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Amazing Stories of the Space Age

True Tales of Nazis in Orbit, Soldiers On The Moon, Orphaned Martian Robots, And Other Fascinating Accounts From The Annals Of Spaceflight

Prometheus Books

NAZIS IN SPACE: PROJECT SILVERBIRD

CLASSIFIED: TOP SECRET IN NAZI GERMANY, DECLASSIFIED AFTER THE END OF WORLD WAR II

A scenario:

March 12, 1945, is a blustery day in Manhattan. Couples are strolling, enjoying the early spring weather. Earnest men dash across crowded boulevards; wool suits, ties, and fedoras are the uniform of the day. It is only 4:00 p.m., but the sidewalks are already shadowed canyons on Wall Street. The district is packed with those departing from work early, eager to begin the trek to the boroughs and home.

Most people are dashing to the subway, while others are engaged in animated conversation as they walk in pairs. The noises of urban life almost drown out the soft, twin pops that echo down the busy avenues, reverberating from the endless expanse of concrete and glass. A few look around, wondering what might have created the odd sound — it was too deep to be a backfiring taxi; it sounded almost like distant artillery. Nobody thinks for a moment that it might signal a few tons of explosive death falling into dense air high above the metropolis. Far downrange, a machine from the future glides silently onward, seeking escape from the impending cataclysm.

Then, a blinding flash of light heats the street to incandescence. Within seconds a shock wave devastates a two-mile-wide section of the city, shattering windows, gutting skyscrapers, and devastating multiple city blocks below. The Chrysler Building and Empire State Building are rendered skeletal, windowless wrecks. Fires rage unchecked, and an estimated 300,000 die within moments. Twice that number are injured. Manhattan is a ruined inferno, its streets scattered with the smoldering forms of the dead and dying. And an invisible enemy — radiation — will stalk the city for weeks.

High above, in the tranquil blackness of space, a lone German pilot attempts to radio his success to Axis ships hiding in the Atlantic, having shaken off his awe at the utter destruction he has wrought. He is mildly surprised to find that his radio no longer functions, but that is of little consequence. His craft, the Silbervogel Amerika Raketenbomber, will cross the United States in record time at Mach 3.4. Soon he will land on Japanese-held territory in the Pacific, and will later be awarded the Reich's highest honor when he returns home by conventional aircraft. His silver spaceship, the bringer of war to American shores, will follow, lashed to the deck of a Japanese aircraft carrier. In Berlin, military planners are certain that World War II will soon be over, and the thousand-year Reich will emerge triumphant.

Of course, this nightmare never occurred outside the overheated minds of a handful of Nazi leaders, a small crew of aerospace engineers, and a brilliant rocket designer. But the Germans did work diligently for a time to develop a nuclear weapon, and Eugen Sanger and his partner Irene Bredt did develop detailed plans for a suborbital skip bomber ultimately intended to bomb Manhattan and other US targets, called the Silverbird.

Sanger was the driving force behind the rocket plane project. Born in 1905, he studied civil engineering as a young man until a stunning new book grabbed his imagination. Hermann Oberth, a German physicist and engineer, had written Die Rakete zu den Planetenräumen (By Rocket into Planetary Space) in 1923. Oberth was an early rocketry pioneer and saw the future clearly: rockets would one day allow people to travel into space. Many scoffed, as people will do when encountering new and visionary ideas, but Sanger, like his future rival Wernher von Braun, was fascinated by the book, and immediately altered his career trajectory to pursue aeronautics.

Sanger joined a group of brilliant young German engineers, the VfR or "Society for Space Travel," that had begun experimenting with rockets. Other nations had their own devotees of rocket propulsion — notably the US and USSR — but the German amateur rocketeers were well organized and made swift progress through the 1930s. As a group they followed the ideas of Oberth, and Sanger and von Braun became enthusiastic devotees. At a time when liquid-fueled rockets were a mere curiosity — Robert Goddard had pioneered the technology in the United States in the 1920s — it was an extremely dangerous endeavor, and experimentation frequently ended in disfiguring explosions. But from such determined origins spring great things, and humanity's reach into space was born in Goddard's workshop and the VfR's fiery experimentation.

In 1932, Sanger joined both the fledgling Nazi party and its elite paramilitary SS — membership in both organizations was beneficial to engineers and scientists seeking to advance their technical careers, especially if the projects in which they were interested had military applications. Like Oberth before him, he wrote of rocket-powered flight for his graduate thesis, which was rejected, as Oberth's had been, for being "too fanciful." Again following in Oberth's footsteps, he later published the treatise as a book.

Sanger's involvement with the Third Reich was preceded by a series of articles he had written for a German aerospace journal about rockets and flight in 1935-36. He was soon engaged to design ramjet engines for the Luftwaffe. But Sanger's passion for rockets could not be long suppressed.

