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02-06-2007, 08:01
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חבר מתאריך: 27.10.04
הודעות: 339
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תוספת בשני גרוש שלי
מתנצל על הקפצת הענף. עד שמצאתי את הספר שחיפשתי, סרקתי והעלתי - לוקח זמן.
מתוך הספר: ROCKETS, MISSILES, AND SPACE TRAVEL
מאת: Willy Ley שנת 1958 (הוצאת ויקינג). תודה למכון "ויצמן".
(pages 408-409)
The long gap between von Opel's rocket-propelled glider and the modern work on rocket airplanes is filled by just one name: that of the Austrian engineer Dr. Eugen Sanger. He was indubitably the first among rocket-aircraft designers who did not grope and hope but attacked the problem systematically. He began his career as a rocket expert with an extensive series of rocket-motor tests conducted in the laboratories of the University of Vienna. These tests were highly successful.
Apparently Dr. Sanger worked mainly with one basic model at that time, with a spherical combustion chamber about 2 in. in diameter. The exhaust nozzle was unusually long, 10 in., and its muzzle end had a diameter equal to that of the combustion chamber. The combustion chamber and the adjacent portion of the nozzle were enclosed in a sturdy cooling jacket (Fig. 77). The fuel was fed into the cooling jacket under high pressure and thereby served a double purpose: it not only cooled the combustion chamber but also relieved it of the pressure created by the combustion by way of furnishing a somewhat higher counterpressure. It was the outer jacket which really took the strain which it could do all the more easily since it remained cool. It also had a higher wall thickness than the combustion chamber itself which had rather thin walls for better heat transfer.
The fuel used by Dr. Sanger was light fuel oil, injected with Bosch injection pumps of the type used in Diesel engines. The injection pressures used covered a wide range—from 30 to 150 atmospheres—but were always -rather high compared to the 20 atmospheres customary at the Raketen-flugplatz and later at Peenemunde. The oxygen was fed directly into the combustion chamber under like pressure; because Dr. Sanger experienced ignition trouble when using liquid oxygen, he preferred gaseous oxygen directly from the customary steel container with appropriate reduction valves. The small rocket motor was suspended in a framework of steel tubing which could swing only horizontally, pressing against a spring device that measured the thrust.
Doctor Sanger reported astonishingly long burning times. A test run lasting 15 min seems to have been normal with him. Many motors ran for 20 min and one even for half an hour. The thrust of the motor was of the order of 55 lb. The exhaust velocity was calculated from the thrust to have been from 2000 to 3500 meters per sec, or from 6500 to 11,500 ft per sec. Even then the photographs still showed what is known as a "fox-tail flame, indicating combustion of unburned fuel particles with the oxygen of the atmosphere outside the nozzle. Doctor Sanger felt certain then—and future development has, of course, borne him out—that the practical problems of larger motors would certainly be solvable.
The next step was to work out the requirements for the rocket airplane itself. Oberth had worked a little on that problem, largely in defense of rocket theory against Valier's loud claims, and had showed that a rocket-propelled plane could get range only by a very steep take-off, by leveling off at a high altitude, getting up to maximum speed by using up all its fuel as quickly as possible, and then operating as a high-speed glider. Sanger came to essentially the same conclusions, but approached the problem more from the point of view of an airplane designer. He decided in favor of a rather shallow take-off (for a rocket, that is) of 30 degrees but aside from that his method was the same as that outlined by Oberth. For an assumed burning time of 20 min he arrived at a total flight time of a few minutes over one hour and an average speed of 1600 mi per hr. Of course he also tried to visualize the appearance of such a stratosphere speedster; Fig. 78 shows a copy of his sketch. When it was first published in 1933 it reminded one of Captain Ferber de Rue's prediction about the projectile dirigible. Now it looks more like a first sketch of the much later American research plane X-1. It isn't, of course.
