Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SHUTTLE/SHUTSTRC.TXT

Text File | 1993-02-05 | 84KB | 1,555 lines

"6_2_3_7.TXT" (2033 bytes) was created on 12-12-88

SPACE SHUTTLE COORDINATE SYSTEM

The space shuttle coordinate reference system is a means of locating
specific points on the shuttle.  The system is measured in inches and
decimal places; Xo designates the longitudinal (forward and aft) axis,
Yo the lateral (inboard and outboard) axis and Z o the vertical (up
and down) axis.  The subscript ''o'' indicates orbiter; similar
reference systems are used for the external tank (T), solid rocket
booster (B), and overall space shuttle system (S).

In each coordinate system, the X-axis zero point is located forward of
the nose tip; that is, the orbiter nose tip location is 236 inches aft
of the zero point (at X o 236), the external tank nose cap tip
location is at XT 322.5, and the solid rocket booster nose tip
location is at XB 200.  In the orbiter, the horizontal X o , Y o
reference plane is located at Z o 400, which is 336.5 inches above the
external tank horizontal XT , YT reference plane located at ZT 400.
The solid rocket booster horizontal XB , YB reference plane is located
at Z B 0 and coincident with the external tank horizontal plane at ZT
400.  The solid rocket booster vertical XB , ZT planes are located at
+ Y S 250.5 and -YS 250.5.  Also, the orbiter, external tank, and
shuttle system center X, Z planes coincide.

From the X = 0 point, aft is positive and forward is negative for all
coordinate systems.  Looking forward, each shuttle element Y-axis
point right of the center plane (starboard) is positive and each
Y-axis point left of center (port) is negative.  The Z axis of each
point within all elements of the shuttle except the SRBs is positive,
with Z = 0 located below the element.  In the SRBs each Z-coordinate
point below the XB , YB reference plane is negative and each point
above that plane is positive.

The shuttle system and shuttle element coordinate systems are related
as follows: the external tank XT 0 point coincides with XS 0, the SRB
XB 0 point is located 543 inches aft, and the Y o , Zo reference plane
is 741 inches aft of X S 0.


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ORBITER STRUCTURE

The orbiter structure is divided into nine major sections: the forward
fuselage, which consists of upper and lower sections that fit clamlike
around a pressurized crew compartment; wings; midfuselage; payload bay
doors; aft fuselage; forward reaction control system; vertical tail;
orbital maneuvering system/reaction control system pods; and body
flap.  The majority of the sections are constructed of conventional
aluminum and protected by reusable surface insulation.

The forward fuselage structure is composed of 2024 aluminum alloy
skin-stringer panels, frames and bulkheads.

The crew compartment is supported within the forward fuselage at four
attachment points and is welded to create a pressure-tight vessel.
The three-level compartment has a side hatch for normal passage and
hatches in the airlock to permit extravehicular and intravehicular
activities.  The side hatch can be jettisoned.

The midfuselage is a 60-foot section of primary load-carrying
structure between the forward and aft fuselages.  It includes the wing
carry-through structure and the payload bay doors.  The skins consist
of integral-machined aluminum panels and aluminum honeycomb sandwich
panels.  The frames are constructed from a combination of aluminum
panels with riveted or machined integral stiffeners and a truss
structure center section.  The upper half of the midfuselage consists
of structural payload bay doors hinged along the side and split at the
top centerline.  The doors are graphite epoxy frames and honeycomb
panel construction.

The aft fuselage includes a truss-type internal structure of
diffusion-bonded elements that transfer the main engine thrust loads
to the midfuselage and external tank.  (In OV-105 , the truss-type
internal structure is of a forging construction.) The aft fuselage's
external surface is of standard construction except for the removable
OMS/RCS pods, which are constructed of graphite epoxy skins and
frames.  An aluminum bulkhead shield with reusable insulation at the
rear of the orbiter protects the rear portion of the aft fuselage.

The wing is constructed of a conventional aluminum alloy, using a
corrugated spar web, truss-type ribs and riveted skin-stringer and
honeycomb covers.  The elevons are constructed of aluminum honeycomb
and are split into two segments to minimize hinge binding and
interaction with the wing.

The vertical tail, a conventional aluminum alloy structure, is a
two-spar, multirib, integrally machined skin assembly.  The tail is
attached to the aft fuselage by bolted fittings at the two main spars.
The rudder/speed brake assembly is divided into upper and lower
sections, which are split longitudinally and actuated individually to
serve as both rudder and speed brake.

These major structural assemblies are mated and held together by
rivets and bolts.  The midfuselage is joined to the forward and aft
fuselage primarily by shear ties, with the midfuselage overlapping the
bulkhead caps at stations Xo 582 and Xo 1307.  The wing is attached to
the midfuselage and aft fuselage primarily by shear ties, except in
the area of the wing carry-through, where the upper panels are
attached with tension bolts.  The vertical tail is attached to the aft
fuselage with bolts that work in both shear and tension.  The body
flap, which has aluminum honeycomb covers, is attached to the lower
aft fuselage by four rotary actuators.


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FORWARD FUSELAGE

The forward fuselage consists of the upper and lower fuselages.  It
houses the crew compartment and supports the forward reaction control
system module, nose cap, nose gear wheel well, nose gear and nose gear
doors.

The forward fuselage is constructed of conventional 2024 aluminum
alloy skin-stringer panels, frames and bulkheads.  The panels are
single curvature and stretch-formed skins with riveted stringers
spaced 3 to 5 inches apart.  The frames are riveted to the
skin-stringer panels.  The major frames are spaced 30 to 36 inches
apart.  The Y o 378 upper forward bulkhead is constructed of flat
aluminum and formed sections riveted and bolted together; the lower is
a machined section.  The bulkhead provides the interface fitting for
the nose section.

The nose section contains large machined beams and struts.  The
structure for the nose landing gear wheel well consists of two support
beams, two upper closeout webs, drag-link support struts, nose landing
gear strut and actuator attachment fittings, and the nose landing gear
door fittings.  The left and right landing gear doors are attached by
hinge fittings in the nose section.  The doors are constructed of
aluminum alloy honeycomb, and although the doors are the same length,
the left door is wider than the right.  Each door has an up-latch
fitting at the forward and aft ends to lock the door closed when the
gear is retracted, and each has a pressure seal in addition to a
thermal barrier.  Lead ballast in the nose wheel well and on the X o
378 bulkhead provides weight and center-of-gravity control.  The nose
wheel well will accommodate 1,350 pounds of ballast, and the X o 378
bulkhead will accommodate a maximum of 2,660 pounds.

The forward fuselage carries the basic body-bending loads (a tendency
to change the radius of a curvature of the body) and reacts nose
landing gear loads.

The forward fuselage is covered with reusable insulation, except for
the six windshields, two overhead windows and side hatch window areas
around the forward RCS engines.  The nose cap is also a reusable
thermal protection system.  It is constructed of reinforced
carbon-carbon and has thermal barriers at the nose cap-structure
interface.

The forward fuselage skin has structural provisions for installing
antennas, deployable air data probes and the door eyelet openings for
the two star trackers.  Two openings are required in the upper forward
fuselage for star tracker viewing.  Each opening has a door for
environmental control.

The forward orbiter/external tank attach fitting is at the Xo 378
bulkhead and the skin panel structure aft of the nose gear wheel well.
Purge and vent control is provided by flexible boots between the
forward fuselage and crew compartment around the windshield windows,
overhead observation window, crew hatch window and star tracker
openings.  The forward fuselage is isolated from the payload bay by a
flexible membrane between the forward fuselage and crew compartment at
Xo 582.

Six forward outer pane windshields are installed on the forward
fuselage.  They are described in the section on windows.  The window
structural frames in the forward fuselage are five-axis machined
parts.

The forward RCS module is constructed of conventional 2024 aluminum
alloy skin-stringer panels and frames.  The panels are composed of
single-curvature and stretch-formed skins with riveted stringers.  The
frames are riveted to the skin-stringer panels.  The forward RCS
module is secured to the forward fuselage nose section and forward
bulkhead of the forward fuselage with 16 fasteners, which permit the
installation and removal of the module.  The components of the forward
RCS are mounted and attached to the module, which will have a reusable
thermal protection cover, in addition to thermal barriers installed
around it and the RCS engine interfaces and the interface-attachment
area to the forward fuselage.

The forward fuselage and forward RCS module are built by Rockwell's
Space Transportation Systems Division, Downey, Calif.


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CREW COMPARTMENT

The three-level crew compartment is constructed of 2219 aluminum alloy
plate with integral stiffening stringers and internal framing welded
together to create a pressure-tight vessel.  The compartment has a
side hatch for normal ingress and egress, a hatch into the airlock
from the middeck, and a hatch from the airlock through the aft
bulkhead into the payload bay for extravehicular activity and payload
bay access.

