Being ahead of your time is a paradox. The further you strive ahead technologically, the bigger your theoretical advantage over your rivals. But as you get further ahead, you run into problems nobody has encountered before.
With the flying wings from the last post, these problems revolved around stability.
This youtube of a pilot from the YB-49 program gives you some idea of what is covered by "problems", but in short a flying wing without a conventional tail had a Dr. Jeckyll and Mr. Hyde personality. Flying Wings are sedate and agreeable to fly -- until you blunder into the Hyde part of the flight envelope. Then, if you get out alive you would count yourself lucky. In the hypothetical world of operational Nazi flying wings, a lot of German pilots would have accidentally bumped into Mr. Hyde.
This was really not a problem the Nazis could have solved, if the Horton Brothers had their way and kept tails entirely out of it. Pure flying wings only returned to serious consideration in the 1970s, after fly-by-wire controls, computers and solid-state electronics had been developed. These new technologies could protect flying wings from their "unrecoverable death" aspects to flying. This technology was undreamed of by World War 2 German Aeronautical engineers.
The rocket-based ideas the Reich had for attacking America suffer acutely from this paradox. The ideas were revolutionary, and would eventually change the world - but these ideas frequently had insoluble problems even on their face, and like Jeckyll and Hyde, the face you didn't see was the real killer. The material problems of the Third Reich sank its Amerika bomber efforts; here the technological aspects alone have the pitches listing as soon as the hull is launched.
The Right Stoff
When reading up for this new post, I discovered something: that the Nazi rocket program that created the V-2 (henceforth the A4) ballistic missile was a incredible break for the Third Reich. First, because it united the Nazis with a group of almost literal starry eyed dreamers in the form of
Verein für Raumschiffahrt [the Society for Space Travel], or VfR. The Nazis wanted missiles for the destruction of various peoples, Nazi super-science, etc, etc, but the VfR wanted to create space rockets, at a time when the Jet Propulsion Laboratory called itself that because 'rockets' were seen as too much a silly sci-fi fictional trope. The second incredible break for the Nazis was that the VfR saw military backing as the only way to underwrite this ambition, and were perfectly happy to create a ballistic missile to further their own ambitions. To that end, the VfR alumni dreamed up a unique development program - the rockets that they planned aimed to be modular, with earlier models forming the basis for later components, with the final rocket in the series being able to send substantial payloads into orbit. The synergy of this rocket with the military? Any rocket capable of orbiting payloads would also be the
world's first ICBM. So the Nazis had found a group that was not only rationalizing production in ways other Nazi industry could only be jealous of, the VfR's end game made their ballistic missile ambitions just the first step in a new world of ordnance types, some of which had not even been conceived of by their superiors.
The VfR was formed in 1927 by engineers and scientists, but also amateur rocket enthusiasts. Inspired by engineer/author/VfR member Hermann Oberth's book
Die Rakete zu den Planetenräumen, [Rocket into Planetary Space], the VfR sought to create the first spacecraft. Grad student Wernher von Braun joined the VfR, as did Dr.
Eugen Sänger, as well as any number of other scientists and engineers that would remain with German rocketry throughout World War 2. One development that would carry into the A4 from the VfR days was the choice of propellant. (Rockets burn fuel with an oxidizer which they carry with them; together this is called the rocket's propellant.) The fuel the VfR settled on was ethanol, diluted by water in a 25%/75% water/ ethanol mix. This was less energetic than the previous fuel, gasoline, but burned at much lower temperatures, which made the building of non-melting rocket engines much easier. The oxidizer the VfR used didn't equivocate: it was liquid oxygen, commonly abbreviated as LOX. Oxygen in liquid form requires energy intensive refrigeration to remain in a liquid state; above -110
Celsius it evaporates, regardless of pressure.
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| Von Braun to the right, harvesting the new prototypes. |
The VfR began to fade in the early 1930s. The ascendant Nazi party was obviously suspicious of any organization not Nazi, and the economic wreck of early 1930s Germany left the organization hard up for cash. At the same time in 1930, the German Army began rocket research, and crossed paths with the VfR; they were allowed to fire test rockets at the Army's artillery range at Kummensdorf. Major Walter Dornberger, an Army engineer and supervisor of the rocket research, was unimpressed with what the Army was doing, and reached out to von Braun to join the Army's research program. Von Braun saw state funding for his great passion (and his PhD) and agreed to join, and the A-series (
Aggregat, German for 'aggregate' [e: 3/19 I'm told by people who know that a closer/more obvious translation is 'power unit/plant") liquid fuel rocket series was born. Von Braun would later write "We felt no moral scruples about the possible future use of our brainchild. We were interested solely in exploring outer space. It was simply a question with us of how the golden cow could be milked most successfully." Dornberger and von Braun would form a dynamic management team that would persist throughout the Second World War, with Dornberger acting as administrator and von Braun being the lead scientist in Germany's liquid-fuel rocket program.
By the late 1930s, interest in rockets had spread in Germany, with von Braun's Army/SS research being but one rocketry lab. Dr.
Sänger had been recruited by the Luftwaffe, and he had his own rocket lab at the Luftwaffe's secret research facility at Trauen, a town between Berlin and Bremen.
Sänger was soon doing impressive research in his own right, operating a firing rocket motor continuously for 30 minutes, using LOX and diesel as propellant. Hellmuth Walter had a lab in Kiel [the adorably named
Wittle Werke] where in addition to his interests in turbine powered U-boats, he had made a successful monopropellant rocket using 80% pure hydrogen peroxide in 1935. The German chemical industry had just perfected a way to industrially refine what would be later called high test Peroxide, and the Luftwaffe almost immediately saw potential, as did Ernst Heinkel. Heinkel was a supervisor of von Braun's work for the Reich Aircraft industry, and was soon dreaming up rocket planes. In 1939 Heinkel built the world's first rocket powered aircraft, the He 176, and Walter's engine would later power the Me 163 rocket fighter. Getting in on the action, too, were engine makers like BMW, and chemical companies like I.G. Farben, who started systematic surveys of the chemistry of rocket propellants. This would soon create a family of rocket and oxidizer combinations, code-named
stoffs. B-stoff for example was the name given to the A4's ethanol and water cocktail, and
A-stoff was LOX.
