Students compete in bow building competition

(December 17th, 2010)
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Nephi Bow 2010
Brigham Young University’s Mechanical Engineering Department sponsored the 3rd annual Nephi’s Bow competition, where students competed by designing and building bows which were judged on engineering design and performance.
The competition was held at the North University Intramural Field on December 9, 2010, under the direction of ME professor Anton Bowden.
The Grand Prize winner was Thomas Calkins (MS in ME), with his bow TC Fiberflex gaining a distance of 91.5 yards. The winners in the ME EN 250 category were Carson Storey (Junior in ME) and Emily Lazalde (Junior in ME) with their bow Gilimore, which came in with 86.5 yards. Ezekiel Merriam (Senior in ME) and his bow Sheik 3 won the All Steel category with 74 yards, and Garen Murray (Senior in MET) won the Engineering Design Award with Little Giant at 71 yards.
Twenty two students brought their bow designs, which were constructed out of steel, wood, fiberglass, carbon fiber, PVC, and even one out of golf club shafts. “I’ve been impressed to see the progression in average distance attained by the students’ bows,” commented Dr. Bowden. “In 2008, the average distance was a short 39 yards.  Last year, the average distance was 46 yards.  This year, the average distance was 65 yards.  The grand prize winner this year attained a distance of 91.5 yards.  Not bad for a non-compound bow with a 50 pound draw weight at a suboptimal 20 degree launch angle!”
Thomas Calkins, the Grand Prize winner, actually built three different bows, but the first two broke. “The first two I made out of carbon fiber,” Calkins said. “But after realizing how brittle the carbon was, I started re-evaluating my design ideas.” He ended up using a fiberglass satin-weave prepreg for his third bow, and designed it using ideas he had learned in MFG 555.
The winners of the ME EN 250 category, Carson Storey and Emily Lazalde, built their bow out of golf club shafts and PVC. They started out using an old truck leaf spring, but they found it was too difficult to machine. So they moved to carbon fiber golf clubs with a steel pipe fitting for the handle, but when they tried to string it, the club snapped at the fitting. They next tried using two steel club shafts inside two pieces of PVC connected by a steel pipe fitting in the center. They found that having the PVC between the clubs and the fitting helped distribute the load so the clubs wouldn’t break at the fitting like the carbon fiber club did. “When we started the competition, I just wanted a bow that would work and not snap in two,” Storey commented. “Winning the award was awesome, but our fun was in building the bow. I’m planning on doing it again next year!”
Ezekiel Merriam, winner of the All Steel category, has participated in this competition every year since it started in 2008. “I spent so much time on my bow the first year,” Merriam said, “I didn’t see a necessity to build a completely new one. I simply improve the bow a little every year based on the previous year’s performance.” Merriam designed the bow by scaling it from a wooden bow design he found in a collection of scholarly articles on archery. After multiple calculations regarding stress, yield strength, deflection, length and width, he spent a lot of time in the metal shop grinding a leaf spring until he got the desired shape. “All together, I spent upwards of forty or fifty hours researching, designing and building this bow,” said Merriam. “I enjoy this competition, and am glad to see the innovations of some of the other participants.   I have also learned that finding a doable solution is sometimes more important than finding the optimal solution.”
For further information on the Nephi’s Bow Competition, contact Dr. Anton Bowden at 801-422-4760.