Redundant pressure window panes are provided in the six forward
windshields, the two overhead viewing windows, the two aft viewing
windows and the side hatch windows; they are described in the window
section.  Approximately 300 penetrations in the pressure shell are
sealed with plates and fittings.  A large removable panel in the aft
bulkhead provides access to the interior of the crew compartment
during initial fabrication and assembly and provides for airlock
installation and removal.  The compartment supports the environmental
control and life support system; avionics; guidance, navigation and
control equipment; inertial measurement units; displays and controls;
star trackers; and crew accommodations for sleeping, waste management,
seats and an optional galley.

The crew compartment is supported within the forward fuselage at only
four attach points to minimize the thermal conductivity between them.
The two major attach points are located at the aft end of the crew
compartment at the flight deck floor level.  The vertical load
reaction link is on the centerline of the forward bulkhead.  The
lateral load reaction is on the lower segment of the aft bulkhead.

The compartment is configured to accommodate a crew of four on the
flight deck and three in the middeck.  In OV-102, four can be
accommodated in the middeck.  The crew cabin arrangement consists of a
flight deck, middeck and lower level equipment bay.

The crew compartment is pressurized to 14.7 psia, plus or minus 0.2
psia, and is maintained at an 80-percent nitrogen and 20-percent
oxygen composition by the ECLSS, which provides a shirt-sleeve
environment for the flight crew.  The crew compartment is designed for
16 psia.

The crew compartment's volume with the airlock in the middeck is 2,325
cubic feet.  If the airlock is in the payload bay, the crew
compartment's cabin volume is 2,625 cubic feet.

The flight deck is the uppermost compartment of the cabin.  The
commander's and pilot's work stations are positioned side by side in
the forward portion of the flight deck.  These stations have controls
and displays for maintaining autonomous control of the vehicle
throughout all mission phases.  Directly behind and to the sides of
the commander and pilot centerline are the mission specialist seats.

The commander's and pilot's seats have two shoulder harnesses and a
lap belt for restraints.  The shoulder harnesses have an inertia reel
lock/unlock feature.  The unlocked position allows the shoulder
harness to move.  The commander and pilot can move their seats along
the orbiter's Z (vertical) and X (longitudinal) axes so they can reach
and see controls better during the ascent and entry phases of flight.
Seat movement for each axis is provided by a single ac motor.  The
total travel distance for the Z and X axes is 10 and 5 inches,
respectively.  Seat adjustment controls are located on the left side
of the seat pan and consist of a three-position toggle switch for
power bus selection and one spring-loaded, three-position toggle
switch each to control horizontal and vertical seat movement.  To
operate the seat, the commander and pilot position the pwr buss sel
switch to AC2 or AC3 for power; to move the seat along the horizontal
axis, the commander and pilot position the horiz contr switch to fwd
to move the seat forward and to aft to move the seat aft.  Similarly,
to move the seat along the vertical axis, the commander and pilot
position the vert contr switch to up to move the seat upward and to
down to move the seat down.  The commander and pilot can position the
pwr buss sel switch to off, removing power from the seat.  If the seat
motors fail, the seat can be adjusted manually.  However, manual seat
adjustment can only take place on orbit and is accomplished with a
special seat adjustment tool provided in the in-flight maintenance
tool kit.  Manual horizontal and vertical seat adjustment controls are
located under the seat pan cushion and on the aft side of the fixed
seat structure.  The seat adjustment tool is a ratchet-driven,
3/16-inch allen wrench, which is inserted into the vertical or
horizontal manual adjustment to move the seat along the Z or X axis.
The seats accommodate stowage of in-flight equipment and have
removable seat cushions and mounting provisions for oxygen and
communications connections to the crew altitude protection system.

Each mission and payload specialist's seat has two shoulder harnesses
and a lap belt for restraints.  The specialists' seats have controls
to manually lock and unlock the tilt of the seat back.  Each seat has
removable seat cushions and mounting provisions for oxygen and
communications connections to the CAPS.  The specialists' seats are
removed and stowed in the middeck on orbit.  No tools are required
since the legs of each seat have quick-disconnect fittings.  Each seat
is 25.5 inches long, 15.5 inches wide and 11 inches high when folded
for stowage.

The aft flight deck has two overhead and aft viewing windows for
viewing orbital operations.  The aft flight deck station also contains
displays and controls for executing attitude or translational
maneuvers for rendezvous, stationkeeping, docking, payload deployment
and retrieval, payload monitoring, remote manipulator system controls
and displays, payload bay door operations and closed-circuit
television operations.

The forward flight deck, which includes the center console and seats,
is approximately 24 square feet.  However, the side console controls
and displays add approximately 3.5 square feet more.  If the center
console is subtracted from the 24 square feet, this would amount to
approximately 5.2 square feet.

The aft flight deck is approximately 40 square feet.

Directly beneath the flight deck is the middeck.  Access to the
middeck is through two interdeck openings, which measure 26 by 28
inches.  Normally, the right interdeck opening is closed and the left
is open.  A ladder attached to the left interdeck access allows easy
passage in 1-g conditions.  The middeck provides crew accommodations
and contains three avionics equipment bays.  The two forward avionics
bays utilize the complete width of the cabin and extend into the
middeck 39 inches from the forward bulkhead.  The aft bay extends into
the middeck 39 inches from the aft bulkhead on the right side of the
airlock.  Just forward of the waste management system is the side
hatch.  The completely stripped middeck is approximately 160 square
feet; the gross mobility area is approximately 100 square feet.

The side hatch in the middeck is used for normal crew entrance/exit
and may be operated from within the crew cabin middeck or externally.
It can be jettisoned for emergencies, as discussed in the escape
system section.  It is attached to the crew cabin tunnel by hinges, a
torque tube and support fittings.  The hatch opens outwardly 90
degrees down with the orbiter horizontal or 90 degrees sideways with
the orbiter vertical.  It is 40 inches in diameter and has a 10-inch
clear-view window in the center of the hatch.  The window consists of
three panes of glass.  The side hatch has a pressure seal that is
compressed by the side hatch latch mechanisms when the hatch is locked
closed.  A thermal barrier of Inconel wire mesh spring with a ceramic
fiber braided sleeve is installed between the reusable surface
insulation tiles on the forward fuselage and the side hatch.  The
total weight of the side hatch is 294 pounds.

Depending on the mission requirements, bunk sleep stations and a
galley can be installed in the middeck.  In addition, three or four
seats of the same type as the mission specialists' seats on the flight
deck can be installed in the middeck.  Three seats over the normal
three could be installed in the middeck for rescue missions if the
bunk sleep stations were removed.

The waste management system, located in the middeck, can also
accommodate payloads in the pressurized crew compartment environment.

The middeck also provides a stowage volume of 140 cubic feet.
Accommodations are included for dining, sleeping, maintenance,
exercising and data management.  On the orbiter centerline, just aft
of the forward avionics equipment bay, an opening in the ceiling
provides access to the inertial measurement units.

The middeck floor contains removable panels that provide access to the
ECLSS equipment.  The middeck equipment bay below the middeck floor
houses the major components of the waste management and air
revitalization systems, such as pumps, fans, lithium hydroxide,
absorbers, heat exchangers and ducting.  This compartment has space
for stowing lithium hydroxide canisters and five separate spaces for
crew equipment stowage with a volume of 29.92 cubic feet.

Modular stowage lockers are used to store the flight crew's personal
gear, mission-necessary equipment, personal hygiene equipment and
experiments.  The modular lockers are made of sandwich panels of
Kevlar/epoxy and a non-metallic core.  This reduced the lockers'
weight by 83 percent compared to all-aluminum lockers, a reduction of
approximately 150 pounds.  There are 42 identical boxes, which are 11
by 18 by 21 inches.

An airlock, located in the middeck, is composed of machined aluminum
sections welded together to form a cylinder with hatch mounting
flanges.  The upper cylindrical section and bulkheads are constructed
of aluminum honeycomb.  Two semicylindrical aluminum sections are
welded to the airlock's primary structure to house the ECLSS and
electrical support equipment.  Each semicylindrical section has three
feedthrough plates for plumbing and cable routings from the orbiter to
the airlock.

Normally, two extravehicular mobility units are stowed in the airlock.
The EMU is an integrated space suit assembly and life support system
that enables flight crew members to leave the pressurized orbiter crew
cabin and work outside the cabin in space.


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AIRLOCK

The airlock is normally located inside the middeck of the spacecraft's
pressurized crew cabin.  It has an inside diameter of 63 inches, is 83
inches long and has two 40-inch- diameter D-shaped openings that are
36 inches across.  It also has two pressure-sealing hatches and a
complement of airlock support systems.  The airlock's volume is 150
cubic feet.

