ISRO, Indian space agency, achieved next milestone after successful test of their RLV (Reusable Launch Vehicle-Technology Demonstrator) vehicle conducted on May 23, 2016. This time prototypes of scramjet engine were launched on atop of rocket booster from Satish Dhawan Space Centre on August 28, 2016.
This is important step in the whole program of development first Indian fully reusable space vehicle based on scramjet propulsion. Whole program started in the early nineties with first important milestone reached in 2005. In this year specialists from Vikram Sarabhai Space Centre (VSSC) performed first ground fire test of the new scramjet engine. Next step was performed in 2010, when ISRO launched on atop of RH-560 two-stage rocket (Advanced Technology Vehicle - ATV-D01) with passive scramjet combustor. This year, after six years, on May 23, ISRO launched HS9 solid fueled launch vehicle with scaled aerodynamic model of the RLV-TD (Reusable Launch Vehicle-Technology Demonstrator) on atop. Various technologies and materials were tested along with whole landing procedure performed on the waters of Bay of Bengal. Again ISRO got closer to ultimate goal: creating scramjet reusable vehicle not later than in 2030 and offer prices per 1 kg of payload delivered to LEO from $500.
This time test flight had more objectives as trial performed on May. ISRO decided to test particular elements and subsystems of the propulsion along with testing any new material. Following elements like air intake, combustor, thermal management system and new materials resistant for high temperatures were tested. According to official statement given after test flight:
"With this flight, critical technologies such as ignition of air breathing engines at supersonic speed, holding the flame at supersonic speed, air intake mechanism and fuel injection systems have been successfully demonstrated."
Test flight of the scramjet engine conducted on Sunday started at 00:30 GMT when two-stage, spin stabilized ATV (Advanced Technology Vehicle) launch vehicle (modified RH-560 sounding rocket) was launched from Satish Dhawan Space Centre, Sriharikota using special rail. Twin scramjet engine was installed on atop of the rocket; whole vehicle with engine and control systems weight 3277 kg. After launch rocket reached altitude of 20 km, when tested scramjet engine was able to be ignited (scramjet engines are using air flowing through combustion chamber with high speed and are able to work after reaching 4 Ma). Engine was operating for around 5 seconds burning liquid hydrogen; maximum speed reached during flight was 6 Ma. Finally, after 300 seconds of flight whole rocket landed in the waters of Bay of Bengal around 320 km from Sriharikota.