A few years later Dr. Sanger was hired by the Hermann Goring Institute, the research laboratories of the Luftwaffe. He informed me of this by writing me an innocuous private letter on office stationery, but he naturally could not tell me anything else. I now know that much of his time was spent not on rockets but on ram jets which the Germans call Lorin ducts. However, he did not abandon rockets completely and one piece of work which he did during the Second World War led, as we'll see later, to one of the most confused postwar episodes in rocket history.
Doctor Sanger did not have anything to do with the rocket-propelled airplanes built or planned by the Germans.
(pages 428-434)
As has been explained in Chapter 11, a transport rocket for long-distance flights has to take off like a rocket; although the public will probably refer to them as rocket planes in the future, the term is misleading. The X-1 was a rocket airplane; the future transports will be winged rockets.
The return into the lower atmosphere should take place at a shallow angle. At one time, during the Second World War, Dr. Eugen Sanger must have wondered what would happen if the angle were too steep. There should be an unconsidered aerodynamic effect, but if there was, there also was a new concept of long-range flights. The new concept produced at first not a new rocket or aircraft, but, in due course of time, a report of four hundred typewritten pages, prepared by Dr. Sanger in collaboration with Dr. Irene Bredt, a mathematician (who became Mrs. Sanger after the war).
Here the story of the "Sanger-Bredt Report"—often called for brevity "the Sanger"—begins. Actually there are two stories, one about the contents of the report, one about its fate. The latter story began in a routine fashion. After Sanger and Bredt had finished their work, a hundred copies of the report were made. Somebody who was duly authorized to do so slapped a big rubber stamp on the front page, reading (in German, of course):
This is a State Secret . . . must be passed personally from hand to hand, or, if with personal address, in double envelope with return receipt. To be transmitted by courier if at all possible, in exceptional cases by mail insured with more than 1000 marks. Any copying, photographing, etc., verboten. To be kept in locked steel safe in rooms which are guarded 24 hours a day. Any neglect of these regulations will be most severely punished.
A list of recipients, eighty of them, was drawn up and appended to the report itself. The State Secret was on its way, by courier in double envelopes with return receipt, in exceptional cases by mail. Professor Heisenberg, the German atomic energy expert, got one. So did Dr. von Braun in Peenemunde. So did General Dornberger, and Professor Willy Messerschmitt. Also Professor Tank of Focke-Wulf aircraft, Professor Dornier of Dornier aircraft, Professor Heinkel of Heinkel aircraft, Professor Mader of Junkers aircraft, Professor Prandtl of the Aerodynamical Research Center in Vienna, and Professor Proll of the Engineering College in Hannover. All very important people, but also very busy people, especially in view of the military situation at that time, for D-Day was not far away. Most of them probably found time to read through the Report, but nobody had time to do anything about it.
Then came V-E Day. All of those just mentioned, including Dr. Sanger himself, were interrogated by the Allies. English and American Intelligence Teams found or were handed copies of the Report, which by that time was mentioned in such a way that you could hear the capital R. In the east the same thing took place. The Russians collected a copy of the Report in the library of a scientist who could not get away in time. Later on they found two more copies. The Report was read by an expert who wrote a digest in Russian which was passed on to higher levels. And to higher levels. Only weeks after the capture of the Report, the digest landed on the desk of Yosif Vissarionovitch Djugashvili, known to history as Stalin. He ordered a full translation made and then summoned a conference about "the Sanger." Present were Vassili Stalin, aviator son of the voshd (boss), Molotov, Malenkov (Politburo), Beriya (Secret Police), Voznesenski (Politburo), Voroshilov—also two experts, Colonel Serov and Lieutenant Colonel Grigory A. Tokayeff (pronounced: toe-KAH-yeff), both of whom had read the Report. A preliminary discussion about V-2 rockets was cut short by Malenkov with the statement that their range was too limited—"Do you think we are going to fight Poland?"