The airlock is sized to accommodate two fully suited flight crew
members simultaneously.  Support functions include airlock
depressurization and repressurization, extravehicular activity
equipment recharge, liquid-cooled garment water cooling, EVA equipment
checkout, donning and communications.  The EVA gear, checkout panel
and recharge stations are located on the internal walls of the
airlock.

The airlock hatches are mounted on the airlock.  The inner hatch is
mounted on the exterior of the airlock (orbiter crew cabin middeck
side) and opens into the middeck.  The inner hatch isolates the
airlock from the orbiter crew cabin.  The outer hatch is mounted
inside the airlock and opens into the airlock.  The outer hatch
isolates the airlock from the unpressurized payload bay when closed
and permits the EVA crew members to exit from the airlock to the
payload bay when open.

Airlock repressurization is controllable from the orbiter crew cabin
middeck and from inside the airlock.  It is performed by equalizing
the airlock's and cabin's pressure with equalization valves mounted on
the inner hatch.  The airlock is depressurized from inside the airlock
by venting the airlock's pressure overboard.  The two D-shaped airlock
hatches open toward the primary pressure source, the orbiter crew
cabin, to achieve pressure-assist sealing when closed.

Each hatch has six interconnected latches and a gearbox/actuator, a
window, a hinge mechanism and hold-open device, a differential
pressure gauge on each side and two equalization valves.

The 4-inch diameter window in each airlock hatch is used for crew
observation from the cabin/airlock and the airlock/payload bay.  The
dual window panes are made of polycarbonate plastic and mounted
directly to the hatch by means of bolts fastened through the panes.
Each hatch window has dual pressure seals, with seal grooves located
in the hatch.

Each airlock hatch has dual pressure seals to maintain pressure
integrity.  One seal is mounted on the airlock hatch and the other on
the airlock structure.  A leak check quick disconnect is installed
between the hatch and the airlock pressure seals to verify hatch
pressure integrity before flight.

The gearbox with latch mechanisms on each hatch allows the flight crew
to open and close the hatch during transfers and EVA operations.  The
gearbox and the latches are mounted on the low-pressure side of each
hatch; with a gearbox handle installed on both sides to permit
operation from either side of the hatch.

Three of the six latches on each hatch are double-acting and have cam
surfaces that force the sealing surfaces apart when the latches are
opened, thereby acting as crew assist devices.  The latches are
interconnected with push-pull rods and an idler bell crank that is
installed between the rods for pivoting the rods.  Self-aligning dual
rotating bearings are used on the rods for attachment to the
bellcranks and the latches.  The gearbox and hatch open support struts
are also connected to the latching system by the same rod/bellcrank
and bearing system.  To latch or unlatch the hatch, the gearbox handle
must be rotated 440 degrees.

The hatch actuator/gearbox is used to provide the mechanical advantage
to open and close the latches.  The hatch actuator lock lever requires
a force of 8 to 10 pounds through an angle of 180 deg rees to unlatch
the actuator.  A minimum rotation of 440 deg rees with a maximum force
of 30 pounds applied to the actuator handle is required to operate the
latches to their fully unlatched positions.

The hinge mechanism for each hatch permits a minimum opening sweep
into the airlock or the crew cabin middeck.  The inner hatch (airlock
to crew cabin) is pulled or pushed forward to the crew cabin
approximately 6 inches.  The hatch pivots up and to the right side.
Positive locks are provided to hold the hatch in both an intermediate
and a full-open position.  A spring-loaded handle on the latch
hold-open bracket releases the lock.  Friction is also provided in the
linkage to prevent the hatch from moving if released during any part
of the swing.

The outer hatch (airlock to payload bay) opens and closes to the
contour of the airlock wall.  The hatch is hinged to be pulled first
into the airlock and then forward at the bottom and rotated down until
it rests with the low-pressure (outer) side facing the airlock ceiling
(middeck floor).  The linkage mechanism guides the hatch from the
closed/open, open/closed position with friction restraint throughout
the stroke.  The hatch has a hold-open hook that snaps into place over
a flange when the hatch is fully open.  The hook is released by
depressing the spring-loaded hook handle and pushing the hatch toward
the closed position.  To support and protect the hatch against the
airlock ceiling, the hatch incorporates two deployable struts.  The
struts are connected to the hatch linkage mechanism and are deployed
when the hatch linkage is rotated open.  When the hatch latches are
rotated closed, the struts are retracted against the hatch.

The airlock hatches can be removed in flight from the hinge mechanism
using pip pins, if required.

The airlock air circulation system provides conditioned air to the
airlock during non-EVA periods.  The airlock revitalization system
duct is attached to the outside airlock wall at launch.  Upon airlock
hatch opening in flight, the duct is rotated by the flight crew
through the cabin/airlock hatch, installed in the airlock and held in
place by a strap holder.  The duct has a removable air diffuser cap,
installed on the end of the flexible duct, which can adjust the air
flow from 216 pounds per hour.  The duct must be rotated out of the
airlock before the cabin/airlock hatch is closed for airlock
depressurization.  During the EVA preparation period, the duct is
rotated out of the airlock and can be used for supplemental air
circulation in the middeck.

To assist the crew member before and after EVA operations, the airlock
incorporates handrails and foot restraints.  Handrails are located
alongside the avionics and ECLSS panels.  Aluminum alloy handholds
mounted on each side of the hatches have oval configurations 0.75 by
1.32 inches and are painted yellow.  They are bonded to the airlock
walls with an epoxyphenolic adhesive.  Each handrail has a clearance
of 2.25 inches between the airlock wall and the handrail to allow the
astronauts to grip it while wearing a pressurized glove.  Foot
restraints are installed on the airlock floor nearer the payload bay
side.  The ceiling handhold is installed nearer the cabin side of the
airlock.  The foot restraints can be rotated 360 degrees by releasing
a spring-loaded latch and lock in every 90 degrees.  A rotation
release knob on the foot restraint is designed for shirt-sleeve
operation and, therefore, must be positioned before the suit is
donned.  The foot restraint is bolted to the floor and cannot be
removed in flight.  It is sized for the EMU boot.  The crew member
first inserts his foot under the toe bar and then rotates his heel
from inboard to outboard until the heel of the boot is captured.

There are four floodlights in the airlock.

If the airlock is relocated to the payload bay from the middeck, it
will function in the same manner as in the middeck.  Insulation is
installed on the airlock's exterior for protection from the extreme
temperatures of space.

For Spacelab pressurized module missions, the airlock remains in the
crew compartment middeck, and a tunnel adapter that mates with the
airlock and the Spacelab tunnel is installed in the payload bay.

The airlock tunnel adapter, hatches, tunnel extension and tunnel
permit the flight crew members to transfer from the spacecraft's
pressurized middeck crew compartment to Spacelab's pressurized
shirt-sleeve environment.

In addition, the airlock, tunnel adapter and hatches permit the EVA
flight crew members to transfer from the airlock/tunnel adapter in the
space suit assembly into the payload bay without depressurizing the
crew cabin and Spacelab.

The Spacelab tunnel and Spacelab are accessed via the tunnel adapter,
which is located in the payload bay and is attached to the airlock at
orbiter station Xo 576 and the tunnel extension at X o 660.  The
tunnel adapter has an inside diameter of 63 inches at its widest
section and tapers in the cone area at each end to two 40-inch-
diameter D-shaped openings 36 inches across.  A 40-inch- diameter
D-shaped opening 36 inches across is located at the top of the tunnel
adapter.  Two pressure-sealing hatches are located in the tunnel
adapter, one in the upper area of the tunnel adapter and one in the
aft end of the tunnel adapter.  The tunnel adapter is a welded
structure constructed of 2219 aluminum with 2.4- by 2.4-inch exposed
structural ribs on the exterior surface and external waffle skin
stiffening.

The hatch located on the middeck side of the airlock is mounted on the
exterior of the airlock and opens into the middeck.  The hatch
isolates the airlock from the crew cabin.  The hatch located in the
tunnel adapter's aft end isolates the tunnel adapter/airlock from the
tunnel extension, tunnel and Spacelab.  This hatch opens into the
tunnel adapter.  The hatch located in the tunnel adapter at the upper
D-shaped opening isolates the airlock/tunnel adapter from the
unpressurized payload bay when closed and permits the EVA crew members
to exit from the airlock/tunnel adapter to the payload bay when open.
This hatch opens into the tunnel adapter.

The hinge mechanism for each hatch permits a minimum opening sweep
into the tunnel adapter or the spacecraft crew cabin middeck.  The
airlock crew cabin hatch in the middeck is pulled/pushed forward to
the middeck approximately 6 inches.  The hatch pivots up and right.
Positive locks are provided to hold the latch in both an intermediate
and a full-open position.  A spring-loaded handle on the latch
hold-open bracket releases the lock.  Friction is provided in the
linkage to prevent the hatch from moving if released during any part
of the swing.

