Edward J. Ruppelt (1923 - 1960) was a United States Air Force officer probably best known for his involvement in Project Blue Book, a formal governmental study of unidentified flying objects. He is generally credited with coining the term "unidentified flying object", to replace the terms "flying saucer" and "flying disk" - which had become widely known - because the military thought them to be "misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. Ruppelt was the director of Project Grudge from late 1951 until it became Project Blue Book in March 1952; he remained with Blue Book until late 1953. UFO researcher Jerome Clark writes, "Most observers of Blue Book agree that the Ruppelt years comprised the project's golden age, when investigations were most capably directed and conducted. Ruppelt himself was open-minded about UFOs and his investigators were not known, as Grudge's were, for force-fitting explanations on cases."