Wernher von Braun’s Fantastic Vision: Ferry Rocket


Fantastic Plastic Models/Allen B. Ury. Used by permission.

Some of the most recognizable and iconic conceptual spacecraft designs ever proposed are those of Wernher von Braun’s space popularization campaign of the 1950s. This post will look at just one of them in detail: the three-stage ferry rocket for launching crews and cargoes through Earth’s atmosphere into Earth orbit that appeared in the pages of Collier’s, a popular American weekly magazine, and the book Across the Space Frontier. I am currently writing a chapter about 1950s space for my forthcoming book; this post is intended as a supplement to that chapter.

The ferry rocket would have been a direct descendant of the Third Reich’s A-4 intermediate-range missile, better known as the V-2. I will describe the development of the A series rockets in my book. For now, it will suffice to note that, in a terrible alternate world where Hitler succeeded in his plans for global domination, enslavement, and genocide, the ferry rocket – had it been built – would probably have been designated A-12 or A-13.

The ferry rocket took three main forms. The first, which von Braun designed in 1948 while interned by the U.S. Army in the New Mexico desert, was relatively stubby. It is not pictured here. As described in Von Braun’s The Mars Project, published first in 1952 in a spaceflight journal in Germany and in the U.S. the following year as a slim book, the ferry rocket’s first stage, to which were attached broad stabilizing fins, was a drum 20 meters in diameter and 29 meters tall with a dry weight of 700 metric tons and a propellant load of 4800 metric tons. The first stage alone would thus have weighed almost twice as much as the three-stage Saturn V rocket configured for Apollo lunar missions, which at about 3000 metric tons remains the largest, heaviest rocket ever built. The second and third stages would have brought the ferry rocket’s total mass at liftoff to a whopping 6400 metric tons, of which propellants would have accounted for 5583 metric tons.

Von Braun’s conservative choice of hydrazine fuel and nitric acid oxidizer was the chief reason his Earth-to-orbit ferry rocket weighed so much. He chose them over more energetic, more efficient cryogenic propellants, such as liquid hydrogen and liquid oxygen, because they were well understood and relatively easily handled. They could, for example, be stored at room temperature without boiling and escaping. The Saturn V, first flown in 1967, relied on liquid oxygen in all three of its stages and liquid hydrogen in its second and third stages.

The second stage would have measured just 14 meters tall from its base, where it joined the top of the first stage, to its top, where it joined the 9.8-meter-diameter base of the third stage. It thus tapered sharply, accentuating the 1948 ferry rocket’s ungainly appearance. The second stage had a dry weight of only 70 metric tons and carried a propellant load of 700 metric tons. It was the only stage that lacked large fins or wings.

The winged, piloted third stage, designed to reach and return from Earth orbit, would have measured 15 meters tall and 52 meters wide across its wings. Von Braun compared its fuselage to a “stubby artillery shell.” He divided its interior volume into two main spaces: a 6.5-meter-long aft compartment for propellants, rocket motors, and valves and pumps; and an 8.5-meter-long, 7.5-meter-wide forward compartment for crew and cargo.

Upon separation from the spent second stage at an altitude of 64 kilometers, the third stage would have weighed 78.5 metric tons. When it reached apogee, the highest point in its elliptical initial orbit, it would have performed the 17-second “Maneuver of Adaptation” to lift its perigee, or orbital low-point, above Earth’s atmosphere. The Adaptation maneuver would have trimmed its weight to 66.6 metric tons. In its nearly circular orbit 1730 kilometers high, the third stage would have completed one circuit of the Earth every two hours.

After dropping off 25 metric tons of cargo, the third stage would have been turned so that its motors faced in its direction of motion. Once positioned, it would have burned 5.2 metric tons of propellants to perform the 14.8-second “Return Maneuver in Orbit.” This would have trimmed its weight to just 27 metric tons, of which five metric tons would have comprised unspecified cargo for return to Earth. After Earth-atmosphere reentry, the gliding third stage would have touched down at a speed of 105 kilometers per hour on wheeled “tricycle” landing gear on a concrete runway near its launch site.

