PSLV-C11: The Launcher
 
PSOM-XLs surrounding
the first stage
 
Nozzle End segment
of the first stage
 

PSLV-C11, chosen to launch Chandrayaan-1 spacecraft, is an uprated version of ISRO's Polar Satellite Launch Vehicle standard configuration. Weighing 316 tonnes at lift-off, the vehicle uses larger strap-on motors (PSOM-XL) to achieve higher payload capability.

PSLV is the trusted workhorse launch Vehicle of ISRO. During 1993-2008 period, PSLV had twelve consecutively successful launches carrying satellites to Sun Synchronous, Low Earth and Geosynchronous Transfer Orbits. Now, its fourteenth flight is being used for launching Chandrayaan-1 to moon.

PSLV has repeatedly proved its reliability and versatility by launching 29 satellites into a variety of orbits. Of these, ten remote sensing satellites of India, an Indian satellite for amateur radio communications, a recoverable Space Capsule (SRE-1) and fourteen satellites from abroad were put into polar Sun Synchronous Orbits (SSO) of 550-820 km heights. Besides, PSLV has launched two satellites from abroad into Low Earth Orbits of low or medium inclinations. This apart, PSLV has launched KALPANA-1, a weather satellite of India, into Geosynchronous Transfer Orbit (GTO).

 
 
 
 
Second Stage
with its Vikas engine
  
Hoisting the
third & fourth stages
PSLV C11 stages at a glance
 
STAGE-1
STAGE-2
STAGE-3
STAGE-4
Nomenclature
Core (PSI)
+
Six Strap-ons
(PSOM-XL)
PS2
PS3
PS4
 Propellant
Solid
HTPB Based
Liquid
UH25+N2O4
Solid
HTPB based
Bi-prop
MMH +
MON-3
 Mass (Tonne)
138.0+6x12
41.5
7.6
2.5
 Max Thrust
4910.0
6x720
800
246
7.31X2
 Burn Time
 (sec)
98
49
147
107.6
525
 Stage Dia (m)
2.8
1.0
2.8
2.0
2.8
 Stage Length
 (m)

20.2
12.4
11.9
3.6
2.9
 Control

SITVC for Pitch
& Yaw,
Reaction Control
Thrusters for Roll,
SITVC in two PSOMs
for Roll Control

Engine Gimball for
Pitch & Yaw,
Hot Gas Reaction Control Motor for
Roll Control
Flex Nozzle for Pitch & Yaw, PS4
RCS for Roll
Engine Gimbal
for pitch, Yawand Roll,
on-off RCS
for Coast
Phase Control

PSLV was initially designed by ISRO to place 1,000 kg class Indian Remote Sensing (IRS) satellites into 900 km polar SunSynchronous Orbits. Since the first successful flight in October 1994, the capability of PSLV was successively enhanced from 850 kg to 1,600 kg. In its ninth flight on May 5, 2005 from the Second Launch Pad (SLP), PSLV launched ISRO's remote sensing satellite,1,560 kg CARTOSAT-1 and the 42 kg Amateur Radio satellite, HAMSAT, into a 620 km polar Sun Synchronous Orbit. The improvement in the capability over successive flights has been achieved through several means. They include increased propellant loading in the stage motors, employing composite material for the satellite mounting structure and changing the sequence of firing of the strap-on motors.

PSLV-C11 is 44.4 metre tall and has four stages using solid and liquid propulsion systems alternately. The first stage, carrying 138 tonne of propellant, is one of the largest solid propellant boosters in the world. Six solid propellant strap-on motors (PSOM-XL), each carrying twelve tonne of solid propellant, are strapped on to the first stage. The second stage carries 41.5 tonne of liquid propellant. The third stage uses 7.6 tonne of solid propellant and the fourth has a twin engine configuration with 2.5 tonne of liquid propellant.

The 3.2 metre diameter metallic bulbous payload fairing protects the satellites and it is discarded after the vehicle has cleared dense atmosphere. PSLV employs a large number of auxiliary systems for stage separation, payload fairing separation and so on. It has sophisticated systems to control the vehicle and guide it through the predetermined trajectory. The vehicle performance is monitored through telemetry and tracking. The main modification in PSLV-C11 compared to its standard configuration is the use of larger strap-on motors (PSOM-XL) containing more propellants.

Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, designed and developed PSLV-C11. ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram developed the inertial systems for the vehicle. Liquid Propulsion Systems Centre (LPSC), also at Thiruvananthapuram, developed the liquid propulsion stages for the second and fourth stages of PSLV-C11 as well as reaction control systems. SDSC SHAR processed the solid motors and carries out launch operations. ISRO Telemetry, Tracking and Command Network (ISTRAC) provides telemetry, tracking and command support during PSLV-C11's flight.
 
PSLV-C11vehicle assembled upto
fourth stage at
Vehicle Assembly Building
 
Chandrayaan-1
in PSLV-C11envelope
 
PSLV-C11 Flight Profile
 
 
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