1935 saw the Army's rocket program start searching for a new test site. There was a need for greater secrecy, as well as ending the constant complaints about the noise, though the most basic reason was that the Aggregate program needed more space, both for testing and production. Von Braun happened upon the future site while visiting friends at Christmas. His friends lived in the town at Anklam, on the banks of the Peen river. Nearby at the river's mouth was an island, Usedom
. This island made for a perfect site for a secret research base. The site was given the name Peen-em-munde, meaning "at the mouth of the Peen".
This move would be completed by 1937, just in time for a contract from the Army. Nazi Germany you may remember, had become worried about Britain maybe *not* being totally cool with their war plans, and this caused a rekindling of interest in strategic bombers that we've covered previously. This strategic rethink gave the Army the shove it needed request a ballistic missile with a range of 300 km (~200 miles), a one ton explosive warhead, and certain physical size limits, as the resulting munition was to be road transportable.
Despite this ferment and research Hitler, initially, was not very interested in strategic missiles; when he was first pitched the idea, he turned it down. At the same time, the SS had emerged after devouring its predecessor, the SA, and had declared all secret research projects their domain. In the case of the liquid rocket staff of von Braun, this takeover also saw the most important heads inducted into the SS. Rocketry now had a very powerful patron in the background, who for the moment was content to remain there.
Aggregate was a massively ambitious project, and every advance in the Aggregate program required multiplying the science and engineering staff by 10. The early experimental rockets, the A1 and A2, were produced with a
staff of about 30. The next prototypes, the A3 and the A5, needed a
staff of about 300. The A4 was going to need a staff of 3000. The most important of these was recruited by Dornberger in 1936,
Dr. Walter Thiel. Thiel was a leading research scientist in rocketry,
and he had sat on von Braun's PhD dissertation committee. Dr. Thiel
would perfect the A4's motor - optimizing the nozzle, shortening the
combustion chamber, and with the help of other Peenemunde scientists (and possibly input from Dr.
Sänger)
used fuel for regenerative cooling - running the ethanol between the
double walls of the rocket engine to cool the engine while warming
the fuel. In an additional cooling feature, tiny holes between the combustion chamber and this flow of ethanol let small drops of fuel
in the chamber, where they evaporated and formed a boundary layer between
the combustion and the walls of the rocket. This feature was removed
during the later production of the A4, but like a lot of the Agregate
series, it was an impressive achievement in its own right.
Anyway, by the late 1930s, all sorts of basic research was being done
into rocketry, and this basic research would suggest further
improvements to the von Braun/Dornberger [Braunberger?] duo. While
Braunberger would have loved to explore these, by now locking in the
design of the A4 forbade giving work already done another pass. So while the science of rocketry would be explored in future Amerika-smashers, as well as other
Nazi guided missile projects, most of these would never see the
light of day.
Peenemunde would become a test range, a research lab, and a prototype factory, with its own supersonic wind tunnel and liquid oxygen plant. From the enthusiast days of the VfW, von Braun and his space-
menchen had come a long way.
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| The Family. |
The Summer of Love
You may have noticed I'm skipping over an actual description of the early A-series rockets; that's because I want to discuss the earlier prototypes and later theoretical projects together. The Agregate series has a confusing chronology, partially because work on rockets after the A4 happened in two distinct phases, one from May 1940 to May 1941, before the A4 was perfected, and the second during the Third Reich's final phase during the fall of 1944 and spring of 1945. The reason for this break is a story in of itself.
In the spring of 1940, Peenemunde is humming along, developing the A4 and growing its science and engineering bench. Then Hitler commits one of those unforced errors he is so famous for. The war at that point was going better than even the Nazis could have dreamed: France was crushed, and the British had been tossed out of continental Europe. So Hitler decides the short, sharp war the Nazis always counted on is happening, and that the war will be over within the year. Hitler then orders all weapons development work to stop unless it'd yield a usable weapon within that timeframe. The lavish budgets going into rocket research were cut. Still, the rocketeers were not defeated. Using what would be named later in
The Producers as "creative accounting", von Braun and the engineers began classifying specific A4 components, such as its fuel pumps, as separate weapons in of themselves. This allowed rocket components to still be worked on while not disobeying Hitler. At the same time, apparently the Peenemunde Brass asked von Braun and company what could be done to extend the A4's range.
I imagine this produced not a little grumbling about "tell me this isn't a government operation", but the liquid rocket staff were nothing if not full of ideas about bigger and better rockets. At the same time, the slack in research allowed von Braun's team to flesh out their plans as to what was next after the A4 was completed. This turn to future designs might have also been a shrewd move by Dornberger and von Braun: the month Hitler crimped Peenemunde's hose [just when the pool was all blown up] Dornberger sent Hitler a letter, describing the possibilities of what the next steps in the Aggregate rocket program could do. This included a multi-stage ballistic missile capable of hitting America. This lull in A4 work allowed later ideas to be worked on until the hose was uncrimped a year later, and Dornberger wisely ordered work on all non-A4 rockets halted. Just to mark this interesting yet confusing period a little more vividly, I'm going to call it the Summer of Love.
With that out of the way, let us talk about the A-series.
The A1 (1933) and A2 (1934) prototypes were small - almost model - liquid fueled rockets. The first A1 test launch ended a half second after it started with a explosion, and it was decided that the oxidizer tank being inside the fuel tank was not a good idea. The stabilization gyroscope was moved from the rocket's nose to the midsection. The A2 made several successful launches. One more thing: all the experimental rockets leading up to the A4 used a tank of compressed nitrogen to percolate the propellants to the combustion chamber. Oh, and apparently the rocketeers tried swapping Dr. Hellmuth Walter's patent high-test peroxide out with the LOX in a A2. The rocketeers then learned you can have too much of a good thing: the resulting explosion killed three Kummersdorf personnel. Non-exploding A2s made 2.9 kN (660 lbs) of thrust.
