The Boeing X-20 Dyna-Soar ("Dynamic Soarer") was a United States Air Force (USAF) program to develop a spaceplane that could be used for a variety of military missions, including aerial reconnaissance, bombing, space rescue, satellite maintenance, and as a space interceptor to sabotage enemy satellites. [1] The program ran from October 24, 1957, to December 10, 1963, cost US$660 million ($6.31 billion in current dollars [2] ), and was cancelled just after spacecraft construction had begun.
Other spacecraft under development at the time, such as Mercury or Vostok, were space capsules with ballistic re-entry profiles that ended in a landing under a parachute. Dyna-Soar was more like an aircraft. It could travel to distant targets at the speed of an intercontinental ballistic missile, was designed to glide to Earth like an aircraft under the control of a pilot, and could land at an airfield. Dyna-Soar could also reach Earth orbit, like conventional, crewed space capsules. [3]
These characteristics made Dyna-Soar a far more advanced concept than other human spaceflight missions of the period. Research into a spaceplane was realized much later in other reusable spacecraft such as the 1981–2011 Space Shuttle [4] [5] and the more recent Boeing X-40 and X-37B spacecraft.
The concept underlying the X-20 was developed in Germany during World War II by Eugen Sänger and Irene Bredt as part of the 1941 Silbervogel proposal. This was a design for a rocket-powered bomber able to attack New York City from bases in Germany and then fly on for landing somewhere in the Pacific Ocean held by the Empire of Japan. The idea would be to use the vehicle's wings to generate lift and pull up into a new ballistic trajectory, exiting the atmosphere again and giving the vehicle time to cool off between the skips. [6] After the war, it was demonstrated that the heating load during the skips was much higher than initially calculated and would have melted the spacecraft. [7]
Following the war, many German scientists were taken to the United States by the Office of Strategic Services's Operation Paperclip, bringing with them detailed knowledge of the Silbervogel project. [8] Among them, Walter Dornberger and Krafft Ehricke moved to Bell Aircraft, where, in 1952, they proposed what was essentially a vertical launch version of Silbervogel known as the "Bomber Missile", or "BoMi". [9] [10]
These studies all proposed various rocket-powered vehicles that could travel vast distances by gliding after being boosted to high speed and altitude by a rocket stage. [11] The rocket booster would place the vehicle onto a suborbital, but exoatmospheric, trajectory, resulting in a brief spaceflight followed by re-entry into the atmosphere. Instead of a full re-entry and landing, the vehicle would use the lift from its wings to redirect its glide angle upward, trading horizontal velocity for vertical velocity. In this way, the vehicle would be "bounced" back into space again. This skip-glide [12] method would repeat until the speed was low enough that the pilot of the vehicle would need to pick a landing spot and glide the vehicle to a landing. This use of hypersonic atmospheric lift meant that the vehicle could greatly extend its range over a ballistic trajectory using the same rocket booster. [11]
There was enough interest in BoMi that by 1956 it had evolved into three separate programs:
Days after the launch of Sputnik 1 on 4 October 1957, on either October 10 [18] or October 24, [19] the USAF Air Research and Development Command (ARDC) consolidated Hywards, Brass Bell, and Robo studies into the Dyna-Soar project, or Weapons System 464L, with a three-step abbreviated development plan. The proposal drew together the existing boost-glide proposals into a single vehicle designed to carry out all the bombing and reconnaissance tasks examined by the earlier studies, and would act as successor to the X-15 research program. [19]
The three stages of the Dyna-Soar program were to be a research vehicle (Dyna-Soar I), a reconnaissance vehicle (Dyna-Soar II, previously Brass Bell), and a vehicle that added strategic bombing capability (Dyna-Soar III, previously Robo). The first glide tests for Dyna-Soar I were expected to be carried out in 1963, followed by powered flights, reaching Mach 18, the following year. A robotic glide missile was to be deployed in 1968, with the fully operational weapons system (Dyna-Soar III) expected by 1974. [20]
In March 1958, nine U.S. aerospace companies tendered for the Dyna-Soar contract. Of these, the field was narrowed to proposals from Bell and Boeing. Even though Bell had the advantage of six years' worth of design studies, the contract for the spaceplane was awarded to Boeing in June 1959 (by which time their original design had changed markedly and now closely resembled what Bell had submitted). In late 1961, the Titan III was chosen as the launch vehicle. [21] The Dyna-Soar was to be launched from Cape Canaveral Air Force Station, Florida.
