Тред №244417

Цитата: Корвет от 05.08.2010 22:46:13
Собственно как и предполагалось...
чем больше КС, тем хуже двигатель...
выдающийся ракетчик Токарев расказывает...


Вот что пишет автору о двигателе F-1 специалист  - ракетчик Токарев О.П.: « Двигатель F-1- однокамерный, а РД-170 – четырехкамерный при близкой мощности. Чем крупнее камера сгорания, тем сложнее обеспечить устойчивое горение в ней.

со всеми вытекающими...
я же говорил...

Цитата: Корвет от 05.08.2010 22:46:13

 

Цитата
THE INJECTOR AND COMBUSTION INSTABILITY

At the outset, planners considered three different injector designs, all of them more or less based on the H-1 injector configuration. "However, stability characteristics were notably poorer," reported Leonard Bostwick, the F-1 engine manager at MSFC. "None of the F-1 injectors exhibited dynamic stability." Once instability got started in the engine, nothing stopped it until the test engineers cut off the propellants and shutdown the entire engine. Obviously, this was not the way to successful missions. The design team tried variations of baffled injectors and flat-faced injectors with little improvement, except that the flat-faced designs could be expected to create more damage than their counterparts with baffles. Finally, all hands agreed that the attempt to scale up the H-1 injector to the F-1 size just would not work. There were too many variables: high chamber pressures, a lower contraction ratio, greater density requirements for the injector, and much larger diameter of the thrust chamber. With the concurrence of MSFC, Rocketdyne began a new path of investigation to select an injector design with inherently stable combustion characteristics.32

The snags in the F-1's progress sharpened high-level skepticism about the feasibility of an engine the F-1's size. During a meeting of the [113] President's Science Advisory Committee early in 1961, one member, Donald Hornig, reportedly expressed strong reservations about the F-1 engine program because of fundamental problems in its development, adding that it might just be too big to make it work. Hugh Dryden, NASA's Deputy Administrator, got wind of these comments and wrote to Hugh Odishaw, of the National Academy of Sciences, to help set the record straight in the scientific advisory community. Dryden reported encouraging progress on new injector designs and characterized the tribulations of the F-1 as inevitable in engine work. "Such development problems are the common experience of every engine development with which I am familiar and are nothing to be concerned about," he counseled, "so long as one makes sure that the developing agency is taking a multipronged approach to obtaining a solution."33 Several new radial injector designs now become candidates for the F-1 engine. To acquire more accurate data, engineers ran tests with scaled-down models in a special low-pressure, two-dimensional transparent thrust chamber. This permitted the use of high-speed photography and "streak movies" to analyze the performance of the injectors in simulated operation. The most promising designs graduated to full-sized models in hot-fire tests which included bomb experiments (as in the H-1) and erratic propellant flows produced by an explosively driven piston. The new designs appeared to have combustion instability, an early concern, under control until 28 June 1962, when combustion instability resulted in the total loss of an F-1 engine. From there on, as von Braun drily remarked, "This problem assumed new proportions.34

Working quickly, MSFC established a combustion stability ad hoc committee, chaired by Jerry Thomson of Marshall, with six permanent members and five consultants chosen from MSFC, Lewis Research Center, the Air Force, industry, and universities. The group got together at Huntsville on 16 July to consider the recent loss of the F-1 engine and to review Rocketdyne's R&D efforts, as well as to provide technical assistance and coordinate all research on the problem. Rocketdyne had established its own stability council by the autumn of 1962 to pursue the issue of F-1 instability and also enlisted the support of leading authorities from government and universities. Rocketdyne's group was headed by Paul Castenholz and Dan Klute, temporarily relieved of their current duties for full-time attention to combustion instability. They reported directly to William J. Brennan, Rocketdyne's chief of propulsion engineering at the time.35

Reacting to deep concern expressed within the Office of Manned Space Flight, von Braun prepared a memo in November 1962 to reassure Seamans and others at Headquarters. Von Braun emphasized Marshall's concern and praised the steps taken by Rocketdyne to deal with the situation, but promised no quick or easy solutions. The memo from von [114] Braun gave a clear insight into the frustrations in searching for answers. Although various organizations had pursued combustion-instability research for the past 10 years, nobody had yet come up with an adequate understanding of the process itself. Therefore, it had not been possible to use suitable criteria in designing injectors to void combustion instability. "Lack of suitable design criteria has forced the industry to adopt almost a completely empirical approach to injector and combustor development," von Braun said. This approach is not only "costly and time consuming," he continued, but also"..."does not add to our understanding because a solution suitable for one engine system is usually not applicable to another." Von Braun urged more extensive research on the task, and suggested that universities in particular could put Ph.D. candidates to work on aspects of combustion and combustion instability for their dissertations.36

