Hindsight, as the saying goes, is a wonderful thing. From a distance of half a century it’s tempting to say that the United States Air Force’s decision to name their revolutionary space plane Dyna-Soar showed more than a touch of hubris. It’s a name with a certain amount of baggage, a hint of ponderous progress and a tendency towards, well let’s face it, extinction.

Dyna-Soar was a weapon system that would fly around the world at speeds and altitudes that would make it invulnerable and leave conventional bombers and reconnaissance craft in it’s wake. Impressive stuff in the late 1950s. Unfortunately, as with so many of the USAF’s attempts to get beyond the atmosphere, this plan had a few major flaws.

The Dyna-Soar story starts, as so many aerospace developments do, in Nazi Germany during the Second World War. Under the Third Reich, incredible strides in aerospace technology were made and all manner of concepts were considered, no matter how futuristic they seemed.

One such proposal came from Dr. Eugene Sanger, who proposed a horizontally launched, rocket boosted glider that could reach an altitude between 60 and 100 miles. Beyond the drag of the atmosphere, the glider, or Silver Bird as Sanger christened it, would move at hypersonic speeds and cover huge distances. Even more impressively, Sanger and his assistant (and wife) Dr. Irene Bredt calculated that by repeatedly skipping on the atmosphere during re-entry, their glider could actually become a truly inter-continental weapon, bombing American cities while being beyond the reach of defences.

It’s easy to see why the concept would have been so appealing to the Nazi’s, but even they realised that it was well beyond the capabilities of 1940s science. Little was known about the demands of the hypersonic, exo-atmospheric environment and the materials needed to survive the challenging conditions simply didn’t exist. While Sanger’s research continued until the end of the war, it remained a theoretical study.

In the immediate post-war scramble for Nazi scientists and know-how, Sanger’s proposals caught the eye of both American and Soviet analysts. The lure of a weapon that could reach around the world unchallenged was simply too tempting to ignore. The US was quick to obtain material and personnel under Operation Paperclip and while Sanger and Bredt decided to remain in Europe, other key players made the move across the Atlantic and were quick to develop plans for advanced technology under the auspices of the military and industry.

One such figure was Walter Dornberger, former head of Germany’s Peenmunde research centre  – home to von Braun’s rocket programme. Dornberger, initially working with the newly formed USAF but then moving into industry for Bell Aircraft, was instrumental in developing the idea of the rocket boosted hypersonic bomber – a concept that became known as Boost Glide. While it became apparent that skipping on the atmosphere, as proposed by Sanger, would place impractical stresses on a winged craft, it would be possible to boost a craft out of the atmosphere and generate sufficient velocity to allow it to cover intercontinental distances, perhaps even circling the Earth completely and gliding back to base for a controlled landing and re-use.

Dornberger and Bell produced a series of concepts for the Air Force from 1952 onwards under the name BoMi (Bomber Missile). These would use a rocket booster to launch a spaceplane on a ballistic trajectory beyond the atmosphere allowing it to fly at near orbital speeds before gliding back to friendly territory. The Air Force, while interested in these ideas was unconvinced that a manned craft was the best means for delivering weapons across these distances, but limited funding was found for further studies. Concerns that the Soviets were also engaged in Boost Glide systems helped propel these initial developments and the BoMi concept continued to be refined, evolving by 1955 into a two phase programme with sub-orbital and orbital versions, encompassing both bomber and reconnaissance roles.

Realising that there were still a number of technical challenges to be solved before a hypersonic weapons system could be developed, the Air Force initiated a support programme, the Hypersonic Weapon R&D System (HYWARDS) in 1956. This research craft would initially be air-launched, with later flights boosted by an ICBM to extend range, speed and altitude. The Air Force viewed HYWARDS as a logical follow on to the X-15, picking up from that craft’s mach 7 design speed. By now, BoMi had become Brass Bell (Weapon System 459L) and was to be boosted by an Atlas Missile.

1956 also saw the Air Force begin studies on the Rocket Bomber (RoBo) project with Convair, Douglas and North American Aviation joining, but with Bell’s Brass Bell proposal seen as the strongest option. Perhaps unsurprisingly, 1957 saw the Air Force amalgamate Brass Bell, RoBo and HYWARDS into a single programme under the designation WS-464L Dyna-Soar (Dynamic Soaring). By 1959 proposals from Bell (working with Martin) and from Boeing, were under consideration and in November that year the contract was officially awarded to Boeing. This must have come as a massive blow to Bell having worked on the concept since 1952.

With Boeing in place, definition of the project could begin in earnest and it seemed Dyna-Soar was on it’s way at last, but in reality this was just the start of a long and frustrating process. Funding for the project had always been difficult to obtain at a meaningful level, but now as a three phase programme was defined the need for funding became more pressing.

By 1959 the Air Force had already seen the Nation’s manned space programme assigned to the recently formed NASA. Eisenhower had never made a secret of the fact he didn’t wish America’s initial forays into space to be conducted by the military and there was little encouragement or additional funding available for the Air Force to create their own manned space programme.

Dyna-Soar also had a more fundamental problem within the Air Force itself – what would it be capable of doing that other proposed systems couldn’t do just as well for a lower cost? The intercontinental delivery of weapons was now within Strategic Air Command’s reach with their upcoming Atlas missiles. The CIA’s Corona spy satellite system, although plagued by early problems, seemed to offer promise for the reconnaissance mission as did the CIA’s A12 aircraft (although knowledge of this would have been strictly limited).