The A3 (1935-1937) was a much larger prototype, the largest that the Kummensdorf facility could handle. While the engine worked, all launches were considered failures. It soon became clear that much work remained to be done on the guidance system and the rocket's supersonic aerodynamics. Von Braun and Dornberger turned this failure into the road to eventual success in the Aggregate program. First,
post hoc analysis of the rocket film was difficult to do, so future test rockets gained their characteristic checkerboard paint, a tradition that lasted to the end of the Saturn V program. Second, it was decided much more work was needed on supersonic aerodynamics. Finally, Von Braun and Dornberger decided that all rocket components should be tested and perfected on the bench, before being used in rockets. This step, so basic to complex engineering projects today, would slow down development but also give the project the best chance of success. The A3 made 14.7 kN (1497 kg) of thrust, was six meters tall, and weighed 748 kilograms (1650 lb) at launch.
The A4 was of course the A4 (1937-1945) - but Von Braun and Dornberger wisely decided to make another prototype rocket in preparation for it, the A5. This rocket, with a simplified guidance system and a new shape, would be very successful and was the prototype for the A4. The A5 made the same amount of thrust as the A3, as it was the same engine.
The A4 is obviously the famous one. It would accomplish its range goal of 320 km (~200 miles) which it could cover in 3 minutes 40 seconds, being able to reach speeds of 5580 km/h (3465 mph) and altitudes of 96,000m (315,000ft). Its velocity at impact was 2900km/h (1800 mph). It didn't quite reach its payload goal, though later rockets slung better than 900 kg of amatol explosive at the enemy. Amatol was mild as far as military explosives go, being just a mixture of TNT and Potassium Nitrate, the latter of which you might recognize as one of the three ingredients of gunpowder. Amatol was however the only explosive in the Nazi arsenal with the thermal stability to survive the high temperatures it'd be exposed to. Weighing nearly 13 metric tons at launch, the A4 made 265 kN (27,012 kg - 59,552 lbs) of thrust.
Now we get to the Summer of Love. The first successor is
by far the most confusing; no source I consulted told the same story. It was called the A9, and was the first missile design that would step seriously away from the A4 template. The idea behind the A9 was very simple: make a projectile that could glide after reaching apogee, extending its range. This idea was worked on during the summer of love, was put away at the end of it, and then renewed in 1944, once work on the A4 finally started to wrap up.
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| Flight of the glider missile. |
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| The A4b. |
The A9 is described below, because here we get to the confusing part. When the ballistic slingers returned to the design, they decided to make a quick and dirty gliding projectile, one that used the gliding concept but dumped most of the research done, to the point von Braun referred to it as a 'bastard missile'. It was called the A4b, and was quite simply an A4 with wings and a larger tail. The A4b had two major problems: first, the gliding guidance system was not designed. Second, the A4 rotates to stabilize itself in flight, and this isn't an issue as the A4 has small control surfaces. The A4b meanwhile had wings and a larger tail, so even to work reasonably in the first ballistic-ish stage, changes to the guidance system would need to be made. The A4b was the only project after the A4 to see a prototype: two launches that ended in failure (Dec 27th 1944 and January 25th 1945), though the second time the rocket broke up only when it had past its apogee and hit the thicker lower atmosphere. Assuming the glide phase could be perfected, it was estimated the A4b would have a range of 435-450 km (270 miles).
Remembering the awkward naming of the A5, the A6 is usually described as another prototype series, this time for testing better liquid rocket propellants. It never made it off of paper. The A7 and the A8 were two further attempts to explore increasing the range of the A4. The A7 also had wings, but unlike the A4b it was going to be launched from an airplane and hopefully fly like a cruise missile. This saw a few aerodynamic dummies dropped from bombers at Peenemunde, but work did not progress far before the project was shelved. The A8 was going to be an A4 with expanded range and payload, and would use whatever new propellant the A6 program identified. The incredibly named Dr. Wolfgang Noeggerath, one of those propellant chemists who started work enthusiastically cataloging hypergolic propellant combinations in the late 1930s, had calculated that an A4 which swapped out its standard propellant for nitric acid and diesel would gain considerable performance as the energy density of this propellant combination was much better than ethanol and LOX. Another favorite with nitric acid was 'visol', the nickname for a range of vinyl ether mixes. Nazi rocket chemists had started work on the next great problem of rocket propellants: finding a combination that could sit in a missile for weeks or months and still be ready to fire. While ethanol was completely shelf stable if sealed from air, LOX was...a lot more difficult. A fueled A4 had only a few hours of viability to launch before too much of its LOX boiled away. These all saw a little work, but this petered out by 1943.
The A9 was the A4b's properly researched big brother. By itself, it would carry the same payload as an A4 but have a projected range of 800 km (500 miles). But this was to be a dual act with the A10. The A10 was the big boy of the Aggregate line. Started in the late 1930s,
it was initially to be a successor for the A4, lobbing a 4000 kg
warhead 500 km. This work was put down as the A4 demanded more
attention, but was picked up again in 1940 as the basis for an Amerika
rocket - the A10 was now to be a booster to the A9. The goal for the A10 was 180 metric tons of thrust. Dr. Thiel thought it was possible, and in the Summer of Love lull designed a rocket that used six A4 propellant tank sets and six A4 fuel pumps, feeding into a single large combustion chamber. While it was hoped that the A10 would, like the A9, benefit from propellant research, the whole setup could also just use the existing setup in the A4.
