Editing Geosynchronous Satellite Launch Vehicle (section)

== Vehicle description ==
The {{cvt|49|m}} tall GSLV, with a lift-off mass of {{cvt|415|MT}}, is a three-stage vehicle with solid, liquid and cryogenic stages respectively. The payload fairing, which is {{cvt|7.8|m}} long and {{cvt|3.4|m}} in diameter, protects the vehicle electronics and the spacecraft during its ascent through the atmosphere. It is discarded when the vehicle reaches an altitude of about {{cvt|115|km}}.<ref name=isroGSLVF04>{{cite web|title=GSLV-F04|url=http://www.isro.gov.in/gslv-d5/d5-updates.aspx|publisher=ISRO|access-date=15 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20140104204430/http://isro.gov.in/gslv-d5/d5-updates.aspx|archive-date=4 January 2014}}</ref>{{Needs update|date=August 2021|reason=Needs to include 4m PLF variants flown on F06 and F10 flights}}

GSLV employs [[S band|S-band]] telemetry and [[C band (IEEE)|C-band]] transponders for enabling vehicle performance monitoring, tracking, range safety / flight safety and preliminary orbit determination. The Redundant Strap Down Inertial Navigation System/Inertial Guidance System of GSLV housed in its equipment bay guides the vehicle from lift-off to spacecraft injection. The digital auto-pilot and closed loop guidance scheme ensure the required altitude maneuver and guide injection of the spacecraft to the specified orbit.

The GSLV can place approximately {{cvt|5000|kg}} into an easterly [[low Earth orbit]] (LEO) or {{cvt|2500|kg}} (for the Mk II version) into an 18° [[geostationary transfer orbit]].

[[File:Strap-on motors of GSLV-F05 being integrated with the core stage.jpg|thumb|upright=1.0|left|Strap-on motors of GSLV-F05 being integrated with the core stage]]

=== Liquid boosters ===
The first GSLV flight, GSLV-D1 used the L40 stage. Subsequent flights of the GSLV used high pressure engines in the strap-on boosters called the L40H.<ref name=isroGSLVD2>{{cite web|title=GSLV-D2
|url=http://isro.gov.in/gslv-d2/gslv-d2.aspx|publisher=ISRO|access-date=15 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20130809215736/http://isro.gov.in/gslv-d2/gslv-d2.aspx|archive-date=9 August 2013}}</ref> The GSLV uses four L40H [[Liquid rocket booster|liquid strap-on boosters]] derived from the L37.5 second stage, which are loaded with 42.6 tons of [[hypergolic]] propellants ([[Unsymmetrical dimethylhydrazine|UDMH]] and [[Dinitrogen tetroxide|N<sub>2</sub>O<sub>4</sub>]]). The propellants are stored in tandem in two independent tanks {{cvt|2.1|m}} diameter. The engine is [[Pump-fed engine|pump-fed]] and generates {{cvt|760|kN}} of thrust, with a burn time of 150 seconds.

=== First stage ===
GSLV-D1 used the S125 stage which contained {{cvt|125|MT}} of solid propellant and had a burn time of 100 seconds. All subsequent launches have used enhanced propellant loaded S139 stage.<ref name=isroGSLVD2/> The S139 stage is 2.8 m in diameter and has a nominal burn time of 100 seconds.<ref name=GSLVD3>{{cite web|url=https://www.isro.gov.in/launchers/gslv|title=GSLV Launcher|publisher=ISRO|access-date=17 March 2021|archive-date=23 March 2019|archive-url=https://web.archive.org/web/20190323171054/https://www.isro.gov.in/launchers/gslv|url-status=dead}}</ref><ref>{{cite web|url=http://www.currentscience.ac.in/Downloads/article_id_093_12_1697_1714_0.pdf|title=Evolution of Indian launch vehicle technologies|publisher=Current Science|access-date=January 27, 2014}}</ref>

[[File:GSLV-F14, INSAT-3DS - Second stage GS2 being placed over first stage GS1.webp|thumb|upright=1.0|left|Hoisting of the GSLV-F14 second stage during vehicle integration]]

=== Second stage ===
The GS2 stage is powered by the [[Vikas (rocket engine)|Vikas engine]]. It has a diameter of {{cvt|2.8|m}}.<ref name=GSLVD3/>

=== Third stage ===
The third stage of the GSLV Mark II is propelled by the Indian [[CE-7.5]] [[cryogenic rocket engine]] while the older defunct Mark I is propelled using a Russian made [[KVD-1]]. It uses liquid hydrogen (LH<sub>2</sub>) and liquid oxygen (LOX)<ref>{{cite web|url=http://www.isro.gov.in/gslv-d5/gslv-d5.aspx|title=GSLV-D5|access-date=4 January 2014|url-status=dead|archive-url=https://web.archive.org/web/20141006082545/http://www.isro.gov.in/gslv-d5/gslv-d5.aspx|archive-date=6 October 2014}}</ref> The Indian cryogenic engine was built at the [[Liquid Propulsion Systems Centre]].<ref>{{cite web|url=http://www.spacenews.com/launch/100415isro-cryogenic-engine-fails.html|archive-url=https://archive.today/20120526091518/http://www.spacenews.com/launch/100415isro-cryogenic-engine-fails.html |url-status=dead|archive-date=May 26, 2012|title=ISRO's Cryogenic Stage Fails in Maiden Flight|publisher=SpaceNews|access-date=November 27, 2013}}</ref><ref name=hindu-gslvd3>{{cite news
|url=http://www.hindu.com/2010/01/01/stories/2010010152721100.htm|archive-url=https://web.archive.org/web/20100105175717/http://www.hindu.com/2010/01/01/stories/2010010152721100.htm|url-status=dead|archive-date=5 January 2010|location=Chennai, India|newspaper=The Hindu|title=GSLV, PSLV flights put off|date=1 January 2010}}</ref> The engine has a default thrust of {{cvt|75|kN}} but is capable of a maximum thrust of {{cvt|93.1|kN}}. In GSLV-F14 mission, a new white coloured C15 stage was introduced which has more environmental-friendly manufacturing processes, better insulation properties and the use of lightweight materials.<ref>{{Cite web |title=GSLV-F14/INSAT-3DS Gallery |url=https://www.isro.gov.in/GSLV_F14_INSAT_3DS_gallery.html |access-date=2024-02-08 |website=www.isro.gov.in}}</ref>
[[File:Payload Fairing with GSAT-6A being Integrated.jpg|thumb|upright=1.0|left|Payload fairing with [[GSAT-6A]] being integrated]]