the New Year

It must be January. Everyone in America is doing one of three things: writing IDEA entries, attending CES/MacWorld, or getting in shape. Since our product development community is busied with the first two, maybe we should take a break and consider the issue on the minds of most other people this month.

Outside of our industry, massive numbers of Americans make a resolution to lose weight every January. Apparently these are non-binding resolutions since about 1/3 of this population remains not just overweight, but obese. (Centers for Disease Control)

istock_largeperson.jpg

About 33% of Americans are obese according to CDC

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