The overall design of the X-20 Dyna-Soar was outlined in March 1960. It had a low-wing delta shape, with winglets for control rather than a more conventional tail. The framework of the craft was to be made from the René 41 super alloy, as were the upper surface panels. The bottom surface was to be made from molybdenum sheets placed over insulated René 41, while the nose-cone was to be made from graphite with zirconia rods. [22]
Due to changing requirements, several versions of the Dyna-Soar were considered, all sharing the same basic shape and layout. A single pilot sat at the front, with an equipment bay situated behind. This bay contained data-collection equipment, weapons, reconnaissance equipment, or a four-person mid-deck in the case of the X-20X shuttle space vehicle. A Martin Marietta Transtage upper stage attached to the aft end of the craft would allow orbital maneuvers and a launch abort capability before being jettisoned before descent into the atmosphere. While falling through the atmosphere an opaque heat shield made from a refractory metal would protect the window at the front of the craft. This heat shield would then be jettisoned after aerobraking so the pilot could see, and safely land. [23]
A drawing in the Space/Aeronautics magazine from before the project's cancellation depicts the craft skimming the atmosphere for an orbital inclination change. It would then fire its rocket to resume orbit. This would be a unique ability for a spacecraft, as the laws of celestial mechanics ordinarily mean a change of plane requires an enormous expenditure of energy. The Dyna-Soar was projected to be able to use this capability to rendezvous with satellites even if the target conducted evasive maneuvers.
Unlike the later Space Shuttle, Dyna-Soar did not have wheels on its tricycle undercarriage, as rubber tires would have caught fire during re-entry. Instead Goodyear developed retractable wire-brush skids made of the same René 41 alloy as the airframe. [24]
In April 1960, seven astronauts were secretly chosen for the Dyna-Soar program: [25]
Neil Armstrong and Bill Dana left the program in mid-1962. On September 19, 1962, Albert Crews was added to the Dyna-Soar program and the names of the six remaining Dyna-Soar astronauts were announced to the public. [26]
By the end of 1962, Dyna-Soar had been designated X-20, the booster (to be used in the Dyna Soar I drop-tests) successfully fired, and the USAF had held an unveiling ceremony for the X-20 in Las Vegas. [27] [28]
The Minneapolis-Honeywell Regulator Company (later the Honeywell Corporation) completed flight tests on an inertial guidance sub-system for the X-20 project at Eglin Air Force Base, Florida, utilizing an NF-101B Voodoo by August 1963. [29]
Boeing B-52C-40-BO Stratofortress 53-0399 [30] was assigned to the program for air-dropping the X-20, similar to the X-15 launch profile. When the X-20 was cancelled, it was used for other air-drop tests including that of the B-1A escape capsule. [31]
Besides the funding issues that often accompany research efforts, the Dyna-Soar program suffered from two major problems: uncertainty over the booster to be used to send the craft into orbit, and a lack of a clear goal for the project.
Many different boosters were proposed to launch Dyna-Soar into orbit.
The original USAF proposal suggested LOX/JP-4, fluorine-ammonia, fluorine-hydrazine, or RMI (X-15) engines, but Boeing, the principal contractor, favored an Atlas-Centaur combination. Eventually, in November 1959, the Air Force stipulated a Titan, [27] : 18 as suggested by failed competitor Martin, but the Titan I was not powerful enough to launch the five-ton X-20 into orbit.
The Titan II and Titan III boosters could launch Dyna-Soar into Earth orbit, as could the Saturn C-1 (later renamed the Saturn I), and all were proposed with various upper-stage and booster combinations. In December 1961, the Titan IIIC was chosen, [27] : 19 ) but the vacillations over the launch system delayed the project and complicated planning.
The original intention for Dyna-Soar, outlined in the Weapons System 464L proposal, called for a project combining aeronautical research with weapons system development. Many questioned whether the USAF should have a crewed space program, when that was the primary domain of NASA. It was frequently emphasized by the Air Force that, unlike the NASA programs, Dyna-Soar allowed for controlled re-entry, and this was where the main effort in the X-20 program was placed.
On January 19, 1963, the Secretary of Defense, Robert McNamara, directed the U.S. Air Force to undertake a study to determine whether Gemini or Dyna-Soar was the more feasible approach to a space-based weapon system. In the middle of March 1963, after receiving the study, Secretary McNamara "stated that the Air Force had been placing too much emphasis on controlled re-entry when it did not have any real objectives for orbital flight". [32] This was seen as a reversal of the Secretary's earlier position on the Dyna-Soar program.
