On July 29, 1999, at 1234 central daylight time, an experimental Underwood Brokaw Bullet, N331TB, was substantially damaged during landing roll. The 14 CFR Part 91 flight had departed the Wittman Regional Airport, Oshkosh, Wisconsin, on a local flight and was landing on runway 18 for a full stop landing. The airplane veered to the left after touchdown and went off the runway. The winds were from 260 degrees at 11 knots with gusts to 17 knots. The private pilot and the passenger were not injured. Visual meteorological conditions prevailed. No flight plan was filed, but the airplane was a scheduled fly-by at the Oshkosh Air Show. The pilot reported that he landed on runway 18 and the winds were from the west at approximately 15 knots. He reported the right wing "picked up" and the airplane "...departed the runway to the left and lost control... ." The airplane's nose gear collapsed and the left wing spar was damaged.