Tokayeff, at Stalin's order, delivered a forty-minute lecture on the contents of the Sanger report. Stalin wanted to know the whereabouts of Sanger. Tokayeff didn't know—-"Possibly Paris?" The outcome of the meeting was that Serov and Tokayeff were ordered to find Sanger and bring him to Russia in "a voluntary-compulsory manner." Vassili Stalin was to accompany them. They took off, first for Berlin. In strictest incognito. With fighter escort. They "looked for Sanger everywhere for months." They also looked for Dr. Bredt, "but no trace of her was ever found."
Of course I had no idea about any of these events then, but a year or so later Tokayeff found himself an official reason to go to London, where he remained, writing his memoirs for the Daily Express. In the installment of these memoirs which was devoted to rockets (published Sunday, January 23, 1949) Tokayeff mentioned* that the meeting had taken place in April 1947. At just about that time Dr. Sanger had written to me from Paris. No secrecy was involved; his letter was uncensored. Irene Bredt, incidentally, was working with him there. I leave unanswered the question of how young Stalin, Serov, and Tokayeff spent their "months of looking," and turn to the report itself.
As has been mentioned, Sanger wondered about what would happen if a winged rocket entered the denser layers of the atmosphere—say the 25-mile layer—too fast and too steeply. The answer was that it would ricochet, like a flat stone hitting the surface of a lake. The ricochet would throw it into layers far too attenuated to support it. Some distance away the rocket would strike the denser layers again and bounce off once more. The path, seen as a whole, would be a wavy line, the "undulations" slowly diminishing in magnitude, both vertically and horizontally. One might say that it would resemble a roller coaster. This type of path increased the possible range of a winged rocket to a surprising extent and in an entirely unforeseen fashion. And on that Sanger built the conception of an antipodal bomber.
Figure 83 shows how the rocket plane itself might look. It would be about 92 ft long, with a wingspread of nearly 50 ft. Its "dry weight" would be 20 metric tons, the fuel and bomb load 80 metric tons, resulting in a take-off weight of 100 metric tons. But with such a weight an unassisted take-off would use up the greater part of the fuel supply. Nor would it be easy to provide a plane of such take-off weight with enough take-off assistance in the usual manner. The way around this difficulty, as designed by Dr. Sanger, was a long straight take-off track, 3 km or roughly 2 mi long. The plane would sit on a kind of sled to which any required number of rocket units could be attached. They would not even need to be high-grade units since they were not supposed to leave the ground. The rocket sled would work for about 11 sec, at the end of which the plane would be at the end of the runway, moving at 500 meters per sec or 1640 ft per sec, fast enough to make it lift. Under its own power it would then climb.
Assuming an exhaust velocity of 3000 meters per second the rocket plane would reach a maximum velocity of 6000 meters per sec or 3.73 mi per sec. That would carry it to a peak altitude of 261 km or 162 mi. But what would occur is best shown in the following table and in Fig. 84.
Altitude Distance from take-off point
mi km mi km
First peak 162 261 1,553 2,500
First low 25 40 2,796 4,500
Second peak 78 125 3,573 5,750
Second low 25 40 4,350 7,000
Third peak 75 120 5,033 8,100
Third low 25 40 5,810 9,350
Fourth peak 56 90 6,214 10,000
Fourth low 25 40 6,711 10,800
Fifth peak 51 82 7,208 11,600
Fifth low 25 40 7,643 12,300
After that there would be four more peaks, each at 60 km altitude, with corresponding low points at 40 km, the horizontal distance from low point to low point being of the order of 1000 km or 600 mi, growing slightly shorter. The ninth low point would be 16,800 km (9818 mi) from take-off point, measured along the ground. Then the plane would remain at 40 km altitude for some time. Some 23,000 km (14,290 mi) from take-off point it would finally begin to lose altitude, and 500 km (310 mi) later, halfway around the earth, it would land. The landing speed, surprisingly, would be only 90 mi per hr, which any pilot can handle. And any large airport could receive the plane. But for this trip it could carry only 300 kg (660 lb) of payload, in addition to its single pilot.
