2015 Winged Launcher TAKEHIRO OKURA Contents 1. Overview ............................................................................................................................................................... 2 2. Spaceplane ............................................................................................................................................................. 2 2.1. Spaceplane .................................................................................................................................................... 2 2.2. Technical aspect ............................................................................................................................................ 3 2.3. Problems ....................................................................................................................................................... 3 3. Winged Launcher .................................................................................................................................................. 4 3.1. Merits and Demerits of Winged Launcher .................................................................................................... 4 3.2. Prospective winged launcher ........................................................................................................................ 4 4. Dream Chaser Orbital Spacecraft .......................................................................................................................... 5 5. Pegasus .................................................................................................................................................................. 6 6. Conclusion ............................................................................................................................................................. 8 7. References ............................................................................................................................................................. 8 1. Overview The space shuttle is a manned spacecraft that has re-use concept. The United States National Aeronautics and Space Administration (NASA) has been launched 135 times from 1981 to 2011. (Figure 1) Since the space shuttle had had the unexpected high cost and risk, the idea that winged spacecraft is inefficient and that the capsule spacecraft is the most efficient is widespread. However, just because the space shuttle had failed does not lead to an absolute negation of the winged spacecraft. This paper researched the possibilities of winged spacecraft. Figure 1. Space Shuttle 2. Spaceplane 2.1. Spaceplane Spaceplane is the next generation of space shuttle and equipped with wings and a rocket engine. (Figure 2) Like an aircraft, the spaceplane can horizontally takeoff and land without a special launch system; therefore this is expected to be ultra-high-speed transport aircraft type of spacecraft that can be used for cargo transportation between the space station and the ground. In the atmosphere, the spaceplane operates as an aircraft; on the other hand, in the space, it operates as a spacecraft. In addition, since the design of spaceplane is based on an aircraft, the spaceplane is expected to be a reusable spacecraft, leading to decreasing the operation cost. Figure 2. History of Spaceplanes 2.2. Technical aspect As technical features of the spaceplane, air breathing (air suction type) is utilized for an engine in the atmosphere. Because in the normal rocket engine, such as liquid oxygen is included as an oxidizer other than liquid hydrogen as fuel, it is difficult to further improve the performance according to the Tsiolkovsky rocket equation. Therefore, it has been considered to use the oxygen in the air as an oxidizer as a jet engine without mounting any oxidizer. Also, the spaceplane has a lift generation mechanism such as wing and lifting body for atmospheric flight. 2.3. Problems In the past, even though it is expected to lead to significant cost saving of spaceflight if the spaceplane is realized, the development of scramjet engine have faced many difficulties. Therefore, it is necessary to be equipped with multiple types of engines according to flight speed and altitude, and rocket engines are also essential in the outer space. As manned spacecraft of space shuttle successor, Orion capsule spacecraft using disposable rocket and Kliper designed as a Soyuz successor spacecraft are reusable spacecrafts. However, these spacecrafts uses disposable type rockets for their launch. 