Maiden launch of Rohini Sounding Rocket (RH 200) with HTPB based propellant
India’s popular and legendary Rohini Sounding Rocket, RH200 (Fig. 1) with new propellant formulation based on Hydroxyl-terminated Polybutadiene (HTPB) was successfully launched from Thumba Equatorial Rocket Launching Station(TERLS), VSSC at 12:17 hrs on 16th September, 2020. This was 180th successive successful flight of RH200 (Meteorological) sounding rocket and the first flight with HTPB based propellant. The mission achieved an altitude of 62.71 km against the predicted nominal 60.61 km in 123 s and released the chaff payload successfully. Performance of the motor was normal.
Figure: RH 200 rocket on the launcher
India started its space journey with the establishment of the Thumba Equatorial Rocket Launching Station on 21.11.1963 by launching the first sounding rocket from Indian soil. Subsequently on 20.11.1967 the first Indian made sounding rocket, RH75 was successfully launched. Over the years, ISRO has developed various sounding rockets for a variety of scientific experiments & meteorological studies. Currently, the RH200, RH300 MkII and RH560 Mk-III rockets are operational which were developed during the early phase of our journey in rocketry.
The first and second stages of RH200 rocket are powered by solid motors. Since inception of RH200 rocket, both solid stages are processed using polyvinyl chloride (PVC) based propellant. As compared to PVC based propellants, HTPB based propellant is more energetic, higher mechanical & interface properties and has less defects due to lower processing temperature. Considering these advantages, efforts were made to replace PVC based propellant with HTPB based propellant for RH200 rocket and series of trials were carried out to achieve desired properties. In addition, composite paper tube based insulation has been implemented to enhance interface properties and rigidity with HTPB propellant.
Prior to maiden flight, performance of the RH200 stages were validated by conducting four static tests for first stage and two static tests for second stage.