LVM3

ISRO initially planned two launcher families, the Polar Satellite Launch Vehicle for low Earth orbit and polar launches and the larger Geosynchronous Satellite Launch Vehicle for payloads to geostationary transfer orbit (GTO). The vehicle was reconceptualized as a more powerful launcher as the ISRO mandate changed. This increase in size allowed the launch of heavier communication and multipurpose satellites, human-rating to launch crewed missions, and future interplanetary exploration. Development of the LVM3 began in the early 2000s, with the first launch planned for 2009–2010. The unsuccessful launch of GSLV D3, due to failure in the cryogenic upper stage, The LVM3, although named "GSLV Mark III" during development, features different systems and components from the GSLV Mark II. To manufacture the LVM3 in public–private partnership (PPP) mode, ISRO and NewSpace India Limited (NSIL) have started working on the project. To investigate possible PPP partnership opportunities for LVM3 production through the Indian private sector, NSIL has hired IIFCL Projects Limited (IPL). On Friday 10 May 2024, NSIL released a request for qualification (RFQ), inviting responses from private partners for the large-scale production of LVM-3. Plans call for a 14-year partnership between ISRO and the chosen commercial entity. The private partner is expected to be able to produce four to six LVM3 rockets annually over the following twelve years, with the first two years serving as the "development phase" for the transfer of technology and know-how. == Vehicle Description ==

Specifications S200 solid boosters The first stage consists of two S200 solid motors, also known as Large Solid Boosters (LSB) attached to the core stage. Each booster is wide, long, and carries of hydroxyl-terminated polybutadiene (HTPB) based propellant in three segments with casings made out of M250 maraging steel. The head-end segment contains 27,100 kg of propellant, the middle segment contains 97,380 kg and the nozzle-end segment is loaded with 82,210 kg of propellants. It is the largest solid-fuel booster after the SLS SRBs, the Space Shuttle SRBs and the Ariane 5 SRBs. The flex nozzles can be vectored up to ±8° by electro-hydraulic actuators with a capacity of using hydro-pneumatic pistons operating in blow-down mode by high pressure oil and nitrogen. They are used for vehicle control during the initial ascent phase. The hydraulic fluid for operating these actuators is stored in an externally mounted cylindrical tank at the base of each booster. These boosters burn for 130 seconds and produce an average thrust of and a peak thrust of each. The simultaneous separation from core stage occurs at T+149 seconds in a normal flight and is initiated using pyrotechnic separation devices and six small solid-fueled jettison motors located in the nose and aft segments of the boosters. The first static fire test of the S200 solid rocket booster, ST-01, was conducted on 24 January 2010. A second static fire test, ST-02, was conducted on 4 September 2011. The booster fired for 140 seconds and again had nominal performance through the test. A third test, ST-03, was conducted on 14 June 2015 to validate the changes from the sub-orbital test flight data. L110 liquid core stage The second stage, designated L110, is a liquid-fueled stage that is tall and wide, and contains of unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide (). It is powered by two Vikas 2 engines, each generating thrust, giving a total thrust of . The L110 is the first clustered liquid-fueled engine designed in India. The Vikas engines uses regenerative cooling, providing improved weight and specific impulse compared to earlier Indian rockets. Each Vikas engine can be individually gimbaled to control vehicle pitch, yaw and roll control. The L110 core stage ignites 114 seconds after liftoff and burns for 203 seconds. ISRO conducted the first static test of the L110 core stage at its Liquid Propulsion Systems Centre (LPSC) test facility at Mahendragiri, Tamil Nadu on 5 March 2010. The test was planned to last 200 seconds, but was terminated at 150 seconds after a leakage in a control system was detected. A second static fire test for the full duration was conducted on 8 September 2010. C25 cryogenic upper stage The cryogenic upper stage, designated C25, is in diameter and long, and contains of propellant LOX and LH2, pressurized by helium stored in submerged bottles. It is powered by a single CE-20 engine, producing of thrust. CE-20 is the first cryogenic engine developed by India which uses a gas generator, as compared to the staged combustion engines used in GSLV. In LVM3-M3 mission, a new white coloured C25 stage was introduced which has more environmental-friendly manufacturing processes, better insulation properties and the use of lightweight materials. The stage also houses the flight computers and Redundant Strap Down Inertial Navigation System of the launch vehicle in its equipment bay. The digital control system of the launcher uses closed-loop guidance throughout the flight to ensure accurate injections of satellites into the target orbit. Communications system of the launch vehicle consists of an S-Band system for telemetry downlink and a C-Band transponder that allows for radar tracking and preliminary orbit determination are also mounted on the C25. The communications link is also used for range safety and flight termination that uses a dedicated system that is located on all stages of the vehicle and features separate avionics. A second static fire test for the full in-flight duration of 640 seconds was completed on 17 February 2017. This test demonstrated consistency in engine performance along with its sub-systems, including the thrust chamber, gas generator, turbopumps and control components for the full duration. After the first flight of the rocket with CARE module, the payload fairing was modified to an ogive shape, and the S200 booster nose cones and inter-tank structure were redesigned to have better aerodynamic performance. The vehicle features a large fairing with a five-meter diameter to provide sufficient space even to large satellites and spacecraft. Separation of fairing in a nominal flight scenario occurs at approximately T+253 seconds and is accomplished by a linear piston cylinder separation and jettisoning mechanism (zip cord) spanning the full length of PLF which is pyrotechnically initiated. The gas pressure generated by the zip cord expands a rubber below that pushes the piston and cylinder apart, pushing the payload fairing halves laterally away from the launcher. The fairing is made of aluminum alloy featuring acoustic absorption blankets. == Variants and upgrades ==