The aft hatch is hinged to be pulled first into the tunnel adapter and
then forward at the bottom.  The top of the hatch is rotated towards
the tunnel and downward until the hatch rests with the Spacelab side
facing the tunnel adapter floor.  The linkage mechanism guides the
hatch from the closed/open, open/closed position with friction
restraint throughout the stroke.  The hatch is held in the open
position by straps and Velcro.

The upper (EVA) hatch in the tunnel adapter opens and closes to the
left wall of the tunnel adapter.  The hatch is hinged to be pulled
first into the tunnel adapter and then forward at the hinge area and
rotated down until it rests against the port wall of the tunnel
adapter.  The linkage mechanism guides the hatch from the closed/open,
open/closed position with friction restraint throughout the stroke.
The hatch is held in the open position by straps and Velcro.

The hatches can be removed in flight from the hinge mechanisms via pip
pins, if required.

The crew compartment, bunk sleep stations (if installed), airlock and
modular stowage lockers are built by Rockwell's Space Transportation
Systems Division, Downey, Calif.  The original crew seat contractor
was AMI of Colorado Springs, Colo., but later Rockwell's Space
Transportation Systems Division.  The Spacelab pressurized module
tunnel adapter and tunnel contractor is McDonnell Douglas
Astronautics, Huntington Beach, Calif.


"6_2_3_8_6.TXT" (5586 bytes) was created on 12-12-88

FORWARD FUSELAGE AND CREW COMPARTMENT WINDOWS

The orbiter windows provide visibility for entry, landing and on-orbit
operations.  For atmospheric flight, the flight crew needs forward,
left and right viewing areas.  On-orbit mission phases require
visibility for rendezvous, docking and payload-handling operations.

The six windows located at the forward flight deck commander and pilot
stations provide forward, left and right viewing.  The two overhead
windows and two payload-viewing windows at the aft station location on
the flight deck provide rendezvous, docking and payload viewing.
There is also a window in the middeck side hatch.

The six planform-shaped forward windows are the thickest pieces of
glass ever produced in the optical quality for see-through viewing.
Each consists of three individual panes.  The innermost pane is
constructed of tempered aluminosilicate glass to withstand the crew
compartment pressure.  It is 0.625 of an inch thick.  Aluminosilicate
glass is a low-expansion glass that can be tempered to provide maximum
mechanical strength.  The exterior of this pane, called a pressure
pane, is coated with a red reflector coating to reflect the infrared
(heat portion) rays while transmitting the visible spectrum.

The center pane is constructed of low-expansion, fused silica glass
because of its high optical quality and excellent thermal shock
resistance.  This pane is 1.3 inches thick.

The inner and outer panes are coated with a high-efficiency,
anti-reflection coating to improve visible light transmission.  These
windows withstand a proof pressure of 8,600 psi at 240 F and 0.017
relative humidity.

The outer pane is made of the same material as the center pane and is
0.625 of an inch thick.  The exterior is uncoated, but the interior is
coated with high-efficiency, anti-reflection coating.  The outer
surface withstands approximately 800 F.

Each of the forward six windows' outer panes measures 42 inches
diagonally, and the center and inner panes each measure 35 inches
diagonally.  The outer panes of the forward six windows are mounted
and attached to the forward fuselage.  The center and inner panes are
mounted and attached to the crew compartment.  Redundant seals are
employed on each window.  No sealing/bonding compounds are used.

The two overhead windows at the flight deck aft station are identical
in construction to the six forward windows except for thickness.  The
inner and center panes are 0.45 of an inch thick, and the outer pane
is 0.68 of an inch thick.  The outer pane is attached to the forward
fuselage, and the center and inner panes are attached to the crew
compartment.  The two overhead windows' clear view area is 20 by 20
inches.  The left-hand overhead window provides the crew members with
a secondary emergency egress.  The inner and center panes open into
the crew cabin, and the outer pane is jettisoned up and over the top
of the orbiter.  This provides a secondary emergency exit area of 20
by 20 inches.

On the aft flight deck, each of the two windows for viewing the
payload bay consists of only two panes of glass, which are identical
to the forward windows' inner and center panes.  The outer thermal
panes are not installed.  Each pane is 0.3 of an inch thick.  The
windows are 14.5 by 11 inches.  Both panes are attached to the crew
compartment.

The side hatch viewing window consists of three panes of glass
identical to the six forward windows.  The inner pane is 11.4 inches
in diameter and 0.25 of an inch thick.  The center pane is 11.4 inches
in diameter and 0.5 of an inch thick.  The outer pane is 15 inches in
diameter and 0.3 of an inch thick.

During orbital operations, the large window areas of transparency
expose the flight crew to sun glare; therefore, window shades and
filters are provided to preclude or minimize exposure.  Shades are
provided for all windows, and filters are supplied for the aft and
overhead viewing windows.  The window shades and filters are stored in
the middeck of the orbiter crew compartment.  Attachment mechanisms
and devices are provided for their installation at each window on the
flight deck.

The forward station window shades (W-1 through W-6) are fabricated
from Kevlar/epoxy glass fabric with silver and Inconel-coated Teflon
tape on the outside surface and paint on the inside surface.  When the
shade is installed next to the inner window pane, a silicone rubber
seal around the periphery deforms to prevent light leakage.  The shade
is held in place by the shade installation guide, the hinge plate and
the Velcro keeper.

The overhead window shades (W-7 and W-8) are nearly the same as the
forward shades; but the rubber seal is deleted, and the shade is
sealed and held in place by a separate seal around the window opening,
a hinge plate and secondary frame, and Velcro retainer.  The overhead
window filters are fabricated from Lexan and are used interchangeably
with the shades.

The aft window shades (W-9 and W-10) are the same as the overhead
window shades except that a 0.63-inch-wide strip of Nomex Velcro has
been added around the perimeter of the shade.  The shade is attached
to the window by pressing the Velcro strip to the pile strip around
the window opening.  The aft window filters are the same as the
overhead window filters except for the addition of the Velcro hook
strip.  The filters and shades are used interchangeably.

The side hatch window cover is permanently attached to the window
frame and is hinged to allow opening and closing.

The contractor for the windows is Corning Glass Co., Corning, N.Y.


"6_2_3_8_6.TXT" (5586 bytes) was created on 12-12-88

Enter {V}iew, {X}MODEM, {Y}MODEM, {K}ERMIT, ? for HELP, or {M}enu [V]...


FORWARD FUSELAGE AND CREW COMPARTMENT WINDOWS

The orbiter windows provide visibility for entry, landing and on-orbit
operations.  For atmospheric flight, the flight crew needs forward,
left and right viewing areas.  On-orbit mission phases require
visibility for rendezvous, docking and payload-handling operations.

The six windows located at the forward flight deck commander and pilot
stations provide forward, left and right viewing.  The two overhead
windows and two payload-viewing windows at the aft station location on
the flight deck provide rendezvous, docking and payload viewing.
There is also a window in the middeck side hatch.

The six planform-shaped forward windows are the thickest pieces of
glass ever produced in the optical quality for see-through viewing.
Each consists of three individual panes.  The innermost pane is
constructed of tempered aluminosilicate glass to withstand the crew
compartment pressure.  It is 0.625 of an inch thick.  Aluminosilicate
glass is a low-expansion glass that can be tempered to provide maximum
mechanical strength.  The exterior of this pane, called a pressure
pane, is coated with a red reflector coating to reflect the infrared
(heat portion) rays while transmitting the visible spectrum.

The center pane is constructed of low-expansion, fused silica glass
because of its high optical quality and excellent thermal shock
resistance.  This pane is 1.3 inches thick.

The inner and outer panes are coated with a high-efficiency,
anti-reflection coating to improve visible light transmission.  These
windows withstand a proof pressure of 8,600 psi at 240 F and 0.017
relative humidity.

The outer pane is made of the same material as the center pane and is
0.625 of an inch thick.  The exterior is uncoated, but the interior is
coated with high-efficiency, anti-reflection coating.  The outer
surface withstands approximately 800 F.

Each of the forward six windows' outer panes measures 42 inches
diagonally, and the center and inner panes each measure 35 inches
diagonally.  The outer panes of the forward six windows are mounted
and attached to the forward fuselage.  The center and inner panes are
mounted and attached to the crew compartment.  Redundant seals are
employed on each window.  No sealing/bonding compounds are used.

The two overhead windows at the flight deck aft station are identical
in construction to the six forward windows except for thickness.  The
inner and center panes are 0.45 of an inch thick, and the outer pane
is 0.68 of an inch thick.  The outer pane is attached to the forward
fuselage, and the center and inner panes are attached to the crew
compartment.  The two overhead windows' clear view area is 20 by 20
inches.  The left-hand overhead window provides the crew members with
a secondary emergency egress.  The inner and center panes open into
the crew cabin, and the outer pane is jettisoned up and over the top
of the orbiter.  This provides a secondary emergency exit area of 20
by 20 inches.