Dyna-Soar was also an expensive program that would not launch a crewed mission until the mid-1960s at the earliest. This high cost and questionable utility made it difficult for the U.S. Air Force to justify the program.
Eventually, the X-20 Dyna-Soar program was canceled on December 10, 1963. [4] On the day that X-20 was canceled, the U.S. Air Force announced another program, the Manned Orbiting Laboratory, a spin-off of Gemini. This program was also eventually canceled.
Another black program, ISINGLASS, which was to be air-launched from a B-52 bomber, was evaluated and some engine work done, but was eventually cancelled as well. [33]
Despite cancellation of the X-20, the affiliated research on spaceplanes influenced the much larger Space Shuttle. The final design also used delta wings for controlled landings. The later, and much smaller Soviet BOR-4 was closer in design philosophy to the Dyna-Soar, [34] while NASA's Martin X-23 PRIME and Martin Marietta X-24A/HL-10 research aircraft also explored aspects of sub-orbital and space flight. [35] The ESA's proposed Hermes crewed spacecraft was superficially similar to but not derived from the X-20.
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program name was Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft where it was the only item funded for development.
Human spaceflight programs have been conducted, started, or planned by multiple countries and companies. Until the 21st century, human spaceflight programs were sponsored exclusively by governments, through either the military or civilian space agencies. With the launch of the privately funded SpaceShipOne in 2004, a new category of human spaceflight programs – commercial human spaceflight – arrived. By the end of 2022, three countries and one private company (SpaceX) had successfully launched humans to Earth orbit, and two private companies had launched humans on a suborbital trajectory.
A reusable launch vehicle has parts that can be recovered and reflown, while carrying payloads from the surface to outer space. Rocket stages are the most common launch vehicle parts aimed for reuse. Smaller parts such as rocket engines and boosters can also be reused, though reusable spacecraft may be launched on top of an expendable launch vehicle. Reusable launch vehicles do not need to make these parts for each launch, therefore reducing its launch cost significantly. However, these benefits are diminished by the cost of recovery and refurbishment.
Silbervogel was a design for a liquid-propellant rocket-powered sub-orbital bomber produced by Eugen Sänger and Irene Bredt in the late 1930s for The Third Reich. It is also known as the RaBo. It was one of a number of designs considered for the Amerikabomber project, which started in the spring of 1942, being focused solely on trans-Atlantic-range piston-engined strategic bombers such as the Messerschmitt Me 264 and the Junkers Ju 390, the only two airframe types which were actually built and flown for the competition. When Walter Dornberger attempted to create interest in military spaceplanes in the United States after World War II he chose the more diplomatic term antipodal bomber.
A spaceplane is a vehicle that can fly and glide like an aircraft in Earth's atmosphere and maneuver like a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbital spaceplanes tend to be more similar to conventional spacecraft, while sub-orbital spaceplanes tend to be more similar to fixed-wing aircraft. All spaceplanes to date have been rocket-powered for takeoff and climb, but have then landed as unpowered gliders.
The NASA X-43 was an experimental unmanned hypersonic aircraft with multiple planned scale variations meant to test various aspects of hypersonic flight. It was part of the X-plane series and specifically of NASA's Hyper-X program developed in the late 1990s. It set several airspeed records for jet aircraft. The X-43 is the fastest jet-powered aircraft on record at approximately Mach 9.6.
The Lockheed Martin X-33 was a proposed uncrewed, sub-scale technology demonstrator suborbital spaceplane that was developed for a period in the 1990s. The X-33 was a technology demonstrator for the VentureStar orbital spaceplane, which was planned to be a next-generation, commercially operated reusable launch vehicle. The X-33 would flight-test a range of technologies that NASA believed it needed for single-stage-to-orbit reusable launch vehicles, such as metallic thermal protection systems, composite cryogenic fuel tanks for liquid hydrogen, the aerospike engine, autonomous (uncrewed) flight control, rapid flight turn-around times through streamlined operations, and its lifting body aerodynamics.
The Boeing X-37, also known as the Orbital Test Vehicle (OTV), is a reusable robotic spacecraft. It is boosted into space by a launch vehicle, then re-enters Earth's atmosphere and lands as a spaceplane. The X-37 is operated by the Department of the Air Force Rapid Capabilities Office, in collaboration with United States Space Force, for orbital spaceflight missions intended to demonstrate reusable space technologies. It is a 120-percent-scaled derivative of the earlier Boeing X-40. The X-37 began as a NASA project in 1999, before being transferred to the United States Department of Defense in 2004. Until 2019, the program was managed by Air Force Space Command.
