Rockets Through Space, page 2
Men have been fighting their way up through this deep blanket of air for a long time now, and have barely begun to gain any real success.
The first passenger-carrying balloon marked the beginning of man’s ascent into the atmosphere. It rose in 1783 to a height of over half a mile, which was the first time men had ever gotten above the ground for any length of time without something on which to stand. The feat threw the whole world into a frenzy of excitement. Kings went up in balloons. The papers were filled with accounts of more and more flights. Stories revived the old idea of going to the Moon, even though wise men knew balloons could not rise out of the atmosphere.
In the long run, nothing came of it. The highest men ever went in a balloon was in 1935. That feat required vast sums of money for a very special type of balloon, designed to carry up men and a few instruments to study the air, as high as it
could go. It reached 72.000 feet—about 14 miles, just nicely into the stratosphere. To go higher than that would cost far more than it could ever be worth, since the lifting power of the air falls off so rapidly. A few unmanned weather balloons have gone about 5 miles higher, but that seems to be the limit.
There was new hope when the airplane was invented. A balloon depends on having a gas inside which is lighter than the air; hence, as the air grows thinner and thinner (until it weighs almost nothing), the difference in weight between the gas and the air becomes less and less. On the other hand, a plane is held up by the lift gained from its forward speed—as it goes faster, it can travel through thinner air. The answer seemed to be to build planes with greater power to go faster and climb higher and higher. Lord Dunsany wrote a story in which such a plane reached a speed high enough to leap completely out of the atmosphere and travel through space to Mars.
It was a good story, but it could not happen.
The trouble is that the kind of powerful engines we know cannot be used at any great height. Normal motors and jets both depend on using oxygen from the air to burn their fuel. At a height of from 12 to 15 miles, the air becomes so thin that there is no way to draw in enough oxygen to keep those motors going efficiently. Instead of going higher than the balloon, the airplane has been forced to stop at a lower level.
There is one exception to that height limit. An experimental plane, built by Douglas Aircraft Co., and named the Skyrocket, has carried a passenger higher than the record set by the balloon. To do this, it had to use a rocket motor—one which needs no oxygen from the air.
This plane was designed for just one job: it was a flying laboratory to explore highspeed flight problems. It could not stay up long, since it burned its fuel at a fantastic rate. It could not even lift itself from the ground. Instead, it was carried up by a B-29 bomber, given a good speed, and then launched in full flight. Once free, it did exactly what it was meant to do. It leaped to a speed of more than 1,200 miles an hour, and its stubby wings carried it higher and higher, to a new record of just over 15 miles, probably the highest any human being has ever been.
It is possible to build rocket planes which can go higher than 15 miles, but even they have limits. After a certain height—probably around 50 miles above the Earth—the air becomes too thin for any practical wing to gain lift. Also, at the speeds needed to reach such a height, air friction begins to heat the plane too rapidly. This has become a problem with current supersonic jet planes, which require cooling to protect the pilot. At a height of 50 miles, the speed would have to be so great that the plane would literally become red-hot!
We shall have to give up the idea of gaining lift from wings and find some way to climb upward directly, using a motor that needs no oxygen from the air to burn its fuel. The only mechanism we have which fits this description is the true rocket, which rises straight up on its own exhaust, and carries both fuel and an oxidizer to burn the fuel in its tanks.
The rocket is not a very good answer. It takes tremendous amounts of fuel—expensive, highly special fuel. It cannot work efficiently at low speeds, but must rush upward as quickly as it can, much too fast for comfort. It is harder than the plane to control, and much less reliable at present. Still, it is the one means of propulsion which actually works better in a vacuum where it needs no air to support it in flight. It does not have to fight against air friction. We have to use it.
We are using the rocket, of course. We have solved most of the difficulties already. The biggest problem was howr to pack enough fuel into it; that was perplexing indeed—so perplexing that a solution looked nearly hopeless 20 years ago. Today, we know enough of the answer to make flights of 100 miles up fairly routine. At least once we sent a rocket about 250 miles above the surface.
No man has yet traveled into space, but we have sent a rocket messenger ahead of us to the beginnings of true space! We are planning on sending many more shortly. After that, it will not be long before space is conquered and occupied by the human race.
rockets and spaceships
The idea of using rockets to get off the I Earth is quite a bit older than the use of balloons. The first story to use rockets for a trip to the Moon was written more than 300 years ago, by Cyrano de Bergerac— the same man about whom the play of the same name is supposed to have been written. De Bergerac had his traveler sit in a box to which a number of skyrockets were attached.
The method was just a lucky guess, however. In those days, anything that would go up was as good a way of getting to the Moon as any other; Cyrano also used bottles filled with dew (because dew “rose” when the Sun came up). Other writers were using flocks of birds to lift their flying devices. They did not really care how it was done, since they were mostly interested in telling the readers what the Moon would be like after the travelers arrived.