On the aft flight deck, each of the two windows for viewing the
payload bay consists of only two panes of glass, which are identical
to the forward windows' inner and center panes.  The outer thermal
panes are not installed.  Each pane is 0.3 of an inch thick.  The
windows are 14.5 by 11 inches.  Both panes are attached to the crew
compartment.

The side hatch viewing window consists of three panes of glass
identical to the six forward windows.  The inner pane is 11.4 inches
in diameter and 0.25 of an inch thick.  The center pane is 11.4 inches
in diameter and 0.5 of an inch thick.  The outer pane is 15 inches in
diameter and 0.3 of an inch thick.

During orbital operations, the large window areas of transparency
expose the flight crew to sun glare; therefore, window shades and
filters are provided to preclude or minimize exposure.  Shades are
provided for all windows, and filters are supplied for the aft and
overhead viewing windows.  The window shades and filters are stored in
the middeck of the orbiter crew compartment.  Attachment mechanisms
and devices are provided for their installation at each window on the
flight deck.

The forward station window shades (W-1 through W-6) are fabricated
from Kevlar/epoxy glass fabric with silver and Inconel-coated Teflon
tape on the outside surface and paint on the inside surface.  When the
shade is installed next to the inner window pane, a silicone rubber
seal around the periphery deforms to prevent light leakage.  The shade
is held in place by the shade installation guide, the hinge plate and
the Velcro keeper.

The overhead window shades (W-7 and W-8) are nearly the same as the
forward shades; but the rubber seal is deleted, and the shade is
sealed and held in place by a separate seal around the window opening,
a hinge plate and secondary frame, and Velcro retainer.  The overhead
window filters are fabricated from Lexan and are used interchangeably
with the shades.

The aft window shades (W-9 and W-10) are the same as the overhead
window shades except that a 0.63-inch-wide strip of Nomex Velcro has
been added around the perimeter of the shade.  The shade is attached
to the window by pressing the Velcro strip to the pile strip around
the window opening.  The aft window filters are the same as the
overhead window filters except for the addition of the Velcro hook
strip.  The filters and shades are used interchangeably.

The side hatch window cover is permanently attached to the window
frame and is hinged to allow opening and closing.

The contractor for the windows is Corning Glass Co., Corning, N.Y.


"6_2_3_8_7.TXT" (4577 bytes) was created on 12-12-88

WING

The wing is an aerodynamic lifting surface that provides conventional
lift and control for the orbiter.  The left and right wings consist of
the wing glove; the intermediate section, which includes the main
landing gear well; the torque box; the forward spar for mounting the
reusable reinforced carbon-carbon leading edge structure thermal
protection system; the wing/elevon interface; the elevon seal panels;
and the elevons.

The wing is constructed of conventional aluminum alloy with a multirib
and spar arrangement with skin-stringer-stiffened covers or honeycomb
skin covers.  Each wing is approximately 60 feet long at the fuselage
intersection and has a maximum thickness of 5 feet.

The forward wing box is an extension of the basic wing that
aerodynamically blends the wing leading edge into the midfuselage wing
glove.  The forward wing box is a conventional design of aluminum
ribs, aluminum tubes and tubular struts.  The upper and lower wing
skin panels are stiffened aluminum.  The leading edge spar is
constructed of corrugated aluminum.

The intermediate wing section consists of the conventional aluminum
multiribs and aluminum tubes.  The upper and lower skin covers are
constructed of aluminum honeycomb.  A portion of the lower wing
surface skin panel includes the main landing gear door.  The
intermediate section houses the main landing gear compartment and
reacts a portion of the main landing gear loads.  A structural rib
supports the outboard main landing gear door hinges and the main
landing gear trunnion and drag link.  The support for the inboard main
landing gear trunnion and drag link attachment is provided by the
midfuselage.  The main landing gear door is conventional aluminum
honeycomb.

The four major spars are constructed of corrugated aluminum to
minimize thermal loads.  The forward spar provides the attachment for
the thermal protection system reusable reinforced carbon-carbon
leading edge structure.  The rear spar provides the attachment
interfaces for the elevons, hinged upper seal panels, and associated
hydraulic and electrical system components.  The upper and lower wing
skin panels are stiffened aluminum.

The elevons provide orbiter flight control during atmospheric flight.
The two-piece elevons are conventional aluminum multirib and beam
construction with aluminum honeycomb skins for compatibility with the
acoustic environment and thermal interaction.  The elevons are divided
into two segments for each wing, and each segment is supported by
three hinges.  The elevons are attached to the flight control system
hydraulic actuators at points along their forward extremities, and all
hinge moments are reacted at these points.  Each elevon travels 40
degrees up and 25 degrees down.

The transition area on the upper surface between the torque box and
the movable elevon consists of a series of hinged panels that provide
a closeout of the wing-to-elevon cavity.  These panels are of Inconel
honeycomb sandwich construction outboard of wing station Y w 312.5 and
of titanium honeycomb sandwich construction inboard of wing station Y
w 312.5.  The upper leading edge of each elevon incorporates titanium
rub strips.  The rub strips are of titanium honeycomb construction and
are not covered with the thermal protection system reusable surface
insulation.  They provide the sealing surface area for the elevon seal
panels.

The exposed areas of the wings, main landing gear doors and elevons
are covered with reusable surface insulation thermal protection system
materials except for the elevon seal panels.

Thermal seals are provided on the elevon lower cove area along with
thermal spring seals on the upper rub panels.  Pressure seals and
thermal barriers are provided on the main landing gear doors.

The wing is attached to the fuselage with a tension bolt splice along
the upper surface.  A shear splice along the lower surface in the area
of the fuselage carry-through completes attachment interface.

Prior to the manufacturing of the wings for Discovery (OV-103) and
Atlantis (OV-104), a weight reduction program resulted in a redesign
of certain areas of the wing structure.  An assessment of wing air
loads was made from actual flight data that indicated greater loads on
the wing structure.  As a result, to maintain positive margins of
safety during ascent, structural modifications were incorporated into
certain areas of the wings.  The modifications consisted of the
addition of doublers and stiffeners.

The wing, elevon and main landing gear door contractor is Grumman
Corp., Bethpage, N.Y.


"6_2_3_8_8.TXT" (3327 bytes) was created on 12-12-88

MIDFUSELAGE

The midfuselage structure interfaces with the forward fuselage, aft
fuselage and wings.  It supports the payload bay doors, hinges,
tie-down fittings, forward wing glove, and various orbiter system
components and forms the payload bay area.

The forward and aft ends of the midfuselage are open, with reinforced
skin and longerons interfacing with the bulkheads of the forward and
aft fuselages.  The midfuselage is primarily an aluminum structure 60
feet long, 17 feet wide and 13 feet high.  It weighs approximately
13,502 pounds.

The midfuselage skins are integrally machined by numerical control.
The panels above the wing glove and the wings for the forward eight
bays have longitudinal T-stringers.  The five aft bays have aluminum
honeycomb panels.  The side skins in the shadow of the wing are also
numerically control machined but have vertical stiffeners.

Twelve main-frame assemblies stabilize the midfuselage structure.  The
assemblies consist of vertical side elements and horizontal elements.
The side elements are machined; whereas the horizontal elements are
boron/aluminum tubes with bonded titanium end fittings, which reduced
the weight by 49 percent (approximately 305 pounds).

In the upper portion of the midfuselage are the sill and door
longerons.  The machined sill longerons not only make up the primary
body-bending elements, but also take the longitudinal loads from
payloads in the payload bay.  The payload bay door longerons and
associated structure are attached to the 13 payload bay door hinges.
These hinges provide the vertical reaction from the payload bay doors.
Five of the hinges react the payload bay door shears.  The sill
longeron also provides the base support for the payload bay
manipulator arm (if installed) and its stowage provisions, the Ku-band
rendezvous antenna, the antenna base support and its stowage
provisions, and the payload bay door actuation system.

The side wall forward of the wing carry-through structure provides the
inboard support for the main landing gear.  The total lateral landing
gear loads are reacted by the midfuselage structure.

The midfuselage also supports the two electrical wire trays that
contain the wiring between the crew compartment and aft fuselage.

Plumbing and wiring in the lower portion of the midfuselage are
supported by fiberglass milk stools.

The remainder of the exposed areas of the midfuselage is covered with
the reusable surface insulation thermal protection system.

Because of additional detailed analysis of actual flight data
concerning descent stress thermal gradient loads, torsional straps
were added to the lower midfuselage stringers in bays 1 through 11.
The torsional straps tie all stringers together similarly to a box
section, which eliminates rotational (torsional) capabilities to
provide positive margins of safety.

