New Year's Eve Ball Grows Bigger and Brighter

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New Year's Eve revelers in Times Square will have a much easier time keeping their eyes on the famous ball when it drops in the final seconds of 2008. A bigger, brighter ball was unveiled this week and will make soon its debut high above Manhattan. At 12 feet across, or double the size of its predecessor, the new ball has four times more surface area available for its LED lighting system and crystal cladding.

And the ball's designers have made good use of all the extra space. Waterford crystals, 2,668 in all, cover the surface. "We believe it's the largest crystal ball in the world," says Jeffrey Straus, president of Countdown Entertainment, one of the organizers of the Times Square New Year's Eve festivities. Those crystals are backlit by 32,256 Philips Luxeon Rebel LEDs. With that many LEDs and a complex lighting control software, the ball can theoretically draw on a palette of more than 16 million colors and display 4.3 billion color combinations.

The new ball, really a geodesic sphere based on a truncated icosahedron, will also become a permanent installation above One Times Square for the first time. "The ball is not only bigger and brighter than ever, but people will be able to go see it any time they want," says Straus.

What the revelers and tourists won't see is all the design engineering work that went into the new ball's structure, motion control system, power distribution, weatherproofing measures and lighting integration. "Making the ball so much bigger and permanent changes the whole game for us," says Roger Bardwell, the chief engineer at Hudson Scenic Studio, the firm responsible for the new ball's mechanical design, systems integration and construction.

BIGGER

The first thing to understand about the new ball is that this sucker is heavy. Really heavy. The previous ball weighed just under 1,110 pounds. It rode up an down on a beefed up flag pole, driven by a stage winch of the type that moves heavy scenery around a theater set.

The new ball weighs is expected to weigh in at just under 12,000 pounds with the structural engineering targeting a weight of 14,000 pounds. About half of that weight increase comes from the extra crystals and LED lighting modules on the ball's surface. Mostly, though, it comes from what what's inside the ball--aluminum structural members, heavy-duty rigging components, power supplies for the LED lighting, enclosures, fans for thermal management, wiring, and more. "Really the ball's weight is more volume dependent than you would think," says Bardwell.

The extra pounds required a much sturdier structural frame than in past balls. Bardwell used welded aluminum tubes, mostly with 1/4- and 3/16-inch walls, to create a structure that was both light weight and strong. He also came up with a new pole design based on a 30-inch-diameter cylindrical tube. "There was some talk at first about going with a tapered pole, like a flag pole," he recalls. But that idea was rejected because it would have complicated the ball's motion control and guidance system.

With the cylindrical pole, Bardwell was able to come up with a simple, yet powerful,  system to move during its 70 ft descent on New Year's Eve. Sets of wheels in the ball's hollow interior roll over the surface of the pole, which also has a welded-on spline to stop the ball from rotating. Another set of smaller wheels engage that spline as the ball travels up and down the pole. The ball is carried by a pair of 3/4-inch-diameter steel cables running up through the center of the pole and through a head block.

A winch still raises and lowers the ball. In this case, though, it's a custom winch system with a 36-inch grooved drum driven by 40-horsepower gearmotor from SEW-Eurodrive. Bardwell explains that the two cables wrap in opposing directions on the same same drum to keep the winch system as compact as possible.  Because the ball travels so slowly, dropping 70 feet over the course of the final minute of the year, the system has "significant amount of reduction," Bardwell says, noting that speed of decent translates to about 6 rpm in the gearmotor's output shaft. Drives from Mitsubishi Electric complete the motion control system. Communications with the ball's control station inside One Times Square run over Ethernet, though much of the communications related to DMX lighting control system run over RS-485.

Turning the ball into a permanent installation likewise presented its share mechanical engineering challenges. For one thing, the permanent ball has to withstand the weather and achieve a UL rating--not just to protect the electronics but to meet New York City building codes. "The old ball cut some corners on weatherproofing because it was only up for a few hours a year. We couldn't get away with that this time around," says Bardwell.

So this ball features 11 custom-designed NEMA 3R enclosures for its 1,500-watt LED power supplies--of which there are 64 in all.  The permanant outdoor location also called for the use of a robust cabling solution for the power distribution. Hudson Scenic went with a UL-rated, UV-stable power distribution cable from Lapp USA. At press time, the design team hadn't decided on all the details for carriers and festooning for the cable, which has to span that 70-ft distance when the ball drops.