Not far away, Wernher von Braun was designing the V-2 ballistic missile that would soon devastate targets in major European cities. His liquid-fueled rocket had a limited range — about 225 miles maximum — and could carry an explosive payload of only about 2,200 pounds, but was an effective terror weapon. By 1944, the V-2 began a campaign of aerial bombardment that, by war's end, launched 3,000 of the unstoppable weapons against Germany's enemies in Europe, primarily London and Antwerp.

Sanger's project had a more daring goal, however, that attracted some within the German leadership to support his efforts. Since 1942, and with origins as far back as 1938, the Luftwaffe had been supporting a project to enable the bombing of the United States from Germany, or nearby conquered territories. The project was called the Amerika Bomber, and would take various forms as the country slid further into World War II. Conventional long-range planes were proposed and prototyped; a "piggyback" ramjet bomber, carried aloft by a conventional plane, was designed. Sanger had larger ambitions, and worked on plans for a rocket-powered bomber he had long called Silbervogel (Silverbird) that would, in essence, bomb the United States from space. The Silverbird would never advance beyond planning and the testing of small models, but it was an inspired design for the 1930s/1940s.

The rocket-powered bomber would be a ten-ton winged craft (100 tons when fueled), the development of which, even in the limited program — calculations, schematics, and wind tunnel tests — would pioneer ideas and technological developments that would later find their place in the future of spaceflight. For starters, the rocket engine, enclosed in the rear of the fuselage, was to be regeneratively cooled, using rocket fuel circulated through the rocket engine's nozzle to prevent it from being melted by the hot exhaust plume. This was a daring design in the day, causing many engineers to furrow their eyebrows at the thought of combustible liquids moving past red-hot metal surfaces, but it ultimately became the standard of most large rocket engines. The body of the rocket plane had wings, but also utilized what would become known as a "lifting body" principle, wherein the entire airframe generated additional lift. It was also flat-bottomed to allow it to skip along the upper atmosphere.

Like the US Air Force's X-15 suborbital rocket plane, which did not fly until 1959, most of the Silverbird's streamlined length contained tanks to hold fuel. It would begin flight by being pushed down a two-mile-long track by a "caboose," a larger, separate rocket motor that would accelerate the rocket plane to about 1,100 mph by the time it lifted from the track about ten seconds later. The "caboose" would stay on the ground, arrested at the end of the track and returned to its starting point for reuse.

The rocket engine in the rear of the Silverbird would burn kerosene and liquid oxygen to produce its own thrust, firing for four to eight minutes with an estimated thrust of an incredible (and doubtless optimistic) 220,000 pounds (for comparison, the X-15's maximum thrust was about 57,000 pounds; the V-2 created 56,000 pounds). Sanger and Bredt calculated, again probably optimistically, that the rocket plane would attain speeds of somewhere between Mach 13 and Mach 20, depending on the weight of the payload and the mission profile (these were slide-rule estimates; had it been developed into a flight prototype, the numbers would likely have been quite different). The maximum altitude would have been between thirty and ninety miles, the latter of which was well above the generally accepted definition of space, which is about sixty-two miles. Once again, this was a region not experienced by human pilots until the advent of the X-15, which had the advantage of being hauled to a significant altitude by a B-52 carrier aircraft before igniting its own rocket engine. In the late 1930s, the altitude record for powered flight stood at about eleven miles.

Sanger reasonably suggested that the pilot be placed in a reclining position, to better endure the 5–10 g of acceleration that would be experienced under power.

After the initial boost, the Silverbird would be carried by its momentum and increase its range by bouncing off the upper atmosphere, much like a properly tossed stone skipping on a lake. The flat wings and underbody, when appropriately angled, would skip off the denser air below. Each rebound would result in an initial altitude gain of about twelve miles, with each "skip" being somewhat shallower as the rocket plane lost energy. Eight such bounces were estimated before the rocket plane (with the fuel exhausted, it would actually be an unpowered glider) would settle into steady flight. It was considered unlikely that the craft would be able to complete a full trip around the globe to Germany, but since Japan had become a military ally in 1939, the Silverbird could land in a Japanese-held territory in the Pacific. It would then be transported back to Germany by ship, or possibly under its own power — Sanger suggested the construction of refueling depots throughout Axis territory, complete with launch facilities, to facilitate this. Depending on where it landed, the rocket plane would have flown a distance of nearly 9,000-10,000 miles during its primary mission. In scenarios where there was no safe landing site available, Sanger suggested a "sacrificial" bomb mission. He wrote, "Since the aircraft gains altitude rapidly after bomb release in a point attack, the pilot can, at the end of this brief climb, parachute from the plane and destroy the empty aircraft to keep it from getting into the hands of the enemy. He will land a few km. away from the point of the impact of his bombs, and be captured." Easier to say if you are the designer and not the pilot.