Also, because of additional detailed analysis of actual flight data
during descent, room-temperature vulcanizing silicone rubber material
was bonded to the lower midfuselage from bay 4 through 12 to act as a
heat sink and distribute temperatures evenly across the bottom of the
midfuselage, which will reduce thermal gradients and ensure positive
margins of safety.

The contractor for the midfuselage is General Dynamics Corp., Convair
Aerospace Division, San Diego, Calif.


"6_2_3_8_9.TXT" (19568 bytes) was created on 12-12-88

PAYLOAD BAY DOORS

The payload bay doors are opened shortly after orbit is achieved to
allow exposure of the environmental control and life support system
radiators for heat rejection of the orbiter's systems.  The payload
bay doors consist of port and starboard doors hinged at each side of
the midfuselage and latched mechanically at the forward and aft
fuselage and at the split-top centerline.  Thermal seals on the doors
provide a relatively air-tight payload compartment when the doors are
closed and latched.  During prelaunch and postlanding, the purge, vent
and drain system permits purging of undesirable gases and maintains a
positive delta pressure for venting of payloads within the payload
area when the doors are closed.

The port and starboard doors are 60 feet long with a combined area of
approximately 1,600 square feet.  Each door is made up of five
segments that are interconnected by circumferential expansion joints.
Each door hinges on 13 Inconel 718 external hinges (five shear and
eight idlers).  The lower half of each hinge attaches to the
midfuselage sill longeron.  The hinges rotate on bearings with dual
rotational surfaces.  There are five shear hinges and eight floating
hinges.  The floating hinges allow fore and aft movement of the door
panels for thermal expansion.

Each door actuation system provides the mechanism to drive each door
side to the open or closed position.  Each mechanism consists of an
electromechanical power drive unit and six rotary gear actuators,
which are connected by torque tubes to each other and to the power
drive unit.  Linkages transmit torque from the rotary actuators to the
doors.

The forward 30-foot sections of both doors incorporate radiators that
can be deployed; they are hinged and latched to the door inner surface
in order to reject the excess heat of the Freon-21 coolant loops from
both sides of the radiator panels when the doors are open.  An
electromechanical actuation system on the door unlatches and deploys
the radiators when open and latches and stows the radiators when
closed.  The radiators may be left in the stowed position for a given
flight and will only radiate the excess heat from the one side.  Fixed
radiator panels are installed on the forward end of the aft payload
bay doors and radiate from one side only.  Kitted fixed radiator
panels may be installed on the aft end of the aft payload bay doors
when required by a specific mission; they also will radiate from only
one side.

During payload bay door closure, the aft flight deck payload bay door
crewman optical alignment sight is used to check door alignment.

When the payload bay doors are closed, they are fixed at the aft
fuselage bulkhead and allowed to move longitudinally at the forward
fuselage.  The doors also accommodate vehicle torsional loads (a force
that causes a body, such as a shaft, to twist about its longitudinal
axis), aerodynamic pressure loads and payload bay vent lag pressures.
The payload bay is not a pressurized area.

Thermal and pressure seals are used to close the gaps at the forward
and aft fuselage interface, door centerline and circumferential
expansion joints.

The doors are 60 feet long.  Each consists of five segments
interconnected by expansion joints.  The chord of each half of these
curved doors is approximately 10 feet, and the doors are 15 feet in
diameter.

The doors are constructed of graphite epoxy composite material, which
reduces the weight by 23 percent over that of aluminum honeycomb
sandwich.  This is a reduction of approximately 900 pounds, which
brings the weight of the doors down to approximately 3,264 pounds.
The payload bay doors are the largest aerospace structure to be
constructed from composite material.

The composite doors will withstand 163-decibel acoustic noise and a
temperature range of minus 170 to plus 135 F.

The doors are made up of subassemblies consisting of graphite epoxy
honeycomb sandwich panels, solid graphite epoxy laminate frames,
expansion joint frames, torque box, seal depressor, centerline beam
intercostals, gussets, end fittings and clips.  There are also
aluminum 2024 shear pins, titanium fittings, and Inconel 718 floating
and shear hinges.  The assembly is joined by mechanical fasteners.
Lightning strike protection is provided by aluminum mesh wire bonded
to the outer skin.

Extravehicular activity handholds are attached in the torque box
areas.

The payload bay doors are covered with reusable surface insulation.

The left door with attached systems weighs approximately 2,375 pounds
and the right weighs about 2,535 pounds.  The right door contains the
centerline latch active mechanisms, which accounts for the weight
difference.  These weights do not include the radiator panel system,
which adds 833 pounds per door.

The PL bay door open/stop/close switch on panel R13 initiates the
payload bay door power and control system through the aft flight deck
data processing system, general-purpose computer and associated
cathode ray tube display and keyboard.  The normal operational mode
for opening and closing the payload bay door bulkhead latches,
centerline latches and payload bay doors is through keyboard entries
in an automatic mode in which the latches are cycled and the doors
controlled in a predetermined sequence.  If a problem occurs in the
predetermined automatic sequence, a manual keyboard capability permits
selection of automatic sequence groupings that can be commanded
individually.  The open position of the switch on panel R13 provides
the signals to a GPC to initiate and sustain the automatic or keyboard
manual bulkhead latches and door opening sequence.  The close position
accomplishes the same as the open position except for the closing
sequence.  The stop position removes the open and close signals,
stopping the sequence in progress.

The PL bay door talkback indicator on panel R13 is functional only in
the automatic sequence and would remain in its initial state in the
manual keyboard mode.  The signal source for the talkback indicator is
a combination of ready-to-latch and door-open limit switch inputs that
are processed by software to establish the talkback indicator state.
The talkback indicator indicates op when the bulkhead latches,
centerline latches and doors are open; cl when the doors are closed
and the centerline and bulkhead latches are closed; and barberpole
when the bulkhead and centerline latches and doors are in transit or
are stopped between open and closed.

When closed, the doors are latched to the forward and aft bulkheads
and along the upper centerline of the doors.  The latching system
consists of 16 bulkhead latches (eight aft and eight forward) and 16
payload bay door centerline latches.  The forward and aft bulkhead
latches are in groups of four ganged latch hooks.  The centerline
latches are also in groups of four ganged latches.  Each centerline
latch gang incorporates four latches, bellcranks, push rods, levers,
rollers and an electromechanical actuator.

The forward and aft bulkhead latches are arranged in groups of four
ganged latches.  Each group is opened or closed by an
electromechanical actuator with two redundant, three-phase ac
reversible motors that receive ac power from mid motor controller
assemblies when commanded in the automatic predetermined sequence or
by manual keyboard entries.  In the automatic mode, the forward and
aft bulkhead latches operate simultaneously.

The forward and aft bulkhead latch groups consist of two ac reversible
motors.  These groups also control an actuator output arm, which
positions active latch mechanisms and disengages or engages four latch
hooks on four corresponding passive rollers on the bulkhead.  The two
ac motors of a bulkhead latch group are commanded through limit
switches to open or close that group of latches.  When the ac motor is
in operation, the brake associated with that motor is released and is
applied when power is removed from the motor.  The limit switches
apply or remove ac power from the motor when that latch group reaches
its open or closed position.  When both motors are operating, the
latch group operating time is 30 seconds; it is 60 seconds when only
one motor is operating.  In addition, each MMCA has its own timer set
to twice the normal operating time to allow for single-motor operation
of a bulkhead latch group without causing a sequence fail signal PLB
doors CRT message and SM alert.

During latching operations for a bulkhead group, the payload bay door
comes in contact with a bulkhead switch module striker when the door
is nearly closed.  A two-out-of-three voting logic of the
ready-to-latch switches precludes premature start signals to the
bulkhead latch motors.  The ready-to-latch switch then activates the
bulkhead latch ac motors, which latches the door closed.  The
door-closed limit switches turn the ac motors off.  The limit switch
contact closures are sent to the CRT display under micro-sw stat
(switch status), which permits the flight crew to observe the change
in the status of the microswitches.  Telemetry can also monitor the
microswitch status.  Torque limiters in each bulkhead latch group
permit slippage if a limit switch fails to turn off the ac motors or
the mechanism jams during latching operations in order to prevent
damage to the motors or mechanisms.  Extravehicular activity
disconnects are provided to permit an EVA flight crew member to close
the door latch manually from inside the payload bay if the mechanism
jams when the doors close.

The payload bay door centerline latch groups are controlled
automatically in a predetermined sequence or manually by individual
latch groups through keyboard entries in a manner similar to the
bulkhead latch groups.  The 16 centerline latches are arranged into
groups of four, similar to the bulkhead latches.

Each centerline latch group consists of two ac reversible electric
motors that drive a rotary shaft and bellcrank and four hooks to
engage a corresponding passive roller to latch the door closed or
disengage the passive roller to unlatch the door.  All 16 centerline
hook assemblies contain alignment rollers to eliminate payload bay
door overlap due to thermal distortion.  Passive shear fittings in
each centerline latch group align door closure and cause the fore and
aft shear loads to react once the doors are closed.