And the ball's structure, surface elements and pole have all been engineered to withstand wind loads of 45.6 pounds per square foot. The old ball didn't have to be engineered for sustained wind loads since the ball-dropping event could be cancelled if winds exceeded a safe threshold. "Designing the structures to account for wind loads was new for me since I usually work on indoor systems," says Bardwell, who performed his structural engineering work on AutoCAD wireframe and solid models as well as Algor FEA software. He also ran all his wind load calculations by a structural engineer.

BRIGHTER

The new ball is not the first one to make extensive use of LED lighting. That honor goes to the ball that rang in 2008. But this new ball takes the LED engineering to a whole new level and shows just quickly this lighting technology is evolving. "Tremendous strides in efficiency and brightness have been made in just a year. The new ball is really a showcase for how quickly LED technology is improving" says John Burne, special projects engineering manager for Lighting Science Group, which designed and developed the ball's LED system.

Consider that the new ball has 32,256 LEDs, more than triple the number of the old ball.

Yet the new ball requires only twice the power. "We're getting more brightness for a given amount of power," he says, crediting the light extraction capabilities of the ball's optical components as well as the efficiency the Philips Luxeon Rebel LEDs. "They're noticeably more efficient than previous devices," he says.  Burne notes that without efficiency gains made over the past year, it would have been impossible to use the building's existing 400 amp service without turning down the ball's brightness.

With all those efficient LEDs in hand, the ball's design team still had to figure out a way to package them and attach them to the ball's structural frame. That turned out to be less than a straightforward process due to the tricky geometry of geodesic spheres. As Burne explains, the size of the Waterford crystals was pre-determined by the dimensions of the previous ball. When the design team first tried to scale up the sphere, they thought they could simply increase the number of facets and use more of the existing crystals to cover the cover the additional surface area. But as they dug into the geometry-and even consulted with Buckminster Fuller Institute-the ball's engineers found they couldn't simply add facets and still use the existing crystal dimensions. "The math just didn't work," says Burne.

So he and his engineers came up with a clever modular design that allowed them scale up the sphere given the constraints imposed by the dimensions of the existing crystal. This design nests four pieces of triangular crystal together, forming a larger triangle that overlays the ball's 672 LED modules. These triangular modules are then grouped into larger triangular "super-modules" that make up the sphere's facets. Framed in stainless-steel for strength and backed with an aluminum composite board, the super-modules are combined into hexagon- and pentagon-shaped "clusters" that form the sphere's overriding geometry. The design makes use of just two sizes of crystal to cover the whole sphere surface. One size of crystal, 1,728 pieces in all, goes into the hexagon clusters. The other size, 960 crystal triangles, goes into the small pentagon clusters.

Most of the assembly of the modules components is handled by bolts, with a smattering of VHB tape for individual components within the modules. Attaching the glass to the LED modules, however, required more thought. Lighting Science engineers ended up molding some of the attachment features into the injection molded cover for the LED module. The covers have molded-in standoffs for the bolt, which runs through the center of the crystal and into the LED module. The cover also has a set of three molded-in recesses that mate with bumps on the underside of the crystal. This arrangement keeps the glass from rotating yet allows a bit of wiggle room to take up CTE differences between the crystals, the polycarbonate cover and metal bolt. The standoff and dimples also provide a gap between the crystal and LED cover, allowing water to drain. "Basically we to secure the glass but not so tightly there would be stress on the crystals," says Burne.

The LED modules themselves consists of LED circuit board, a plastic reflector and cover, with the latter two components molded from Lexan polycarbonate. Burne says most of the design effort involved optimizing the facets within the module's metallized plastic reflector, which not only increases the overall brightness extracted from individual LEDs but also keeps them from appearing as too many individuated points of light.

"Heat dissipation was also an issue because it affects LED life," says Burne, who adds that the ball has been engineered for a minimum five year life span. The new ball has two different ways to protect against excessive temperatures. Each module contains temperature sensors and circuitry that automatically dim the modules if they overheat. Other temperature sensors keep an eye on the heat from the LED power supplies. They can dim all the ball's lights as needed or activate a set of three blowers to remove heat from the ball's interior. "I don't think we'll ever need the blowers," says Burne. "They're more of an insurance policy."