Welcome To ISRO :: GSLV

The Geo-synchronous Satellite Launch Vehicle (GSLV) is designed to place satellites in Geo-Synchronous Transfer Orbit (GTO). It adopts the flight-proven solid and liquid stages of ISRO’s Polar Satellite Launch Vehicle (PSLV) and a cryogenic upper stage. The first development flight, GSLV-D1, carries experimental communication satellite, GSAT-1.

GSLV is a three stage vehicle, 49m tall. The first stage, GS1, comprises a solid propellant motor (S125) and four liquid propellant strap-on stages(L40). The second stage (GS2) is powered by a single liquid propellant engine (L37.5). The third stage (GS3) is a cryogenic stage (C12) with re-startable engines.

Parameter	GS1 Stage (First Stage)		GS2 stage (Second stage)	GS3 stage (Third stage)
Parameter	S125 booster	L40 strapon</td>	GS2 stage (Second stage)	GS3 stage (Third stage)
Length (m)	20.3	19.7	11.6	8.7
Dia (m)	2.8	2.1	2.8	2.8
Total mass (t)	156	46	42.8	15
Propellant mass (t)	129	40	38	12.5
Case/Tank material	M250 steel	Aluminium Alloy	Aluminium Alloy	Aluminium Alloy
Propellant	HTPB	UDMH & N₂O₄	UDMH & N₂O₄	LH2 & LOX
Burn time (s)	100	160	150	720
Max. Vac. Thrust (kN)	4700	680	720	73.5
Specific impulse (Ns/kg)	2610	2750	2890	4510
Control system	Multi-port SITVC	EGC single plane gimballing	EGC two plane gimballing for pitch & yaw control. Hot gas RCS for roll control.	2 steering engines for thrust phase control & cold gas RCS for coast phase control.