The centerline latch group ac reversible motors are automatically
turned off by limit switches when the latches are opened or closed.
Each motor has a brake that operates similarly to the brakes in the
bulkhead motors.  When both motors are operating, the nominal
operating time is 20 seconds.  If only one motor is operating, the
time is 40 seconds.  Each mid motor controller assembly has its own
timer set to twice the normal operating time to allow single-motor
operation of the centerline latch group without causing a sequence
fail signal PLB doors CRT message and SM alert.

Torque limiters in the centerline latch groups allow slippage if limit
switches fail to turn off an electrical drive motor or the mechanisms
jam to prevent damage to the motors or mechanism.

EVA disconnects in a centerline latch group can be used to isolate a
jammed latch from the group.

The payload bay doors are driven by a rotary actuator consisting of
two electrical three-phase reversible ac motors per power drive unit.
There is one power drive unit for right doors and one for the left
doors.

The power drive unit drives a 55-foot-long torque shaft.  The shaft
turns the rotary actuators, which causes the push rod, bell crank and
link to push the doors open.  The same arrangement pulls the doors
closed.

The payload bay door opening and closing sequence is controlled
automatically through in a predetermined sequence or manually through
keyboard entries.  The starboard doors must be opened first and closed
last due to the arrangement of the centerline latching mechanism and
the structural and seal overlap.  Limit switches on each power drive
unit turn the ac motors off when the doors are open or closed.  Each
ac motor has an associated brake that operates similarly to the
bulkhead and centerline latch motors.  When both motors are operating,
the nominal time for payload bay door opening or closing is 63
seconds.  If only one motor is operating, the time is 126 seconds.
Each MMCA has its own timer set to twice the normal operating time to
allow single-motor operation of the payload bay doors without causing
a sequence fail signal PLB doors CRT message and an SM alert .

Torque limiters are incorporated into the rotary actuators to avoid
damaging the drive motors or mechanisms if limit switches fail to turn
off an electrical drive motor or the mechanisms jam.

Two bolts on the bellcrank and the bolt connecting the link to the
rotary actuator can be EVA disconnect points if the linkage fails when
the doors close.  The power drive unit can be disengaged manually on
the ground or on orbit.

The payload bay doors open through an angle of 175.5 degrees.

Two radiator panels on each forward payload bay door can be deployed
when the doors are opened on orbit and stowed when the doors are
closed before entry, or they can be left in the stowed position for a
given flight.  Freon-21 coolant loop 1 flows through the left-hand
radiator panels, and the No.  2 loop flows through the right-hand
panels.  On orbit, the panels radiate excess heat collected by the
Freon-21 coolant loops from heat exchangers and cold plates throughout
the orbiter.  Coolant flows through the radiators from aft to forward.
The radiator panels mounted on the forward end of the aft payload bay
doors are fixed to the bay doors.

The radiator deploy and stow operation is controlled manually from the
aft flight deck panel R13.  The PL bay mech (payload bay mechanisms)
pwr, radiator latch and radiator control sys switches control the
panels.  Four indicators show the radiator latch and deploy status.

When the payload bay doors are fully open, the PL bay mech sys 1 and
sys 2 switches are positioned to on .  The sys 1 and sys 2 switches
positioned to on provide ac bus power to both right- and left-side
radiator latch control actuators.

The radiator latch control sys A switch positioned to release applies
ac power to one ac reversible drive motor on each starboard and port
panel.  When each motor is in operation, the brake is removed.  Each
ac drive motor rotates a torque shaft, which operates push rods that
unlatch six latches on each of the two right and two left radiator
panels.  The linkages and latches are attached to the payload bay
doors, and passive rollers are attached to the radiator panels.  The
operating time for releasing the latches with one motor is
approximately 52 seconds.  Limit switches remove power from the ac
motors.  The brake is applied for each motor.  The radiator stdb
(starboard) and port talkback indicators above the latch control sys A
and B switches indicate rel when the corresponding latches are
released and barberpole when in transit.  When the radiator latch
control sys B switch is positioned to release, ac power is applied to
the remaining ac reversible drive motor on each right panel and each
left panel.  This remaining ac drive motor will operate the same
rotating shaft and unlatch the same six latches on each of the two
right and two left radiator panels.  Separate limit switches remove
power from these ac motors.  The radiator stdb and port talkback
indicators above the latch control sys A and B switches indicate rel
when the corresponding latches are released and barberpole when in
transit and have the same operating time as in system A.  If both
switches were positioned to rel simultaneously, the operating time
would be approximately 26 seconds.

Positioning the radiator latch control sys A and/or B switch to latch
reverses the action and latches the radiator panels to the payload bay
doors.  The talkback indicators indicate lat when the panels are
latched and barberpole when in transit.

The off position of the radiator latch control sys A and/or B switch
removes power from the corresponding control system, which stops the
motors and latch system movement.

Torque limiters in the power drive system prevent damage to the system
in the event of jamming or binding during operation.

The radiator control sys A switch positioned to deploy applies ac
power to one ac reversible drive motor on the right panel and one ac
reversible drive motor on the left panel.  The motors are not operable
until the MMCAs have received two signals from the radiator panel
unlatch drives, which prevents inadvertent deployment of the radiators
while still latched.  When power is applied to the left and right
motors, the brake is removed and the rotary actuator shaft rotates and
pushes the respective radiator panels away from the payload bay doors
to the deployed position.  Separate limit switches turn the ac motors
off and apply the brake for each motor.  The operating time for
deployment with one motor is 86 seconds.  The radiator stdb and port
talkback indicators above the radiator control sys A and B switches
indicate dpy when the corresponding panels are deployed and barberpole
when in transit.  When the radiator control sys B switch is positioned
to deploy, ac power is applied to the remaining ac reversible drive
motor on the right radiator panel and the remaining ac reversible
drive motor on the left panel.  This remaining ac drive motor operates
the same rotary actuator shaft and pushes the respective radiator
panel away from the payload bay doors to the deployed position.
Separate limit switches turn the ac motors off.  The radiator stdb and
port talkback indicators above the radiator control sys A and B
switches indicate dpy when the corresponding panels are deployed and
barberpole when in transit and have the same operating time as in
system A.  If both switches are positioned to deploy simultaneously,
the operating time is 43 seconds.

Positioning the radiator control sys A and/or B switch to stow
reverses the action, stowing the radiators to the payload bay doors.
The talkback indicators indicate sto when the panels are stowed and
barberpole in transit.

The off position of the radiator control sys A and/or B switch removes
power from the corresponding control system, stopping the motors and
radiator panel movement.

When the radiators are deployed, they are 35.5 degrees from the
payload bay doors.

Torque limiters on the power drive system prevent damage to the system
in the event of jamming or binding during operation.

Each rotary crank can be disengaged from the rotary actuator (via EVA
operations) by retracting a shear pin.  Retraction allows the crank to
rotate around an alternate pivot and permits the crew to stow the
panels if the system fails.  If the power drive unit fails, all four
shear pins must be removed to allow manual stowing of the radiators.
The pins are accessible when the radiators are fully deployed.  No
disengagement is planned if the radiators fail to deploy.

The contractors are Rockwell's Tulsa Division, Tulsa, Okla.  (payload
bay doors); Curtiss Wright, Caldwell, N.J.  (payload bay door power
drive unit, rotary actuators, drive shafts, torque tubes and
couplings, radiator deploy/latch actuator and latch mechanism); Hoover
Electric, Los Angeles, Calif.  (payload bay door electromechanical
rotary actuators); Vought Corp., Dallas, Texas (radiators); Rockwell's
Space Transportation Systems Division, Downey, Calif.  (latches,
linkages and actuators).

"6_2_3_8_10.TXT" (4494 bytes) was created on 12-12-88

AFT FUSELAGE

The aft fuselage consists of an outer shell, thrust structure and
internal secondary structure.  It is approximately 18 feet long, 22
feet wide and 20 feet high.

The aft fuselage supports and interfaces with the left-hand and
right-hand aft orbital maneuvering system/reaction control system
pods, the wing aft spar, midfuselage, orbiter/external tank rear
attachments, space shuttle main engines, aft heat shield, body flap,
vertical tail and two T-0 launch umbilical panels.

The aft fuselage provides the load path to the midfuselage main
longerons, main wing spar continuity across the forward bulkhead of
the aft fuselage, structural support for the body flap, and structural
housing around all internal systems for protection from operational
environments (pressure, thermal and acoustic) and controlled internal
pressures during flight.

The forward bulkhead closes off the aft fuselage from the midfuselage
and is composed of machined and beaded sheet metal aluminum segments.
The upper portion of the bulkhead attaches to the front spar of the
vertical tail.