All this requires an exhaust velocity of 3000 meters per sec, which is not yet standard. Before progressing to this example Dr. Sanger had calculated shorter ranges. These, however, involved the necessity of turning around, if the plane was to be used for military missions and was not supposed to fall into the hands of the enemy the first time it was used. Turning the plane around at a rate of speed close to 1 mi per sec was found to be exceedingly tough. In all probability many things would go wrong, and enormous quantities of fuel would be needed. Turning around was not completely impossible, but going straight ahead to land at an antipodal base was much easier. That was simpler in other respects too. If the planes started from a base in Germany, say Berlin, for bombing missions, the problem was just one of proper direction. If you are finally to land at an antipodal point it is unimportant whether you go east or west. By the same token the return flight could be utilized as a bombing run too, either on the same target or on another one.
The scheme is, in principle, easy to understand. It did involve a terrifying amount of mathematical work. But it calculated neatly—except for a few geographical facts which could not be changed. To begin with, the antipodal point for points in Germany happens to be in the Australia and New Zealand area. A deviation of a few hundred or even a thousand miles from the mathematical point would not have mattered much, but if the areas where the planes would have to land were not already occupied by New Zealand, Australian, or even American forces, they soon would be.
Furthermore the target cities were not located just where the "flight plan" needed them. Any bomb-dropping would have to be done in a low point of the trajectory. Even then the bombs would cover a horizontal range of some 200 to 400 mi, depending on the speed at the moment of release. That not only made aiming hard, it also required a target city within such a range of a low point.
It is unlikely that the people who founded the larger cities belonging to the Allies had such a possibility in mind. But, for flights from German soil, the large cities are in locations which would have been chosen if the prospect had been foreseen. Everything important is located under a peak. With one exception—and for that reason Allied officers found maps on which New York was labeled "Ziel Eins" (Target no. 1). New York could have been hit from a low point, with the bomber proceeding to Japan or at least to a part of the Pacific then still under Japanese domination.
There was one more possibility. Why stop at the antipodal point? Why not go all the way around to take-off base again? Calculation showed that this would need an exhaust velocity of 4000 meters per second, which would result in a maximum velocity of 7000 meters per second (4.4 mi per sec), with the first peak at 280 km (174 mi) altitude, 3500 km (2175 mi) from take-off point, and the first low at the usual altitude of 40 km, 6750 km (4194 mi) from take-off point. There would also be nine peaks, with the ninth low 27,500 km (17,088 mi) from take-off point. Landing, on the take-off point, would take place 13,060 sec after take-off, or, in round figures, 3 hr 40 min.
The Report concluded by recommending the one-base concept as the more useful one, and then listed the research projects which would have to be carried out to make it possible.
It is easy to understand why none of the important Germans who read this report did much about it; it was clearly and obviously too late for anything of the kind. They may also have felt that even if such bombers were available, bomb loads of 660 lb for the antipodal bomber or of 8300 lb for the round-the-world bomber would not have had any military effect. It is equally easy to understand why the important Russians were agog about Sanger's report. With fission bombs the carrying capacity looked more than ample. It is probably correct that Sanger's antipodal bomber could be realized in five to eight years of intense effort. But it would be an effort which would be almost impossible to conceal from the world. Nor would the final result be a very versatile weapon and the location of both home base and antipodal base would probably be known to most Military Intelligence sections a few months before the first bulldozer arrived on the scene for grading the runways.
It was an interesting idea but it is not likely to be realized. This method of extending the range probably won't serve for peaceful purposes. And for military purposes there is the long-range missile.
א. הטאבים בטבלה נעלמו, אך אפשר לשחזר אותה ללא בעיות.
ב. רציתי לצרף 4 שרטוטים שסרקתי אולם האייקון של "הכנס תמונה" לא מוביל למקום מתאים ו- "העלאת קובץ" מכניסה אותי ללולאה. אם אפשר, אשמח לרענון הזכרון איך מוסיפים תמונה.
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