The proposed three phase approach had an initial test stage to prove the aerodynamic and propulsive systems at hypersonic speeds and altitudes beyond 300,000 feet in support of the development of a full weapons system, essentially the role previously assigned to HYWARDS. A second phase would see Dyna-Soar take on longer range Boost Glide flights with the ability to perform reconnaissance missions and deliver weapons with the required precision. The final phase would see Dyna-Soar achieving orbital flight.

From the outset, it appeared that this three stage approach, although well reasoned, would take too long and be too costly. Initial sub-orbital flights had been proposed from Cape Canaveral down to a landing site at Fortaleza in Brazil, but the State Department soon pointed out that an agreement allowing continued Air Force use of sites in Brazil was unlikely to be renewed. The Titan 1 missile was slated for this mission, but as missile technology developed the Titan II was now suggested as a better option. The Atlas missile and the Army (later NASA Marshall’s) Saturn 1 were also proposed.

But even within a year of Dyna-Soar being initiated, voices within the Department of Defence were questioning it’s usefulness. Much effort was expended to prove that a manned re-usable, hypersonic craft could offer a level of flexibility that the alternatives could not, but doubts were never really silenced. Successive revisions of the development plans now followed and with each revision, each change of role or booster, re-design would be required pushing back the first flight dates while pushing up the costs. To compound the problem, the funding for the initial phases never materialised at the projected levels.

Work on the delta winged Dyna-Soar glider continued with the assistance of NASA who, while not contributing financially, did provide invaluable support on the technical aspects of development. This made sense as Dyna-Soar seemed to offer a logical and desirable step beyond the X-15. In 1960 the Air Force named the initial group of Astronauts for the programme, including NASA project pilot Neil Armstrong. Work on the human factors elements of the design and the flight profiles progressed, but elsewhere problems were mounting.

The Air Force’s recently formed Space Systems Division put forward plans for a lifting body craft called SAINT, aiming to perform many of the tasks already outlined for Dyna-Soar. The result was a series of comparative studies to decide which offered the best use of the limited budget. But not all of the problems were confined to the Air Force. The new Kennedy administration was now examining the Air Force’s proposed role in space and while not entirely dismissive Secretary of Defence Robert McNamara again questioned whether Dyna-Soar was the best way to achieve the proposed goals.

So began an effort to streamline and re-orient the programme. Out went the sub-orbital phase, instead an increased emphasis was put on Dyna-Soar as an orbital system with an expanded role to include the interception and inspection enemy craft. This meant an orbital interstage would now be needed to allow for  orbital manoeuvres and a de-orbit burn. This in turn increased the weight and complexity of the system and necessitated the move to a more powerful booster, the Titan III.

McNamara also insisted that the Dyna-Soar should receive a designation reflecting it’s role as an experimental vehicle in it’s initial stages, and so in 1962 it became the X-20 Dyna-Soar. Unfortunately none of this served to loosen up the official purse strings and underfunding again caused schedules to slip.

McNamara also questioned whether the Air Force would be better served developing their own version of NASA’s then-in-development Gemini craft, once again initiating a series of comparative studies during which the Air Force decided that it would still far rather have a craft that could fly back to Edwards AFB than one that had to be hoisted out of the sea by the Navy.

After limping along underfunded and seemingly unloved for years, the inevitable happened in December 1963 when McNamara announced the cancellation of the X-20 Dyna-Soar. So after over a decade of effort since the first Boost Glide proposals from Bell, the project was dead.

Looking back, the root of Dyna-Soar’s problems was really it’s lack of a clear role. It could have done many things but wasn’t unique in it’s ability to do any of them. NASAs decision to pursue the Space Race with ballistic capsules also undermined it’s utility as the next evolutionary step after the X-15. The Air Force never did manage to make a clear case for putting it’s pilot’s in space. The reconnaissance mission fell to the National Reconnaissance Office and their increasingly advanced Keyhole satellites and the bomber mission was essentially redundant in a world with more ICBMs than it could ever need.

Many within NASA and the Air Force believed that the X-20 could have flown and met it’s mission. Boeing’s design for the craft was sound and a great deal of research had already been carried out to validate the various concepts involved. Had it been given a purely research role and followed on from the X-15 as a joint NASA/Air Force project, Dyna-Soar would have greatly enhanced America’s knowledge of hypersonic flight and the lessons learned would certainly have helped in the development of the Shuttle, but neither organisation had the budget to allow that. The necessity to justify it’s existence in terms of a weapon system placed pressures on the project that it could never really live up to. Attempts to make Dyna-Soar all things to all people ironically made it more vulnerable to cancellation.

As it was, the Air Force did move on to plans for a military version of the now proven Gemini named Blue Gemini leading to a Manned Orbiting Laboratory, but that is a whole other story.

Sources:

History of the Dyna-Soar  – Clarence J. Geiger

The Rise and Fall of Dyna-Soar: A history of Air Force hypersonic R&D – Major Roy Franklin Houchin II

Secret Projects: Military Space Technology – Bill Rose

The X-Planes: X-1 to X-45 – Jay Miller

The X-15 Rocket Plane: Flying the First Wings into Space – Michelle L. Evans

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