The main frame of the
ship is made of trusses of different sizes and
alloys located every 25 metes across the
exterior with smalles trusses spaced
more tightly inside the ship to provide internal
strength for the decks and other structure. This
frame provides the structural integrity of the
spacecraft
for when it is at rest. Radio antennas,
the deflector shield, and other things of that
nature are attached to the outside of the ship.
The structural
integrity of the ship is maintained not by the
frame during flight, but by something called the
structural integrity field (SIF). The film
makers came
up with this when they realized the huge
accelerations from the propulsion system would
squish the ship. This field allows the ship to
accelerate
without being deformed or destroyed. This is all
hypothetical and according to a book for
Trekkies, so to the real physics. The shear
weight of the
ship in Earth's gravity would cause it to bend
and deform, which would make it impossible to
use because all of the interior components would
be broken.
There are many layers to the hull to allow for insulation from
the cold and shielding from the radiation from space. The
layers are used mainly for running utilities
and as a pathway for the SIF. On the front of the ship
deterioration from space particles would be a problem, so the
combat this the deflector shield system. Inertial
would be a huge problem on a ship this large, when
accelerating, so another system called the Inertial Damping
Field (IDF) was also added to the series. If not added
the crew and everything else contained within the ship would
be flattened against the back wall during acceleration and
"turned to chunky salsa" (not so good for them).
This system is similar to the SIF, but acts within the
confines of the ship and not on the ship itself. This science
is quite hazy, which is why the crew can still be knocked
down during battles from the lag time of the IDF
reacting to the changes in motion of the ship.