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Special considerations exist for planetoid
configurations:
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Planetoid hulls are generally free for the
taking, but there is a transportation charge from the belt to the orbital
shipyard. Fusion tunneling is used to hollow out passages and compartments.
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A planetoid can use only 80 percent of its
volume; the remainder is unusable and must be left in place to maintain
structural integrity.
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A buffered planetoid can use only 65 percent
of its volume; the remainder is unusable and must be left in place to maintain
structural integrity and to serve as armor.
Although a planetoid is essentially free,
there is a cost of §1,000 per interior (non-waste) displacement ton for fusion
tunneling and hollowing of passages and compartments. In addition, there is a
transportation charge (§100 per displacement ton) to bring the planetoid into
orbit above the shipyard.
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Example 1: A 1,000-ton asteroid is
selected for conversion into a planetoid hull. Towing costs §100,000. It will
have 800 tons (11,200 cubic meters) of interior space, which will cost
§800,000. The total for the hull is §900,000.
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Example 2: A 1,000-ton asteroid is
selected for conversion into a buffered planetoid hull. Towing costs §100,000.
It will have 650 tons (9,100 cubic meters) of interior space, which will cost
§650,000. The total for the hull is §750,000.
Choose a hull from the Consolidated Hull
Table. Multiply the volume of a planetoid hull by 0.2 and a buffered planetoid
hull by 0.35. This is the amount of material that must go into the structure of
the vessel.
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Example 1: Our 1,000-ton planetoid
requires 200 tons (2800 cubic meters) of structure.
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Example 2: Our 1,000-ton buffered
planetoid requires 350 tons (4900 cubic meters) of structure.
Additional armor may be added to the hull if
the designer so desires. This is added in the same manner as armoring a regular
spacecraft and the volume of this additional armor comes out of the tunneled
space in the hull.
For material volume purposes, the planetoid is
considered to have a spherical hull. The material making up the planetoid hull
has a mass of 6 tonnes per cubic meter, and a toughness of 1.5. Planetoid hulls
have a thickness of 80 cm (AV120) and buffered planetoids hulls have a thickness
of 140 cm (AV210).
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Example 1: Our 1,000-ton planetoid
hull has a material volume of 28. The thickness of the hull is 80 cm, meaning
that 2240 cubic meters of material goes into the external shell. This shell
masses 13,440 tonnes.
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Example 2: Our 1,000-ton buffered
planetoid has a material volume of 28. The thickness of the hull is 140 cm,
meaning that 3920 cubic meters of material goes into the external shell. This
shell masses 23,520 tonnes.
Material remaining after the shell is
determined goes into the vessel's interior structure. Planetoid and buffered
planetoid hulls are not stressed to handle high accelerations, so such hulls
have a much lower maximum acceleration. Multiply the remaining volume of
material by 1.5 and divide by 10 times the material volume of the hull (from the
Consolidated Hull Table) to get the maximum Gs the vessel can accelerate.
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Example 1: Our 1,000 ton planetoid
has 560 cubic meters of interior structure (2800 - 2240). This gives it a
maximum acceleration of 3Gs ((560 × 1.5) ÷ (28 × 10)).
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Example 2: Our 1,000-ton buffered
planetoid has 980 cubic meters of interior structure (4900 - 3920). This gives
it a maximum acceleration of 5.25Gs ((980 × 1.5) ÷ (28 × 10)).
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