After the first manned flight of the Wright brothers, it did not take more than 20 years to consider space flight, with the concepts and dreams of two men interested in reaching outer space. Herman Oberth, one of the founding fathers of rocketry and astronautics, and Wernher von Braun, his student, later known for helping Germany’s Rocket Development Program and The Space program of the United States. After Wernher’s studies, the ballistic missile V-2  became the first artificial object to reach space. Next, ideas of creating orbital and space transportation grew, and proposals of vehicles that combine propulsion engines, wings, and spacecraft control were emerging.

Reaching outer space is no easy task, but considering re-entry to earth with the same vehicle is even more complex since it involves crossing several atmosphere layers in which the flight dynamics and atmospheric conditions change significantly. Therefore, designing a vehicle that overcomes all of these stages is challenging. One difficulty would be deciding the type of take-off or launching, some examples of launching systems include using a mothership (aircraft carrier), or rocket busters. Another challenge is the endurance to the space environment, and a notable one, the atmospheric re-entry.

One of the first concepts of spaceplane was the Silbervogel, a sub-orbital bomber invented by Eugen Sänger and Irene Bredt in the late 1930s. This incorporated rocket technology and the principles of fixed-wing aircraft, performing flight at Mach 13 (approximately 12,348 km/h) and a cruize altitude of 160 km. The spaceplane was intended to take off utilizing a rail track using rockets and to have a range of 23,400 km. This project did not go beyond drawings, however, after the war, copies of the paper fell into the Americans and Russians.

Numerous studies were appearing with variations of the Sänger and Bredt proposal, continuing with the idea in the United States. The hypersonic rocket-powered aircraft X-15, a spaceplane in the X-plane series. It was developed with a joint program by NASA, the Air Force, the Navy, and North American Aviation, and it is considered the most aeronautical successful research program in history.

Because of the large fuel consumption of its rocket engine, the X-15 needed a mothership aircraft, so it is launched from a B-52 aircraft at about 45,000 ft and speeds upward of 500 mph. The wonderful thing about this aircraft is the data collected for reaching the edge of outer space is important information for aircraft and spacecraft design. In addition to training for the promotion for pilots to astronauts, a well-known pilot was Neil Armstrong, later astronaut and the first man on the Moon.

The aircraft met some records of altitude and speed, the X-15 has exceeded a speed of 7,274 Km/h, a record that is still unbeatable. It also had reached an altitude of 107.8 Km, a record for a winged aircraft.

Thus, this program added important achievements such as the demonstration that pilots can control a rocket-powered aircraft beyond the atmosphere, pilot the aircraft in the edge of the earth without air, and re-enter in the atmosphere for landing on a runway. This is the main idea and concept of a Space Shuttle mission.

One important fact of this vehicle is that was the first to use reaction controls for the airless environment, and control in a place where conventional aerodynamic controls do not work, giving spacecraft capabilities. Thereby, the same control concept is used in space shuttles.

The United States led efforts to continue designing and developing these types of aircraft, but in the 60’s the scope was reduced and the efforts were directed to the Gemini Program. The Gemini program comprises usage of space capsules launched by a rocket and landed by a parachute, a different approach as it is with airplanes.

NASA and the Air Force continued collaborating on developing spaceplanes testing models based on fuselage sustentation or wingless. These singular vehicles with these shapes, were the M2-F1, M2-F2, M2-F3, HL-10, X-24A, and X-24B. They generated valuable information about aerodynamic lift without conventional wings and based on the idea of the aircraft reentry in the atmosphere. Thereby the program also led to the development of the Space Shuttle Program.

The X-24B as a research vehicle, helped to obtain the needed information for the reentry shapes, so the program contributed to writing the flight plan of the Space Shuttle landings.

The Space Shuttle Program

Again the main idea arose, the vehicle that fulfilled many flight features. It is tagged partially reusable, using rocket boosters and an external tank, the last not reusable. the space shuttle orbiter is the spaceplane.

The operational flight began in 1982, with the official program name of Space Transportation System (STS). The space shuttle program had 30 years of achievements in a space mission, many remarkable transportation missions as helping construct the International Space Station (ISS), and carrying the Hubble Space Telescope as well as repairing satellites.

As many of us know that the space shuttle is exciting. When the first test STS-1, flying outer space in a two-day mission, the space shuttle orbited the earth 36 times. STS-1 was also the first U.S. crewed space vehicle launched without an uncrewed powered test flight.

Personally, looking back on it, I think the shuttle has been one of the most marvelous vehicles that has ever gone into space or done anything

Bob Crippen, the iconic pilot on the first space shuttle mission in 1981.

So briefly, how it operates. The space shuttle is launched by rockets and used its integrated engines as well. After that, at an altitude of 46,000 meters, it releases the solid rocket boosters. Therefore, the flight continues with the spaceplane engines but with the external fuel tank still engaged. Finally, it released the external fuel tank and continue the trajectory to orbit.

While in orbit and depending on the mission assigned, it reaches the orbit needed for the work, and the operations and services start in the space working as a spacecraft. An example of known missions entailed scientific payload as telescopes and docking with the Mir Space Station.

For the re-entry at the earth, the spaceplane maneuvers to an upside-down with the right orientation to re-enter the atmosphere, using the reaction control system jets. The reentry was defined at an altitude of 120 km and a travel speed of Mach 25. Thus, descending at a lower atmosphere where ailerons and control surfaces can be effective because of the air presence like an airplane. At the end of the flight, the spaceplane lands on an assigned runway.

Facts:

• For Fiscal Year 2010, the average cost to prepare and launch a shuttle mission was approximately $775 million.
• Shuttle Endeavour, the orbiter built to replace shuttle Challenger, cost approximately $1.7 billion to build.
• The life of the shuttleprogram has cost $113.7 billion. (Not adjusted for inflation).

The retirement of this program type was announced in January 2004. Once the construction of the ISS was completed, it was planned the usage of this spaceplane. However other missions were approved. It was not until the 2011 that the final mission was performed with the Atlantis space shuttle.

Others Spaceplane design concepts

The Orbital Test Vehicle (OTV) the Boeing X-37, a reusable robotic spacecraft, it has a launch vehicle and after its operation in space returns to earth as and spaceplane. The main purpose is served as test for the Reusable Space Technologies.

The Dream Chaser, a reusable spaceplane intended to operate for space transportation and supply the ISS with cargo. In the same way as all spaceplanes were created, this descended from a series of spaceplanes such as The wingless lifting body aircraft from NASA.

Among others designs of spaceplanes, are the Spaceship one and Spaceship two, experimental air-launched rocket-powered aircraft. Being launched by a mothership aircraft. this project and its achievements are comparable to the X-15 explained before. It was the first private spacecraft and this company was owned by the Virgin group.

There are many conceptual designs of spaceplane, but reaching outer space as a complex task also expensive, requires the actual researches to look for other variants and approaches, and we take for granted that next years will be many more models. The thing we can see is that these operations of reaching space was devised by the thoughts of rocket scientists, pilots, engineers and of course dreamers.

REFERENCES:

http://www.astronautix.com/s/saengerantipodalbomber.html
https://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-16-DFRC.html
https://history.nasa.gov/x15/cover.html
https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-011-DFRC.html
https://www.nasa.gov/pdf/566250main_SHUTTLE%20ERA%20FACTS_040412.pdf
https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104539/x-37b-orbital-test-vehicle/
https://www.sncorp.com/what-we-do/dream-chaser-space-vehicle/
https://www.space.com/16769-spaceshipone-first-private-spacecraft.html