Solid Rocket Boosters provide the main thrust to lift the rockets off the pad.

1. GOKUL LAKSHMANAN
M.TEC H TH ER MA L A N D FLU ID EN GIN EER IN G
NASA’S SPACE LAUNCH SYSTEM:
AHEAVY-LIFT PLATFORM FOR ENTIRELY NEW
MISSIONS

2. Contents
 Solid Rocket Booster (SRB)
 SRB testing
 Components
 Operation sequence
 Range safety system

3. Solid Rocket Booster (SRB)
 2 Solid fuel rocket boosters
used for primary
propulsion
 Provided the majority of
the thrust during the first
two minutes of flight.
 Thrust :16000 kN
 Burn time 124 seconds
 Fuel : Poly-butadiene
acrylonitrile, Ammonium
perchlorate composite
propellant

4.  Burns up to an altitude of about 45 km
 Non - reusable
 Material : Aluminum / Steel and composite materials
 Operation : Igniting, Steering and Jettison of the
boosters

6. SRB Testing

7. Components
1. Hold-down posts
 Each solid rocket booster has four hold-down posts
 Hold-down bolts hold the SRB and launcher
platform together
 Hold down nuts contains NASA Standard
Detonators(NSD) which were ignited at SRB ignition
commands
 NSD ignite and splits the nut into two or more parts
 Hold-down bolt travels downward
 Bolt were stopped by the stud deceleration stand
which contains sand
 The SRB bolt is 710 mm long and 89 mm in diameter

9. 2. Electrical power distribution
 DC power is distributed to each SRB via SRB buses
labeled A, B and C
 SLS main DC buses A, B and C supplies power to
corresponding SRB buses A, B and C.
 In addition, SLS main DC bus C supplied backup power
to SRB buses A and B, and SLS bus B supplied backup
power to SRB bus C.
 This electrical power distribution arrangement allowed
all SRB buses to remain powered in the event one SLS
main bus failed
 The nominal operating voltage was 28±4 volts DC.

11. 3. Hydraulic power units
 Two self-contained, independent Hydraulic Power
Units (HPUs) on each SRB
 HPU consisted of an auxiliary power unit, hydraulic
pump, hydraulic reservoir and hydraulic fluid
manifold
 The APUs were fueled by hydrazine
 Generates mechanical shaft power to drive a
hydraulic pump that produced hydraulic pressure for
the SRB hydraulic system.

12.  Hydrazine is feed into a gas generator. The gas
generator decompose the hydrazine into hot, high-
pressure gas
 A turbine converted this into mechanical power,
driving a gearbox.
 The gearbox drive the fuel pump, its own lubrication
pump, and the HPU hydraulic pump.
 The waste gas from gas generator now cooler and at
low pressure, was passed back over the gas generator
housing to cool it before being dumped overboard.

13.  Each HPU is connected to servo actuators
 The hydraulic pump speed was 3600 rpm and
supplied hydraulic pressure of 21.03 ± 0.34 Mpa
 Hydraulic pressure is used to drive Thrust vector
controller
 The hydraulic system is operated from T minus 28
seconds until SRB separation from the SLS

15. 4. Thrust vector control
 Each SRB had two hydraulic servo actuators, to
move the nozzle up/down and side-to-side.
 This provided thrust vectoring to help control the
vehicle in all three axes (roll, pitch, and yaw).
 Each SRB servo actuator consist of four independent,
servo valves that receive signals from the drivers.
 Each servo valve control one actuator ram and thus
nozzle to control the direction of thrust.

17. 5. Propellant
Component Description % by weight
Ammonium
Perchlorate
oxidizer 69.6% by weight
Aluminum fuel 16%
Iron oxide a catalyst 0.4%
Poly butadiene
acrylonitrile
Serves as a binder that hold the
mixture together and acted as
secondary fuel
12.04%

18. OPERATION SEQUENCE
1. Ignition
 Ignition can occur only when a manual lock pin from
each SRB has been removed.
 The ground crew removes the pin during prelaunch
activities at T minus five minutes
 The solid rocket booster ignition commands are
issued when four cryogenic engines are at or above
90% rated thrust
 The solid rocket ignition commands were sent by the
on-board computers

19.  The fire commands
cause the NSDs on the
SRB to fire.
 This ignites a pyro
booster charge.
 The booster charge
ignites the propellant in
the SRB which fires down
the entire vertical length

20.  This ignites the solid
rocket propellant along
its entire surface area
instantaneously.
 At t minus zero, the two
SRBs are ignited, under
command of the four
onboard computers

21.  Separation of the four
explosive bolts on each SRB
is initiated
 The two umbilical cords are
retracted
 The onboard master timing
unit and event timer are
started
 The four cryogenic engines
are at 100% and the ground
launch sequence is
terminated and liftoff occurs

22. 2. Separation
 The SRBs are jettisoned from SLS at altitude, about
45 km.
 SRB separation is initiated when chamber pressure
of both SRBs is less than or equal to 340 kPa.
 The SRBs separate from the SLS within 30
milliseconds of the firing command.

23.  The forward attachment point consists a nut-bolt
system. It contains one NSD pressure cartridge.
 The aft attachment points consist of three separate
struts: upper, diagonal and lower. Each strut
contains one bolt with an NSD pressure cartridge at
each end.
 Detonating the NSD via electrical system separates
the SRB’s

24. 3. Descent and Recovery
 The SRBs are jettisoned
from the SLS at 2 minutes
and an altitude of about 45
km.
 After continuing to rise to
about 67 km the SRBs begin
to fall back to earth
 Once back in the
atmosphere are slowed by a
parachute system to prevent
damage on ocean impact

25.  Nose cap separation occurs at a nominal altitude of
5km, about 218 seconds after SRB separation.
 This triggers the parachute to open and SRB falls to
ocean
 A command is sent from the SNS to the SRB just
before separation to apply battery power to the
recovery logic network
 SRB is recovered by US Navy

26. SRB Flash Down into Ocean

27. Range safety system
 A range safety system provides destruction of rocket or
its parts with on-board explosives by remote command if
the rocket is out of control
 This limits the danger to people on the ground from
crashing pieces, explosions, fire, poisonous substances,
etc.
 Two RSSs one in each SRB.
 Capable of receiving command messages transmitted
from the ground station.
 The RSS was used only when the shuttle vehicle violates
launch trajectory

28.  Two confined detonating fuse manifolds (CDF)
 The NSDs provide the spark to ignite the CDF which
results in booster destruction.
 The safe and arm device provides mechanical
isolation between the NSDs and the CDF before
launch and during the SRB separation sequence.