The October 1951 Symposium on Space Travel, held at the Hayden Planetarium in New York City, brought von Braun’s ferry rocket and other spacecraft concepts to the attention of Collier’s editors. On 22 March 1952, they published “Man Will Conquer Space Soon,” a colorful 28-page overview of the Hayden symposium. A description of Von Braun’s ferry rocket, tailored to educate and excite the man in the street, filled nine of those pages; articles on von Braun’s proposed wheel-shaped space station and problems of space medicine and space law rounded out the special section.

“Man Will Conquer Space Soon” was popular enough that it was expanded to 147 pages and published late in 1952 as a book called Across the Space Frontier. A detailed account of Von Braun’s ferry rocket took up more than a third of the book.

It is important to note that the ferry rocket von Braun described in “Man Will Conquer Space Soon” and Across the Space Frontier was not the one he published in The Mars Project and unveiled at the Hayden Planetarium. Working closely with von Braun, artists Rolf Klep and Chesley Bonestell had transformed his stumpy 1948 design into a graceful tapered arrow that loomed silvery gray over its tropical island or sea-coast launch site. The 1952 design is presented in model form in this post courtesy of modeler and model historian Allen B. Ury (Fantastic Plastic: A Virtual Museum of Flying Wonders!).

Because he sought to sway non-specialist Americans, von Braun abandoned the metric system in his new ferry rocket description. In keeping with my policy of employing the measurement units used in my source materials, I will, too.

The 1952 ferry rocket would begin its voyage to Earth orbit and back within an enormous assembly building. Its three stages would be stacked empty – that is, without propellants – atop a square mobile launch pad with a roughly 70-foot-diameter hole at its center. The pad would sit atop four parallel tracks leading to the launch site, where propellant loading would take place. The tapered, finned first stage would measure 65 feet across its base, stand 120 feet tall, and weigh 770 tons without propellants.

The second stage, 44 feet in diameter at its base and 68 feet tall with an empty weight of 77 tons, would be hoisted atop the first stage within the assembly building. Finally, the winged third stage, which von Braun nicknamed the “cabin stage,” would be positioned atop the second stage. With an empty weight 78.5 tons it would measure 19 feet across and 77 feet tall with a wingspan of 156 feet.

To help to avoid damage in the event of a propellant-loading or launch accident, the assembly building would be located several miles from the ferry rocket launch site. As it crept along the four tracks, the 1952 ferry rocket would stand 265 feet tall atop its launch pad; that is, nearly 75 feet taller than its 1948 counterpart, or about the same height as a 24-story skyscraper.

Upon arrival at the launch site, crews would position the hole in the launch pad over a subterranean exhaust tunnel that would divert fire from the first-stage engines to an exhaust outlet a safe distance away from the rocket. They would then begin filling its tanks. The first stage would hold 5250 tons of hydrazine fuel and nitric acid oxidizer; the second stage, 770 tons; and the third, 90 tons. In each stage, the oxidizer tank would sit on top of the fuel tank.

Many modern launch vehicles seek to limit the number of rocket motors they use to climb into space, opting for a few large motors over many small ones. Von Braun, for his part, opted for 51 rocket motors in his ferry rocket first stage, 34 in its second stage, and five in its third stage. He did this in part to permit all three stages of the 1952 ferry rocket to use one type of motor, thereby enabling cost-saving rocket motor mass-production.

Ring-shaped tanks surrounding the propellant distribution systems, located between the bottoms of the hydrazine tanks and the tops of the rocket motors on each stage, would contain hydrogen peroxide. Decomposing the hydrogen peroxide using a catalyst would yield high-temperature steam for driving turbopumps. These would feed propellants into the rocket motors at a prodigious rate.

Von Braun noted that the 51 first-stage motors, with a combined thrust of nearly 28 million pounds, would drain the 5250 tons of propellants in the first stage in just 84 seconds; that is, at a rate of about 61 tons per second. The second-stage motors, with a combined thrust of 1750 tons, would expend their propellants in 124 seconds at a rate of 6.1 tons per second.

The first stage would climb slowly at first, but by the time it shut down would have subjected the six-person ferry rocket crew, strapped safely into protective acceleration couches, to a maximum acceleration of nearly nine times the pull of Earth’s gravity. The second stage would subject the crew to a maximum acceleration of about eight times the pull of Earth’s gravity.

