28 July 2012

Millimeters Between Archer Gold and Silver!

The final of men's team archery was a nail-biter!  Let me set the stage.  The powerful South Korean team set the world record in the ranking round with a score of 2087, hitting 145 bulls-eyes (67.13% of their shots).  The US team finished 4th; they tied China, but the Chinese team had one more bulls-eye.  Italy was seeded 6th and had to compete in the first round; US and Italy had first-round byes, along with South Korea and China.  The Italians stunned China in the first round with a 220-216 win; the US team knocked off South Korea in the semifinals with an impressive 224-219 victory.  The South Koreans had just taken out Ukraine in the quarterfinals with an Olympic record-tying score of 227-220.  Italy beat Mexico in the semifinals after Mexico upset the #2-seeded French team.  It was US vs Italy for the gold.


Archers stand 70 m (230 feet) from their target.  The bulls-eye, which is worth 10 points if hit, is just 12.2 cm (4.80 inches) in diameter.  That means that if an archer is able to sight perfectly the center of the bulls-eye, there is only 0.05 degree (1/20th of a degree or 3' of arc) margin of error to the left or right.  That the South Koreans hit two out of three bulls-eyes in the ranking round was incredible!  Throw in the London wind that was present for all competitors, and hitting the bulls-eye is even more impressive.


Italy entered the final round of the gold-medal match just one point ahead at 192-191.  The US went first.  Jake Kaminski hit an 8, followed by Jacob Wukie's bulls-eye.  Brady Ellison then hit a 9, just a millimeter or two to the left of the 10 line.  The Italians followed with Mauro Nespoli's 9 and Marco Galiazzo's 8.  They were down 209 to 218 with Michele Frangilli coming up for the final shot.  His last shot was an 8; now a bulls-eye would mean gold for Italy.  He coolly sighted his target and fired.  His shot hit the line on the left of the bulls-eye, only a millimeter or two better than Ellison's shot.  That was the difference between gold and silver as the Italians beat the US, 219-218.


As a side note, there is a cute energy calculation you can do for archery.  Each participant shoots 72 arrows during the ranking round.  The recurve bows they use have the distinctive outward curve at the edges of the bows.  Recurve bows are quite efficient at about 85%.  Before each shot, the bow stores about 60 J of energy.  Estimating the energy conversion in the archer's body to be 25% efficient, archers expend about 17.3 kJ during the ranking round.  That is equivalent to roughly 4 Calories, which is the nutritional energy content in a Diet Coke.  So, when I see archers competing in the ranking round, I see a can of Diet Coke!

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