A History of the Dyna-Soar

Over the last few days, I’ve been doing some research into the USAF Dyna-Soar or X-20 program, and its story is much more interesting than I realized. Like many of the unrealized programs of the early space age, its impact extends far beyond its immediate application. Dyna-Soar is typically referenced in passing as an upgraded version of the X-15, an aircraft capable of achieving orbiting, but this connection is misleading. Dyna-Soar came from an entirely different place than the X-15, and its story is much more complicated than a simple cancelled research program. (A worker inspects a full-scale mockup of Dyna-Soar. Reader’s Digest described the vehicle as a cross between a porpoise and a manta ray. Early 1960s. Photo: Smithsonian Air and Space Museum.)

Dyna-Soar has its roots, like many great technologies of the space age, in Germany. In the early 1930s in Austria, aeronautical engineer Dr. Eugen Sänger and mathematician Irene Bredt – who were also husband and wife – designed a boost glide vehicle. The original design used a rocket powered sled for launch (like the spaceship in Fireball XL5), but the drag penalty as it gained altitude made it impossible. A rocket, however, could do the trick. The couple’s final design called for a winger vehicle to launch to such an altitude that it would bounce off the atmosphere. As it approached its target, it would reenter the atmosphere nose first before gliding to a runway landing at a preselected point. Traveling this way the vehicle could reach any target on the planet in a little over an hour.

The idea was published in the Austrian journal Flight in 1935 and immediately caught the attention of the German Army. Weaponized, the vehicle would become a formidable bomber. That it could glide to a safe landing not only made it a recoverable weapon, it opened the door for a piloted high altitude bomber. Like Wernher von Braun’s rockets, Sänger’s boost glide vehicle was a military acquisition that wouldn’t violate the Treaty of Versailles.

The German high command established a lab at Trauen for Sänger and Bredt to develop their hypersonic skip glide vehicle, which quickly took on the designation of an antipodal bomber. Work at Trauen, like at Peenemünde, remained top secret; not until 1940 did von Braun and Sänger learn of one another and introduce each other to their work.

Unlike von Braun’s rockets, boost glide technology proved elusive as the war progressed. Nevertheless, the German Army remained optimistic. In 1944, just months before the war ended, the antipodal bomber was on paper in the development stages as the continuation of the A-series weapons. The A-series was possibly Germany’s greatest asset during the war that included the V-1 and the V-2 – the V-2’s original designation was the A-4. Its name was changed for propaganda purposes; the ‘v‘ stands for ‘vergeltungswaffe‘ or ‘vengeance weapon’. The antipodal bomber was to be the A-10, though it was referred to as the less innocuous ‘Amerika Bomber’.  (Left, a schematic comparison. From left to right: the V-2, a modified V-2 the A-4b, the A-10/Amerika Bomber, and a modified A-10 with increased range.)

Lucky for America, the ‘Amerika Bomber’ never got to the developmental stages. In 1944, Sänger and Bredt published a 400-page final report on their antipodal bomber and distributed it among German politicians, military leaders, and scientists. But by then the country in shambles and fighting a losing battle. There was no funding left for such a program and the report was little more than an academic interest for its recipients.

The Allies, on the other hand, were much more interested in the report and had the funds to pursue the antipodal bomber.

After the war ended in 1945, the Soviet Union and the United States tore through Germany seeking ‘intellectual reparations’ – scientists, documents, and hardware that would unlock the secrets of Germany’s powerful bombs. The antipodal bomber was high on the list along with von Braun and the technology of the V-2. Both countries found Sänger’s report along with other documents, but neither secured the man himself.

He wasn’t one of the 110 men von Braun named under Project Paperclip. Although he was later invited to the US to work at Bell Aircraft, he turned down the invitation when he learned he couldn’t bring his own researchers. Stalin could never find Sänger. He was so obsessed with the idea of an antipodal bomber that in the late 1940s he sent a team to Paris where Sänger was known to be working, but the attempted kidnapping was thwarted by the French secret police. Sänger spent a brief period in Egypt before returning to Germany where he worked at the Stuttgart Propulsion Institute until his death in 1964. (Left, the Nazi Rocketeers after surrendering to the American Army. Von Braun is central with a broken arm, Dornberger is on the left. 1945.)

His antipodal bomber, however, did make it to the US. Walter Dornberger, former leader of the V-2 program and one of Von Braun’s colleagues from Peenemünde, had seen Sänger’s research in Germany. He was developing missiles for the USAF at the Wright-Patterson Air Force Base in 1952 when he suggested the antipodal bomber would be a worthwhile addition to the US military’s arsenal. The suggestion went to the National Advisory Committee for Aeronautics (NACA), which promptly endorsed a feasibility study of a long range manned space bomber. (Right, the rocketeers at Peenemünde congratulate one another after a successful A-4 test. Dornberger is on the left shaking hands with Rudolph Hermarn. October 3, 1942.)

