Largest wind tunnel for testing cars has tiny red panic button

There's nothing quite like walking through the GM's Aerodynamic Laboratory, an enormous Batcave-sized test facility where you'd expect to find a next-gen Tumbler being put through its paces as it's prepared for real world roughing.

Located in Warren, Michigan, the GM wind tunnel's been open since 1980 and operates 24 hours for five days a week. A drabby-looking building is all you'll see topside, but like all heavy-duty scientific facilities, the awesome stuff is deep underground.

The General Motors Aerodynamic Laboratory may not be the largest wind tunnel in the world (that honor belongs to the U.S. Military's 80-by-120-foot Moffett Field built in 1940s), but it is the world's largest one dedicated to automobile testing — and it's quite the whopper.

Quiet in the "Test Zone" Please!

Whenever anyone spoke inside of the "test section" of the wind tunnel, it sounded like we were in a recording studio. Well, I wasn't imagining things. The walls inside of the 18 by 34 by 71-foot-long test zone are made out of reinforced concrete almost 20 inches thick. With walls that solid, it's no wonder the test zone was so soundproof.

This portion of the wind tunnel isn't just for killing echoes, it's essentially where the bulk of aerodynamic vehicle testing happens. On the floor is a series of circular scales that measure forces such as friction and pressure, and changes in velocity and wind, etc. Without painstaking aerodynamic testing on life-sized clay car models, GM wouldn't be able to design cars such as Chevy's Cruze, which gets 39 miles per gallon. So, really, the shape of a car isn't only there for looks, it's there to improve car efficiency — and it's all thanks to time in the wind tunnel.

While I wasn't lucky enough to see a real GM smoke test — a technician told us the smoke wand, pictured in the gallery below, was busted — I did get a better feel for how small a car is compared to the forces of nature — just by staring up at GM's gargantuan-sized 43-foot diameter wind turbine. Switched off, the giant wind turbine looks like some kind of top-secret missile or an airship, and it is definitely an impressive sight.

The Massive Wind Turbine

According to official GM engineering specs, the wind turbine's six laminated spruce blades are capable of generating 4,500 horsepower while rotating at a max of 270 rotations per minute (RPM), hitting wind speeds of 415 miles per hour.

Although the turbine fan can generate that much wind power, the actual maximum wind speed in the car testing zone can only top out at 138 miles per hour; GM wouldn't want its clay prototypes flipping all over the place, you know?

And, that's right: spruce. The blades are made of wood and they're over 30 years old just like the turbine. They all have sacrificial, replaceable tips, too, as the turbine's tips are more prone to damage from high-speed debris or scraping a wall.

Built in 1980, the Aerodynamic Lab also comes with a tiny little red panic emergency stop button. Pressing the unmarked and uncovered button will bring the fan to a complete halt, allowing engineers to assess the situation and act accordingly. It's a nice retro reminder of its Cold War era factory design roots — a world prior to the software prowess we have today. I'm ecstatic that a button like that really exists and isn't merely a fictional exaggeration.

After I saw GM's massive wind tunnel, I couldn't help but wonder. If GM's taking this much consideration into aerodynamic design for its vehicles and putting this much effort into ensuring airbags eject correctly and not by accident why hasn't, say, Toyota, Honda or any other automaker built a larger wind tunnel?

The answers: math and computer simulations. These days, computer simulations can make a very accurate prediction on how a car will perform in real world conditions such as a crash or against mother nature. Like a crash test, the physical wind tunnel and tests are only there for GM to confirm the computer simulations — to make sure all external forces are accounted for.

Via GM

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