AVATAR is a single-stage reusable spaceplane capable of horizontal takeoff and landing, being developed by India's Defense Research and Development Organization along with Indian Space Research Organization and other research institutions; it could be used for cheaper military and civilian satellite launches. According to the Designers, Hyperplane projects of the 1980's - the X-30, Tu-2000 etc, failed due to their immense weight. Hence it is the weight which is the promising aspect of AVATAR. It is planned to be the size of a MiG-25. AVATAR was first announced in May 1998 at the 'Aero India 98' exhibition held at Bangalore.
Weighing only 25 tons - 60 per cent of which is liquid hydrogen fuel - Avatar is said to be capable of entering into a 100-km orbit in a single stage and launching satellites weighing up to one ton.AVATAR would take off like a conventional airplane using turbo ramjet engines that burn hydrogen and atmospheric oxygen, once at a cruising altitude it would use scramjet (Liquid air cycle engine) propulsion to accelerate from mach 4 to mach 8. During the cruising phase an on board system would collect air from the atmosphere, from which liquid oxygen would be separated (Liquification) and stored. The liquid oxygen collected would then be used to burn the stored hydrogen in the final flight phase (flight beyond the atmosphere) to attain orbit.
The vehicle would be designed to permit at least 100 launches and atmospheric re entries. AVATAR is a revolutionary space craft that reduces the cost of launching satellites dramatically. The overall cost of launching the AVATAR RLV may be 80 to 90 times less. AVATAR is projected to weigh 25 tons and the payload will be weighing up to 1000kg.
The AVATAR is very different from a space shuttle, each being different in terms of technology and technical capabilities. AVATAR is fully automatic where as a space shuttle is semi automatic. ISRO also has plans for manned version of AVATAR. This implies that India would use the RLV for launching humans as well as using it as a supply vessel to a space station in the future
It is also said that the AVATAR will make space solar power (SSP) stations affordable providing a global solution for the coming energy crisis. The idea being that a string of satellites in space will convert sunlight into microwaves and beam to earth where it will be turned into electricity. Till now SSP stations were unthinkable because of high cost of space launches but Avatar can change that, Indian scientist’s hope.
AVATAR design has already been patented in India and applications for registration of the design have been filed in patent offices in the United States, Germany, Russia and even China.
The dream of making a vehicle which can take off from a runway like an aircraft, and to return to the runway after deploying the spacecraft in the desired orbit (or Single-stage-to-orbit or SSTO) can be fulfilled only by the availability of more advanced high strength but low density materials so that the structural mass of the vehicle could be reduced considerably from the present levels. The advent of nano-technology could play a deciding factor in developing such exotic materials. However, the material technology available today can realize a Two Stage To Orbit (TSTO) vehicle only and the configuration of the vehicle which is being considered. However, the before realizing the RLV-TSTO it is important to perfect many critical technologies pertaining to hypersonic reentry vehicles. Hence a technology demonstrator vehicle (RLV-TD) is developed for the immediate future by utilizing the current capabilities and the ultimate goal is to development of SSTO AVATAR in the long term
To develop a fully functional SSTO AVATAR RLV, ISRO is conducting a series of technology demonstration missions they are named as RLV TD. RLV TD has been configured to act as a flying test bed to evaluate various technologies namely Hyper sonic flight, Autonomous Landing, Powered Cruise Flight using air breathing propulsion .These technologies will be developed through a series of experimental flights. A total of four flights are planned by ISRO.
HEX (Hypersonic Flight Experiment): completed successfully on 23 May 2016.
LEX (Landing Experiment)
REX (Return Flight Experiment)
SPEX (Scramjet Propulsion Experiment)
HEX (RLV -TD)
The configuration of RLV-TD is similar to that of an aircraft and combines the complexity of both launch vehicles and aircraft. The winged RLV-TD has been configured to act as a flying test bed to evaluate various technologies, namely, hypersonic flight, autonomous landing and powered cruise flight. In future, this vehicle will be scaled up to become the first stage of India’s reusable two stage orbital launch vehicle.
RLV-TD consists of a fuselage (body), a nose cap, double delta wings and twin vertical tails. It also features symmetrically placed active control surfaces called Elevons and Rudder. This technology demonstrator was boosted to Mach no: 5 by a conventional solid booster (HS9) designed for low burn rate. The selection of materials like special alloys, composites and insulation materials for developing an RLV-TD and the crafting of its parts is very complex and demands highly skilled manpower. Many high technology machinery and test equipment were utilized for building this vehicle.
Objectives of RLV-TD:
· Hypersonic aero thermodynamic characterization of wing body
· Evaluation of autonomous Navigation, Guidance and Control (NGC) schemes
· Integrated flight management
· Thermal Protection System Evaluation
Achievements of this mission
RLV-TD was successfully flight tested on May 23, 2016 from SDSC SHAR Sriharikota validating the critical technologies such as autonomous navigation, guidance & control, reusable thermal protection system and re-entry mission management.
ISRO achieved another milestone in realizing AVATAR by successfully conducted scramjet engine test on August 28, 2016.
After a smooth countdown of 12 hours, the solid rocket booster carrying the Scramjet Engines lifted off at 0600 hrs (6:00 am) IST. The important flight events, namely, burn out of booster rocket stage, ignition of second stage solid rocket, functioning of Scramjet engines for 5 seconds followed by burn out of the second stage took place exactly as planned.
After a flight of about 300 seconds, the vehicle touched down in the Bay of Bengal, approximately 320 km from Sriharikota. The vehicle was successfully tracked during its flight from the ground stations at Sriharikota.
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. The Scramjet engine designed by ISRO uses Hydrogen as fuel and the Oxygen from the atmospheric air as the oxidiser. The August 28 test was the maiden short duration experimental test of ISRO’s Scramjet engine with a hypersonic flight at Mach 6.
Some of the technological challenges handled by ISRO during the development of Scramjet engine include the design and development of Hypersonic engine air intake, the supersonic combustor, development of materials withstanding very high temperatures, computational tools to simulate hypersonic flow, ensuring performance and operability of the engine across a wide range of flight speeds, proper thermal management and ground testing of the engines.
India is only the fourth country to demonstrate the flight testing of a Scramjet Engine.
Note: - According to some reliable sources the primary R&D is doing by DRDO, ISRO doesn’t have any role in AVATAR. But some sources say ISRO also involved in this project, some interviews of ISRO scientists also pointing towards the possibility of ISRO, s involvement in developing similar kind of technologies expected to use in AVATAR. Any way the technology is similar in between RLV and avatar in many areas, so treat this article as only a technical/informative article .