The first stage would shut down under the guidance of an autopilot at an altitude of 24.9 miles, 31.1 miles down-range of the launch site, moving toward the north-east at a velocity of about 5256 miles per hour. It would then separate, clearing the way for the second-stage motors to ignite. The ferry rocket would by this time have tipped from an ascent angle at liftoff of 90° (that is, straight up) to one of 20.5°. After first-stage shutdown, the crew would for a moment feel weightless. The second-stage engine would then ignite, momentarily blasting a conical shield atop the first stage with fire before moving away rapidly bearing the third stage.

The first stage would then deploy from its base a 217-foot-wide “ring-shaped ribbon parachute” made of steel mesh. At its deployment altitude, air resistance would be minimal, so stage and parachute would continue to coast upward to an altitude of about 40 miles before turning nose-down and falling toward the ocean. The conical blast shield would help to protect it from aerodynamic heating during descent. It would attain a descent velocity of 150 feet per second by the time it fell to 150 feet above the water. At that moment, small solid-propellant motors would ignite and burn for two seconds, gently lowering the first stage into the sea 189 miles downrange of the launch site.

A large recovery ship, pre-positioned to collect the stage, would soon arrive. Von Braun envisioned it as a specialized “seagoing drydock” that would partially submerge by filling on board tanks with sea water, move its drydock section under the bobbing first stage, then pump seawater from its tanks to raise the stage clear of the ocean. The ship would then set course for a special harbor close to the launch site so that the first stage could be inspected, refurbished, and reused. The same harbor would, von Braun explained, serve freighters that would deliver thousands of tons of rocket propellants to the launch site.

The 1952 ferry rocket’s second stage would shut down 39.8 miles high and 332 miles downrange of the launch site moving at 14,364 miles per hour and tipped at a gentle angle of just 2.5°. After the third-stage motors blasted its top-mounted protective shield with fire, it would deploy a 75-foot-diameter ring-shaped steel-mesh parachute. The stage would ignite solid-propellant braking motors and slip into the water 906 miles down-range of the launch site just eight minutes after ferry rocket liftoff. A specialized recovery ship would then close in to collect the stage and transport it to the launch site harbor.


Fantastic Plastic Models/Allen B. Ury. Used by permission.

The five engines of the winged third stage – which was, in fact, von Braun’s orbital spaceship – would fire under autopilot control for 84 seconds, burning about 65 tons of its 91.3-ton supply of propellants and subjecting its crew to acceleration equal to twice Earth’s gravitational pull. The engines would shut down 705 miles down-range of the launch site at an altitude of 63.3 miles after pushing the third stage to a velocity of 18,468 miles per hour.

Momentum would carry the third stage toward its operational altitude of 1075 miles. The stage would lose velocity as it climbed and would remain in an elliptical orbit with a perigee of only 63.3 miles. To circularize its orbit and regain speed, the autopilot would fire the motors at apogee for 15.4 seconds, burning 12.1 tons of the 26.3 tons of propellants left on board. This would yield a circular-orbit velocity of 15,840 miles per hour. In 1075-mile-high circular orbit, the third stage and its 36 tons of cargo would need exactly two hours to orbit the Earth.

The ferry rockets would be essential for the establishment of a 250-foot-wide wheel-shaped space station in near-polar 1075-mile-high orbit. The space station will not be described further here, except to say that von Braun thought that it could be operational in 1963 for a total cost of $4 billion. He estimated that perhaps a dozen ferry rocket flights would be needed to launch and assemble all the necessary space station components. After its completion, it would serve as the ferry rocket fleet’s only destination in space. Third stages would remain at a distance from the station; von Braun worried that rocket motor firings might damage it. Instead of docking, pressurized space taxis would carry crew and cargo between third stages and the station.

After completing its mission, the third stage would turn using on-board momentum wheels to point its aft end in its direction of flight, then would fire its five engines for 14.8 seconds. The maneuver, which would occur very nearly over the planned landing site (that is to say, only a few miles from the launch site), would expend 5.7 tons of propellants to nudge the third stage into an elliptical orbit with a 49.7-mile perigee. The third stage would coast toward perigee for 51 minutes. It would reach perigee, halfway around the world from the landing site, moving at 18,500 miles per hour; that is, fast enough to ascend to a 1075-mile-high apogee.

