Project GRUDGE was a United States Air Force investigation into unidentified flying objects, formed when Project Sign was renamed1. The USAF studied unidentified aerial phenomena in 1948 and 1949 under both Project Sign and Project Grudge2, with the United States Air Force (USAF) as the operating body2. In 1952, Project Grudge was itself renamed Project Blue Book3.
According to “In Plain Sight”, the air force’s first Project Grudge report announced that it would stop investigating unidentified flying objects4, and the same report attributed such sightings to mass hysteria, hoaxes or the misinterpretation of conventional objects5. Project Grudge is described as having debunked the phenomenon as the result of natural causes6.
Edward Ruppelt later said that there was a widespread view within the programme that Project Grudge operated under a directive to debunk all sightings7. Edward Ruppelt went on to lead its successor, Project Blue Book.
Chris Ramsay states that the Roswell Unidentified Flying Object (UFO) crash and the sighting by Kenneth Arnold - the Kenneth Arnold Unidentified Flying Object (UFO) sighting - followed by the Aztec crash, prompted government and military interest in UFOs that led to the formation of Project Grudge, which later became Project Blue Book8.
Luis Elizondo has said he conducted a deep dive into government historical records covering Project Blue Book and its predecessors, Project Sign and Project Grudge9.