The critical part of the flight profile would be the bomb run over the United States, and Manhattan was mentioned as a primary target. The rocket plane would time a dip into the atmosphere to coincide with its travel toward New York, and release its bomb payload, up to 8,000 pounds, to glide to the target. While any attempt at accuracy at this altitude and speed was unlikely to succeed, if the explosive landed anywhere that was densely populated, it would mean a huge propaganda victory for the Reich. For very high altitude bombing, or when a target was not visible due to cloud cover, Sanger rather incredibly suggested that the pilot could navigate via the stars, clearly visible from the Silverbird's intended altitudes, to release the bomb at the proper time and place.

Sanger continues, "Since the target, for the distances involved, will not be visible, the release on an area will be aimed indirectly, e.g. by celestial navigation. Thus it is independent of weather and visibility at the target. Because of this, it does not reach the accuracy of release on a point, and we must expect spreads of several kilometers. So with aerial bombing one cannot hit particular points, but rather a correspondingly large area, with sufficient probability. To achieve an anticipated effect on this whole surface, a single drop will not suffice, rather we will have to project several bombs toward the same target; these will distribute themselves over the surrounding surface according to the laws of chance. The distribution of hits inside the area will not be uniform; the bombs will strike more frequently in the neighborhood of the target than far away; there will also be unavoidable bomb-hits far outside the area being attacked. However, on the basis of laws of probability, the bomb distribution can be predicted well enough so that the goal of the attack can be achieved with the same or even greater accuracy than for point attack." Sanger clearly had great plans for his fleet of rocket bombers. He suggested that the largest single bomb would be approximately thirty-three feet long, the smallest about ten.

In any event, wherever the massive bomb fell, the destruction would have been impressive — 8,000 pounds of high explosive is a major destructive force. Dropping from a high altitude would increase the energy imparted to the target, he reasoned. "Entirely new conditions occur for the area bomb, which has a velocity of impact 10 times as great. The energy of impact is much greater than the energy content of the explosives in the bomb. The strength of the material of the bomb itself will permit it to penetrate a structure, or even to go through a city with numerous buildings, because of the small angle of impact; it will not permit penetration into the earth." In other words, a glancing explosion at the surface of a city would cause a huge, destructive shock wave.

The psychological impact of either kind of bombing would have been immense. By the time serious planning was underway, the Doolittle raid on Tokyo was a couple of years old, but still remembered by the Empire of Japan as a serious blow to their sense of security. That nation had thought itself safe from Allied attack on home soil, and the relatively small number of Doolittle's bombs that succeeded in hitting their targets had left a huge mental scar. An 8,000-pound weapon falling on Manhattan would yield an explosive equivalent in excess of sixteen of Doolittle's 500-pound bombs, and would have had a huge impact on the American psyche, long secure in the knowledge that the war was being fought far from home.

A sign of the optimism that seemed to infect Sanger through 1944 can be seen in his targeting suggestions, for which he wrote, "From the characteristics given for the rocket bomber it follows that this is not the development of an improved military craft, which will gradually replace present types, but rather that a problem has been solved for which no solution existed up to now, namely, bombardment and bombing over distances of 1,000 to 20,000 km. With a single rocket bomber point attacks can be made, from Central Europe, on distant point targets like a warship on the high seas, a canal lock; even a single man in the other hemisphere can be fired upon...." With very limited abilities to target at these speeds and altitudes, however, smiting President Roosevelt might have been a challenge. Sanger continues, "With a group of 100 rocket bombers, surfaces of the size of a large city at arbitrary places on the earth's surface can be completely destroyed in a few days." The Fuhrer must have wept tears of joy when he read this, though he was evidently not sufficiently moved to fund the construction of even one Silverbird.

This was just one scenario — there were also more technologically advanced designs for bringing destruction to America. From 1939 onward, the Nazis had been working on nuclear fission with the ultimate goal of building atomic weapons. It was a vastly smaller undertaking than the Manhattan Project in the United States, but by the end of the war it had made significant progress toward creating enough fissionable material to create an atom bomb. If this device had been made available to a flight-ready Silverbird, the results would have been quite more dramatic than even an 8,000-pound mega bomb. Had Manhattan been successfully targeted, even a Hiroshima-sized bomb would have devastated much of the city. It was an unfulfilled dream, but a terrifying one.

But with the German war machine being ground down and Hitler's iron control of the campaign becoming increasingly irrational, the military's resources were being rapidly consumed. Their atomic bomb effort was comparatively small, and the Silverbird never made it beyond the mock-up stage. There would be no surprise attack on New York City.

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Excerpted from Amazing Stories of the Space Age by Rod Pyle. Copyright © 2017 Rod Pyle. Excerpted by permission of Prometheus Books.
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