The third stage would use its aerodynamic surfaces to hold itself within Earth’s atmosphere and shed speed over a 13,650-mile glide-path. Aerodynamic heating would boost its surface temperature to 1350° F, causing it to glow cherry red. To deal with the heat, von Braun proposed to circulate coolant between the hull and the outer wall of the crew cabin. Clear coolant would also flow between panes of glass making up the pilot’s canopy and viewports.

The third stage would slow to below the speed of sound (740 miles per hour) at an altitude of 14.9 miles. A short time later, the 29.7-ton glider would extend its landing gear and touch down on a concrete runway at just 65 miles per hour.

“Man Will Conquer Space Soon” was the first in an eight-part series of Collier’s space articles spread over about two years. On 9 March 1955, soon after the Collier’s series ended, Walt Disney Studios aired Man In Space, the first in a series of educational films Disney produced in collaboration with von Braun and his colleagues Willy Ley and Ernst Stuhlinger. The film included an animated account of the first piloted sortie into Earth orbit.

In keeping with its relatively limited mission goals, the 1955 Disney ferry rocket was smaller than its predecessors, though it retained the graceful lines of the 1952 Collier’s design. In Man In Space, it lifts off from a spaceport on an atoll in the Pacific. Its barrel-shaped third stage carry only a single rocket motor and is distinct from the delta-wing crew-carrying glider. The glider has no obvious cargo compartment. For Earth-atmosphere reentry, the crew would cast off the spent third stage and ignite a single motor built into the glider’s tail. Judging only by information presented in the film, it is not clear whether any part of the Disney ferry rocket would be reused. Von Braun’s expansive vision had begun to contract as the reality of space travel moved ever nearer; within months of the premiere of Man In Space, the U.S. and Russia would declare that they would launch science satellites during the International Geophysical Year set to begin on 1 July 1957.


Across the Space Frontier, Cornelius Ryan, editor, The Viking Press, New York, 1952.

The Mars Project (2nd edition), Wernher von Braun, The University of Illinois Press, Urbana, 1962.

Man In Space, Tomorrowland: Disney in Space and Beyond, Walt Disney Treasures DVD series, 2004.

Beyond Apollo chronicles space history through missions and programs that didn’t happen. It is a space history blog, not a blog devoted to current space policy. It is not meant to be in any way discouraging; rather, it is intended to inform and inspire. Comments are encouraged. Off-topic comments might be deleted.

The Mathematics of Ebola Trigger Stark Warnings: Act Now or Regret It

Daliborlev (CC), FLickr

Daliborlev (CC), Flickr

The Ebola epidemic in Africa has continued to expand since I last wrote about it, and as of a week ago, has accounted for more than 4,200 cases and 2,200 deaths in five countries: Guinea, Liberia, Nigeria, Senegal and Sierra Leone. That is extraordinary: Since the virus was discovered, no Ebola outbreak’s toll has risen above several hundred cases. This now truly is a type of epidemic that the world has never seen before. In light of that, several articles were published recently that are very worth reading.

The most arresting is a piece published last week in the journal Eurosurveillance, which is the peer-reviewed publication of the European Centre for Disease Prevention and Control (the EU’s Stockholm-based version of the US CDC). The piece is an attempt to assess mathematically how the epidemic is growing, by using case reports to determine the “reproductive number.” (Note for non-epidemiology geeks: The basic reproductive number — usually shorted to R0 or “R-nought” — expresses how many cases of disease are likely to be caused by any one infected person. An R0 of less than 1 means an outbreak will die out; an R0 of more than 1 means an outbreak can be expected to increase. If you saw the movie Contagion, this is what Kate Winslet stood up and wrote on a whiteboard early in the film.)

The Eurosurveillance paper, by two researchers from the University of Tokyo and Arizona State University, attempts to derive what the reproductive rate has been in Guinea, Liberia and Sierra Leone. (Note for actual epidemiology geeks: The calculation is for the effective reproductive number, pegged to a point in time, hence actually Rt.) They come up with an R of at least 1, and in some cases 2; that is, at certain points, sick persons have caused disease in two others.

You can see how that could quickly get out of hand, and in fact, that is what the researchers predict. Here is their stop-you-in-your-tracks assessment:

In a worst-case hypothetical scenario, should the outbreak continue with recent trends, the case burden could gain an additional 77,181 to 277,124 cases by the end of 2014.