The A9 was the second stage to the A10. At the A10's apogee, the
A9 would separate, fire its engine, and then climb to a peak of 350 km
(this is reckoned
to be in low earth orbit, though critically the A9/10 could not achieve
orbit, hence all the malarkey with boost gliding.) On the downward
curve,
the A9 would attain an estimated 10,800 km/h (6710 mph). Then, when the
atmosphere was thick enough, it would use its control surfaces to
glide, supersonic in the upper atmosphere, until reaching its target.
Supersonic wind tunnel tests changed its initial winged A4 configuration
to what would
later be called a lifting body, with a fuselage blending into sharply
raked wings.
As before, guidance system necessary for the glide attack was never developed.
In a running theme for all the post-A4 ideas, the A4's guidance system
was the hardest component of the A4 to get working with 1940s
technology, and unlike other aspects of the Aggregate rockets, it didn't
work in any task but the A4's city bombardment.
Dornberger estimated in his letter to Hitler that at that time, May 1940, the A9/10 multistage would take until 1945 or 1946 to complete, if started immediately. Unlike
other post A4 projects, both these rockets would see some development
time, with a test stand in Peenemunde being built for a engine that made 200 metric tons of thrust. While neither would be built, the level of work done on these made it plausible construction of prototypes could have started.
There's two more rockets after the A9/10 combo, but these were purely design studies. The A11 was a third stage to the A9/10. The A11 was just on the edge of being able to place small (less than 300 kg) into orbit, but was pitched as a way to keep communication with Japan. The A11 was going to be six A10 rockets mashed together, making 1,080 metric tons of thrust. The final Voltron-like gestalt of the Agregate rockets was going to be the A12, which was another, larger stage on the A9/A10/A11 conglomeration. It was, of course, six A11s [that's 36 A10s, or 216 A4 rocket motors, if you prefer] mashed together, making 6480 tons of thrust. This rocket, assuming it worked, would be able to orbit payloads of 10 metric tons. These last two, however, were shelved-
- in May 1941 when the Summer of Love ended. Dornberger forbade work on anything but the A4, and it would be another year and change before the A4 would be successfully fly on the 3rd of October 1942. This was the launch that preceded the famous announcement over Peenemunde's PA system by Dornberger that Peenemmunde had created the world's first spaceship.
One additional boost to the program was the accidental death of the Nazi Minister of Armaments Fritz Todt on February 8th, 1942. Todt had never been a big fan of the Aggregate program, but his successor, Albert Speer, appreciated the possibilities of the new rocket technology, and would as far as he was able, act as an advocate for it. This was fortunate for the A-series, as now that the technical goals had been achieved, it was time for Nazi industrial politics to slither out of its nest.
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| The A4's motor. |
Ride the Snake
The A4 was a technical triumph, the product of 12 years of work - and this was the start of much more work. Now the basic design had to be revised to make it suitable for mass production, and
Reichsführer-SS Henrich Himmler took authority away from Dornberger and von Braun's team to make further changes to get the new weapon into production as soon as possible. (Given the possible improvements Peenemunde was already considering, this was wise.) In late 1942 work also started on building the industrial infrastructure A4 production would need. In addition to factories for manufacturing, liquid oxygen production also had to be expanded. In the not-yet sarcastically named Greater German Reich, total liquid oxygen production could only meet the needs of 15 launches per day - and some of that was being used elsewhere for welding. [In an irony, one of these rocket manufacturing plants was going to be Zeppelin's production facilities at Friedrichshafen.]
The Peenemunde staff, much to their annoyance, were reassigned to A4 production problems. Up to this point they had been blazing entirely new trails; now they were working on a constant parade of manufacturing issues, which they felt was beneath them. Dr. Thiel in particular is reported on being burnt out by the end of 1942, thinking the A4 was a doomed project, and wanted to return to academia. I've been skipping over how many rocket explosions the program had produced, but now that the prototype worked, the Peenemunde suddenly found themselves vaporizing test stands again, trying to perfect a mass- production model. That couldn't have been easy on the nerves.
Indeed, the A4 program became the hottest thing in
lederhosen - and that was a problem. For instance, German industry was increasingly enthusiastic about the possibilities of rocketry, and in spring 1943 made an offer to the Third Reich to buy Peenemunde and all its rocket intellectual property. It would then make Peenemunde a state owned by German industrial giants, who would administer the place themselves. It would then produce A4s and sell them to the Third Reich at a fixed price. This odd plan was never implemented.
The tide of political complications kept coming in. Once the A4 was proved viable, the Nazis saw fit to convene a steering committee for getting the A4 mass produced, and appointed Gerhard Degenkolb to head up the committee. Degenkolb was a fanatical Nazi who through a management style you'd expect of a fanatical Nazi: he demanding absolute obedience no matter how ill-advised his commands were. He dove headfirst into his new job, setting production goals and threatening people, and soon the Nazis had parallel production committees. One was chaired by Dornberger and knew what it was doing, and another parallel bureaucracy that was setting goals and trying to legislate production without any sort of real understanding. Dornberger would come in to find Degenkolb had set production targets of 600 missiles a month by the end of 1943 without any planning as to how this was to be done.
The A4's viability also saw Army generals jumping in to the program to demonstrate how important their input was. From the start, the Army and Peenemunde had agreed that the A4 would be road mobile and fire from relatively simple launch areas. The Generals disagreed, and thought the REAL way to deploy the A4 was from a few concrete missile fortresses, constructed in France. In addition to being bomb proof, it was hoped these missile bunkers would produce the LOX needed for the A4s on site. Dornberger fought this as idiocy, understanding that these missile castles would attract Allied bomber attacks. This conflict went all the way to literally Hitler, who decided in favor of the Army, saying "every bomb that drops on [these bunkers] is one not falling on Germany" at a decision-with-Hitler meeting on July 7th, 1943. As if this wasn't enough, the A4 suddenly had a rival. The Luftwaffe started developing a missile that was the opposite of the A4, the Fiesler 103, later known as the V-1 or buzz bomb, the world's first cruise missile. Cheap and low tech, the Fi 103 was intercept-able by aircraft or artillery - but was also very simple to make, and could carry a much more potent warhead.