In 1865, a French writer named Achille Eyraud used the idea of rocket motors in describing a trip to Venus; but this time it was not an accident. He knew there was no air between the worlds, and he gave an accurate explanation of why rockets would work. Nobody paid much attention, however; more people were reading another book by a second French writer, Jules Verne, whose Trip Around the Moon was also published in 1865. This story described a shell fired from a huge gun at such a speed that it could escape Earth. It would have killed anyone inside from the terrific acceleration and have burned up in the air from its speed, of course; but to most readers, at the time, it seemed more practical than rockets. Yet the idea of using rockets slowly caught on as more and more people began to realize there was no other conceivable way to get off Earth.
The rocket itself had been around for a long time before De Bergerac’s story appeared. It was invented by the Chinese, probably less than a thousand years ago, and was much like a modern skyrocket. It was simply a tube, filled with solid gunpowder, having a hole in one end for the exhaust gas, and some kind of stick or tail to guide it through the air. Its first use was in war, apparently in the 13th century, where the sight and sound of such fire-breathing monsters must have frightened the enemy out of his wits.
For a long time, the rocket’s chief uses were in displays for celebrations and for war, where it could start fires, act as a self propelled shell, and carry light ropes across streams. It was used in the War of 1812, where the sight of such rockets inspired the line about “the rocket’s red glare,” in the anthem, The Star-Spangled Banner, and again in the War Between the States. Then it dropped out of use for a while, but in World War II it was back again, more useful than ever. Small rockets were fired from a bazooka (a portable rocket launcher) to break through tank armor, others were used against aircraft, and still others were used to get heavily loaded airplanes off the ground quickly.
Ammunition makers did a good business in such rockets, and there were Ions: technical books on them, as well as quite a few* engineers and technicians trained to make and use them. None of these people were interested in space travel. They were too busy with practical things to spend time with hopeless dreams. Besides, all their experience was with solid-powder rockets, which were not well suited for building spaceships.
The powder rocket was too hard to control. Once it was ignited, it did not stop burning until the fuel was used up, and its rate of combustion could be regulated only by the way it was built. This fact made handling a ship with such fuel very difficult. In addition, the powder fuels in general use wore not good enough; the exhaust gas was too slow to drive the rocket to the speed needed, unless an impossible amount of fuel were used for the size of the ship.
Liquid fuel was the answer, since a liquid could be controlled by valves, and since a mixture of liquid oxygen and liquid hydrogen gave the hottest flame (and the highest exhaust velocity) then possible. Nobody, however, had any real experience with liquid-fuel rockets, and some of the problems seemed unsolvable. Both oxygen and hydrogen become liquid only at. very low temperatures and extremely high pressures. They are highly explosive and hard to store, requiring wrong tanks that add to the weight problem. Liquid oxygen is so corrosive that even a touch of oil in the outlet valve can explode violently when the oxygen touches it.
There were other fuels to replace the hydrogen—not as good, but still better than the solid-powder fuels. Gasoline and alcohol both were potential fuels, but there was no easy solution to the need for something to oxidize the fuel. It seemed that nothing could replace liquid oxygen; it was the only oxidizer which could be supplied in sufficient quantity to burn up the fuel at the rate needed.
Even with such fuels, the problem seemed hopeless. As early as 1920, the American Robert H. Goddard was doing some work with rockets in an attempt to find a way to explore the higher stratosphere, but nobody paid much attention. The idea of getting to space by rocket brought only amused smiles from the experts.
Then, in 1923, the whole picture changed. Nothing new was invented then; no new rocket was built; nobody found a way to do anything that could not be done before. Yet suddenly, people were forced to see that space travel was possible. All this happened because a young German professor wrote a book and paid part of the cost to have it published. After that, it was only a question of time and work before space would be conquered.
The man was named Hennann Oberth. He had never worked with rockets, and he had done no experimenting with fuels. Instead, he had simply turned to mathematics to figure out what could be done. His book, The Rocket into Interplanetary Space, gave the results of his figuring. It proved finally that rockets could be built to cross space to other planets, and showed how such ships could operate.
The book did something more. It created rocket fan clubs among the readers. There were several such clubs, the most active of which was the German Rocket Society. Among the members were Oberth, Willy Ley and the young Wernher von Braun. In the end, it was because of this group that practical rockets were to be built, though it hardly seemed possible at the time.
In spite of its name, it was not a real scientific group, like the American Engineering Society, but a true fan club. The members were mostly young, and filled with plenty of enthusiasm and almost no experience. They had not done any real work with rockets of any kind. They had almost no money. To any real engineer, they must have seemed like a group of children playing with a new hobby.
Such people had made history before, however. The airplane was developed by two brothers who built bicycles for a living and flew strange kites as a hobby. The radio industry—at least the broadcasting part—was developed by a group of people who made a hobby of experimenting with Marconi’s invention of the radio telegraph.
In the case of the German Rocket Society, things moved slowly at first. The group scraped together a little money and a place to work and began building rocket motors. They could not build ships until they had learned how to make an explosion chamber for the mixing of the dangerous fuel and oxygen combination. These small tubes with their fuel lines were not meant to fly; instead, they were firmly fastened down, while the amount of thrust was measured, and new designs were tried. Fortunately, in spite of accidents, no one was injured seriously.
