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

Text File | 1993-02-06 | 13KB | 258 lines

"6_2_3_11_2.TXT" (7826 bytes) was created on 12-12-88

ORBITER FLIGHT CREW ESCAPE SYSTEMS

IN-FLIGHT CREW ESCAPE SYSTEM

The in-flight crew escape system is provided for use only when the
orbiter would be in controlled gliding flight and unable to reach a
runway.  This condition would normally lead to ditching.  The crew
escape system provides the flight crew with an alternative to water
ditching or to landing on terrain other than a landing site.  The
probability of the flight crew surviving a ditching is very slim.

The hardware changes required to the orbiters enable the flight crew
to equalize the pressurized crew compartment with the outside pressure
via the depressurization valve opened by pyrotechnics in the crew
compartment aft bulkhead that would be manually activated by a flight
crew member in the middeck of the crew compartment; pyrotechnically
jettison the crew ingress/egress side hatch manually in the middeck of
the crew compartment; and bail out from the middeck through the
ingress/egress side hatch opening after manually deploying the escape
pole through, outside and down from the side hatch opening.  One by
one, each flight crew member attaches a lanyard hook assembly, which
surrounds the deployed escape pole, to his or her parachute harness
and egresses through the side hatch opening.  Attached to the escape
pole, the crew member slides down the pole and off the end.  The
escape pole provides each crew member with a trajectory that takes the
crew member below the orbiter's left wing.

Changes were also made in the software of the orbiter's
general-purpose computers.  The software changes were required for the
primary avionics software system and the backup flight system for
transatlantic-landing and glide-return-to-launch-site abort modes.
The changes provide the orbiter with an automatic-mode input by flight
crew members through keyboards at the commander's and/or pilot's panel
C3, which provides the orbiter with an automatic stable flight for
crew bailout.  This software change, which is required to allow the
flight crew commander's departure, automatically controls the
orbiter's velocity and angle of attack to the desired bailout
conditions.

The crew would make the escape decision at an altitude of
approximately 60,000 feet and would immediately make an input to the
flight control system software autopilot mode.

When the orbiter descends to an altitude of approximately 30,000 feet,
its airspeed must be decreased to approximately 200 knots (230 mph).
At approximately 25,000 feet, a crew member in the middeck (referred
to as the jump master and seated in the forward left seat in the
middeck) raises a cover on the left side of the crew compartment
middeck at floor level and pulls the T-handle, which activates the
pyrotechnics for the depressurization valve at the crew compartment X
o 576 aft bulkhead.  This equalizes the crew compartment cabin and
outside pressure before the side hatch is jettisoned.

At approximately 25,000 feet, the software for the automatic autopilot
mode changes the orbiter's angle of attack to approximately 15
degrees.  This angle of attack must remain nearly constant for
approximately three minutes until the orbiter reaches an altitude of
approximately 2,000 feet.

At approximately 25,000 feet, the jump master jettisons the side hatch
by pulling the hatch jettison T-handle next to the depressurization
T-handle.  When the T-handle is pulled, pyrotechnics separate the
hatch assembly by severing the side hatch hinge, and three pyrotechnic
thrusters jettison the tunnel/hatch from the orbiter at a velocity of
approximately 50 feet per second.

The jump master pulls the pip pin on the escape pole and pulls the
ratchet handle down, which permits the two telescoping sections of the
escape pole to be deployed through the hatch opening by spring
tension.

A magazine assembly located near the side hatch contains a lanyard
assembly for each flight crew member.  Each lanyard assembly consists
of a hook attached to a Kevlar strap that surrounds the escape pole.
Five roller bearings on each strap surround the pole and permit the
lanyard to roll freely down the pole.  Each flight crew member
positions himself or herself at the hatch opening and attaches himself
or herself to the escape pole via the lanyard hook assembly and jumps
out the hatch opening.

Each lanyard assembly incorporates an energy absorber rated at 1,000
pounds.  The Kevlar strap consists of two sections of permanent Nomex
thread stitching and a section of breakaway Kevlar thread stitching.
When the crew member exits the side hatch on the escape pole, the
breakaway Kevlar thread stitching can break away, providing the crew
member with an energy absorber.  The crew member slides down the
escape pole and off the end into a free-fall.  The escape pole extends
downward 9.8 feet from the side hatch and provides the crew member
with a trajectory that will carry him or her beneath the orbiter's
left wing.

It would take approximately 90 seconds for a maximum crew of eight to
bail out.  After the first crew member bails out from the middeck, the
remaining crew members follow at approximately 12-second intervals
until all are out by approximately 10,000 feet altitude.

A handhold was added in the middeck next to the side hatch to permit
the crew members to position themselves through the side hatch opening
for bailout.

The escape pole is constructed of aluminum and steel.  The arched
housing for the pole is 126.75 inches long and is attached to the
middeck ceiling above the airlock hatch and at the 2 o'clock position
at the side hatch for deployment during launch and entry.  The escape
pole telescopes from the middeck housing through the side hatch in two
sections.  The primary extension is 73 inches long, and the end
extension is 32 inches long.  The diameter of the housing is 3.5
inches.  The two telescoping sections are slightly smaller in
diameter.  The escape pole weighs approximately 241 pounds-248 pounds
with attachments.

On orbit, the escape pole's primary stowage position requires
unpinning the escape pole at the starboard and port attachments,
rotating the pole so it is flat against the middeck ceiling and
strapping it to the ceiling.  An alternate on-orbit stowage approach
also requires unpinning the escape pole at the starboard and port
attachments, rotating it so it is flat against the middeck ceiling and
strapping it to the ceiling.

