Frank Clarke Newlon, 77, a retired Air Force colonel who headed the Washington office of the Praeger Publishing Co. and then turned to writing, died of pneumonia Dec. 15 at Georgetown University Hospital.

Col. Newlon, who had lived in Washington since 1947, was born in Iowa. He attended Grinnell College and then worked for newspapers in the Midwest and Texas, where he became managing editor of The Dallas Dispatch.

During World War II, he was commissioned in the Army Air Forces and served in Europe. He remained in the Air Force when it became a separate service. His assignments included further service in Europe, where he was with NATO in Paris and also was stationed in Norway, and in Washington. He was chief of the information division of the Air Force Department of Public Affairs when he retired in 1958.

For the next six years, Col. Newlon headed his own public relations firm. In 1964, he became head of the Washington office of Praeger. He held that post until the late 1960s, when Praeger was purchased by the Encyclopedia Britannica.

Col. Newlon then turned to writing. He published more than 15 books on space exploration, biography and political and historical affairs. They included studies of Mexico, the Middle East, southern Africa and China.

He was a member of the International Club and the National Press Club.

Survivors include his wife, Florence Elizabeth Newlon of Washington; two sons, Michael, of Iowa City, Iowa, and Richard, of Arlington, and a granddaughter.