In yet another remarkable achievement, the Indian Space Research Organisation (ISRO) successfully conducted a hot test on a liquid rocket engine fabricated using Additive Manufacturing (AM) technology. This feat was accomplished on Friday.

The engine in question is the PS4 engine utilized in the upper stage of the Polar Satellite Launch Vehicle (PSLV). Traditionally, the PS4 engine has been crafted through conventional machining and welding methods. It serves as the fourth stage of the PSLV and boasts a thrust of 7.33 kilonewtons in vacuum conditions. Additionally, the same engine finds application in the Reaction Control System (RCS) of the first stage (PS1) of the PSLV.

According to information provided by ISRO, the engine employs earth-storable bipropellant combinations consisting of Nitrogen Tetroxide as the oxidizer and Mono Methyl Hydrazine as the fuel in pressure-fed mode. This engine was developed by the Liquid Propulsion Systems Centre (LPSC) of ISRO.

LPSC undertook a redesign of the engine, making it compatible with the Design for Additive Manufacturing (DfAM) concept, resulting in significant advantages. The utilization of the Laser Powder Bed Fusion technique led to a reduction in the number of parts from 14 to a single piece, thereby eliminating 19 weld joints. This not only saved substantially on raw material usage per engine but also reduced the overall production time by 60%, as confirmed by ISRO.

The manufacturing of this engine was carried out by the Indian industry player, M/s WIPRO 3D. Subsequently, the engine underwent hot testing at the ISRO Propulsion Complex in Mahendragiri.

As part of the development program, the injector head of the engine was conceptualized and subjected to successful hot testing in earlier stages. Detailed flow and thermal modeling, structural simulation, and cold flow characterization of the prototype hardware were conducted to instill confidence for the hot test.

Following this, four successful developmental hot tests of the integrated engine were conducted, accumulating a duration of 74 seconds, thereby validating the engine’s performance parameters. Furthermore, the engine underwent a successful test for the full qualification duration of 665 seconds, during which all performance parameters were observed to be as anticipated. ISRO has planned to incorporate this AM PS4 engine into its regular PSLV program.