For quite a while, all the society could do was to keep building better motors and writing up the results for other hobbyists, but they learned, little by little. Their motors burned out under the terrible heat of the explosions. Their funds were always giving out. And at times the situation looked hopeless. There seemed to be no way to build a tube that would direct the burning gas without the tube itself melting.
The society members found the answer to that. Nothing could stand the heat for any length of time, no matter how thick the rocket walls. So they made the walls thinner! Around those thin walls, they pumped the fuel before it reached the rocket explosion chamber. The fuel soaked up heat, cooling the rocket walls, and was warmed enough to fire much better. In that manner the temperature of the metal could be kept low enough so that the motors could continue working—at least most of the time.
In 1931, the first liquid-fuel rockets were actually flown. The first ones made only limited ascents, but, during the year, flights reached up over half a mile and were considered highly successful. These early rockets were still tiny things, weighing little over 10 pounds at the most. They were smaller and less spectacular than the powder rockets already in use—but they proved that liquid-fuel motors could be used. Great things were expected in the near future.
This was in Germany, however, and politics came into the scene. Hitler took over the Government, and things became very difficult. Wernher von Braun was drafted into the German Army. Later, Oberth was also drafted to work for the Government, though not much use was made of his ability. Willy Ley left Germany to go to the United States, and the rest of the group was torn with political strife and disagreements, while the Hitler Government began rounding up all the men who had been a part of the rocket society.
The future looked very bad for rocket work. The group had proved its idea so well that everyone now accepted rockets as a means to reach space eventually, but it seemed to be in the very far future. The American Rocket Society and the British Rocket Society were doing some work, but nothing of great importance came from their efforts, and enthusiasm cooled off as war began to threaten. It seemed that the last hope was gone when the war actually began. The powder rocket was being used for all sorts of things, but nobody seemed to have time to experiment with liquid-fuel motors.
Yet the very political troubles that had halted research now suddenly became the means for more work. Hitler was growing desperate and ready to try anything. There were men in Germany working on atomic explosives—fortunately for the Allies with no success. Everything from the pages of science fiction was thought of, and among the ideas was that of a rocket big enough to carry a bomb for hundreds of miles against England.
Now, for the first time, there was money for real research, along with laboratories, technicians and equipment. Hitler himself was interested (as he was also interested in astrology and various kinds of fortune-telling and magic). Wernher von Braun was put in charge of a secret installation at the fishing village of Peenemunde on the Baltic Sea. He had top priority and some 400 million marks to spend during the years of work.
There was no thought of better tiny rockets now. The Germans were working on the big ones. New problems came up. The biggest one, aside from the fuel (which was alcohol mixed with water to cool the motor, together with liquid oxygen to burn it), was the problem of pumping the fuel to the motor. A rocket motor burns up an incredible amount of fuel in a very short time. In a normal automobile engine, a gallon of fuel will burn for about 20 minutes at normal cruising speed; almost any pump can handle that much. In a rocket motor, as much as 50 gallons every second has to be pumped, and at high pressures, too. When one of the liquids is oxygen, the problem becomes even tougher.
The German scientists found the answer —one that would have been impossible a few years before. The pump was to be a steam-powered turbine, but with the steam developed in a new way.
Most medicine cabinets contain the chemical needed for the process. Hydrogen peroxide had been known and used for a long time, but previously, men had been forced to use only a very dilute solution of it. The medicine-chest bottle contains only 3 percent hydrogen peroxide. When the solution was made much stronger, the peroxide had a nasty habit of exploding. The compound is made by adding one atom of oxygen to a molecule of water (giving two atoms of hydrogen and two of oxygen), and it breaks down to give back the free oxygen and water, plus enough heat to turn the water into high-pressure steam.
Now, however, it was discovered that completely pure hydrogen peroxide would explode only when it touched certain substances, and that by keeping all traces of such substances out, the pure peroxide could be used. In the pump, it touched such an impurity and flashed into steam, driving the pump. The hydrogen-peroxide pump was the lightest and surest way of doing the job, and the real answer to developing big rockets.
There were plenty of lesser puzzles, but those were all solved. In 1944, after long experiments, the V-2 rockets began falling on London. The tiny rocket had grown up. It was being used in a horrible way, but that was no fault of the rocket idea, and it did not make the real progress any the less.
Over a thousand of such rockets were
fired. Carrying- about a ton of payload (explosive warheads in this case), they rose to a Height of 60 miles, reached a speed of 3,600 miles an hour, and traveled nearly 200 miles with their load. To do this, the actual rocket motor operated for only a little over 1 minute, with the rest of the journey continued on the speed built up! One V-2 that got out of control rose to a height of 100 miles before dropping back, far higher than am thing made by man had gone before. Now the makers of the powder rockets had to admit defeat; nothing they could make would equal the liquid-fuel rocket.