There were technical challenges – notably the heat of atmospheric reentry and pilotability during descent – but these weren’t Dornberger’s biggest challenges. Rather, he needed to persuade the American people that getting a man in space wasn’t pure fantasy if the manned bomber would ever fly. Luckily for Dornberger, Wernher von Braun was working with Walt Disney to promote America’s manned spaceflight program. By the time the NACA-mandated study was finished, there was no question men had a place in space, and the boost glide bomber was deemed a worthwhile investment.

The first iteration of the program in 1957 called for the development of a ‘piloted very high altitude weapons system.’ But it took on a secondary application after the Soviet Union launched Sputnik in October. It became a multipurpose vehicle, a bomber as well as a way to get an American in space. (Left, Walt Disney visits with von Braun at the Marshall Spaceflight Centre. 1954.)

In January 1958, the USAF invited the NACA to participate in the ‘multipurpose manned bomber’ program. Months of negotiations ended with shared responsibility: the USAF would focus on the vehicle’s weapons system while the NACA would research and develop a sound aerodynamic design. The intention behind this cooperation was to “maximize the vehicle’s capabilities from both the military weapons system development and the aeronautical-astronautical research viewpoints.” By the end of 1958, NASA had taken the place of the NACA and a two-stage program was in place. A boost glide vehicle research vehicle would come first followed by the appropriate weaponization system.

This clearcut plan didn’t last, and throughout 1959 the multipurpose manned hypersonic bomber program underwent multiple revisions. In February, development of a bombardment system was upgraded to a primary goal over any non-military applications. In April, suborbital hypersonic flight took over as the program’s main objective. In May, any development and focusing only on research was cancelled in favour of a determination of the military potential of boost glide systems.

Finally in November 1959, a concrete decision was made. Boeing Aircraft was awarded the contract to build the hypersonic glider, and the Martin Company was awarded the contract for the booster. Boeing also made an important contribution at this point. It christened the program Dyna-Soar, short for dynamic soaring.

Formal contracts brought more revisions, and another research stage was established at the end of 1959. Phase Alpha, was instituted to determine the applicability of Dyna-Soar to manned orbital flight.

1960 began with good news for Dyna-Soar. The USAF completed Phase Alpha in March and determined the vehicle’s low lift-to-drag ratio made it ideal for the investigation of manned reentry from orbit and the pursuit of manned orbital flight. This officially cleared Dyna-Soar for development towards stage 1 suborbital test flights. Better news came midway through the year when the Department of Defence (DOD) officially endorsed Dyna-Soar with a financial commitment that allowed the USAF to approve stages II and III, the advanced orbital stages of the program. (An artist’s impression of Dyna-Soar in orbit. Photo: Boeing.)

Almost immediately, the USAF developed a new plan to accelerate the program and move up the  expected flight date for Dyna-Soar. Its launch vehicle, however, was the missing piece of the puzzle. In November, studies began into the feasibility of the Titan missile as the launch vehicle.

1961 changed the space game. In April, the space race took on a new dimension when the Soviet Union put Yuri Gagarin in orbit. Perhaps as a reaction to the Soviet feat, the DOD announced its commitment of $100 million – a little over $720 million in 2010 – to the USAF for the fiscal year 1962 for the development of Dyna-Soar also in April. With funding secured for another year, the USAF finalized its contracts and reviewed its multi-stage development program. Boeing proposed a streamlined approach that would accelerate the program by cutting out suborbital flights and proceeding from unmanned flight right into orbit.

Dyna-Soar really began to take shape in the latter half of 1961. A delegation of USAF and NASA representatives travelled to Boeing’s plant in Seattle to inspect a mockup of the glider in September, but the program as a whole was still under intense scrutiny. USAF General Bernard A. Schriever (left) called for and directed a study into the manned military and space capabilities of Dyna-Soar, and the result overturned the program’s development yet again. Schriever recommended separating the program into halves. He placed the emphasis on an abbreviated development plan that would see completion of a militarized Dyna-Soar in advance of its non-military counterpart. This non-military application was reestablished as a research program into the problems associated with manned orbital flight.

Dyna-Soar began facing significant setbacks in early 1962. In January, the USAF cancelled all development towards stage III – what was to be advanced multi-orbital flights. In February, suborbital flights were formally cancelled (as per Boeing’s recommendation). More striking, however, was the cancellation of all military applications Dyna-Soar might have. On February 23, DOD Secretary Robert McNamara officially announced Dyna-Soar would nothing more than an orbital research program.

