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MUMBAI:
ISRO has achieved a significant milestone through the successful
test of indigenously developed Cryogenic Stage, to be employed as
the upper stage of India's Geosynchronous Satellite Launch Vehicle
(GSLV). The test was conducted for its full flight duration of 720
seconds today (15 November, 2007) at Liquid Propulsion test facility
at Mahendragiri, in Tamil Nadu. With this test, the indigenous Cryogenic
Upper Stage has been fully qualified on the ground. The flight stage
is getting ready for use in the next mission of GSLV (GSLV-D3) in
2008.
It
may be recalled that a ground test for 480 seconds of the complete
stage was conducted on 4 August, 2007.
The indigenous Cryogenic Upper Stage (CUS) is powered by a regeneratively
cooled cryogenic engine, which works on staged combustion cycle
developing a thrust of 69.5 kN in vacuum. The other stage systems
include insulated propellant tanks, booster pumps, inter-stage structures,
fill and drain systems, pressurisation systems, gas bottles, command
block, igniters, pyro valves and cold gas orientation and stabilisation
system. Liquid Oxygen (LOX) and Liquid Hydrogen (LH2) from the respective
tanks are fed by individual booster pumps to the main turbo-pump,
which rotates at 39,000 rpm to ensure a high flow rate of 16.5 kg/sec
of propellants into the combustion chamber. The main turbine is
driven by the hot gas produced in a pre-burner. Thrust control and
mixture ratio control are achieved by two independent regulators.
LOX and Gaseous Hydrogen (GH2) are ignited by pyrogen type igniters
in the pre-burner as well as in the main and steering engines.
Apart
from the complexities in the fabrication of stage tanks, structures,
engine and its sub-systems and control components, CUS employs special
materials like Aluminum, Titanium, Nickel and their alloys, bi-metallic
materials and polyimides. Stringent quality control and elaborate
safety measures have to be ensured during assembly and integration.
Liquid
Propulsion Systems Centre (LPSC) is the lead centre for the development
of Cryogenic Upper Stage with the involvement of Vikram Sarabhai
Space Centre (VSSC) and other ISRO centres as well as several industries,
both in public and private sector.
The
successful ground test of the indigenous Cryogenic Upper Stage for
the full flight duration has validated the design robustness and
performance adequacy for its use in GSLV.
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