Project Rainbow

Project Rainbow is the name commonly given to two separate United States secret military projects in the 20th century, both concerned with stealth and radar invisibility: one of which is considered a conspiracy theory while the other appears to be factual. At least one recent, anonymous, writer in the UFO/conspiracy underground has linked the two projects, though this is by no means considered a mainstream viewpoint.

# The near-mythical 1943 Philadelphia Experiment, denied by all official sources and considered fictitious by mainstream historians, but a major element of UFO lore. The Philadelphia Experiment is claimed to be variously an attempt at radar invisibility, optical invisibility, or physical teleportation of a US Navy ship, with results ranging from deaths, insanity, disappearances, time travel, "fusion" of bodies with material objects, to extra-terrestrial or occult contact. The legend of the experiment, like that of the Roswell UFO crash, has developed through multiple fictional and non-fictional publications in the late 20th century. See the main Philadelphia Experiment article for more detail.
# A project in the 1950s United States Air Force stealth technology program, involving wires and ferrite cores mounted on the fuselage of the Lockheed U-2 aircraft. This Project RAINBOW is attested by mainstream historians of military technology. The project was considered a failure at the time, though it may have influenced later developments in stealth technology.

Lockheed Stealth

From "Lockheed Stealth" (Sweetman 2001):

:Consequently, only a few months after the first mission, Lockheed started a project to reduce the U-2's detectability by radar — primarily, by long-range, low-frequency early-warning radars working in the 65-85 megahertz (MHz) range. Two approaches were tested. Under Project Rainbow, a prototype U-2 was fitted with an elaborate system of thin-gauge wires, supported by nonconductive poles (first bamboo and later fiberglass) around the wing and tail, and stretching to the nose and fuselage. The wire formed a perimeter, standing off from the leading and trailing edge of the wing by about a foot. The wire carried precisely spaced ferrite beads. The Rainbow system, also known as the trapeze, was designed to create a radar echo that would mimic the echo from the airframe — but half a wavelength out of phase, so that it would precisely null the natural echo. The second approach was nicknamed "wallpaper." A flexible plastic material containing a layer of printed circuits, it was glued to parts of the U-2's fuselage, nose and tail.

References

* Bill Sweetman, "Lockheed Stealth", Zenith Press, 2001. ISBN 0-7603-1940-5.