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CAD Helps to Move Mountains
Alibre Design helps an engineer get an innovative avalanche blaster out on the slopes
Werner Greipl, Contributing Writer -- Design News, May 15, 2006
Throwing dynamite out of a helicopter window may help to mitigateavalanches, but it is a bit nerve-wracking. Having two hundred kilograms of dynamite in the cabin and some guy in the back with a lighter or some matches always made me feel a tad nervous.
It was such a hairy situation that it made me think there must be a better way to produce controlled avalanches. The suspicion that I could explode at any moment was a powerful motivator. In this case, nervousness was definitely the mother of invention.
My invention is Avalanche Blast, an airborne method to move snow off a mountain without the use of conventional explosives.
Moving Mountains
Most avalanche mitigation is performed in one of two ways. The way with which I'm most familiar as a pilot is airborne: you close the roads, fly the helicopter full of dynamite, light the dynamite and throw it on the mountainside. The other common way, used extensively in Canada, also uses conventional charges, but shot from the ground out of artillery.
In both cases, conventional charges do not always detonate when they hit the snow. Roughly half of them are duds. Unexploded dynamite or artillery charges then remain on the slope, which is another kind of hazard. If you leave the stuff there, the snow melts in the springtime, and hikers will come across what appears to be a battlefield. For this reason, the Italian government requires all unexploded charges to be retrieved within 24 hours. Trekking up the mountain during winter in an endangered area to pick up a clump of unexploded dynamite is not a particularly safe job, either.
Transporting and storing explosives is obviously risky — some jurisdictions in the Italian Alps, where I often work, intensely regulate their use. For example, they require permits three weeks in advance. Such permits get pretty inconvenient when your work depends on the weather.
Building a CAD Model
I came up with the idea for the device with my partners in the Italian helicopter firm Elikos, Gabriel and Marco Kostner, who often faced the same dangerous situations. We envisioned a device that could deliver the same explosive force without using explosives. Since I am also a mechanical engineer, it was up to me to design the device.
The concept of Avalanche Blast was to build a machine that would hang from the helicopter from a tether a safe distance away from the cabin. The device would fill a 1.5-m meteorological balloon at the base of the apparatus with explosive gas. The gases — oxygen and hydrogen — used are fairly safe to transport in canisters by themselves and do not require a permit. Mixed together inside the balloon at a critical proportion, however, the gases become very volatile. When ignited by remote control, the balloon will explode with a force equivalent to 2 to 4 kg of dynamite.
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At the beginning I started modeling the design with an old version of CAD software I had, but I quickly decided to look around for a more up-to-date program. A friend from the U.S. sent me information about Alibre. I downloaded the free test version, called Alibre Design Xpress. The free version isn't limited in functionality, only in the number of parts the user can assemble. This was great, because I could test out all of the features before I purchased it.
After just making a few parts and small subassemblies, I found Alibre Design very easy to pick up and the parametrics were capable of handling the design I had in mind. My design would have movable mechanisms, including swinging frames with locks to hold the canisters of gas with the ability to be quickly changed during a helicopter pit stop. I also designed a magazine of 11 latex balloons that would rotate around the base and automatically load in a new balloon. Alibre Design allowed me to create the kinematic concept I had in mind.
Obviously, since this project had more than 300 model parts in the entire assembly, I upgraded to the full version of Alibre Design. I feel it is very reasonably priced (under $1,000), considering its power. I had limited experience modeling solids, but Alibre Design's commands were straightforward and it didn't take me long to get used to it. I also received a lot of good advice from Alibre's German support desk representative Ralf Schroedter, who was very helpful and able to guide me if I had to learn a new feature to draft a particularly difficult part. In all, I finished the whole design in only two weeks.
Everything is cost driven and my philosophy in designing such a machine is to keep it as simple as possible. If you're able to build it in your own garage, more or less, then you do not need expensive Computer Numeric Controlled (CNC) milling machines. Though the Avalanche Blast machine is quite complex, there's only three parts which required a CNC manufacturing process. For those parts I simply exported the models to the milling module from the modeling software, and sent them to an outside fabricator without any problem.
Going Commercial!
My partners at Elikos tested the Avalanche Blast prototype for two seasons around ski resorts and mountain passes in the Dolomite region of Italy. More than 500 balloons were fired. In contrast to conventional explosives, which maybe detonate 50 percent of the time, Avalanche Blast successfully moved snow at a rate of 80 percent.
The device can fill and fire 11 balloons on a single flight. The operator in the helicopter can load a new balloon in just 30 seconds. The assembly also makes for a quick refill on the ground. Hydrogen and oxygen canisters can be replaced in only five minutes. In addition, the machine has many safety interlocks built in, as well as a camera allowing the operator to directly monitor the balloon area.
Avalanche Blast eliminates the need for explosives in the helicopter cabin. Unexploded charges do not remain afterward, and the balloon material is biodegradable. Compared to traditional methods, Avalanche Blast is safer and more environmentally friendly — which should make everyone feel less nervous.
After successful testing, my company sold the Avalanche Blast concept to a French manufacturer, T.A.S., which makes ground-based avalanche control systems. Soon, they will make this safe and effective airborne method commercially available.
| Useful Links | ||
| //Check out the links below for more info// | ||
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For a free trial of Alibre Design CAD Software, go to:
http://rbi.ims.ca/4922-700 |
To view a video clip of Avalanche Blast in action, go to:
http://rbi.ims.ca/4922-701 |
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CAD Helps to Move Mountains
Alibre Design helps an engineer get an innovative avalanche blaster out on the slopes
