PONTIAC, Mich., Feb. 2 (UPI) -- Authorities in Michigan said a man was hospitalized with second-degree burns when his homemade sledding rocket pack exploded. The Oakland County Sheriff's Office said the 62-year-old Independence Township man constructed a backpack from a motorcycle muffler filled with gasoline and gunpowder and put on a motorcycle helmet before sledding down his back yard hill with the fuse lit, the Detroit Free Press reported Tuesday. "At some point during the ride, the device exploded," Undersheriff Mike McCabe told The Detroit News. "Apparently, he has this sledding party every year, and he always does outrageous things at it, but he's never blown himself up before." McCabe said the man suffered burns to 18 percent of his body, including second-degree burns to his right side and his face.