Intensive experiments began in late January 1957 at the Nevada
Test Site. All the tests were conducted by the Sandia Laboratory of
Albuquerque, The tests determined the adequacy of safety controls,
handling procedures and stability. The field tests assured that.
rigging had been devised which would hold the balloons and prevent
their escape. They assured also that a deflation system, devised to
lower the balloon quickly whenever necessary, such as during high
winds, was satisfactory. The safety‘ device burns a large hole in
the top of the balloon so the helium inside the balloon can escape
rapidly. This causes the balloon to come down immediately, Balloon
tests have been made under many conditions, such as in high winds
and thunderstorms, and because of such experiments, the Test Organization has expressed confidence that there will be no difficulty in
controlling the balloons during actual detonations of nuclear devices
conducted with balloons,
Two balloon sizes are being used during Plumbbob. One type is
67 feet in diameter and the other 75 feet in diameter. The smaller
balloon will lift a one-ton device to 1,500 feet and still have
enough lift to provide control. The larger balloon will lift about
two or two-and-a-half tons to the same altitude and still provide
sufficient lift for control.
The shot balloons are anchored with four cables, including a
main vertical cable and three guy cables, all operated by remotely
controlled winches located in heavily shielded underground bunkers.
Operation of the cables is from the Control Point where an operator
sits at a console with buttons for pulling in or letting out the
cables, The operator has before him two television screens which
picture the balloon's precise location through the use of two tele-
vision cameras located on the ground near the balloon.
The control
cables have dynamometers to relay to the operator the amount of
tension on each cable. Maneuvering the cables helps prevent the
balloon from moving.
If any one of the cables should break because of high winds or
other strain, the operator first would attempt to operate and lower
the balloon by manual control. Should this system fail, the opera-
tor can activate an automatic deflation device at the console in the
Control Point. Should neither of these systems work for any reason,
a barometric device would activate the deflation system at a certain
altitude should the balloon escape.
Should the barometric system
fail, the balloon automatically will split its seams and descend
when it redéhes 5,000 feet over ground level.
Because a balloon
moves somewhat even in slight winds, recording devices such as
cameras and collimators have been re-designed to obtain adequate
scientific data during balloon-borne nuclear tests. Some instrument recordings will be carried by cable to underground bunkers.
Balloons are used for tests not requiring the precise posi-
tioning for which: towers are necessary. Detonation from a balloon,
because it can be flown higher than the top of any tower used so far,
will significantly reduce the amount of surface materials drawn into
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