NASAS SPACE LAUNCH SYSTEM: A HEAVY-LIFT PLATFORM FOR ENTIRELY NEW MISSIONS

GOKUL LAKSHMANANM.TECH THERMAL AND FLUID ENGINEERING

NASAS SPACE LAUNCH SYSTEM:A HEAVY-LIFT PLATFORM FOR ENTIRELY NEW MISSIONS

ContentsSolid Rocket Booster (SRB)SRB testingComponentsOperation sequenceRange safety system

Solid Rocket Booster (SRB) 2 Solid fuel rocket boosters used for primary propulsionProvided the majority of the thrust during the first two minutes of flight.Thrust :16000 kNBurn time 124 secondsFuel : Poly-butadiene acrylonitrile,Ammonium perchlorate composite propellant

Burns up to an altitude of about 45kmNon - reusableMaterial : Aluminum / Steel and composite materialsOperation : Igniting, Steering and Jettison of the boosters

SRB Testing

ComponentsHold-down postsEach solid rocket booster has four hold-down postsHold-down bolts hold the SRB and launcher platform togetherHold down nuts contains NASA Standard Detonators(NSD) which were ignited at SRB ignition commandsNSD ignite and splits the nut into two or more partsHold-down bolt travels downwardBolt were stopped by the stud deceleration stand which contains sandThe SRB bolt is 710mm long and 89mm in diameter

Electrical power distribution DC power is distributed to each SRB via SRB buses labeled A, B and CSLS 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 failedThe nominal operating voltage was 284 volts DC.

Hydraulic power unitsTwo self-contained, independent Hydraulic Power Units (HPUs) on each SRBHPU consisted of an auxiliary power unit, hydraulic pump, hydraulic reservoir and hydraulic fluid manifoldThe APUs were fueled by hydrazine Generates mechanical shaft power to drive a hydraulic pump that produced hydraulic pressure for the SRB hydraulic system.

Hydrazine is feed into a gas generator. The gas generator decompose the hydrazine into hot, high-pressure gasA 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.

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

Thrust vector controlEach 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.

Propellant ComponentDescription% by weightAmmonium Perchlorateoxidizer69.6% by weight

Aluminumfuel16%Iron oxide a catalyst0.4%Poly butadiene acrylonitrileServes as a binder that hold the mixture together and acted as secondary fuel12.04%

OPERATION SEQUENCE IgnitionIgnition 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 minutesThe solid rocket booster ignition commands are issued when four cryogenic engines are at or above 90% rated thrustThe solid rocket ignition commands were sent by the on-board computers

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

Typical pyrotechnic formulations consist either of flammable materials such as nitrocellulose and/or black powder 19

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

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

SeparationThe 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.

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 SRBs

Descent and RecoveryThe 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

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 oceanA command is sent from the SNS to the SRB just before separation to apply battery power to the recovery logic networkSRB is recovered by US Navy

SRB Flash Down into Ocean

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

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.

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