The Fulton surface-to-air recovery system (STARS), also known as Skyhook, is a system used by the Central Intelligence Agency (CIA), United States Air Force, and United States Navy for retrieving individuals on the ground using aircraft such as the MC-130E Combat Talon I and B-17 Flying Fortress. It involves using an overall-type harness and a self-inflating balloon with an attached lift line. An MC-130E engages the line with its V-shaped yoke and the person is reeled on board. Red flags on the lift line guide the pilot during daylight recoveries; lights on the lift line are used for night recoveries. Recovery kits were designed for one- and two-man retrievals.
This system was developed by inventor Robert Edison Fulton, Jr., for the CIA in the early 1950s. It was an evolution from a similar system that was used during World War II by American and British forces to retrieve both personnel and downed assault gliders following airborne operations. The earlier system did not use a balloon, but a line stretched between a pair of poles set in the ground on either side of the person to be retrieved. An aircraft, usually a C-47 Skytrain, trailed a grappling hook that engaged the line, which was attached to the person to be retrieved.
Development of the recovery system
Experiments with the recovery system began in 1950 by the CIA and Air Force. Using a weather balloon, nylon line, and weights of , Fulton made numerous pickup attempts as he sought to develop a reliable procedure. Successful at last, Fulton took photographs and sent them to Admiral Luis de Florez, who had become the director of technical research at the CIA. Believing that the program could best be handled by the military, de Florez put Fulton in touch with the Office of Naval Research (ONR), where he obtained a development contract from ONR's Air Programs Division.
Over the next few years, Fulton refined the air and ground equipment for the pickup system. Based at El Centro, California, he conducted numerous flights over the Colorado Desert using a Navy P-2V Neptune. He gradually increased the weight of the pickup until the line began to break. A braided nylon line with a test strength of solved the problem. A major problem was the design of the locking device, or sky anchor, that secured the line to the aircraft. Fulton considered the solution of this issue the most demanding part of the entire developmental process.
Further tests were conducted at Eglin Air Force Base, Florida, from 1 August 1959, using RB-69A, 54-4307, a CIA P2V-7U, according to an agency document.
After experiments with instrumented dummies, Fulton continued to experiment with live pigs, as pigs have a nervous system close to humans. Lifted off the ground, the pig began to spin as it flew through the air at . It arrived on board uninjured, but in a disoriented state. When it recovered, it attacked the crew.
By 1958, the Fulton aerial retrieval system, or "Skyhook", was finished. The ground system could be dropped from an aircraft and contained the necessary equipment for a pickup, including a harness, for cargo or a person, attached to of high-strength, braided nylon line and a dirigible-shaped balloon inflated by a helium bottle.
The pickup aircraft was equipped with two tubular steel "horns", long and spread at a 70° angle from its nose. The aircraft flew into the line, aiming at a bright mylar marker placed at the level. As the line was caught between the forks on the nose of the aircraft, the balloon was released and a spring-loaded trigger mechanism (sky anchor) secured the line to the aircraft. After the initial pickup, the line was snared by the pickup crew using a J-hook and attached to a powered winch and the person or cargo pulled on board. To prevent the pickup line from interfering with the aircraft's propellers in the case of an unsuccessful catch, the aircraft had deflector cables strung from the nose to the wingtips.
Later the US Navy tested the Fulton system fitted to modified S-2 Tracker carrier-based antisubmarine patrol aircraft for use in rescuing downed pilots. It is unknown whether a Fulton equipped S-2 was ever used on a combat mission.