Project Sign, also known as Project Saucer, was an official U.S. government study of unidentified flying objects (UFOs) conducted by the United States Air Force (USAF) throughout most of 1948. This project came before Project Grudge.
History
The project was started in 1948 by Air Force General Nathan Farragut Twining, who led the Air Technical Service Command. It was first called Project SAUCER. The purpose of the project was to gather, examine, and share with the government all information about UFO sightings, because officials believed these sightings might affect national security.
On April 27, 1949, the U.S. Air Force shared a report written by the Intelligence Division of the Air Materiel Command at Wright-Patterson Field, Ohio. The report said that while some UFOs looked like real aircraft, there was not enough evidence to determine where they came from. Most sightings were explained by normal causes, but the report suggested that investigations of all UFO reports should continue.
Project Sign was first mentioned in the 1956 book The Report on Unidentified Flying Objects by retired Air Force Captain Edward J. Ruppelt, who later led Project Blue Book. In the book, Ruppelt claimed that Project Sign had created a "Top Secret Estimate of the Situation" that concluded UFOs were real. However, no copy of this document or other proof of Ruppelt’s claim has been found. Popular Mechanics described the report as "probably more like a story than real." In a hearing of the Eighty-ninth Congress, Second Session, on January 18, 1966, L. Mendel Rivers stated that no such estimate had ever existed.
After Project Sign, Project Grudge was started because officials believed UFO reports could be used by foreign powers to cause fear among people. This made UFO sightings a military concern during the Cold War. Project Grudge concluded that UFO reports were mostly the result of: A. Mistakenly identifying regular objects, B. A mild form of group fear or nervousness, C. People making up stories to create a hoax or gain attention, and D. Individuals with mental health issues.
Caldwell investigation
In May 1949, members of Project Sign received a letter from a person who owned shares in an aircraft company. The letter explained that the company had built planes similar to the "flying saucers" that were widely discussed in newspapers at the time. This happened during a period of public interest in unidentified flying objects, which began after Kenneth Arnold reported seeing strange objects over Mount Rainier and the Roswell Incident. The U.S. Air Force had asked people to share sightings of flying saucers, and the shareholder believed that an invention by Jonathan Edward Caldwell, called the disk-rotor, might explain these reports.
Following the clues, the team, with help from Maryland police, visited an old farm in Glen Burnie, Maryland (near Baltimore). There, they found broken parts of Caldwell’s disk-rotor aircraft. They also spoke with a former test pilot who described an attempt to fly the machine in 1937–1938. The team concluded that the early models of the aircraft could not be responsible for the flying saucer sightings reported across the country.
Photographs of the damaged disk-rotor machine are still included in books about UFOs. Earlier books often described the images as "crashed" flying saucers, suggesting the U.S. Air Force had possession of such vehicles. More recently, the images are usually linked to claims that Nazi Germany developed working flying saucers near the end of World War II. These images are often grouped with other disk-shaped aircraft, such as the Avrocar, Sack AS-6, and Vought V-173, to show that such designs were both possible and studied.