Chennai: The Indian Space Agency has achieved yet another
milestone, when it successfully conducted Low Altitude Escape Motor (LEM)
Static Test of Crew Escape System for its first manned Gaganyaan mission.
ISRO sources today said another important milestone in the Gaganyaan
project is completed, by successfully test-firing the LEM of Crew Escape
System (CES), from Sriharikota yesterday.
The CES takes away the Crew module of the Gaganyaan mission in case of
any eventuality and rescues the astronauts.
In case of mission-abort during the initial phase of flight, LEM provides the
required thrust to CES, to take away Crew Module from the launch vehicle.
LEM is a distinctive special purpose solid rocket motor with four reverse
flow nozzles and generates a maximum sea level thrust of 842 kN (nominal)
with a burn time of 5.98 s (nominal).
“The nozzle end of LEM is mounted at the fore end of the launch vehicle
unlike at aft end in conventional rocket motors to avoid exhaust plume
impingement on crew module. This necessitates the use of reverse
flow multiple nozzles in this solid rocket motor. The reverse flow nozzle
implies the reversal of the exhaust gas flow direction in the nozzle
region”, ISRO said.
The main objectives of the static test were to evaluate motor ballistic
parameters, validate motor subsystem performance and confirm
the design margins, evaluate the thermal performance of nozzle liners
especially to confirm the erosion/ablative characteristics, validate
the integrity of all interfaces, besides evaluation of the head-end, mounted
safe arm (HMSA) based ignition system performance and the side
thrust due to misalignment and variation in flow and other functional
parameters including flow reversal.
