roberts@iisat.uucp (Greg Roberts) (10/27/89)
This is extracted from "National Space Transportation System Reference"
Volume 1
Systems and Facilities
June 1988
It is reproduced without permission from NASA
Range Safety System
The shuttle vehicle has three RSSs. One is located in each SRB and one in
the external tank. Any one or all three are capable of receiving two command
messages (arm and fire) transmitted from the ground station. The RSS is used
only when the vehicle violates a launch trajectory red line.
An RSS consists of two antenna couplers, command receivers/decoders, a dual
distributor, a safe and arm device with two NSDs, two confined detonating
fuse manifolds, seven CDF assemblies and one linear-shaped charge.
The antenna couplers provide the proper impedence for radio frequency and
ground support equipment. The command receivers are tuned to RSS command
frequencies and provide the input signal to the distributors when an RSS
command is sent. The command decoders use a code plug to prevent any command
signal other than the proper command signal from getting into the distributors.
The distributors contain the logic to supply valid destruct commands to the
pyrotechnics.
The NSDs provide the spark to ignite the CDF, which in turn ignites the LSC
for shuttle vehicle destruction. The safe and arm device provides mechanical
isolation between the NSDs and the CDF before launch and during the SRB
separation sequence.
The first message, called arm, allows the onboard logic to enable a destruct
The first message, called arm, allows the onboard logic to enable a destruct
and illuminates a light on the flight deck display and control panel at the
commander and pilot station. The second message transmitted is the fire
command.
The SRB distributors in the SRBs and the ET are cross-strapped together.Thus
if one SRB received an arm or destruct signal, the signal would also be sent
to the other SRB and ET.
CDF = confined detonating fuse
NSD = NASA standard detonator
LSC = linear shaped charge
my text from here..
From the figure on page 52, the antennas are located located on the nose of
each SRB, two located opposite eachother along the Z axis of the vehicle.
Now...here is the million dollar question. Once the light comes on in the
flight deck area, and everyone quits playing cards, what does the crew do
next?
--
Greg Roberts International Information Service (IIS)
UUCP: {uunet,utai,watmath}!dalcs!iisat!roberts
Bitnet/Uucp: roberts@iisat.uucpbill@bert.Rosemount.COM (William M. Hawkins) (10/29/89)
Would someone please describe the NASA Standard Detonator? I did work for Hercules in the early 60s on electroexplosive devices (EEDs). State of the art then was a 1 watt/1 amp no-fire device, and the considerably more expensive exploding wire device. It really is a tricky business to get something to ignite only when you intend it to. Maybe there hasn't been any progress, and that's why they still use mechanical safe/arm equipment. bill@bert.rosemount.com
rick@ofa123.FIDONET.ORG (Rick Ellis) (04/13/90)
RANGE SAFETY SYSTEM
The shuttle vehicle has three RSSs. One is located in each SRB and one
in the external tank. Any one or all three are capable of receiving two
command messages (arm and fire) transmitted from the ground station. The RSS
is used only when the shuttle vehicle violates a launch trajectory red line.
An RSS consists of two antenna couplers, command receivers/decoders,
a dual distributor, a safe and arm device with two NSDs, two confined
detonating fuse manifolds, seven CDF assemblies and one linear-shaped charge.
The antenna couplers provide the proper impedance for radio frequency
and ground support equipment commands. The command receivers are tuned to RSS
command frequencies and provide the input signal to the distributors when an
RSS command is sent. The command decoders use a code plug to prevent any
command signal other than the proper command signal from getting into the
distributors. The distributors contain the logic to supply valid destruct
commands to the RSS pyrotechnics.
The NSDs provide the spark to ignite the CDF, which in turn ignites
the LSC for shuttle vehicle destruction. The safe and arm device provides
mechanical isolation between the NSDs and the CDF before launch and during
the SRB separation sequence.
The first message, called arm, allows the onboard logic to enable a
destruct and illuminates a light on the flight deck display and control panel
at the commander and pilot station. The second message transmitted is the
fire command.
The SRB distributors in the SRBs and the ET are cross-strapped
together. Thus, if one SRB received an arm or destruct signal, the signal
would also be sent to the other SRB and the ET.
Electrical power from the RSS battery in each SRB is routed to RSS
system A. The recovery battery in each SRB is used to power RSS system B as
well as the recovery system in the SRB. The SRB RSS is powered down during
the separation sequence, and the SRB recovery system is powered up.
Electrical power for the ET RSS system A and system B is independently
supplied by two RSS batteries on the ET.
--
Rick Ellis
...!{dhw68k,zardoz,lawnet,conexch}!ofa123!rick rick@ofa123.FIDONET.ORG
714 544-0934 2400/1200/300