A winning idea for wall-climbing
Last month we told you about a team of Brigham Young University engineering students, who created a clever Batman-inspired wall-climbing system. They were competing in the U.S. Air Force Research Laboratory’s 2012 Service Academy and University Engineering Challenge, in which teams had to design gadgets that would allow soldiers to safely and quickly ascend vertical surfaces. Given that the Brigham Young entry didn’t take first place, however, we thought it only made sense to take a look at the entry that did ... and that would be a little something known as the Personal Vacuum Assisted Climber (PVAC), designed by a team from Utah State University.
The contest took place April 16th to 20th, at Wright State University’s Calamityville tactical laboratory in Fairborn, Ohio. It was required that all competing devices must allow users to climb higher, faster and with less effort than current techniques allow. The devices also had to be reusable, permit multiple pitches within one climb, allow the operator to keep one hand free for using other equipment, and be capable of getting three people each carrying 300-pound (136 kg) loads up a 90-foot (27.5-meter) vertical silo within 20 minutes.
At the heart of the two PVAC units were two back-mounted carpet extractor motors. These each created suction with a three-stage impeller, were powered by seven lithium-polymer batteries, and created a seal against the wall using connected handheld pads lined with closed-cell foam. A pressure release lever on each pad allowed it to be secured against the wall when being used by the climber to pull themselves up, then released so it could be lifted higher.
A gauge indicated safe vacuum levels, while a volt meter let climbers know if they were about to run out of juice (as it turned out, they just made it).
Hanging beneath each pad was a stirrup, with a foot rest made from fiberglass rebar. Users placed one foot in each stirrup, then set to climbing the wall. “The motion of the system is like that of climbing a ladder,” team leader TJ Morton told us. “The only difference is the climber must learn to correctly distribute his weight as he climbs.”
Two PVAC-equipped climbers scaled the Calamityville silo, trailing climbing rope behind them as they went. When they reached the top, they secured the end of this rope to the wall face using a “glue pad” – this consisted of fiberglass mesh with a nylon rope-attachment strap sewn into it, and very fast drying, high strength superglue. Once that patch was secure, two other climbers (still waiting below) attached ascending devices to the ropes, then winched themselves up to join their colleagues at the top.
Although the contest didn’t require it, the PVAC system also allowed climbers to get up around a protruding ledge at the top of the silo. This was accomplished with the addition of rope-style rock-climbing ladders and “daisy chain” climbing straps, that could be attached to the pads when needed.
“We feel that we were successful in completing the challenge because of the extensive testing we did prior to the competition,” said TJ. “There were many impressive designs and ideas displayed, but very few had the success they had hoped for. We feel that we did a fair amount of testing and we still had a few hiccups at the competition. So, the biggest lesson we took away from this is that testing leads to success and that you can never test too much.”
Source: Wright-Patterson Air Force Base