India: ISRO’s 3D printed liquid rocket engine eliminates hot testing

The Indian Space Research Organization (ISRO) has announced the successful hot testing of its 3D printed liquid rocket engine.

According to ISRO, the hot test of the engine manufactured using additive manufacturing (AM) technology was done on May 9. The test lasted 665 seconds (11 minutes 5 seconds).

The liquid rocket engine used for the test was the PS4 engine of the PSLV upper stage.

Engine manufactured by conventional system versus additive manufacturing

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

The engine uses ground-storable bipropellant combinations of nitrogen tetroxide as an oxidizer and mono methyl hydrazine as a fuel in pressurized feed mode. It was developed by the Liquid Propulsion Systems Center (LPSC), ISRO.

LPSC redesigned the PS4 engine to make it design-friendly for additive manufacturing, which gave it certain advantages.

The Laser Powder Bed Fusion technique employed has reduced the number of parts from 14 to a single part and eliminated 19 solder joints. This led to significant cuts in the use of raw materials per engine.

The process used 13.7 kg of metal powder compared to 565 kg of forging and sheets for the conventional manufacturing process, according to ISRO.

It also significantly reduced the production time to manufacture an engine, by approximately 60%.

Engine fabrication was done in WIPRO 3D and the engine was hot tested at ISRO Propulsion Complex, Mahendragiri.

Engine hot test

As part of the development process, the engine injection head was performed and successfully tested earlier.

Detailed thermal and flow modeling, structural simulation and cold flow characterization of the proto-hardware were performed to gain confidence for hot testing.

Four successful development hot tests of the integrated engine were previously conducted for a combined duration of 74 seconds. These combined tests validated the engine’s performance parameters.

The engine was then successfully tested for the full qualification duration of 665 seconds. On testing, it was observed that it passed all performance parameters and is ready to be deployed.

ISRO plans to induct the AM PS4 engine into the regular PSLV programme.

PSLV program of ISRO

The Polar Satellite Launch Vehicle (PSLV) is a third generation launch vehicle of India. It is the first Indian launch vehicle equipped with liquid stages.

After its first successful launch in October 1994, PSLV emerged as a reliable launch vehicle in India. The vehicle has launched numerous satellites from Indian and foreign customers.

In addition, the vehicle successfully launched two spacecraft Chandrayaan-1, in 2008, and the Mars Orbiter spacecraft, in 2013, which later traveled to the Moon and Mars, respectively.

PSLV earned its title ‘ISRO’s workhorse’ by consistently delivering multiple satellites into low Earth orbits. It can carry up to 1,750 kg of payload in sun-synchronized polar orbits 372.8 miles (600 km) high.