McNamara’s amendment was formalized on June 26, 1962, when the DOD gave Dyna-Soar its secondary designation of X-20, effectively securing its position in the long line of X-series research planes. Dyna-Soar/X-20 was unveiled as such at a press conference in Las Vegas that September along with a full scale mock-up. For a while, it looked like Dyna-Soar would thrive as a research program. After its public unveiling, the DOD announced the X-20’s budget at $130 million for 1963 and $125 million in 1964. (Right, Robert McNamara.)

NASA, however, was taking its own great strides in space and proving that the ballistic approach to manned spaceflight was viable. By the beginning of 1963, NASA had successfully sent three Mercury missions into orbit and its follow up program, Project Gemini, was already in its early developmental stages. More importantly, Gemini stood firmly in place as a necessary bridge between Earth orbital Mercury flights and the Apollo lunar landing.

Dyna-Soar simply did not factor in to the nation’s success in the space race, and was subjected to yet another review in March of 1963. DOD Secretary Robert McNamara ordered parallel reviews of both Dyna-Soar and Gemini. Specifically, the USAF was directed to compare the potential of Dyna-Soar against the potential of a militarized version of Gemini.

The writing was on the wall at this point, and in the latter half of 1963 Dyna-Soar lost what little momentum it had left. In December, McNamara formally announced its cancellation. In the news briefing announcing the cancellation, the principle reason for its cancellation boiled down to a poor return on investment – at the time of its cancellation, Dyna-Soar had cost close to $400 million (over $2.8 billion in 2010). (Right, an artist’s impression of Dyna-Soar’s launch.)

Dyna-Soar, McNamara explained, was primarily aimed at answering questions about hypersonic atmospheric reentry techniques, but the X-15 and Mercury programs had already yielded significant data on these questions. McNamara also cited the limited capability of Dyna-Soar. The glider could not, nor was it ever intended to, ferry supplies to an orbital space station, facilitate or undertake an extended orbital mission, or place substantial payloads in orbit. Compared with the capabilities NASA was displaying, there was no need for a second less versatile and less capable manned space program.

In the same new briefing, McNamara announced the USAF’s replacement for Dyna-Soar: a militarized version of Gemini called Gemini B or the Manned Orbiting Laboratory (MOL, pictured). This program never made it to manned flights.

Hindsight reveals that the odds were against Dyna-Soar from the beginning. While boost glide vehicles had been on the drawing board in Germany, capsules were on the drawing board in America. The US Army Air Force (precursor to the USAF), US Navy, as well as the Department of Defence had begun studying the feasibility and potential applications of satellite-style vehicles in the mid 1940s.

Around the time Dyna-Soar began to take shape, ballistic approaches to spaceflight were also under consideration. In July 1953, representatives from the NACA, USAF, and US Navy met to compare different approaches to the man in space problem; both capsules and space planes were covered. This meeting ultimately led to the X-15 program since hypersonic flight was one of the principle unknowns. But it also led to the USAF’s “Manned Ballistic Rocket Research System” program that began in 1956, the aim of which was to study the recovery of manned capsules from orbit. As the Mercury program came together in the late 1950s, it became clear that the ballistic approach was preferable for the short term in getting a man in space. There were less variables and more chance to redundancies built into the vehicle. It’s likely that only a catastrophic failure in Mercury could have led to Dyna-Soar ending up as America’s primary manned space vehicle. (Right, a launch of an unmanned MOL, one of the few of the program.)

Hindsight also suggests that development of Dyna-Soar could have had benefits, even if the program was less immediately necessary within the context of the space race. Had it succeeded, Dyna-Soar could have been an asset to more than just the USAF. It could have served as an aid, tug boat, or life boat for Apollo crews in orbit. It could have been a reusable taxi to the space station and docked onboard for an emergency return home – something that seems particularly useful in light of NASA’s newfound reliance on Russia to reach low Earth orbit. A militarized version of Dyna-Soar could certainly have had applications not only as a manned bomber but as a supplier for military units overseas – delivering either arms or good. It could also have been a formidable spy plane to the intelligence community traveling higher and faster than the U-2. It could turn out that NASA or a private company like Space X revisits the idea of a one-man orbital vehicle, giving the US the chance to benefit from what Dyna-Soar offered decades ago.

An artist's impression of the scene after a successful Dyna-Soar/X-20 flight. Photo: Astronautix.

Suggested Reading/Selected Sources

The USAF’s “Story of Dyna-Soar” Video. Part 1. Part 2.

Dyna-Soar Hypersonic Strategic Weapons System compiled by Robert Goodwin. Apogee Books: Burlington. 2003.

“Man in Space: U.S. Air Force Manned Space Projects” Spacecraft Films. 2007.

Martin Co. Dyna Soar – Aerospace Projects Review Blog

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