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Going 52 mph in the Slow Lane

Gravity Racer
Extreme Gravity Racer

GM designers and engineers recently raced a sleek, highly aerodynamic car at two charity events in California, and The New York Times was there to report on it. The GM entry competed against cars built by other auto design teams, including Audi, Bentley, Chrysler and Ferrari. Except for its four wheels, the submarine-shaped car doesn’t have much in common with the Nextel Cup Series racecars — it’s powered only by gravity. It’s the kind of soapbox derby car you would build if you had a team of car designers and automotive engineers helping you. At one of its races, the car hit 52 mph, went into a spinout, and crossed the finish line backwards. We asked its driver, GM designer Niki Smart, to tell us about the experience.

Q. How long has GM been involved in the Extreme Gravity series?

A. Last year was the first year that we got involved. That one was in Irvine and consisted of a straight 30-foot ramp and then a runout to the finish. No turning was involved; it was a straight line from start to end. This was pretty much the same way they ran the event the first year. It was run this way, I believe, so that the regular kids’ soapboxes could run amongst the professional teams, albeit from a little further down the ramp. These cars reached speeds of around 25 mph.

Q. Tell us about the GM entry in the last series. How did it compare to your past entries?

A. The vehicle this year differs greatly from last year because we were to race on a completely different type of course at one of the two venues. The first was to be a steep, fast, wide, smooth winding drop of more than 200 feet, the “corkscrew” at Laguna Seca racetrack in Monterey, California. This is a very well-known course for racing cars.

It was an interesting challenge to design and build a gravity car for this venue. The race was due to happen during the Monterey Historic weekend in August. This was a highlight weekend with Pebble Beach Concours and also Italian Concourso at Quail Lodge. All in all, this would provide some good exposure at the track, where a lot of the corporate sponsors would have guests as part of the weekend anyway.


Now, running at up to 60 mph, the drag factor was becoming very important and entering corners at that speed meant that the lateral stability was critical for smooth cornering and maintaining speed onto the next straight. We tested last year’s car at Laguna Seca as a basis for this year’s design. We used a two and four-wheel steer set up and found gains in the four-wheel-steer system so went with that. We also found an optimum weight distribution where all four wheels were evenly loaded and did an equal amount of steering. The wide, billiard-table-smooth surface of the racetrack meant we focused on smooth progressive weight transfer through the corners, trying to upset the car as little as possible. The track was 80 feet wide at some points, so it was possible to make the corners a smooth line and maintain high speeds. At this point, there was also an intention to have a run-out onto the finishing straight to show a comparison between each team’s car’s ability to keep rolling as far as it could go with the cornering speed it maintained through the last turn onto the finishing straight.

But all this design time was somewhat wasted because the venue for the race was changed to a local park road in Monterey at the last minute. This came as a frustrating shock with less than two weeks to go. We had no time to change our design. It turned out we had a design that wasn’t best suited to the hill, but we were still very competitive and had an action-packed day with a number of spins. I kept the team busy all day, which I am sure they will thank me for one day.

Gravity Racer
Extreme Gravity Racer

Q. Who designed the GM entry?

A. This year the team consisted of: Project Manager Steve Anderson, Engineer Matt Ferguson, Fabricators Paul Day, Larry Jackson, Jay Brett, Nate Hranek and myself. I also designed and drove the vehicle. We received considerable help from outside companies with materials and processes, and our own facility squeezed in the project amongst our normal daily duties and projects. Our sponsors were: Nike, which provided clothing for the whole team; Michelin tires; Aircraft Windshield, which provided the canopy for the car; United Resin, which provided resins and glass fiber cloth; Accu-air, which provided welding supplies and nitrogen for the tires; and Pyrotect, which provided the seatbelt harness.

Q. How did you first get involved as a racecar driver in the Extreme Gravity series?

A. Designing the car and testing last year’s car as the development mule for this year, it became a natural step for me (175 lbs) to drive this year’s car. And with a maximum (combined driver and vehicle) weight of 320 lbs, it wasn’t so critical to be lightweight, as in last year’s race, when one of our Alias modeler designers, Allessandro Zezza, drove the car.

Q. What qualifications do you need to drive this vehicle?

A. You need to be smooth above all else and have the nerve to not use the brakes unless absolutely necessary. Once you brake, you can’t put your foot on the gas to get going again. Only the hill gives you the gravity you need to gain speed, yet every movement you make and every direction change you take only slows the car down. To use the brakes was never the plan at Monterey Race Track. At the park road, it was impossible not to need them.

Q. How do you practice?

A. It’s hard to practice with the cars as they are not motorized so you cannot travel with traffic, but they are very fast (given a hill to go down), so you would be breaking almost all the speed limits on public roads. We did test at a canyon road up in Malibu, but that was a disastrous day, as whenever a car came we had to close the course to let them pass * racetracks are the ideal place if you can access them.

Q. Tell us about your last race.

A. We had a few problems with the heavy demands of the park road. The road was very narrow (especially at speeds over 50 mph) and had areas of heavy braking, which upset our car violently to the point of spinning. One particular spin happened at the fastest point on the course, at almost 54 mph, and I was lucky to not to hit the rock face on one side of the track or shoot off the other side of the road where I would have dropped 30 feet or so (if I was fortunate enough to miss the hundreds of big trees that lined to course).

All in all, we were one of the fastest cars but had a design that was not best suited to the road course. We had stability issues under braking, and on that type of course, that meant our overall times were slower. The fastest car had a very rear-biased weight distribution and rear wheel braking. This was ideal for this course but would have been less optimal for the original venue. I think all the teams would like to run the cars on the Laguna Seca track at some point, just to satisfy our curiosity if nothing else.

Q. Are there learnings for GM vehicles from the Extreme Gravity cars?

A. It does make you appreciate efficiency in the most basic of terms. There is something very gratifying in attaining such high speeds and cornering forces without an engine. With the absence of a gas pedal and engine you became very focused on smooth driving and not wasting an ounce of energy unless you had to. It makes you realize how much gas you could save by not accelerating and braking unnecessarily * a practice that is tough to achieve in every day driving, but as most of us know once you get a car up to cruising speed it is much more efficient if you keep a steady speed.

Lightweight materials and build quality were also vital in designing and producing a featherweight vehicle of this type. It does make you question why cars are so heavy when there are so many gains to be had in making them lighter. Obviously our little racecar didn’t have to pass any crash tests and isn’t expected to endure a number of years of usage, so it is important not to get too carried away comparing the two. However, it does make you think about the benefit of much lighter cars.

Q. What have you learned as a designer from this experience?

A. As with any project, you always tend to gain valuable experience but what was most gratifying was to see how much a small team was able to achieve in such a small amount of time and on a small budget (even though it was largely thanks to our sponsors). I think GM could benefit a lot from allowing small teams of people to explore ideas out of the mainstream pursuits of a vehicle manufacturer. Even though they don’t directly translate to products of today, they are an invaluable exercise in getting the best out of a situation that is free from a lot of the politics and logistical constraints of our daily work. It’s like a vacation for the mind, and we all need our vacations.

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