Before the Apollo 11 Moon landing in 1969, NASA began studies of Space Shuttle designs as early as October 1968. The early studies were denoted "Phase A", and in June 1970, "Phase B", which were more detailed and specific. The primary intended use of the Space Shuttle was supporting the future space station, ferrying a minimum crew of four and about 20,000 pounds (9,100 kg) of cargo, and being able to be rapidly turned around for future flights.
The DARPA FALCON Project is a two-part joint project between the Defense Advanced Research Projects Agency (DARPA) and the United States Air Force (USAF) and is part of Prompt Global Strike. The first part of the project aims to develop a Small Launch System (SLS) capable of accelerating hypersonic gliding weapons as well as launching small satellites into Earth orbit. The second part of the project aims to develop Hypersonic Weapon Systems (HWS): a short term high performance hypersonic gliding weapon previously named the X-41 Common Aero Vehicle (CAV) that could be launched from Expendable Launch Vehicles (ELV), Reusable Launch Vehicles (RLVs), Hypersonic Cruise Vehicles (HCV), or Space Maneuvering Vehicles (SMP), and a long term hypersonic cruise aircraft named the Hypersonic Cruise Vehicle (HCV). This two-part program was announced in 2003 and continued into 2006.
Blackstar is the reported code-name of a secret United States orbital spaceplane system. The possible existence of the Blackstar program was reported in March 2006 by Aviation Week & Space Technology magazine; the magazine reported that the program had been underway since at least the early 1990s, and that the impetus for Blackstar was to allow the United States government to retain orbital reconnaissance capabilities jeopardized following the 1986 Challenger disaster. The article also said that the United States Air Force's Space Command was unaware of Blackstar, suggesting it was operated by an intelligence agency such as the National Reconnaissance Office.
ASSET, or Aerothermodynamic Elastic Structural Systems Environmental Tests was an experimental US space project involving the testing of an uncrewed sub-scale reentry vehicle.
Hypersonic flight is flight through the atmosphere below altitudes of about 90 km at speeds greater than Mach 5, a speed where dissociation of air begins to become significant and high heat loads exist. Speeds over Mach 25 have been achieved below the thermosphere as of 2020.
The Approach and Landing Tests were a series of sixteen 1977 taxi and flight trials of the prototype Space Shuttle Enterprise to test the vehicle's flight characteristics, eleven while mated to the Shuttle Carrier Aircraft and five in crewed free flight.
USA-212 was the first flight of the Boeing X-37B Orbital Test Vehicle 1, an American robotic vertical-takeoff, horizontal-landing (VTHL) spaceplane. It was launched aboard an Atlas V rocket from Cape Canaveral on 22 April 2010, and operated in low Earth orbit. Its designation is part of the USA series.
Aircraft can have different ways to take off and land. Conventional airplanes accelerate along the ground until sufficient lift is generated for takeoff, and reverse the process to land. Some airplanes can take off at low speed, this being a short takeoff. Some aircraft such as helicopters and Harrier jump jets can take off and land vertically. Rockets also usually take off vertically, but some designs can land horizontally.
The Space Launching System, or Space Launcher System, (SLS), was a 1960s-era design program of the US Air Force for a family of launch vehicles based around a set of common components. After a series of studies in the late 1950s, the Air Force had concluded that the maximum efficiency would be gained by using only liquid hydrogen fuel for upper stages, which demanded the use of boosters based on segmented solid fuel rockets. By combining one of three upper stages with three different diameters of solids built to any length needed, the SLS provided wide flexibility in launch capability.
The DARPA XS-1 was an experimental spaceplane/booster with the planned capability to deliver small satellites into orbit for the U.S. Military. It was reported to be designed to be reusable as frequently as once a day, with a stated goal of doing so for 10 days straight. The XS-1 was intended to directly replace the first stage of a multistage rocket by taking off vertically and flying to hypersonic speed and high suborbital altitude, enabling one or more expendable upper stages to separate and deploy a payload into low Earth orbit. The XS-1 would then return to Earth, where it could ostensibly be serviced fast enough to repeat the process at least once every 24 hours.
Non-ballistic atmospheric entry is a class of atmospheric entry trajectories that follow a non-ballistic trajectory by employing aerodynamic lift in the high upper atmosphere. It includes trajectories such as skip and glide.