This lead to a very fateful day, the 26th May 1943, when the A4 and the Fi 103 had a fly-off in front of the Nazi's top leadership. In a reversal of fortune, this fly-off had been masterminded by RLM head Ernst Milch, to show up the (Army/SS) A4 with the (Luftwaffe) Fi 103. As it happened, the Fi 103 had problems working, while the A4 performed flawlessly. This day is important in the A4 story because it finally won Hitler over completely to Team Rocket. Hitler would later actually write a letter apologizing to Dornberger about not getting the rocket thing earlier, saying "I have had to apologize only to two men in my whole life. The first was Field Marshal von Brauchitsch.
I did not listen to him when he told me again and again how important
your research was. The second man is yourself. I never believed that
your work would be successful." Here was a technology that checked all of Hitler's boxes. It didn't require pilots. It used fuel that was not gasoline. Once in flight, it was unstoppable by air defenses. It promised the retaliation that the Luftwaffe was unable to deliver against Hitler's enemies. Hitler then made the A4 the Third Reich's top industrial priority, even above jet turbines.
To that end, plans for rocket production in factories in Peenemunde and elsewhere were made. But these plans would see a little hicup along the way, which lead to quick revision.
Hail Hydra
The Allies had been well aware of Germany's ballistic missile research, and now alarmed at how close the missile was to production, decided to tip their hand. After Winston Churchill himself authorized Operation Hydra, 600 Allied night bombers attacked Peenemunde on the 17th of August 1943. The goal of the attack was simple: to try and disrupt the missile's production by destroying facilities and more importantly, killing as may German scientific staff as possible. The raid did cause significant damage, but Peenemunde was a Missile test range, and by necessity, a place built to be resistant to explosions. Almost no technical personnel would be killed, as regrettably, most bombs fell on the barracks of the Polish "guest workers" instead. The one technical person the allied Raid *did* manage to kill, however, was a devastating blow to the development of projects past the A4, because it was none other than Dr. Thiel himself. Thiel had been in a slit trench with his family during the raid, and the trench took a direct hit. Dreams of new and bigger rocket engines, already crowded out by the nonstop struggle to make the A4 production ready, became that much more unlikely.
The raid was also an embossed card from the Allies to the Nazis that they were aware of what the Nazis were doing. Shortly after, the two alternate sites for A4 manufacture were bombed to shattered bricks and twisted metal. But, the SS had not been idle on the missile portfolio in 1943.
Day and night Allied strategic bomber attacks were now doing serious damage to Reich industry, so the SS had started digging many bomb-proof production spaces wherever they could find suitable rock. They would in fact construct some 250 of these spaces, and it was obvious that the A4 would need space like that if it was to enter production. So, the A4 would be made in the most infamous of these subterranean factories: Mittelwerk.
Mittelwerk ['Central Works'] was the stuff of nightmares, an Amazon fulfillment center taken to its logical conclusion. It was near Nordhausen, a campus of the Mittelbau-Dora concentration camp. Mittelwek has started innocuously, as a gypsum mine, and expanded as a underground fuel and
chemical storage facility, and was then repurposed and expanded further to be a series of
underground factories. It was managed and laid out by Hans Kammler, the civil engineer that had helped design Auschwitz. Mittelwek's purpose then was twofold: to make Nazi war weapons, while extracting as much labor as possible from
untermenchen before killing them. It was always very good at the second, to the point an on site cremotorium was needed, and eventually managed to get the hang of rocket building. In addition to the A4, the Fi 103 was produced there, alongside several other aircraft manufacturing plants. By the time production had wound down in March 1945, some 5000 A4 missiles would have been constructed. Built mainly by Polish, Soviet, and 'criminal' forced labor, it's estimated some 10,000 people died while working on A4s, with a further 5,000 dying in other parts of the A4 production system - three times more people than would actually be killed by operational A4s. Both von Braun and Dornberger would oversee Mittelwerk, with von Braun himself calculating how many slaves would have to be delivered to replace the ones that died that week. I emphasize this because starting with Operation Paperclip (which aimed to shield Nazi scientists from war crimes tribunals in addition to employing them), and for about twenty-five years after the war's end, the role of von Braun and Dornberger in the Nazi regime was whitewashed. Only in the 1970s did some awareness generally develop that the factory making A4s and Fi 103s did not only use slaves, it was a factory that was about as integrated into the holocaust as the SS could make it.
I'm going to skip over the actual deployment of the A4, as this post is already long enough, and the campaign is closely studied, but the first successful A4 was launched on September 6th, 1944 at Paris. Both these launches failed, and were complicated by 'skirmishes with the Belgian resistance', which is not generally a thing that say, NASA would have to contend with. The launch target may have been a tip of the hat to how the Army saw the A4: as a successor to "Big Bertha", the legendary long range gun that bombarded Paris in 1918. It was only in the fall of 1944 that von Braun and the Peenemunde staff finally had the time to consider new missiles in the A-series. A rocket to hit America with was now considered a high priority, and so the A9/A10 program was activated again, as well as somewhat desultory efforts to make a longer ranged winged A4, as noted above.
As I've said, the A9/A10 had been fleshed out fairly well over the course of the war; unlike most of the other missiles past the A4, it was possible to start construction of prototypes. And it is here that the program fails to launch and crashes back into its launchpad, exploding with a whole series of real and theoretical failures:
First, theoretical work had suggested that if the A9 was constructed from steel, it would be able to handle the high temperatures the A9 would encounter in flight. These calculations were wrong, and post war research would show that the temperatures the A9 would have faced were twice what were expected. To deal with that, lots of fancy metals were needed that if Germany had at all, it was making into jet turbines.
Second, A9/A10 didn't have the range to hit America from continental Europe. Even with the boost-gliding of an A9, the missile had a range of
4800km (2800 miles), a fair distance shorter than the magic 5500 km mark
needed to hit New York City from continental Europe. This "not actually
intercontinental" feature puts it in good company with other proposed
Amerika bombers.
