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

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one-third the 3 dB cutoff frequency due to surface
tolerances, we can expect 7/>/0.8.
MASS PRODUCTION SAVINGS
Except for the VLA design (which involved small
quantity production) the costs that were used in
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establishing the cost-versus-size relationship (9) were the
material and labor costs for producing a single unit. With
large volume production substantial reductions in the
unit cost are to be expected. Two cases need to be
considered: volume production of an existing design,
and semiautomated production of a design adapted to
mass production methods.
When an existing design is produced in quantity at a
constant rate, cost reductions can occur through
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L_ J L • L L
10 2 I0 3
DIAMETER,
Figure 8-6. Antenna cost versus diameter.
$10 million. The foundation and the mechanical drive
system (i.e., servos, gears, bearings) might add another
$900,000 to bring the total material and purchased parts
to around $1.5 million. This still leaves roughly $8.5
million for the labor of fabrication, assembly, erection
and
testing.
Another reason for the low value of the exponent is
the increased sophistication in design capability from the
use of computers. It should be realized that the
constancy of the exponent breaks down at some value of
diameter. It is obviously not as cheap on an area basis to
make a 10 km diameter steerable dish as a 100-m
diameter dish. However, we believe that the exponent
remains constant through the sizes considered in this
study.
Based on equation (9) the total structural cost for an
array will be simply
where
ea=
R =
r_ =
fl
R
C = $1156da 2- (10)
r/
equivalent clear aperture diameter of the array
cost reduction factor from mass production
aperture efficiency of the elements.
The efficiency r/is the product of the efficiency due to
surface tolerances and the illumination efficiency. With
careful feed horn design and for frequencies up to about
1. Contract purchase of large volumes of materials
2. Direct factory purchase with scheduled delivery of
prefabricated purchased parts
3. Efficient layout of fabrication and assembly lines
4. Efficient work scheduling and labor deployment
5. Reduction of fabrication and assembly labor
through tooling, jigs, and fixtures
6. Reduction of fabrication and assembly time from
accrued experience in doing each operation
7. On-site production
Contract purchases of materials could easily reduce the
material costs by 10% while factory purchases of
prefabricated purchased parts (bearings, gears, servomotors,
etc.) can save up to 40% for these items.
Accurate estimates of labor cost reductions cannot be
made without an exhaustive detailed study, or past
experience. However, it is typical in a wide variety of
products for start-up costs (which represent initial
production of one to several units) to exceed final costs
(which represent steady-state experienced production)
by 150% to 200% or more.
When mass production is anticipated, additional savings
are possible by:
1. Designing the structure to take advantage of well
known low cost processes
2. Integrating the design of the product and the
factory to produce it
3. Eliminating all selective assembly and hand adjustment
through extensive tooling
4. Replacing hand fabrication by stamping, die forming,
die casting and other suitable processes
5. Making widespread use of automated numerically
controlled machines both for piece-part production
and assembly
6. Using automatically fabricated material-saving tapered
structural sections
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