LPSC happy with performance of Test Vehicle-D1 mission’s propulsion system

Centre Director says the system gave a perfect performance as expected during the entire duration of mission

As the Indian Space Research Organisation (ISRO) celebrates Saturday’s successful Test Vehicle-D1 (TV-D1) mission, the Liquid Propulsion Systems Centre (LPSC) at Valiamala here is happy with the way the propulsion system it designed for the mission has performed.

The propulsion system on TV-D1 gave a “perfect performance as expected” during the entire duration of the mission, senior ISRO scientist and LPSC Director V. Narayanan, back in Thiruvananthapuram from Sriharikota, told The Hindu on Sunday. The ‘technical glitch’ that delayed the launch on Saturday had been quickly tracked to a “small error” in monitoring the health parameters of the mission, he said.

One of the several test missions planned ahead of the Gaganyaan human spaceflight mission, this mission successfully demonstrated in-flight abort capability and recovery of the crew escape system (CES). The ISRO will now use this single-stage test vehicle to demonstrate CES capabilities at varying altitudes and Mach speeds, Dr. Narayanan said. In the TV-D1 mission, the CES separated from the vehicle at an altitude of 11.8 km on achieving Mach 1.2 speed.

19.7 tonnes of propellant

For the test vehicle, the LPSC developed a liquid propulsion stage based on the L-40 stage of the Geosynchronous Satellite Launch Vehicle (GSLV). The vehicle was powered by a “truncated” version of the Vikas engine. It used a propellant combination of UH25 and nitrogen tetroxide (N2O4). “We had tested the modified Vikas engine at (ISRO Propulsion Complex) Mahendragiri. For the TV-D1 mission, we loaded 19.7 tonnes of propellant,” Dr. Narayanan said.

The Saturday morning launch, initially scheduled for 8 a.m., had sent ISRO into a tizzy after it was abruptly halted seconds before lift-off. Within minutes, the glitch was identified as an error in monitoring the parameters, Dr. Narayanan said. The space agency went ahead after correcting the anomaly. The launch resumed at 10 a.m.

“The engine was functioning normally. If the problem was with the propulsion system, it would have taken several days to return to the launchpad,” he said.

Along with other ISRO units, the LPSC played a major role in the TV-D1 mission, contributing highly complex components. For the actual Gaganyaan mission, the LPSC will be responsible for critical systems, including human-rated cryogenic and earth-storable liquid propellant rocket stages, and crew and service module propulsion systems.

Liquid engine for lift-off

For rocket buffs, Saturday’s TV-D1 mission is interesting from another angle. It was the first time an ISRO launch vehicle fired a liquid engine alone first for lift-off. For instance, in the LVM3 (formerly GSLV Mk-III), the solid boosters fire first at lift-off followed by the liquid engines, whereas in the PSLV, the first stage and strapons are entirely solid propellant-fuelled ones. In the GSLV, on the other hand, the liquid and solid motors both power the lift-off.