The side hatch water coolant lines for side hatch thermal conditioning
were modified to accommodate the installation of the side hatch
pyrotechnic separation system.

The flight crew members' seats were also modified to accommodate the
seat/crew altitude protection system suit for each crew member.

The pyrotechnically operated crew compartment depressurization valve
consists of two flapper valves with debris screens on the crew
compartment side and payload bay side that open to depressurize the
crew compartment and close when the pressure equalizes.

It is noted that the hatch jettison features could be used in a
landing emergency.

The crew member's altitude protection suit includes an emergency
oxygen system, pilot and drogue parachutes that are operated
automatically and have manual backup, a main parachute that is
operated automatically and has manual backup, a seawater activation
release system, flotation devices, a life raft and survival equipment.
The crew altitude protection suit and its associated equipment weigh
approximately 70 pounds.

The side hatch jettison thruster contractor is OEA, Denver, Colo.  The
pyrotechnics contractor for the hatch tunnel, hinge and the energy
transfer system lines is Explosive Technology, Fairfield, Calif.  The
escape pole is government-furnished equipment that is supplied by
NASA's Johnson Space Center, Houston, Texas, as is the crew altitude
protection suit.


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EMERGENCY EGRESS SLIDE

The emergency egress slide provides the orbiter flight crew members
with a rapid and safe emergency egress through the orbiter middeck
ingress/egress side hatch after a normal opening of the side hatch or
after jettisoning of the side hatch at the nominal end-of-mission
landing site or at a remote or emergency landing site.

The emergency egress slide replaces the emergency egress side hatch
bar, which required the flight crew members to drop approximately 10.5
feet to the ground.  This drop could cause injury to the flight crew
members and prevent an injured flight crew member from moving to a
safe distance from the orbiter.

The emergency egress slide will support return- to- launch- site,
transatlantic-landing, abort-once-around and normal end-of-mission
landings.

The system will be activated manually by the flight crew rotating the
slide from the middeck through the egress side hatch opening onto the
side hatch if the hatch has not been jettisoned or through the egress
side hatch opening if the hatch has been jettisoned.  The flight crew
pulls a lanyard to inflate the slide with a self-contained air bottle
supply.  The slide allows the safe egress of the flight crew members
to the ground within 60 seconds after the side hatch is fully opened
or jettisoned; accommodates the egress of the flight crew members
wearing the launch and entry crew altitude protection system;
accommodates the egress of incapacitated crew members; withstands and
remains functional in the egress environment for a minimum of six
minutes after deployment; and can be released from the side hatch to
permit fire truck access.

The slide is installed inside the middeck below the side hatch where
it will not inhibit ingress/egress when the system is not required and
not interfere with normal on-orbit operations.

The egress slide contractor is Inflatable Systems Inc., a division of
OEA, Denver, Colo.


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SECONDARY EMERGENCY EGRESS

The left-hand flight deck overhead window provides the flight crew
with a secondary emergency egress route.  The left overhead window
consists of three panes of glass, an inner pane attached to the crew
compartment and a center and outer pane attached to the upper forward
fuselage.

When the secondary emergency egress path is utilized, pulling the T
handle located forward of the flight deck center console (between the
commander and pilot) activates the overhead window jettison system.
When initiated, the center and outer panes are jettisoned as a unit,
upward and aft.  A time delay in the pyrotechnic firing circuit delays
the initiation of the jettisoning of the inner pane 0.3 of a second
after the center and outer panes are jettisoned.  Upon the initiation
of the jettisoning of the inner window pane, it rotates downward and
aft into the crew compartment aft flight deck on hinges located at the
aft portion of the window frame.  A capture device attenuates the
opening rate and holds the window in   position.

The overhead window jettison system consists primarily of expanding
tube assemblies, mild detonating fuses, frangible bolts and associated
initiators.

The left overhead window jettison system can be initiated from the
outside of the orbiter on the right side of the forward fuselage by
ground   personnel.

Egress steps are mounted at the aft flight deck station (left side) to
assist the flight crew up through the  window.

Emergency ground descent devices are stowed on the overhead aft flight
deck adjacent to the left overhead window.  One device is provided for
each flight crew member.  The emergency ground descent device enables
flight crew members to lower themselves to the ground over the side of
the   orbiter.

SIDE HATCH JETTISON

The middeck ingress/egress side hatch was modified to provide the
capability of pyrotechnically jettisoning the side hatch for emergency
egress on the ground.  In addition, a crew compartment pressure
equalization valve provided at the crew compartment aft bulkhead, X o
576, is also pyrotechnically activated to equalize cabin/outside
pressure before the jettisoning of the side hatch.

A panel on the left side of the middeck of the crew compartment
contains two T-handles.  One T-handle controls the initiation of the
pyrotechnic pressure equalization valves, which equalize the cabin
pressure with outside pressure.

The other T-handle in the same panel in the middeck jettisons the side
hatch pyrotechnically.  When this T-handle is activated, pyrotechnics
sever the hinges of the side hatch and three pyrotechnic tunnel/hatch
thrusters are initiated, which jettisons the side hatch from the
orbiter.

The side hatch jettison thruster contractor is OEA, Denver, Colo.  The
pyrotechnics contractor for the hatch tunnel, hinges and the energy
transfer system lines is Explosive Technology, Fairfield, Calif.