Human-rating certification While the LVM3 is being human rated for Gaganyaan project, the rocket was always designed with potential human spaceflight applications in consideration. The maximum acceleration during ascent phase of flight was limited to 4 Gs for crew comfort and a diameter payload fairing was used to be able to accommodate large modules like space station segments. Furthermore, a number of changes to make safety-critical subsystems reliable are planned for lower operating margins, redundancy, stringent qualification requirements, revaluation, and strengthening of components. Avionics improvement will incorporate a Quad-redundant Navigation and Guidance Computer (NGC), Dual chain Telemetry & Telecommand Processor (TTCP) and an Integrated Health Monitoring System (LVHM). The launch vehicle will have the High Thrust Vikas engines (HTVE) of L110 core stage operating at a chamber pressure of 58.5 bar instead of 62 bar. Human rated S200 (HS200) boosters will operate at chamber pressure of 55.5 bar instead of 58.8 bar and its segment joints will have three O-rings each. Electro mechanical actuators and digital stage controllers will be employed in HS200, L110 and C25 stages. Mating with semi-cryogenic stage The L110 core stage in the LVM3 is planned to be replaced by the SC120, a kerolox stage powered by the SE-2000 engine to increase its payload capacity to to geostationary transfer orbit (GTO). The SCE-200 uses kerosene instead of unsymmetrical dimethylhydrazine (UDMH) as fuel and has a thrust of around 200 tonnes. Four such engines can be clustered in a rocket without strap-on boosters to deliver up to to GTO. The first propellant tank for the SC120 was delivered in October 2021 by HAL. The SC120 powered version of LVM3 will not be used for the crewed mission of the Gaganyaan spacecraft. In September 2019, in an interview by AstrotalkUK, S. Somanath, director of Vikram Sarabhai Space Centre claimed that the SE-2000 engine was ready to begin testing. As per an agreement between India and Ukraine signed in 2005, Ukraine was expected to test components of the SE-2000 engine, so an upgraded version of the LVM3 was not expected before 2022. The SE-2000 engine is reported to be based on the Ukrainian RD-810, which is itself proposed for use on the Mayak family of launch vehicles. In 2025, Russia has also offered to integrate the RD-191M engine on future variants of the LVM3. Induction of upgraded cryogenic stage The C25 stage with nearly propellant load will be replaced by the C32, with a higher propellant load of . The C32 stage will be re-startable and with uprated CE-20 engine. Total mass of avionics will be brought down by using miniaturised components. On 30 November 2020, Hindustan Aeronautics Limited delivered an aluminium alloy-based cryogenic tank to ISRO. The tank has a capacity of of fuel, and a volume of . On 9 November 2022, CE-20 cryogenic engine of upper stage was tested with an uprated thrust regime of 21.8 tonnes in November 2022. Along a suitable stage with additional propellant loading this could increase payload capacity of LVM3 to GTO by up to . On 23 December 2022, CE-20 engine E9 was hot tested for a duration of 650 seconds. For the first 40 seconds of the test, the engine was operated at 20.2 tonne thrust level, after this engine was operated at 20 tonne off-nominal zones and then for 435 seconds it was operated at 22.2 tonne thrust level. With this test, the 'E9' engine has been qualified for induction in flight. It is hoped that after introduction of this stage, GTO payload capacity can be raised to 6 tonnes. On 10 March 2026, ISRO tested a sea level hot test of the CE-20 engine at 22 tonnes using nozzle protection system and multi-element igniter. Test was successful and lasted 165 seconds. Previous tests were conducted at 19 tonnes. This engine in particular has undergone record number of hot tests (20) successfully. It has also demonstrated several key technologies at 20 & 22 tonne thrust, including the Gaganyaan mission. == Launch statistics ==