Third, there was the problem of the A9's guidance.
The A4’s CEP [circular error probable] was a circular 6 km over its maximum 320 km range. CEP is a metric used in guns and artillery to express the accuracy of a given gun minus the more usual variables, and describes the circle that the gun/cannon/missile will fall 50% inside of, and 50% outside of. In other words, a A4 launched at a target had a 50% probability of hitting within 6 km of the aiming point. Now, as 20% of all operational A4s failed within sight of the launch point, I suspect that accuracy of A4s that made it to target was somewhat higher than that, and this also likely improved as manufacturing improved.[Note: I had a section here on the A4's guidance which I'm going to do as a seperate post, as I think it gives a good idea about why improving guidance was such an intractable problem for Nazi Germany.]
Still, this system couldn’t guide anything intercontinental. In the book Command and Control, General Curtis LeMay, commander of the post-war USAF strategic air command, estimated that a hypothetical intercontinental A4 would have a CEP of 100 miles (160 km) which was too large, even for the bombardment of enemy cities as the A4 was used for. Even the A4 had to deal with an intimidating series of variables, and intercontinental guidance systems have to take into account quite a few more, like the rotation of the earth relative to its launch point and target, and the speed of this rotation depends on latitude. “If the missile’s velocity was miscalculated by 0.05%, the warhead could miss its target by 20 miles.” (From the book Command and Control, page 225.) The A4’s guidance system was completely out of its depth with this sort of challenge. Any new system would have to be a clean-sheet design.
So: the upper stage of the A9/A10 was manned. It was hoped U-boats at sea and automated weather stations in Greenland and Labrador could assist in navigation. The manned part was for, if you pardon the pun, terminal guidance; the pilot would target his craft optically, and then bail out once locked on to Manhattan or Scranton, Pennsylvania. Hopefully, to stretch that word in ways never intended, the pilot would bail out over the ocean and survive the cold Atlantic to be rescued by submarine. The whole thing is so implausible that one of the books I consulted on this dismissed the whole idea out of hand as just too silly, even in this arena [viz. hypothetical Nazi weapon programs,] which is saying something.
Of course, even these problems were theoretical, production space at Mittelwerk set aside for A9/A10 prototype production was taken over by a synthetic fuel plant, and that was that.
So, the idea went nowhere, only existing as plans which von Braun packed away and hid in a disused mine, along with all the other papers from the A-series program. Peenemunde was evacuated in February 1945 as the Soviets advanced, and production in Mittelwerk wound down on March 1945. Von Braun and Dornberger eventually made their way to Oberammergau, where they surrendered to the Allies.
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| Regular mortar rockets, but submarine. |
PRUFSTAND XII
In May 1942, a Type IX U-boat, U-511, fired while submerged 21 cm artillery rockets from an improvised rocket rack. This had been something of a weekend experiment for Von Braun and Peenemünde staff - the captain of the U-boat, Friedrich Steinhoff, had a brother who was the Peenemünde rocket engineer in involved with guidance systems, Ernst Steinhoff. Captain Steinhoff had seen the eastern seaboard of the United States through his U-boat's periscope, and had wondered if it would be possible to attack land targets while submerged. The test was totally successful, and aside from some improvised paraffin for waterproofing, the rockets flew completely normally.
The Kriegsmarine didn’t much care about the results. This was because Peenemünde was of course an
Army research group and because the Navy wanted to sink ships, not give
der Fuhrer any unfortunate, resource splitting ideas about submarine rocket bombardment. This is perhaps why when the German Navy did start working on its own rocket, it was something that in no way could be used for non-naval purposes: a large rocket that a U-boat could fire in self defense to sink Allied escort ships. This was still being worked on when the war ended, though one Type XXI U-boat was equipped with a single launch tube for this testing this weapon.
That didn't stop related ideas from being proposed.
In 1943
Deutsche Arbeitsfront [German Labor Front, the Nazi organization that replaced all unions] official Otto Lafferenz, witnessed a test launch, likely the same test launch that made the A4 in the eyes of Hitler. Lafferenz was a cog of influence in the Third Reich machine. He had been a key player in the creation of the Volkswagen. Hitler and Henry Ford were mutual admirers, and Hitler loved the idea of creating a people's car for the Third Reich. Ferdinand Porsche would design it (possibly cribbing parts or the design entirely from Jewish Hungarian engineer Josef Ganz) and the car was announced with great Nazi fanfare. Lafferenz got the idea of a "subscription fee" for the workers under the German Labor Front, a deduction from worker salaries to pay for the Volkswagen and a factory to build it in. When Hitler laid the cornerstone of the factory on the 26th of May 1938, he dubbed the VW the "Strength Through Joy Car", an ad campaign that was not taken up post-war. Of course, the workers never got the Volkswagen they paid for; once the factory was complete, it was used to make
Kübelwagens for the German army. The Nazis were dicks.
Anyway, so when Lafferenz got a brilliant idea in late 1943 as to how to attack America with the A4, he could pitch his idea directly to Dornberger himself: after the test launch, Lafferenz went to Peenemunde and suggested to Dornberger using towed submarine barges to take A4 to bombard the US eastern seaboard. This was considered a good enough idea that some work was done on it. This project was known as PRUFSTAND XII, or ‘launch stand 12’.
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| To steal somebody else's perfect comment: "I'm the guy in the control room six feet under the business end of a
V-2, ten feet above what appears to be a fuck-off huge tank of
pressurized LOX, fifty plus feet underwater, attached to a submarine by a
cable."
|
The advantage to the plan was that making a barge submarine was relatively easy. Just using steel and leftover U-boat bits, you could make a barge that could submerge itself, and be towed by a U-boat. These ballast tanks could also flip the barge into a launch position on the surface. Most sources agree that the missile was to be launched from the surface for simplicity's sake. Another advantage to this plan is that the launch could be made far out to sea, away from America's coastal defenses. Eager Nazi beavers figured the forthcoming type XXI U-boat could tow up to three such barges. The construction of a prototype submarine barge happened in 1944 at the Vulcan shipyard at Stettin. This apparently did some towing and submerging tests with a U-boat.
