Project Cyclops, A Design... - Department of Earth and Planetary ...

coverage is limitedto at mosta 30° zenithangle.The
proposed concept isillustrated in FigureF-5.
E
I
No computations have been made on this proposal
except to consider some of the factors in the pointing
accuracy. Consider a cable under load AT as shown in
Figure F-6, where AT = 5000 Ib and cable area = 2 sq in.
with E = 15× 106 psi, then
N
-G-S
AL 5000 X (40 X 12)
AE 2X(15X 106 )
= 0.008 in.
h'
W
CABLE FOR 8=50 ° D/2= 5Oft
WINCH Ion 0 = h'/D _ h' : 29fl
Figure F-5. Tethered buoyant telescope.
The three control cables are always in tension. The
direction is controlled by selective winching of cables.
The buoyancy provides some stiffness against rotation of
the antenna in the horizontal plane but lateral guying
may be needed. The structure is self-leveling, gravity
deformation is minimum and wind loading is relatively
small.
The total structural height when the element is at
zenith is approximately h + 29 ft from ground level. For
a lO0-ft diameter dish, it is estimated that h _ 40 ft. It
should be noted that most of the element is protected
from direct exposure to wind; therefore, operation
should be possible in high winds assuming a way is found
to protect the fluid from wind effects. The fluid basin
could be above or below ground level; if it is below
ground, holes could be made by precision blasting.
CABLE UNDER LOAD
Figure
F-6.
A = CABLE
AREA
It can be seen that fluctuation in the vertical plane can
be kept very small. Oscillations in the horizontal plane
can be minimized by keeping large tensions in the cable,
and by additional guys.
The structure is inherently failsafe in that if a cable
breaks, the dish goes up, not down. It seems likely that
the dish costs would be less than those for present
dishes, since more uniform support is provided by the
fluid.
-I
o
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