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). The project was active for most of 1948 and was followed by 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, study, and share information about UFO sightings with the government, because officials believed UFOs might affect national security.
On April 27, 1949, the U.S. Air Force released a report written by the Intelligence Division of the Air Materiel Command at Wright-Patterson Field, Ohio. The report said that some UFOs looked like real aircraft, but there was not enough information to determine where they came from. Most sightings were explained by normal causes, but the report suggested that investigations of UFOs should continue.
Project Sign was first mentioned in a 1956 book titled The Report on Unidentified Flying Objects, written by retired Air Force Captain Edward J. Ruppelt. Ruppelt later led Project Blue Book. In the book, he 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 mythological than real." In a 1966 hearing, L. Mendel Rivers stated that no such estimate had ever been made.
After Project Sign, Project Grudge was started because officials believed UFO reports could be used by a foreign power to cause fear in the public. This happened during the Cold War, after World War II. Project Grudge concluded that UFO reports were most often the result of: A. Mistaken identification of ordinary objects, B. A mild form of mass hysteria and nervousness about war, C. People who made up stories to create hoaxes or gain attention, and D. Individuals with mental health issues.
Caldwell investigation
In May 1949, members of Project Sign received a letter from a shareholder of an aeronautical company. The shareholder explained that the company had built aircraft similar to the "flying saucers" that were widely discussed in the media at the time. This occurred during a period of public interest in UFOs, following reports by Kenneth Arnold about seeing unidentified flying objects over Mount Rainier and the Roswell Incident. The U.S. Air Force had asked people to report sightings of flying saucers, and the shareholder believed that inventor Jonathan Edward Caldwell’s disk-rotor design might explain these sightings.
Project Sign investigators, with the help of Maryland police, visited an abandoned farm in Glen Burnie, Maryland, near Baltimore. There, they found the damaged remains 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 prototypes could not be responsible for the widespread reports of "flying saucers" across the country.
Photographs of the broken disk-rotor aircraft continue to appear in books about UFOs. In earlier works, these images were sometimes described as "crashed" flying saucers, suggesting the U.S. Air Force had possession of such vehicles. More recently, the disk-rotor has been linked to claims that Nazi Germany developed functional flying saucers near the end of World War II. These claims often group the disk-rotor 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.