On the positive side of the ledger, using a submarine for strategic strikes against land targets would be a revolutionary idea that would see a lot of research post war. Even the idea of using towed containers to carry missiles was examined by the Soviets and the United States.
Nothing came of this project for a simple reason: the A4 was extremely unsuited for it. The missile itself was fragile to the point operational units were instructed to treat the missile as 'you would treat an egg.' As a missile that took thirty trucks and about 100 men to launch on land, it was not the sort of thing you could just bodge into a barge and a month later expect to work. The liquid oxygen part of the propellant, too, was an intractable problem. Fully fueled missiles had to be launched in a matter of hours, before too much of the oxygen boiled away. It was estimated a U-boat and its missile would take 30 days to go from Germany to a firing position off the US seaboard.
The Cold War superpowers, faced with the same problem, would do what the Germans would have had to do but couldn't: design a 'navalized' version of their ballistic missiles. The USSR and America, of course, also could work on the other two problems: guidance systems that were accurate to tens-of-meters over thousands of kilometers, and have nuclear weapons, which made a missile orders of magnitude more destructive. Had the A4 barge attack thing worked, it would have been a purely propaganda exercise, like an Amerika bomber strike. One fact that the British especially like to cite is that the sum total weight of explosives delivered by the V weapons was still less than a single late war Allied Night Bomber raid. So imagine that, and now imagine having to tow your A4s across the Atlantic first in submarines.
Interest seems to have briefly returned to the project in 1945. As mentioned before, the Nazis had done a fair bit of work to develop new propellants,: one of these being nitric acid and visol. It was thought at the time that the visols were non-corrosive and shelf stable. This combination was to be the propellant of the
Wasserfall SAM. There's a line of thinking out there that says very late in World War 2, the Germans wanted to build A4s with this propellant combo and use them in the submarine barges. This could be, though my own instinct is that sudden frantic interest in Prufstand XII had more to do with "you can't draft me! I'm building a WAR-WINNING weapon!" thing, or was part of a propaganda con the Nazis had going.
In early 1945, the Germans managed to via propaganda broadcasts make
vague promises on submarine-launched rocket attacks - V-1s or V-2s -
against the United States, with even Albert Speer making allusions to missile attacks via submarine in a radio address. The USA, worried about this and the
possibility of WMDs missiles,
mounted
Operation Teardrop
to protect against this. Working on a submarine barge would have been a useful bit of theater to sell the lie. By March 1945, angry
tweets from the Nazi propaganda machine were in many ways all the Third
Reich had left, and misinformation campaigns playing up Nazi
wunderwaffen was about the only trick the Allies fell for.
One more point: America immediately after the end of the war, found itself on the same path Nazi Germany had been on, first experimenting with captured A4s, and then moving on to develop storable propellants. Like Germany, America was soon sold on using visols with nitric acid, and bought
stainless steel drums and even stainless steel railway tank cars for
storing visols. It was
then that it was discovered visol 1) corrodes, even stainless steel, and
2) gunk (the technical term) starts to precipitate out of visols after
about a week, which if used would very likely clog fuel lines at the
vital ignition moment. The USAF then had to scrap a bunch of stainless steel
railcars now clogged with unidentifiable gunk.
What is Reality
Those among you who know your space-stuff may have marked that a lot of the running around on this issue was caused by the Germans not having a large enough rocket to reach America (or orbit) directly. The basic physics of rockets was well understood even then, and it was clear that to get a rocket to do either of those things, you were going to need to have new engines and have a rocket that was much bigger than the A4. That made the idea a non-starter for the Nazi top brass, as even an optimistic estimate as to how long this would take to develop was something like 5+ years, a time span not really sellable in wartime.
The Von Braun/Peenemunde approch was to attack the problem obliquely, via their modular rocket systems. There was another team, though, that had a different solution.
The team was Professors Eugen
Sänger and Irene Bredt, and their creation was the
Silbervogel, or Silverbird spaceplane. It's also known by the astonishingly modest name
Raumgleiter, or space glider.
We got introduced to
Sänger a while ago, as he was a VfR alumni who found himself at the head of a rocket lab during the
explosion of interest flourishing of rocket science in the Prewar Third Reich. At the
Trauen lab,
Sänger would meet Dr. Irene Bredt,
physics Phd and later head thermodynamicyst at Trauen. While they would marry postwar,
Sänger and Bredt were clearly birds of a feather even before the war's start, as they began drawing up plans for the Silver Bird and their scheme to sidestep the restrictions that kept spacecraft from orbit.
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| Range chart. |
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| Two visualizations of skip-flying. |
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| A chart estimating bombing effectiveness with various tactics. |
These plans showed up unsolicited on the RLM's doorstep on in 1941. You can actually read this 175 page submission's 1944 version
[here], as it was translated post-war. The craft described by the text was phenomenal. The Silver Bird was to be a space-plane that would first use a rocket engine much more powerful than the A4's to climb to the top of earth's atmosphere while gaining enormous speed: 36,000 km/h. Instead of launching vertically, like von Braun's rockets, the Silver Bird would launch via a three kilometer long rail. It would have its own engine, but be boosted through the lower atmosphere by a first stage rocket that would be jettisoned once empty. Then...have you seen
Apollo 13? Do you remember where the space capsule has to hit the atmosphere at the right angle, too steep you burn up, too shallow you'll skip off the atmosphere? Well, the
Silbervogel aimed to skip off the atmosphere in a controlled fashion, using the atmosphere as a stone would as it skips across a pond. While each skip would rob momentum from the Silver Bird, starting from 36,000 km/h give you a hell of a lot of momentum. Once the
Silbervogel had lost sufficient speed, it would re-enter the atmosphere and land like a glider (or the space shuttle.) The documents promised an incredible spread between range and payload, with strikes on Britain allowing for 65 metric tons of bombs per Silver Bird. Trans Atlantic flights figured a bomb load of 3.6 metric tons. The
Raumgleiter attack speed “just” 14,000 km/h at a 50 km altitude. It would be manned by a single pilot. In practice, the Silver Bird is not all that different from the A9; it used a lifting body with small control surfaces.
