Designing the ARC’TERYX Evolutionary Life-saving Airbag Rescue System

Skiers, snowboarders, snowmobilers and hikers familiar with existing avalanche airbag systems can attest that current products, while dramatically increasing one’s chances of surviving an avalanche, can be expensive, cumbersome and difficult to use and maintain due to many reasons including:

• Once used, cylinders and cartridges must be refilled, which involves additional time and cost
• Extra cartridges need to be stored in backpacks
• Refilling cylinders is a time-consuming process requiring access to a compressor and leaving time for cylinders to cool down before being topped off
• A refilled cylinder requires a new O-ring and reapplying silicone grease before resealing
• Cylinders must be empty prior to flying within the United States according to US Department of Transportation restrictions

ARC’TERYX engineers set out to address these issues and others with their designs. They developed the concept of using an electrically-powered blower system to inflate an avalanche airbag backpack system.
The main advantages of an electrically inflated airbag include:

• It allows for multiple inflations for training or repeated use
• It provides cost-free triggering of the airbag
• It’s compact and relatively lightweight
• It’s safe and legal for commercial air travel, including for use in helicopters
• There are different levels of performance depending on battery selection

Assuming from the start that the impeller would need to be optimized either by investing in software and training to do the work in-house (a very daunting prospect) or by an engineering consultant (also challenging for a one-off design for a product that did not exist) ARC’TERYX needed a partner with a diverse background in blower/compressor designs and technology rather than one committed only to one outdoor gear industry to develop the required blower style and be able to optimize the solution, taking into account feedback from the company’s tooling and manufacturing side.

According to Gordon Rose, senior industrial designer for ARC’TERYX, he tested various air blowers, including ducted fans, centrifugal blowers and mixed flow blowers, with and without venturi systems as proof of concept work. However, since he had no formal background in rotor engineering, Rose needed a partner to help optimize the blower system. This led him to ADT.

“I was initially drawn to ADT when looking for design software to help me design the blower”, said Rose. “But, after contacting ADT and discussing the complexity of the project, we decided a much better solution was to use ADT’s design expertise and have them optimize the blower system rather than to acquire their software system”.

Using the 3D Inverse Design methodology in ADT’s TURBOdesign Suite software, ADT’s engineers examined the parameters of ARC’TERYX’s required performance characteristics, the available power and all the blowers Rose had experimented with before offering ARC’TERYX definitive advice on the most appropriate blower technology - a centrifugal blower.

“Our system requires two aspects to be optimized that are at opposite ends of the performance spectrum - relatively high pressure for initial deployment of the airbag from the backpack and then maximum air-flow to fill the bag quickly with no back-pressure”, said Rose.

Because of the two opposing goals, the use of 3D Inverse Design methodology was justified and required to find an optimal design. Rose added, “The other factors critical to our system were maximum efficiency and minimum size. Both have implications beyond the blower design as the weight and power requirements for the battery are critical to the overall weight of the backpack system, and the size of the blower dictates the space requirements. The use of ADT’s 3D Inverse Design methodology ensured we could optimize all these factors and be 100% confident before committing to the final design, tooling costs, etc”.

ARC’TERYX executives had concerns about the injection moulding tooling costs, so they wanted to try several design concepts. ADT quickly provided design alternatives for testing these concepts.

All the development work was done using 3D prototype impellers or existing components with the assumption that if they worked well enough then a future version could be refined and improved upon for size and efficiency. The testing phase resulted in good data for available power, torque and rpm, though the impellers were not optimized.

After establishing the project parameters and discussing the various concerns for manufacturing and other variables like motor power, ARC’TERYX had ADT provide digital files for several potential design solutions for the impeller and housing. Rose converted these into 3D mechanical drawings and built rapid prototypes and cast polyurethane prototypes to test the blowers in the company’s airbag system.

Rose collected the data such as power loading, rpm, inflation times and pressure achieved and then discussed the geometry with the tool and die maker (for injection moulds). Rose provided feedback to ADT along with comments on how to improve the final product. ADT used the feedback to redefine geometries and proposed alternate solutions.

Through several design iterations they all arrived at the final solution, at which point Rose made a number of prototype systems for bench testing and for field evaluation in the full airbag backpacks prior to committing to tooling and final design of the other components in the system (DC motors, batteries, controllers).

ARC’TERYX proved the system was workable and applied for international patents covering the entire technology platform. After this, the team optimized all aspects of the technology platform, including the battery system (or alternative), the electronic control system and the air blower.

The entire blower project development took approximately 12 months, including the physical testing at three stages (NOTE: There was a five-month pause mid-project while Rose confirmed the company’s battery/motor technology could support the blower requirements). Next, ARC’TERYX began production tooling to produce units for Conformité Européenne (CE) and Underwriters Laboratories (UL) testing and approval. Tooling and production of the blower, including motors, bearings, check-valves, etc., took about 10 months.

By hiring ADT design engineers to develop the blower for its first-of-its-kind avalanche airbag system, ARC’TERYX realized these significant benefits:

• Confidence: ADT employed its huge body of historical knowledge and experience with all types of blowers, pumps, compressors, turbines, etc., to advise ARC’TERYX of the ideal system to use
• Risk reduction: ADT provided access to state-of-the-art software and engineering knowledge, so ARC’TERYX did not have to commit to training or new software platforms
• Optimization: ARC’TERYX is confident they have the optimal solution
• Time and cost savings: ARC’TERYX saved both time and investment by avoiding software purchases and in-house training
  
  

“Even with investments in software and in-house training we would not have achieved as good a result or have tested so many options”, commented Rose. “By working with ADT and doing physical testing in-house, we avoided possible problematic design concepts. Having the ability to test concepts so quickly and thoroughly and then revise them as needed was a very valuable, though hidden, return”.