Reusable launch vehicle
- 1. Technical Seminar on REUSABLE LAUNCH VEHICLE Presentation by: Mrunal Mohadikar
- 2. WHAT IS REUSABLE LAUNCH VEHICLE ? • A Reusable launch vehicle (RLV) refers to a vehicle which can be used for several missions. • A Reusable Launch Vehicle is the space analog of an aircraft. Ideally it takes off vertically on the back of an expendable rocket and then glides back down like an aircraft. During landing phase, an RLV can either land on a runway or perform a splashdown. • The main advantage of an RLV is it can be used multiple times, hopefully with low servicing costs. The expendable rocket that is used for launching the RLV can also be designed to be used multiple times. A successful RLV would surely cut down mission costs and make space travel more accessible.
- 3. HISTORY The thought of Reusable launch vehicles started in 1950’s, but serious attempts at completely reusable launch vehicles started in the 1990s. The most prominent were the McDonnell-Douglas DC-X and the Lockheed Martin X-33 VentureStar. DC-X X-33 VentureStar
- 4. TODAY • SpaceX is a recent player in the private launch market succeeding in converting its Falcon 9 expandable launch vehicle into a partially reusable vehicle by returning the first stage for reuse. • On 23 November 2015, Blue Origin New Shepard rocket became the first proven Vertical Take-off Vertical Landing (VTVL) rocket which can reach space 100.5 kilometers.
- 5. Working of an RLV • Subsonic and supersonic Stage • Hypersonic Stage • Space Stage • Re Entry Stage - Upto about 100,000 feet or 30 km. - Use a combination of conventional jet-engine and ramjet engine. - Plane is accelerated to a speed of mach 4 or mach 5. - At an altitude of about 100,000 feet and at a velocity of about mach 4. - Combustion and ignition takes place in milliseconds. - Scramjet engines takes RLV to mach 15. - Rocket engines are fired as there isn’t enough oxygen for scramjet engines. - RLV is accelerated to mach 25. - Rocket engine takes RLV to payload release site and required operations are performed. - RLV performs de-orbit operations to slow itself down. - It drops to lower orbit and enters upper atmospheric layers. - RLV uses its aerodynamics to glide down once it reaches dense air.
- 6. Design of an RLV Body: The body has to withstand very high stresses. It has to cope with the rapid change in temperatures which changes from -250°C in shade to 250°C in direct sunlight. Wings: Delta wings provides enough lift to fly to space and also reduce the friction during re-entry. Cockpit: Cockpit has double-paned glass windows which can withstand the force of flight, pressure and vacuum. Oxygen bottles are used to add breathable air. An absorber system removes the exhaled carbon dioxide. Electrical Power: The power required is taken from lithium batteries which could be charged, if needed by using solar energy.
- 7. RLV Concepts
- 8. Stages to orbit • Single-stage-to-orbit (SSTO) reaches the space orbit carrying small payloads of 9,000 to 20,000kg without losing any hardware to LEO. • Two-stage-to-orbit (TSTO or DSTO) are two independent vehicles which interactions while launching. • Cross Feed has two or three similar stages are stacked side by side, and burn in parallel. They carry heavy payloads to outer space.
- 9. Vertical Landing • Parachutes could be used to land vertically, either at sea, or with the use of small landing rockets, on land • Rockets could be used to softland the vehicle on the ground from the subsonic speeds reached at low altitude. This typically requires about 10% of the landing weight of the vehicle to be propellant. • Alternately, autogyro or helicopter rotor. This requires perhaps 2-3% of the landing weight for the rotor.
- 11. Retro-Propulsion/ Backward Propulsion • Retro-propulsion means firing your rocket engines against your velocity vector in order to decelerate. • The vehicle fires its rockets towards the surface to slow the craft’s descent, after parachutes had already brought it below the speed of sound. • It is very expensive in the sense that the fuel required for landing must be carried to space, which erodes the useable payload capacity of the launch system.
- 12. Mid-Air Recovery (MAR) • The reentering vehicle is slowed by means of parachutes, and then a specially equipped aircraft matches the vehicle's trajectory and catches it in mid-air. • This approach avoids high impact accelerations and/or emersion in salt water. • MAR can be up to (and beyond) a 10 ton payload. It has been successfully demonstrated for 1000 lbs class objects
- 13. Launch Assistance/Non Rocket Space Launch • Stratolaunch uses an aircraft to gain some initial velocity and altitude; either by towing, carrying or even simply refueling a vehicle at altitude. • Rocket sled launch (ground based launch assist) • Launch loop or Lofstrom loop • Space Tether or Tether Propulsion • Space Elevator Stratolaunch Rocket Sled Launch Launch loop Space Tether Space Elevator
- 14. Preparing for Reuse • The vehicle requires extensive inspection and refurbishment. • Each and every part of the launch vehicle needed to be individually inspected. For example the orbiter’s thermal protection tiles needed to be individually inspected (and potentially replaced). • Main engines needed to be removed to undergo extensive inspection and overhaul. • Parts contaminated with ocean salt water and had to be cleaned, disassembled, and refurbished before reuse.
- 16. Advantages of an RLV • Cost is the first and foremost consideration, Reusable Launch Vehicles reduce cost very much by avoiding repeatedly making of new use and throw launch vehicles. • International Space Station needs periodical replenishment and may need other support missions from earth even at short notice. RLVs become very useful in these circumstances. • India is getting and trying to get more commercial launches of other nations' satellites. By using dependable RLV s the frequency of missions can be increased and more number of commercial payloads can be carried into space.
- 17. Reusable launch systems have the highest development costs and technical risks, but the technology is within current state of the art. Current efforts to economically recover and reuse launch vehicle elements are more promising than they have ever been. A reusable system has extremely low direct operating costs. A future reusable launch vehicle should be constructed within low cost, use cryogenic engine for all stages. Autonomous reusable launch vehicles are considered to be low cost alternatives. Future RLV are to be developed through an extensive flight demonstration. Conclusion
- 18. References Research Papers: • Bhavana Y, Mani Shankar N and Prarthana BK (2013) “Reusable Launch Vehicle: Evolution Redefined”. J Aeronaut Aerospace Eng: 2-2 • Mohamed M. Ragab, F. McNeil Cheatwood, Stephen J. Hughes and Allen Lowry “Launch Vehicle Recovery and Reuse”. Acta Astronautica: 41-11 Thesis: • Greg J. Gstattenbauer “Cost Comparison Of Expendable, Hybrid, And Reusable Launch Vehicles”. Air Force Institute of Technology, Ohio Websites: • Wikipedia • Quora • YouTube • ISRO (isro.gov.in/launchers/rlv-td) • SpaceX (spacex.com/news/2013/03/31/reusability-key-making- human-life-multi-planetary)
- 19. Thank You!
Editor's Notes
- #2: Presentation Made By: Mrunal Mohadikar