Strikes against the hated New York were also sketched out, as well as an estimate as to how many tons of bombs and flights it would take to reduce Manhattan to rubble: somewhere between 420 tons to ~ 5000 metric tons of bombs, assuming they could achieve accuracy like a conventional bomber. (a not small assumption we'll get to.)
The heart of the Silver Bird was a new rocket engine design, one that produced vastly more thrust than the contemporary A4. This was achieved through regenerative cooling, which Dr. Thiel might have picked up from Dr.
Sänger. The first stage of this skytrain had a short but extremely strong burn of 600 tons of thrust, (600,000 kg, or 660 tons) consuming its fuel in just 12-18 seconds. I'm not really clear if this was part of the rocket sled or if the inital acceleration down the 3 km rail was
another rocket, and the first stage fired when the
Silbervogel went airborn. At any rate, the first stage seems to be about getting the
Silbervogel out of the lower atmosphere. Then, the Silver Bird itself would spread its wings and fire a longer-burning but less powerful engine producing 100 tons (100,000 kg or 110 tons) of thrust for three to eight minutes. Then, it would entered into its controlled bounce phase of flight.
To put that in perspective, the A4 made only 27,000 kg of thrust. Or to put it another way, the legendary F-1 rocket engine, five of which made up the first stage of the Saturn V, made 690,000 kg thrust, so the Silver Bird was assuming an engine power that was simply incredible. This is made slightly more palatable in that the F-1 was developed only 15 years later, but this engine was still something else.
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| I've been doing this too long, it's bugging me this thing is flying in from the west instead of NNE. |
So, undefinable globe-spanning spaceplane, capable of reducing the enemy's cities to rubble regardless of location. How could the Nazis say no to that?
A few ways. The RLM rejected this idea out of hand as being too ambitious, and for once, they were right. All these ideas were very interesting, but it's clear that the Silver Bird wasn't so much touching on unexplored ideas as ramming into them at supersonic speeds; even von Braun's ICBM was a scaling up of an existing idea. Actual development along these lines post war revealed other issues that would have likely doomed the project, even assuming the Greater Reich would have been around in the early 1950s to develop it.
The main problem was very similar to the A9's issues: the temperature stresses were considerably beyond what Third Reich materials science was capable of handling. Unlike the A9, it seems like exotic metals were under consideration from the start, but I still think the heat (not to mention other stresses) would have been too much for the craft, unless foolish time travelers could have lent
Sänger all of NASA's 1970s material science. I'm not a highfalutin Phd in flyin' stuff, but I also think the skimming would be very difficult if not impossible to control. Later supersonic and high altitude test flights in the 1950s and '60 would show that the edge of space is difficult to fly even at supersonic speeds, because - aerodynamics stops working when there is no air. (The crash of one of the X-15 craft is a good example of this; the X-15 was also a later project of Walter Dornberger.) This was all stuff that would have to be found out experimentally, at least a few that would end as an explosion raining down exotic alloys.
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| The only empirical research done on the Silbervogel was building and testing rocket engines. |
Weirdly, Sänger himself also found flaws in the plan. Unlike the A9, the Raumgleiter was always pictured as piloted. But, it still had the problem of guidance to contend with. Like von Braun, Sänger could only weakly gesture at the type of guidance systems an accurate bomb strike would need from 50 km up. Sänger calculated that two bombs released at a 50 km altitude could land up to 1500 km apart, which raised serious questions of the project's utility. Some sort of guidance system would have had to have been devised for ordnance, but this was a project not even explored on paper. Astronautix quotes Sänger as estimating a 20 year development time, and that would be an enormous ask right now, today. Back in the 1940s, such an estimate must have seemed ludicrous.
Despite the RLM's dismissal of the project, work continued at the Trauen lab on the Silbervogel. While most of this was sketches and design studies, several small-scale tests were made at a regenerative cooling rocket engine. This would be the legacy of the Silver Bird; this sort of rocket engine is still used today, and is called the Sänger-Bredt engine in honor of its inventors.
So, all these ideas would be revolutionary - but they didn't give the Reich victory, or even a respite. In a irony, it was the primitive V-1 that would consume the most Allied resources in defense, because it alone was the only missile that could be intercepted or shot down. The other thing I learned was a bit more subtle. The story really shows that the "winning through better technology" really was a forlorn hope to counter the Allies Material superiority. The Nazis did manage to advance ahead of their enemies in rocketry, and the A4, once launched, was impossible to defend against. But RnD advantage only lasts a short time, and you got that advantage through - resources. While you were working on Rockets, even if the enemy was not, they were spending money on all sorts of other advances that you are not. So unless this secret advance literally wins the war for you at a stroke, your bigger enemy will adapt and you're back to where you started, materially speaking.
One more thing: the Nazis had missiles but no way to deliver them to
American targets. While the Japanese had developed aircraft-carrying
submarines, and had attempted to build a fleet of 24 globe spanning
submarine carriers in the I-400 series. You want an alternative history with attacks on America?
Get the I-400s built a year or two earlier, and then load them with
German missiles.
Part of the America Bombers Series
Part 1: Black Gay Hitler
Part 2: Vague Plans and Flying Boats
Part 3: Walking on Sunshine
Part 4: Stuffing arrogant mouths
Part 5: Eris is Goddess
Part 6: Ragnarocky Road
Part 7: Look Busy and Hope Americans Capture You
Appendix: A4 Guidance
