Dan Conway of Chetek, Wis., and Trudy Rapp of Alexandria overcame 35 mile-per-hour winds and tough opposition yesterday to win their respective divisions at The Atheltics Congress National 15-Kilometer chanpionships at East Potomac Park. Both runners set national age-class records.

Conway, a 42-year-old high school physical education teacher, slowly pulled away from Bob Jenkins of Salem and Peter Nye of Alexandia after jostling with them for six miles to win in 48:29.9 Conway's time chopped more than two minutes off the national age-42 record set last year by Geoff Pietch. It gave Conway his second consecutive national title in as many weeks. He won the TAC 10-K title last week in Seattle with an equally impressive 31:03 clocking.

Baltimore's Mike Sabino led for the first 1 1/2 miles as Jenkins, Nye and Conway stayed a few strides behind. "We were playing around helping each other break the wind as we went into the final straightaway." Conway said. "We stayed even through the 10K and I started to pull away as we got the wind to or back. It wasn't like a surge or anything. I was just real steady."

Rapp, the 44-year-old mother of swimming standouts Susie and Jenny Rapp, moved ahead of local rival Mary Ellen Williams on the first of three loops around Hains Point and never was challenged. She crossed the finish line in a strong 58:08, taking nearly three minutes off the national age-44 record set in 1977 by Dorthy Stock of California.

Ed Benham, the 74-year-old veteran horse jockey from Ocean City, added the national 15K record for his age group to his already long list of national honors, running 67:48 to cut nearly six minutes off the old mark. The 5-foot-5, 110-pound runner said, despite his performance, "I'm still favoring my right leg from a hamstring pull.

George Vernosky of Bethesday finished 10th in the overall race, won the 50-54 age group and set national age-51 and 50-54 records with a time of 51:49.