The ISRO has successfully conducted a long-duration test of its PS4 engine, re-designed for production using cutting-edge additive manufacturing (3D printing) techniques and crafted in Indian industry. The new engine, now a single piece, saves 97 per cent of raw materials and reduces production time by 60 per cent. 

The space agency achieved the major milestone with the successful hot testing of a liquid rocket engine manufactured through additive manufacturing technology for a duration of 665 seconds on May 9. The engine used is the PS4 engine of PSLV (Polar Satellite Launch Vehicle) upper stage. 

The PS4 engine manufactured in the conventional machining and welding route has been in use for the fourth stage of PSLV which has a thrust of 7.33 kN in vacuum condition. The same engine is also used in the Reaction Control System (RCS) of the first stage (PS1) of PSLV. 

The engine uses the earth-storable bipropellant combinations of Nitrogen Tetroxide as oxidiser and Mono Methyl Hydrazine as fuel in pressure-fed mode. It was developed by ISRO’s Liquid Propulsion Systems Centre (LPSC). LPSC redesigned the engine making it amenable to the Design for Additive Manufacturing (DfAM) concept thereby gaining considerable advantages.

Benefits of 3D-printed PS4 engine:

• The Laser Powder Bed Fusion technique employed has brought down the number of parts from 14 to a single-piece, and eliminated 19 weld joints, saving significantly on the raw material usage per engine (13.7 kg of metal powder compared to the 565 kg of forgings and sheets for conventional manufacturing process) and reduced 60 per cent in the overall production time.

• The engine was hot tested at ISRO Propulsion Complex, Mahendragiri, Tamil Nadu. 

• As part of the development programme, the injector head of the engine was realised and successfully hot tested earlier. 

• Detailed flow and thermal modelling, structural simulation, and cold flow characterisation of the proto hardware were carried out to gain confidence for the hot test.

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