In the meantime, two more engines were lost in tests. D. Brainerd Holmes wanted a special briefing on the problem, which he received on 31 January 1963. At the end of the presentation, Holmes commented that the goal of beating the Russians to the moon seemed to be mired in F-1 problems. He asked if it was not time to start work on a backup scheme. The briefing team, which included representatives from MSFC and Rocketdyne, convinced Holmes that new work would detract from solving F-1 difficulties, which appeared to be succumbing to intensive government-industry engineering and university research.37 In March, however, Holmes wrote to von Braun, reemphasizing the need to get the F-1 effort on schedule to avoid slips in launch dates and the lunar landing goal. "I regard this problem as one of great seriousness," Holmes wrote, and asked to be kept informed on a daily basis.38

It took 12 months for Rocketdyne to work out a baffled injector design that functioned well enough to pass the preflight rating tests. Some vexatious anomalies persisted, however, especially in the injector's inability to recover from combustion oscillations artificially induced by bombs detonated inside the thrust chamber. This situation called for added research before the F-1 could pass muster for the final flight-rated design. By July 1964, with combustion stability work continuing, Rocketdyne received an additional contract of $22 million, including miscellaneous hardware and services, with a special allocation to accelerate the company's research in combustion stability.39

Significant theoretical work was accomplished by two Princeton researchers, David Harrje and Luigi Crocco, along with Richard Priem of the Lewis Research Center. When Crocco was in Europe on sabbatical during the academic year 1963-1964, he maintained correspondence with MSFC; NASA Headquarters even approved von Braun's request to send Rocketdyne and Marshall representatives to talk with Crocco in [115] Rome.40 To investigate the phenomenon of unstable combustion, engineers and researchers employed a wide range of instrumented apparatus and other aids. Among other paraphernalia, investigators introduced high-speed instrumentation to diagnose combustion in the thrust chamber and to evaluate modifications to the original designs. The exacting attention to details led to apparently minor changes that actually proved to be of major significance. After careful calculations of the effect, enlarging the diameters of the fuel injection orifices was later judged one of the most important single contributions to improved stability. Other careful changes included readjustment of the angles at which the fuel and oxidizer impinged.41 Several techniques of rather dramatic nature were also applied in the instability research. For the layman, the most bizarre aspect of F-1 testing (like the H-1) involved the use of small bombs to upset the thrust exhaust pattern to measure the engine's ability to recover from the disturbance. By varying the size of the bombs, test engineers could create instability of different intensities and evaluate the ability of the engine to restore stable conditions.

This procedure offered an immense saving in time and costs, because it eliminated the old methods of running hundreds of engine tests in an effort to acquire a quantity of useful statistics. Moreover, the ability to artificially subject the F-1 injector to severe operational stresses eventually resulted in a superior design with excellent damping characteristics. During early tests, self-triggered instability continued for more than 1600 milliseconds-a highly dangerous condition. The successful design recovered from deliberately triggered instability in less than 100 milliseconds. The final product included the redesigned orifices for LOX and fuel to improve the distribution pattern of propellants as well as a rearrangement of the injector baffles. The baffled injector, as opposed to the flat-faced type, was particularly effective in recovery during the deliberately triggered instability tests. The minute, exacting requirements of engine development were such that these seemingly insignificant changes required some 18 months to prove out, and the flight-rated model of the F-1 injector did not receive MSFC's imprimatur until January 1965.42

In the course of F-1 engine development, Rocketdyne personnel consistently emphasized the combustion stability investigations as one of the company's stiffest challenges, and its solution as one of its most satisfying achievements. Although engineers expected difficulties in this area because big engines with high chamber pressures inevitably developed random and unpredictable combustion instability, the size of the F-1 dramatically increased the size of the challenge. Rocketdyne managed to cope with the problem, although, as Brennan admitted in an address to the American Institute of Aeronautics and Astronautics in 1967, "the [116] causes of such instability are still not completely understood."43 Even though the F-1 engine performed satisfactorily, uncertainty concerning combustion instability persisted a decade later.*

