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loons during the early postwar years from var- ious sites across the United States. These bal- loons were ostensibly for meteorological and scientific purposes and, while the specifica- tion for Skyhook balloons was variable, they were usually designed to achieve a constant level in the stratosphere and carry a useful payload for several days. The average Sky- hook balloon had an approximate length of 75ft (22.9m) and a diameter of about 100ft (30.5m). Some larger balloons were pro- duced for unusual missions with lengths in excess of 400ft (122m) and diameters of 300ft (91m). These relatively inexpensive enclosures were made from polythene and manufac- tured by the Aeronautical Research Division of General Mills; helium was always used as the lift gas. Under good atmospheric condi- antial size would make them visible at an altitude of 100,000ft (30,500m) or even higher, with an observable slant range in excess of 85 miles (136km) when conditions permitted. The balloons would be seen to alter colour during sunset and sunrise, which could be quite dramatic when viewed from Top left: A Skyhook balloon is prepared for launch from the deck of the US Navy Aircraft Carrier Valley Forge in 1960. US Navy Top right: A US Navy Skyhook balloon shortly after launch. US Navy Right: Skyhook balloon No 93 leaving the deck of USS Norton Sound (AV-11) on 31st May 1949. US Navy Top left: A Skyhook balloon is prepared for launch from the deck of the US Navy Aircraft Carrier Valley Forge in 1960. US Navy 113 Top right: A US Navy Skyhook balloon shortly after launch. US Navy Right: Skyhook balloon No 93 leaving the deck of USS Norton Sound (AV-11) on 31st May 1949. US Navy Lighter-Than-Air Vehicles and the UFO Connection