As everyone on the planet knows, the Olympic flame begins its journey at a torch-lighting ceremony in
Greece. But the torch itself is born anew for each Olympics, and this is not your average, stick-in-the
mud, light-up-the-luau kind of torch. Ideally Olympic torches never go out, despite wind or rain or passing tornadoes. But because each host city creates a new look, the burner must be built from scratch to get the most robust flame for that design. "We thought, hey it's just a torch, how hard could it be?" says Andy Delano, a grad student on the Georgia Institute of Technology team headed by Sam Shelton that spent almost two years engineering this year's model. Harder than expected, as it turns out.
That first sunny day in Athens with a steady wind flapping the fire, the flame burned blue-hot, almost white, and was invisible to television cameras. Atlanta's Olympic committee summoned the engineers at Georgia Tech for a fix. Their solution was to change the fuel from propane, which burns efficiently and saves fuel, to propylene, a welding fuel that burns hotter and has a bright, orange flame. So while the ceremonial flame winged its way to Los Angeles, the torch manufacturer worked to empty the torches it had already prepared and pour in the new fuel.
Blowin' (out) in the WindDuring those first few days of the U.S. tour, the propylene flame burned a beautiful orange, but it too kept blowing out. The Georgia team had built a special lantern to carry a back-up flame from Greece, but the problem needed a solution. Shelton and Delano, who at times traveled with the relay to keep an eye on the torch's health, realized within hours that a side-effect of the switch in fuel type was to blame.
Early prototypes of the torch used a pilot light much like those in gas stoves. If the flame blew out,
the pilot light would quickly relight it. The concept worked great in the lab, even in front of a fan.
Outside, however, the pilot light went out almost as often as the main flame. So the engineers opted
for a single flame shielded by the decorative reeds atop the torch. Nestled an inch or two into the
torch, the flame stayed reasonably well lighted even in the wind.
But when they changed the fuel, the hotter propylene flame threatened to melt the torch's wreath of
brass reeds, so the team created a protective insert. Trouble was, the insert pushed the flame up above
the reeds, and the torch flickered out on one out of almost every four runners. After Sam and Andy
discovered the culprit, Delano rode ahead and removed the problematic inserts.
Rain check
Rain hasn't been as much of a problem, although Shelton expected it to be. "At one point we thought we might have to have some kind of cover for a person running in the rain," he says. The team tested prototypes in the faculty shower down the hall. They discovered that a very small opening at the top of the torch minimized the amount of water that seeped in. When a few drops did seep through, the fuel bubbled indifferently past them and continued burning. In a rain-darkened sky, the flame actually appears to glow brighter, Delano says.
With the rain and the wind conquered -- and a new insert to protect the reeds without affecting the flame -- the relay has continued for days at a time without a torch going out. That may not sound like much, but it's one of the best records for keeping an Olympic torch lit.
Karen Celia Fox author of this report, produces the radio show "Science Report" from the American Institute of Physics.