ISRO GSLV MK III
(By Pandiya Rajan)
On June 5, 2017, Geosynchronous Satellite Launch Vehicle MK-III lifted GSAT-19 satellite onboard weighing 3,136 kg to the targeted Geosynchronous Transfer Orbit of 170km by 36,000 km(radius of earth should be included to get the periapse and apoapse of the orbit respectively). Everything going according to plan, exactly as the countdown timer struck zero mark, the two solid fuel filled strapon motors (S200) got ignited simultaneously and the vehicle lifted off. ISRO states in its website, "to reduce the disturbance moment due to differential thrust between two motors in flight, both of them were processed as a pair during the motor segments castings."
The gargauntan vehicle lifted off exactly as per flight plan and all the three stages worked exactly as per the expected performance.
At 112.66 seconds after the ignition of solid stage, the liquid motors(L110) got ignited. Both the stages burned simultaneously to give extra boost to the vehicle. Solid strapon motors separated from the vehicle at 140.84 seconds after lift off. The liquid stage burned satisfactorily and separated from the vehicle after 206 seconds of its ignition. The last cryo stage took over the lifting off operation. In ISRO's parlance, the last stage was called C-25. In ISRO's own words, the specialty of cryogenic upper stage C25 is that it is a high performance cryo stage carrying a propellant combination of liquid Hydrogen stored at 20K and liquid Oxygen stored at 77K.
Whole mission of placing GSAT-19 in a GTO at an altitude of 170km above earth surface was clinical in its precision. This maiden developmental flight mission was a success which cleared the decks for the second mission GSLV MK-III D2. This success is evidently another golden feather in ISRO's already crowded cap.