In an engineering design showdown between Batman and Spider-Man, who would win?
It was Spider-Man, hands down, at last month's Air Force Research Laboratory Design Challenge, where a Utah State University student team claimed the top prize for designing and building equipment that enabled climbers to stick to a sheer concrete face.
The students called their device Personnel Vacuum Assisted Climber, or PVAC, which used hand-held suction pads connected to stirrups.
"The biggest challenge was to have a big enough pressure differential and a good enough seal to hold them to the wall," said team leader T.J. Morton. "Our calculations showed our vacuum ascender can hold anywhere between 500 to 700 pounds, depending on the altitude."
Air Force pararescue jumpers tested the 17 university teams' entries April 17-20 on a 90-foot concrete silo in the ominously named Ohio town of Calamityville, where judges concluded the Aggie gear performed best.
A losing Brigham Young University team drew lots of attention with its device inspired by Batman movies. The BYU entry launched a grappling hook and cable to the top of the structure and then winched up climbers. Second-place finisher, University of Minnesota-Duluth, deployed a vacuum-operated, wall-climbing robot that set an anchor at the top.
"The breadth of solutions was impressive," said event coordinator Devon Parker in an Air Force news release. "These students overcame some significant engineering challenges to create workable devices."
The Air Force Research Laboratory (AFRL) challenge this year asked teams to develop ascending devices that were faster and easier to use than current techniques allow.
The target was to get four soldiers up a sheer 90-foot face in 20 minutes with a device that weighed less than 20 pounds. The Air Force gave each team $20,000 and nine months to develop solutions.
"The logistics of this project became real very quick," said USU team member Dan Aguirre. "Someone was actually relying on our design to climb a wall. You can't get that in a textbook."
USU mechanical engineering professor Steve Hansen assembled a crew of 15 undergraduates last fall to work on the project as part of their senior-year "capstone" experience.
He broke them into two groups to independently hash out ideas. The hard part was keeping the two groups from talking to each other for half a semester, he said. The groups proposed completely different solutions: One envisioned climbers sticking to the wall while the other had climbers ascending a rope anchored to the top.
Instead of simply taking the most promising proposal, Hansen insisted the team incorporate the best elements from each into their device.
The group's equipment consisted of two battery-powered PVAC units, designed to get the first two men up the face; a winch-powered rope ascender to pull up the other two; and an anchor equipped with fast-curing adhesive.
The team didn't meet the weight goal: Each vacuum ascender weighed 48 pounds; the rope ascender weighed 25 pounds.
Rigorous testing was key to the team's success, according to Morton, who graduated this spring and just started a job at Rio Tinto's Kennecott mine. The team used the ascenders numerous times on a 30-foot silo, where they encountered a problem with the pressure-release mechanism.
Based on testing, the team predicted the vacuum-assisted climbers would reach 90 feet in 23 to 25 minutes. In the Ohio competition, the climbers reached the target in 28 minutes, just as the batteries began to fade.
For bonus points, the Aggie team got three of the four climbers on the silo roof thanks to accessory equipment to help them around the roof lip.
"Understanding and learning to deal with ambiguity is a wonderful life lesson," USU engineering dean Scott Hinton said in a news release. "In spite of all the ambiguity in the competition, the students kept going, thinking on their feet, adapting and doing what needed to be done."
Now the Air Force may give USU another $100,000 to refine the device for possible field use by the military and commercialization, according to Hansen.
"AFRL gets the benefit of some very creative ideas that address a real military need, while the students get an opportunity to work under real-world conditions," said Alok Das, the lab's senior scientist for design innovation. "They gain experience in rapid prototyping and engineering a solution to a customer need, knowing that their design could truly make a difference."
The USU team included students Steven Daniels, Val Callisaya, Tyson Burtenshaw, Keith Bates, Garrett Vaughan, Rhet Astle, Bobby Johnson, Marc Ortega, Trevor Park, James Robbins, Michael Deakin, Daniel Aguirre, Alyssa Wahlin and Jordan Stott.
O For video of Air Force climbers using Utah State's PVAC, visit http://youtu.be/6PncjDDYKcE