The internal thrust structure supports the three SSMEs.  The upper
section of the thrust structure supports the upper SSME, and the lower
section of the thrust structure supports the two lower SSMEs.  The
internal thrust structure includes the SSMEs, load reaction truss
structures, engine interface fittings and the actuator support
structure.  It supports the SSMEs, the SSME low-pressure turbopumps
and propellant lines.  The two orbiter/external tank aft attach points
interface at the longeron fittings.

The internal thrust structure is composed mainly of 28 machined,
diffusion-bonded truss members.  In diffusion bonding, titanium strips
are bonded together under heat, pressure and time.  This fuses the
titanium strips into a single hollow, homogeneous mass that is lighter
and stronger than a forged part.  In looking at the cross section of a
diffusion bond, one sees no weld line.  It is a homogeneous parent
metal, yet composed of pieces joined by diffusion bonding.  (In
OV-105, the internal thrust structure is a forging.) In selected
areas, the titanium construction is reinforced with boron/epoxy
tubular struts to minimize weight and add stiffness.  This reduced the
weight by 21 percent, approximately 900 pounds.

The upper thrust structure of the aft fuselage is of integral-machined
aluminum construction with aluminum frames except for the vertical fin
support frame, which is titanium.  The skin panels are integrally
machined aluminum and attach to each side of the vertical fin to react
drag and torsion loading.

The outer shell of the aft fuselage is constructed of
integral-machined aluminum.  Various penetrations are provided in the
shell for access to installed systems.  The exposed outer areas of the
aft fuselage are covered with reusable thermal protection system.

The secondary structure of the aft fuselage is of conventional
aluminum construction except that titanium and fiberglass are used for
thermal isolation of equipment.  The aft fuselage secondary structures
consist of brackets, buildup webs, truss members, and machined
fittings, as required by system loading and support constraints.
Certain system components, such as the avionics shelves, are
shock-mounted to the secondary structure.  The secondary structure
includes support provisions for the auxiliary power units, hydraulics,
ammonia boiler, flash evaporator and electrical wire runs.

The two external tank umbilical areas interface with the orbiter's two
aft external tank attach points and the external tank's liquid oxygen
and hydrogen feed lines and electrical wire runs.  The umbilicals are
retracted, and the umbilical areas are closed off after external tank
separation by an electromechanically operated beryllium door at each
umbilical.  Thermal barriers are employed at each umbilical door.  The
exposed area of each closed door is covered with reusable surface
insulation.

The aft fuselage heat shield and seal provide a closeout of the
orbiter aft base area.  The aft heat shield consists of a base heat
shield of machined aluminum.  Attached to the base heat shield are
domes of honeycomb construction that support flexible and sliding seal
assemblies.  The engine-mounted heat shield is of Inconel honeycomb
construction and is removable for access to the main engine power
heads.  The heat shield is covered with a reusable thermal protection
system except for the Inconel segments.


"6_2_3_8_11.TXT" (1989 bytes) was created on 12-12-88

ORBITAL MANEUVERING SYSTEM/ REACTION CONTROL SYSTEM PODS

The orbital maneuvering system/reaction control system left- and
right-hand pods are attached to the upper aft fuselage left and right
sides.  Each pod is fabricated primarily of graphite epoxy composite
and aluminum.  Each pod is 21.8 feet long and 11.37 feet wide at its
aft end and 8.41 feet wide at its forward end, with a surface area of
approximately 435 square feet.  Each pod is divided into two
compartments: the OMS and the RCS housings.  Each pod houses all the
OMS and RCS propulsion components and is attached to the aft fuselage
with 11 bolts.  The pod skin panels are graphite epoxy honeycomb
sandwich.  The forward and aft bulkhead aft tank support bulkhead and
floor truss beam are machined aluminum 2124.  The centerline beam is
2024 aluminum sheet with titanium stiffeners and graphite epoxy
frames.  The OMS thrust structure is conventional 2124 aluminum
construction.  The cross braces are aluminum tubing, and the attach
fittings at the forward and aft fittings are 2124 aluminum.  The
intermediate fittings are corrosion-resistant steel.  The RCS housing,
which attaches to the OMS pod structure, contains the RCS thrusters
and associated propellant feed lines.  The RCS housing is constructed
of aluminum sheet metal, including flat outer skins.  The curved outer
skin panels are graphite epoxy honeycomb sandwich.  Twenty-four doors
in the skins provide access to the OMS and RCS and attach points.

The two graphite epoxy pods per spacecraft reduce the weight by 10
percent, approximately 450 pounds.  The pods will withstand
162-decibel acoustic noise and a temperature range from minus 170 to
plus 135 F.

The exposed areas of the OMS/RCS pods are covered with a reusable
thermal protection system, and a pressure and thermal seal is
installed at the OMS/RCS pod aft fuselage interface.  Thermal barriers
are installed, and they interface with the RCS thrusters and reusable
thermal protection system.


"6_2_3_8_12.TXT" (2216 bytes) was created on 12-12-88

BODY FLAP

The body flap thermally shields the three SSMEs during entry and
provides the orbiter with pitch control trim during its atmospheric
flight after entry.

The body flap is an aluminum structure consisting of ribs, spars, skin
panels and a trailing edge assembly.  The main upper and lower forward
honeycomb skin panels are joined to the ribs, spars and honeycomb
trailing edge with structural fasteners.  The removable upper forward
honeycomb skin panels complete the body flap structure.

The upper skin panels aft of the forward spar and the entire lower
skin panels are mechanically attached to the ribs.  The forward upper
skin consists of five removable access panels attached to the ribs
with quick-release fasteners.  The four integral-machined aluminum
actuator ribs provide the aft fuselage interface through self-aligning
bearings.  Two bearings are located in each rib for attachment to the
four rotary actuators located in the aft fuselage, which are
controlled by the flight control system and the hydraulically actuated
rotary actuators.  The remaining ribs consist of eight stability ribs
and two closeout ribs constructed of chemically milled aluminum webs
bonded to aluminum honeycomb core.  The forward spar web is of
chemically milled sheets with flanged holes and stiffened beads.  The
spar web is riveted to the ribs.  The trailing edge includes the rear
spar, which is composed of piano-hinge half-cap angles, chemically
milled skins, honeycomb aluminum core, closeouts and plates.  The
trailing edge attaches to the upper and lower forward panels by the
piano-hinge halves and hinge pins.  Two moisture drain lines and one
hydraulic fluid drain line penetrate the trailing edge honeycomb core
for horizontal and vertical drainage.

The body flap is covered with a reusable thermal protection system and
an articulating pressure and thermal seal to its forward cover area on
the lower surface of the body flap to block heat and air flow from the
structures.

The aft fuselage is built by Rockwell's Space Transportation Systems
Division, Downey, Calif.  The OMS/RCS pods are built by McDonnell
Douglas, St.  Louis, Mo.  The body flap is built by Rockwell's
Columbus, Ohio, division.


"6_2_3_8_13.TXT" (2044 bytes) was created on 12-12-88


VERTICAL TAIL

The vertical tail consists of a structural fin surface, the
rudder/speed brake surface, a tip and a lower trailing edge.  The
rudder splits into two halves to serve as a speed brake.

The vertical tail structure fin is made of aluminum.  The main torque
box is constructed of integral-machined skins and strings, ribs, and
two machined spars.  The fin is attached by two tension tie bolts at
the root of the front spar of the vertical tail to the forward
bulkhead of the aft fuselage and by eight shear bolts at the root of
the vertical tail rear spar to the upper structural surface of the aft
fuselage.

The rudder/speed brake control surface is made of conventional
aluminum ribs and spars with aluminum honeycomb skin panels and is
attached through rotating hinge parts to the vertical tail fin.

The lower trailing edge area of the fin, which houses the rudder/speed
brake power drive unit, is made of aluminum honeycomb skin.

The hydraulic power drive unit/mechanical rotary actuation system
drives left- and right-hand drive shafts in the same direction for
rudder control of plus or minus 27 degrees.  For speed brake control,
the drive shafts turn in opposite directions for a maximum of 49.3
degrees each.  The rotary drive actions are also combined for joint
rudder/speed brake control.  The hydraulic power drive unit is
controlled by the orbiter flight control system.

The vertical tail structure is designed for a 163-decibel acoustic
environment with a maximum temperature of 350 F.

All-Inconel honeycomb conical seals house the rotary actuators and
provide a pressure and thermal seal that withstands a maximum of 1,200
F.

The split halves of the rudder panels and trailing edge contain a
thermal barrier seal.

The vertical tail and rudder/speed brake are covered with a reusable
thermal protection system.  A thermal barrier is also employed at the
interface of the vertical stabilizer and aft fuselage.

The contractor for the vertical tail and rudder/speed brake is
Fairchild Republic, Farmingdale, N.Y.