That is a jaw-dropping number.

The epidemic curves of the Ebola epidemic; look especially at the line for Liberia. From Nishiura and Chowell; original here.

The epidemic curves of the Ebola epidemic; look especially at the line for Liberia. From Nishiura and Chowell; original here.

What should we do with information like this? At the end of last week, two public health experts published warnings that we need to act urgently in response.

First, Dr. Richard E. Besser: He is now the chief health editor of ABC News, but earlier was acting director of the US CDC, including during the 2009-10 pandemic of H1N1 flu; so, someone who understands what it takes to stand up a public-health response to an epidemic. In his piece in the Washington Post, “The world yawns as Ebola takes hold in West Africa,” he says bluntly: “I don’t think the world is getting the message.”

He goes on:

The level of response to the Ebola outbreak is totally inadequate. At the CDC, we learned that a military-style response during a major health crisis saves lives…

We need to establish large field hospitals staffed by Americans to treat the sick. We need to implement infection-control practices to save the lives of health-care providers. We need to staff burial teams to curb disease transmission at funerals. We need to implement systems to detect new flare-ups that can be quickly extinguished. A few thousand U.S. troops could provide the support that is so desperately needed.

Aid ought to be provided on humanitarian grounds alone, he argues — but if that isn’t adequate rationale, he adds that aid offered now could protect us in the West from the non-medical effects of Ebola’s continuing to spread: “Epidemics destabilize governments, and many governments in West Africa have a very short history of stability. U.S. aid would improve global security.”

Should we really be concerned about the global effect of this Ebola epidemic? In the New York Times, Dr. Michael T. Osterholm of the University of Minnesota* — an epidemiologist and federal advisor famous for inadvertently predicting the 2001 anthrax attacks — says yes, we should. In “What We’re Afraid to Say About Ebola,” he warns: “The Ebola epidemic in West Africa has the potential to alter history as much as any plague has ever done.”

He goes on:

There are two possible future chapters to this story that should keep us up at night.

The first possibility is that the Ebola virus spreads from West Africa to megacities in other regions of the developing world. This outbreak is very different from the 19 that have occurred in Africa over the past 40 years. It is much easier to control Ebola infections in isolated villages. But there has been a 300 percent increase in Africa’s population over the last four decades, much of it in large city slums…

The second possibility is one that virologists are loath to discuss openly but are definitely considering in private: that an Ebola virus could mutate to become transmissible through the air… viruses like Ebola are notoriously sloppy in replicating, meaning the virus entering one person may be genetically different from the virus entering the next. The current Ebola virus’s hyper-evolution is unprecedented; there has been more human-to-human transmission in the past four months than most likely occurred in the last 500 to 1,000 years. Each new infection represents trillions of throws of the genetic dice.

Like Besser, Osterholm says that the speed, size and organization of the response that is needed demands a governmental investment, but he looks beyond the US government alone:

We need someone to take over the position of “command and control.” The United Nations is the only international organization that can direct the immense amount of medical, public health and humanitarian aid that must come from many different countries and nongovernmental groups to smother this epidemic. Thus far it has played at best a collaborating role, and with everyone in charge, no one is in charge.

A Security Council resolution could give the United Nations total responsibility for controlling the outbreak, while respecting West African nations’ sovereignty as much as possible. The United Nations could, for instance, secure aircraft and landing rights…

The United Nations should provide whatever number of beds are needed; the World Health Organization has recommended 1,500, but we may need thousands more. It should also coordinate the recruitment and training around the world of medical and nursing staff, in particular by bringing in local residents who have survived Ebola, and are no longer at risk of infection. Many countries are pledging medical resources, but donations will not result in an effective treatment system if no single group is responsible for coordinating them.

I’ve spent enough time around public health people, in the US and in the field, to understand that they prefer to express themselves conservatively. So when they indulge in apocalyptic language, it is unusual, and notable.

When one of the most senior disease detectives in the US begins talking about “plague,” knowing how emotive that word can be, and another suggests calling out the military, it is time to start paying attention.

*Disclosure: From 2006 to 2010, I worked part-time at the disease news site, CIDRAP, that Osterholm founded. For that matter, I used to be in a book club with Besser, too.