Boeing X-20 Dyna-Soar

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. The program ran from October 24, 1957, to December 10, 1963, cost US$660 million ($ in 2024 dollars), 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.

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 and the more recent Boeing X-40 and X-37B spacecraft.

Background

thumb|Artist's conception of an X-20 Dyna-Soar after separation from booster (1961).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 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. 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.

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. Among them, Walter Dornberger and Krafft Ehricke moved to Bell Aircraft, where, in 1952, they proposed what was essentially a vertical launch version of known as the "Bomber Missile", or "BoMi".

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. 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 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.

Brass Bell, a long-range reconnaissance vehicle.
Hywards (Hypersonic Weapons Research and Development Supporting system), a smaller prototype system to develop the technologies needed for Robo and Brass Bell.

Development

frame|Boeing mock-up of X-20 Dyna-SoarDays after the launch of Sputnik 1 on 4 October 1957, on either October 10 or October 24, 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.

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.

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.

Operational history

In April 1960, seven astronauts were secretly chosen for the Dyna-Soar program:

Neil Armstrong (1930–2012; NASA) 1960–1962
William H. "Bill" Dana (1930–2014; NASA) 1960–1962
Henry C. Gordon (1925–1996; Air Force) 1960–1963
Pete Knight (1929–2004; Air Force) 1960–1963
Russell L. Rogers (1928–1967; Air Force) 1960–1963
Milt Thompson (1926–1993; NASA) 1960–1963
James W. Wood (1924–1990; Air Force) 1960–1963

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.

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.

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, using an NF-101B Voodoo by August 1963.

Boeing B-52C-40-BO Stratofortress 53-0399 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.

Problems

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.thumb|An artist's impression of Dyna-Soar being launched using a Titan booster, with large fins added to the Titan's first stage

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, 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.

Legacy

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, 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. The ESA's proposed Hermes crewed spacecraft was superficially similar to but not derived from the X-20.

Specifications (as designed)

thumb|Orthographically projected diagram of the X-20.

thumb|Possible X-20 Dyna-Soar launchers.

Media

The 1959 Twilight Zone season 1 episode titled "And When the Sky Was Opened" made reference to a spacecraft called the X-20 which had a similar profile but could carry a crew of three.
In 1962, the fifth book in Donald A. Wollheim's Mike Mars series, Mike Mars flies the Dyna-Soar, had the title character fly an emergency rescue mission in the Dyna-Soar.
John Berryman's 1963 short story "The Trouble with Telstar" featured a Dyna-Soar being used to intercept communications satellites for repair.
The 1969 Hollywood film drama Marooned featured a rescue craft modeled somewhat after the Dyna-Soar (called the X-RV for experimental rescue vehicle) being hurriedly deployed to rescue astronauts aboard a crippled Apollo command capsule. This was lampooned in Mad Magazine as the XRT, the experimental rescue thing.

References

Notes

Bibliography

Caidin, Martin. Wings into Space: The History and Future of Winged Space Flight. New York: Holt, Rinehart and Winston Inc., 1964.
Dornberger, Walter R. "The Rocket-Propelled Commercial Airliner". Dyna-Soar: Hypersonic Strategic Weapons System, Research Report No 135.. Minneapolis, Minnesota: University of Minnesota, Institute of Technology, 1956.
Duffy, James P. Target: America, Hitler's Plan to Attack the United States. Santa Barbara, California: Praeger, 2004. .
Dyna-Soar: Hypersonic Strategic Weapons System: Structure Description Report. Andrews Air Force Base, Maryland: Air Force Systems Command, 1961, pp. 145–189.
Geiger, Clarence J. History of the X-20A Dyna-Soar. Vol. 1: AFSC Historical Publications Series 63-50-I, Document ID ASD-TR-63-50-I. Wright-Patterson AFB, Ohio: Aeronautical Systems Division Information Office, 1963.
Houchin, Roy. U.S. Hypersonic Research and Development: The Rise and Fall of Dyna-Soar, 1944–1963. London: Routledge, 2006. .

External links

Dyna Soar at Encyclopedia Astronautica
Official United States Air Force film from the 1960 describing the spacecraft.
Tsien Space Plane 1949 at Encyclopedia Astronautica
Tsien Space Plane 1978
Transonic aerodynamic characteristics of the Dyna-Soar glider and Titan 3 launch vehicle configuration with various fin arrangements (PDF format) NASA report – April 1963
American X-Vehicles: An Inventory X-1 to X-50, SP-2000-4531 – June 2003; NASA online PDF Monograph
LIFE 22 Feb 1963 article about X-20 and the pilots training to fly it.