Although combustion instability and injector development became the pacing items in the F-1 program, other thrust chamber problem areas required constant troubleshooting by Marshall and Rocketdyne engineers. During the first half of 1965, MSFC monitors at Rocketdyne's production facilities in Canoga Park, California, were worried about cracks in the thrust chamber jacket, while MSFC monitors at the Edwards Air Force Base test site were frustrated by cracks in the thrust chamber tubes. Engine 014 had been in and out of the test stand more than once for injector changes and thrust chamber tube repairs. In April 1965, the MSFC monitor at Edwards reported to Huntsville that the engine was back in the test stand once more. "Engine 014 apparently has a dog of a thrust chamber," he wrote in exasperation.44 Another troubleshooting effort that required considerable attention concerned a manufacturing sequence for the injectors. Unhappily, the problem appeared after a number of engine deliveries to the Boeing Company, the contractor for the S-IC first stage of the Saturn V. The injector incorporated multiorificed copper fuel and oxidizer rings, held by steel lands (rings) installed in a stainless steel body. To attach the copper rings to the steel lands of the injector body, workers performed a brazing operation. As test runs on R&D engines accumulated more and more time, the brazed bond joint failed, with very bad separation between the copper rings and steel lands. Analysis of all prior engine deliveries disclosed similar minute failures. In a somewhat elegant solution, new procedures called for replacements using gold-plated lands to offer a superior bonding surface during brazing. During the spring and summer of 1965, this investigation involved considerable testing and metallurgical analysis, not only to pinpoint the problem, but to confirm the effectiveness of the new procedures. Finally, several engines had to be retrofitted with the new "gold-plated" injectors.45

Цитата: жОпаньки !!! от 20.07.2010 11:05:56
Откуда вы взяли этот тезис? Можете его обосновать?

Двигатели F-1 были спроектированы ещё за 10 лет до полёта Аполлона-11. Они были разработаны даже не для НАСА, а для ВВС США в соответствии с их запросом от 1955 года. НАСА воспользовалось уже спроектированным двиглом. Правда, он был сырой и требовалась доработка, но времени и средств для этого было достаточно. К 1961 году движок был практически полностью готов и испытан.

Цитата: жОпаньки !!! от 20.07.2010 11:05:56

 

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During 1966, the last year before the F-1 and J-2 powered Saturn V was scheduled for its first unmanned launch, the F-1 passed NASA's first article configuration inspection, the first major Apollo-Saturn propulsion.....

The F-1 test stand in the Mohave Desert towered 76 meters (note man at base). [125]

....system to Pass this exam, and on 6 September the F-1 received complete qualification for manned missions. The final tests for MSFC occurred on 15 November, with the acceptance firing of the S-IC-3 first stage: subsequent acceptance firings were earmarked for the Mississippi Test Facility near the Gulf, a more convenient location in terms of logistics between the test site and launch facilities at KSC. Before the epochal voyage of Apollo 11 began on 16 July 1969, five Saturn V launch vehicles lifted off from Cape Kennedy: one in 1967; two in 1968; and two more in early 1969. Despite the thousands of metric tons of cryogenic materials already consumed in research and in the hundreds upon hundreds of tests already accomplished, the pace of research involving the F-1 only seemed to quicken in the concluding months before Apollo 11 began its flight. Dozens of additional tests of the complete engine were run at Huntsville and at Edwards, as contractors and NASA engineers determinedly verified the maturity and reliability of the mammoth rocket engine.55

SUMMARY: H-1 AND F-1

Although the F-1 had its roots in early Air Force studies, it was a "newer" engine than the H-1. Troubles with the F-1, however, were primarily a function of proportions, not innovations. Both engines used the same liquid oxygen and RP-1 propellants, but size and performance characteristics made the F-1 fundamentally different. The H-1 experienced R&D Problems as it was uprated in thrust. Taking proven H-1 components, such as the injector, and scaling them up to F-1 requirements turned out to be not only difficult but basically impossible.

* In a note to the author (8 July 1976), John Sloop, a senior NASA propulsion engineer, noted that combustion instability, like engine knock, has long been studied, and engineers had learned to deal with it. But neither was yet fully comprehended.

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