After the second successful launch of the GSLV Mk II satellite launch vehicle on August 27, using the indigenous C12 Cryogenic Upper Stage, Indian Space Research Organisation (ISRO) is planning to increase the thrust of the cryogenic stage to orbit higher weight satellites.
Scientists are confident that the present capability to loft 2.2 tonne satellite to GTO, could be increased to 2.5 tonne, with minor tweaks.
With the improved launch capability, ISRO hopes to tap the medium weight commercial satellite launch category, which have demand from foreign countries.
The thrust will be increased by optimizing the mass and increasing the thrust of the C12 CUS, after which a series of tests will be carried out to validate the enhancement.
The C12 CUS has a propellant loading of 12.5 tonne and provides a 7.5 tonne thrust for 720 seconds.
Further measures include tweaking the four liquid strap on boosters on the first stage and second stage Vikas liquid engine, along with reducing the mass of the avionics bay.
ISRO is also developing the GSLV Mk III launch vehicle, which will be capable of lofting satellites weighting up to 4000 kg into Geosynchronous Transfer Orbit (36000 km). The first development flight of the Mk III was carried out in 2014, without the C25 Cryogenic stage.
The C25 Cryogenic engine was successfully bench tested in July for 25 per cent more than its in flight burn duration.
On Aug 27, the 416 tonne, 49 m tall GSLV-D6 successfully orbited the 2117 kg GSAT-6 military communication satellite in to a 35,939 km GTO, after 17 minutes from lift off.
Cryogenic engines are essential to orbit heavier satellites to GTO, as they are more efficient and provide more thrust than rocket engines using earth storable propellants.
In a cryogenic engine, the oxygen is the oxidizer and is stored as liquid at –183 deg C and Hydrogen as the fuel at –253 deg C to achieve high mass flow rate to generate sufficient thrust.