3. Winged Launcher 3.1. Merits and Demerits of Winged Launcher The main merit of winged launcher is that the spacecraft can come back to pin-point to the runway, which allows that it is not necessary to transport the spacecraft since it returns the shortest location in maintenance field. The next merit is that a large number of recovery corps are unnecessary, and doctors and researchers can treat people in spacecraft and get feedback immediately. On the other hand, the capsule type spacecraft needs a large ship and at least a helicopter and a crane if it is in the sea. Even if it is in land, a helicopter and vehicle are necessary for recovery. The last one is that when it is returning, gravity load and impact on crews and research equipment can be small. The main demerit of winged launcher is that the construction costs and maintenance costs for wings, landing gear, and control system are higher than the capsule type. And, the mission cannot be a long term space flight so that crews would not forget the control feeling and how to control spacecraft. There is a damage risk due to the debris because the heat-resistant panels in the orbit are not covered with anything. Furthermore, during atmospheric re-entry, it is difficult for the winged launcher to be aerodynamic naturally stable compared to the capsule type. 3.2. Prospective winged launcher After the Space Shuttle retirement, the United States left the next manned spacecraft development (CCDev) to the private sector. Even though a lot of spacecraft have been developed at the same time, Dream Chaser spacecraft developed by Sierra Nevada Corporation is the only one winged spacecraft. (Figure 3) In addition, the U.S. Air Force have been developing their own winged unmanned spacecraft called X-37B. Figure 3. Image of Dream Chase Cargo System 4. Dream Chaser Orbital Spacecraft The Dream Chaser Orbital Spacecraft is designed to carry 2-7 people to and from low Earth orbit (LEO). (Figure 4) The vehicle was launched in vertical state by mounting on the Atlas V rocket and lands horizontally on the runway. The size of the Dream Chaser is about one-third of the size of fuselage of the space shuttle, and it is planed that it is possible to re-use 30 times. Figure 4. Rough Design of Dream Chaser Twin hybrid-rocket was adopted to the engine, and propellant was a combination of hydroxyl- terminated polybutadiene (HTPD) and nitrous oxide, which could lead to the gravitational acceleration 1.5G at the time of re-entry. However, this plan was changed, and a liquid propulsion system was adopted because a hybrid motor is required to be replaced every time and costs higher. Table 1. Specification of Dream Chaser Orbital Spacecraft Crew 2-7 Length 9.0 m Wing Span 7.0 m Volume 16.0 m3 Mass 11,300 kg Re-entry Less than 1.5 G 5. Pegasus Pegasus rocket with three-stage solid rocket has a winged-type shape and is mounted on an L- 1011 carrier aircraft. (Figure 5) The Pegasus is released from the carrier aircraft that is flying. This is the first air-launched type of satellite launch rocket, and this can reach to Mach 8 as a flying object with wings. The Pegasus can carry payloads of up to 443 kg into low Earth orbit (LEO). Figure 5. Pegasus mounted on a carrier aircraft The Pegasus is consist of three solid propellant stages and monopropellant fourth stage which is optional. (Table 2) Table 2. Specification of Pegasus spacecraft Pegasus Pegasus hybrid Pegasus XL Total length 15.43 m 15.43 m 17.41 m Wing span 6.71 m 6.71 m 6.71 m Mass 19270 kg 19270 kg 22690 kg Payload to LEO 350 kg 350 kg 440 kg First Stage Engine Orion50S Orion50S Orion50SXL Length 8.86 m 8.86 m 10.27 m Mass 14020 kg 14020 kg 15383 kg Propellant QDL-1 QDL-1 QDL-1 Mass of propellant 12163 kg 12163 kg 15014 kg Thrust (vacuum) 464.8 kN 464.8 kN 625.9 kN Isp (vacuum) 294 s 294 s 295 s Burn time 75.3 s 75.3 s 68.6 s Second Stage Engine Orion50 Orion50 Orion50XL Length 2.67 m 2.67 m 3.11 m Mass 3379 kg 3379 kg 4341 kg Propellant QDL-1 QDL-1 QDL-1 Mass of propellant 3025 kg 3025 kg 3925 kg Thrust (vacuum) 114.5 kN 114.5 kN 160.5 kN Isp (vacuum) 292 s 292 s 289 s Burn time 75.6 s 75.6 s 69.4 s Third Stage Engine Orion38 Length 1.34 m Mass 896 kg Propellant QDL-1 Mass of propellant 770 kg Thrust (vacuum) 32.2 kN Isp (vacuum) 287 s Burn time 68.5 s Fourth Stage (Option) Engine HAPS (MR-107K) Length 0.8 m Mass 100 kg Propellant Hydrazine Mass of propellant 41 kg Thrust (vacuum) 0.67 kN Isp (vacuum) 235 s Burn time 142 s 6. Conclusion This paper introduces several kinds of winged launchers that are cost-effective. The spaceplane is still in the middle of development, but many organizations and universities study and improve the performance of the spaceplane. These effort will reduce the launch cost and enable more deeper space exploration. Also, the Pegasus mission allows to use reusable aircraft, leading to reducing the launch cost. Since this mission has resulted in many successes, further development and saving cost can be expected. 7. References