Success Story

Eleven Exploding Luftballons:

Alibre Design User Finds New Way to Move Mountains

Avalanche Blast is the brainchild of Werner Greipl, who designed the 1387-part assembly in Alibre Design - the fastest growing 3D parametric solid modeling software. Greipl, a helicopter engineer, pilot, and alpine rescue instructor based out of Ottobrunn, Germany, learned the 3D CAD software at the same time he was developing his ideas and sketching out the initial parts for Avalanche Blast. "I got the free trial version and then did the whole job in two weeks," says Greipl. "The Alibre approach is quite straightforward. It didn't take me long to get used to it."

The inspiration for Avalanche Blast came through conversations in 2003 with Greipl's pilot colleagues, Gabriel and Marco Kostner from the Italian helicopter firm EliKos. In this case, nervousness was the mother of invention. Greipl and the Kostners had previously relied on conventional explosives when flying avalanche management missions.

"As we were throwing dynamite out of the helicopter's side door, it was always a little touchy," explains Greipl. "Having 50 kilograms of dynamite or more in the cabin and some guy sitting in the back with a lighter or some matches - it always made me feel a little nervous."

So Greipl decided to define his idea in Alibre Design of a device that could induce snow blasts without the hazards of storing and transporting conventional explosives.

Slightly larger than an oil drum, the apparatus of Avalanche Blast hangs a safe distance below a helicopter at the end of a tether. The machine holds tanks of oxygen and hydrogen, gases which inflate a 1.5 meter weather balloon at the bottom of the assembly. The gas becomes volatile when mixed at a critical proportion. Through remote control, the operator in the cabin can ignite the balloon as it strikes the snow, creating an explosive force comparable to three or four kilograms of dynamite. The operator can inflate a new latex balloon in less than 30 seconds; Avalanche Blast's initial design fires eleven balloons in a single flight.

Greipl looked around for affordable software that was powerful enough to make the movable mechanisms that allow oxygen and hydrogen canisters to be changed quickly during a helicopter pit stop. "Alibre Design allowed me to make the kinematic model of the design that I had in mind. All the movement of the machine -- the change of the magazine and the filling unit -- consists of moving parts that disassemble and re-assemble." In the prototype design, canisters only take five minutes to replace.

The design also completely eliminates the need for conventional explosives, which not only make the cabin dangerous, but also the ground below. Conventional charges explode only 50 percent of the time when they land in the snow. Unexploded charges, if not retrieved, remain on the mountain until the snow melts, leaving potential surprises for springtime hikers. EliKos recently tested Avalanche Blast for two seasons of avalanche control in the Dolomite region of Italy. In over 500 blasts, the device successfully moved snow 80 percent of the time.

Greipl, a university-educated mechanical engineer, constructed the vast majority of solid parts in his own shop from Alibre Design's 3D models. Only three parts required outsourcing to a Computer Numerical Control (CNC) fabricator. Through Alibre Design, these 3D parts could be easily communicated to subcontractors, says Greipl. "There's also an easy milling program module included in Alibre Design Professional. I just exported the files without any problem."

The Luftballoon ingenuity has paid off for the German helicopter expert. The inventor has recently sold the Avalanche Blast design to a French manufacturer, Technologie Alpine de Sécurité (T.A.S.), which manufactures the ground-based GAZEX gas-powered avalanche control systems. T.A.S. plans to make the airborne Avalanche Blast commercially available soon. Griepl was glad he put his ideas into Alibre Design: "For a good price, Alibre Design gave me high performance."