A SKI JUMPER NEEDS to have just the right amount of crazy. Too much, you become a bobsledder. Too little, you never even try. Of the two U.S. women with real hopes to medal in the Sochi Games—the first Olympics to include women’s ski jumping—one, 19-year-old reigning world champion Sarah Hendrickson, seems to excel because she’s ethereal and light. The other, former champ Lindsey Van, 29, appears to defy gravity to escape a character that, even she admits, can be heavy and dark. Last fall, Van was lounging around with teammates Jessica Jerome, Alissa Johnson, and Abby Hughes before the U.S. National Championships at the 90-meter “normal” hill in Lake Placid, New York—a slope Van had barreled down 5,000 times. All four women grew up together in Park City, Utah.…