ISRO announced on 28 December 2015 about postponing test of Reusable Launch Vehicle from February to April 2016.
According to New Indian Express, Indian Space Research Organization informed about delayed in planning test flight of RLV. RLV is prototype of future scramjet unmanned reusable space plane launched on atop of single booster from PSLV rocket. Firstly scheduled on mid-2015 and postponed to February 2016, RLV demonstrator will be launched on April 2016 due the technical issues connected with minor leakage spotted recently during tests. Mission planned on April is called Hypersonic Flight Experiment and will consist launching RLV space plane on atop PSLV booster to altitude of 48 km. On this altitude, RLV will perform separation from booster and continue descent through the power of inertia to altitude of 70 km. Next phase is entry with hypersonic speed (according to chairman of Centre for Management Development, Trivandrum, G. Madhavan Nair objective is reaching speed in range 6 Ma- 10 Ma during 900 s suborbital flight), performing different maneuvers to simulate horizontal landing, deploying parachute and splashdown in the waters of Bay of Bengal. This mission will provide necessary information about RLV construction and flight procedures like correct in terms of aerodynamics in hypersonic flight, level of induced loads during flight in atmosphere, strength of carbon fiber utilized for manufacturing nose of the RLV, efficiency of heat shields, technology utilized for separating from first stage and possibilities of recovery RLV by Indian Navy and Coast Guard from the sea. Launch will be performed from Satish Dhawan Space Centre. Launch vehicle will be modified single S9 booster of PSLV rocket. Equipped with stabilizing fins on base shroud and secondary injection thrust vector control will be assembled with RLV by interstage. S9 booster is fueled with HTPB and generates 510 kN of thrust.
RLV history originates in early nineties when ISRO decided to establish own program of developing small reusable Hyperplane space plane launched on atop of rocket first stage. Program was developed by ISRO and gave a result as Avatar space plane. Avatar ("Aerobic Vehicle for Hypersonic Aerospace TrAnspoRtation), presented for the first time on 1998 in Bangalore on India 98 exhibition. It was cooperation between ISRO and India's Defense Research and Development Organization. It was designed as reusable and single stage scramjet launch vehicle with capability of horizontal take-off and landing with weight at 25 t and payload capability in LEO missions at 1000 kg. Avatar maiden flight is planned for 2025. Still RLV is independent ISRO project and step for achieving objective which is possessing launch vehicle for light military and commercial satellites with price per kilogram of payload at $500. Present test flights should be considered as beginning of Indian way for space plane, not necessary Avatar - in general RLV is technology demonstrator potentially for future space plane. Development of future space plane started from creating propulsion. First test of supersonic combustion were performed in 2006. In 2010 ISRO launched ATV-D01 (Advanced Technology Vehicle) rocket - it was weighing 3000 kg test vehicle with passive scramjet engine combustor on atop. Announced in 2012, RLV will test technology for further development. It will weigh around 1500 kg and will be probably launched without own propulsion. To continue tests with horizontal landing and eventually scramjet propulsion it is necessary to build 5 km long airstrip near Satish Dhawan Space Centre. Further planned test flights will cover landing (LEX (Landing Experiment)), return flight (REX (Return Flight Experiment)) and scramjet test during flights (SPEX (Scramjet Propulsion Experiment)).