Projects Sign, Grudge and Blue Book

From the UAP Encyclopedia, the open encyclopedia of UFO and UAP history · 🏛️ Program or study

Contents 3
Projects Sign, Grudge and Blue Book
Wright-Patterson Air Force Base
Wright-Patterson Air Force Base Photo: United States Air Force · Public domain · via Wikimedia Commons
TypeProgram or study
Also known asAir Force UFO projects
On the Timeline1 event, 1972

Projects Sign, Grudge and Blue Book were the three U.S. Air Force investigations of UFOs, run one after another at Wright-Patterson Air Force Base in Ohio from 1948 to 1969.

  • Project Sign (1948–49) began after Gen. Nathan Twining's 1947 memo. Some of its staff reportedly concluded that UFOs could be interplanetary.
  • Project Grudge (1949–52) took a dismissive approach and explained reports as misidentifications or hoaxes.
  • Project Blue Book (1952–69) was the longest. Under Edward Ruppelt and later officers, it collected about 12,600 reports, leaving 701 unexplained.

Legacy

Illustration of official papers and files
Illustration: official papers and files. An artist's impression drawn for this site, not a photograph of the event.

The projects closed after the 1968 Condon Report. Their records were released through the National Archives and are a key source for UFO history. Critics say they were understaffed and more concerned with public relations than investigation.

On the UAP Timeline

Illustration of an open book about flying saucers
Illustration: an open book about flying saucers. An artist's impression drawn for this site, not a photograph of the event.
  • Hynek's The UFO Experience (May 1972) — Blue Book adviser J. Allen Hynek writes that Blue Book was a cover-up and the problem was glossed over.

References

This page was last edited on 29 October 2026. Articles are written in our own words from the sources listed under References; disputed claims are attributed to the people who made them.

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