China's Space Program News Thread

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escobar

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View attachment 97025
Successful launch of KZ-1A Y16, putting Centispace-1 S3 and S4 into orbit.
LEO based sats for Enhanced Global Navigation Satellite System. Using LEO satellites to enhance GNSS can expand the coverage area, improve the anti-interference performance of signals, provide more abundant observations, and accelerate the convergence speed of precise positioning to achieve global high-precision real-time navigation and positioning.
 

escobar

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Successful launch of Long March 2D from XSLC, placing Yaogan-35 05 group satellites into orbit.
It hasn't even been 2 hours since the successful launch of KZ-1A Y16
The Yaogan-35 system (likely real purpose is electronic intelligence) has been deployed very rapidly: All five triplets of satellites were launched within 10 months, and the last four in less than three months. In recent years, there is perhaps no example of such a rapid deployment of a new space system. Compared to traditional spacecraft, the development time has been reduced by 70%, and the duration of testing at the test site by 80%. The chosen inclination of 35° provides excellent conditions for monitoring Taiwan, FIC, as well as for China's southern and eastern neighbors, from India to Japan.
 

sunnymaxi

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China marks a milestone in new-gen heavy-duty rocket devt with successful engine test

By GT staff reporters Published: Sep 06, 2022 08:39 PM

The closed expander cycle hydrogen-oxygen rocket engine's first thrust chamber extrusion test in December 2021. Photo: from web's first thrust chamber extrusion test in December 2021. Photo: from web

The closed expander cycle hydrogen-oxygen rocket engine's first thrust chamber extrusion test in December 2021. Photo: from web

China has successfully conducted a whole-craft running test for its 25 ton-level closed expander cycle hydrogen-oxygen rocket engine for the first time recently, which its developers claimed marked the world's largest scale testing for the kind and a key technology breakthrough for the country's development of the new-generation super heavy-lift launch vehicle.

The CASC revealed on its official website in December 2021 that the closed expander cycle hydrogen-oxygen rocket engine system has the advantages of high performance and high reliability, and has the ability of multiple starts and of large-scale variable thrust adjustment.

It can be used for complex space missions such as manned moon landing, manned Mars landing and deep space exploration, according to the CASC.

According to the CASC, the new engine, the most powerful one of its kind worldwide, is three times stronger than the ones currently deployed for the upper stage of Chinese rocket in active service, and reaches a world leading class. It is a landmark product that China has advanced to the world space power.

When reached by the Global Times on Tuesday, the engine developers with the Sixth Academy of the state-owned aerospace giant China Aerospace Science and Technology Corporation (CASC), declined to provide further details of the new engine model and no video footage is available to show the test process. However, space observers speculated that the new engine system is likely to be used as the third stage and upper stage for the country's highly anticipated Long March-9 super heavy-lift rocket, which would boost China's future space endeavors in the fields including manned Moon and Mars landing, among other deep space exploration programs.

A space expert, who asked not to be named, told the Global Times on Tuesday that the exciting 25-ton engine being tested could be the YF-79 engines, which is even more powerful than the current YF-75D engine atop the Long March-5 - the strongest Chinese launch vehicle to date.

Four such YF-79 engines working in a group to constitute the third stage for the Long March-9 heavy duty vehicle, providing a thrust of some 100 tons, the expert noted.

So far, China has announced a successful running test for its domestically developed 500-ton level liquid-oxygen kerosene rocket engine, which is speculated to be codenamed the YF-130 rocket engine with a 50 percent rated working condition in March 2021; and the completion of the development of a prototype for the 220-ton YF-90 oxygen-hydrogen rocket engine in July 2021, according to media reports.

Space observers said that it seems that the YF-130 rocket engine for the Long March-9 vehicle's first stage, the YF-90 engine for the second stage, and now the YF-79 rocket engine for the third and upper stage have all achieved major development breakthroughs. China is moving closer to the final completion of the heavy-duty launch vehicle which will help the country to develop to be a world space power.

According to what Jiang Jie, the chief designer with the China Academy of Launch Vehicle who is also a China Academy of Sciences academician, has said in March, the development of the super heavy-lift which is of epoch-making significance, would take eight to 10 years.

Space observers noted that according to all the information gathered, the maiden flight for the new generation super heavy-lift vehicle could be expected within the next five year plan of 2026 to 30.
YF-79

The Chinese rocket scientists said they had found methods for boosting the thrust. They invented a new heat exchanger consisting of many rib-like components that can absorb heat from the surface of the combustion chamber and pass it to liquid hydrogen with unprecedented efficiency, according to a recent paper by the team in the peer-reviewed Journal of Rocket Propulsion.

The components were made with the latest 3D-printing technology to produce an extremely smooth surface that can speed up heat exchange much faster than traditional components. The researchers also used new titanium alloys to make gas-powered fuel pumps that can maintain high efficiency while working in extreme conditions, according to the paper.
 

escobar

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The difference between a standard expander and expander bleed is equal to the difference between open cycle (such as RS-68) and closed cycle (such as RS-25). Nobody would call RS-68 and RS-25 as variants of one another. For the same logic, I would avoid mixing LE-9 with any standard expander engine such as YF-79. It is like orange and apple.
There is the BE-3U engine (3x as powerful as YF-79) to be used to power New Glenn second stage but also expander bleed. There's a hard limit physics wise in terms of how much thrust you can get out of a pure expander, this Chinese engine is obviously closer to it than anyone's ever gotten.
 

taxiya

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YF-79

The Chinese rocket scientists said they had found methods for boosting the thrust. They invented a new heat exchanger consisting of many rib-like components that can absorb heat from the surface of the combustion chamber and pass it to liquid hydrogen with unprecedented efficiency, according to a recent paper by the team in the peer-reviewed Journal of Rocket Propulsion.

The components were made with the latest 3D-printing technology to produce an extremely smooth surface that can speed up heat exchange much faster than traditional components. The researchers also used new titanium alloys to make gas-powered fuel pumps that can maintain high efficiency while working in extreme conditions, according to the paper.
do you have the paper? or the title of the paper? It would be great to read it. Besides how they achieved it, I guess the paper may also tell something about their view of the theoretical limit of expander cycle. I would like to get a figure from a professional source to verify the wikipedia's 300kN.
 

sunnymaxi

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do you have the paper? or the title of the paper? It would be great to read it. Besides how they achieved it, I guess the paper may also tell something about their view of the theoretical limit of expander cycle. I would like to get a figure from a professional source to verify the wikipedia's 300kN.
sadly i don't have. i just get this information from SCMP article. i m trying to find paper link on different Chinese websites and Weibo.

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taxiya

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sadly i don't have. i just get this information from SCMP article. i m trying to find paper link on different Chinese websites and Weibo.

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Never mind, I checked my collections, I guess the paper is "25 tf膨胀循环氢氧发动机研制进展" published in 2022.

According to the paper, there are three main things to comment:
  1. the 3D printing is only about the "power head" where the injectors and plates are printed in one piece.
  2. The paper did not mention the fabrication method of the heat exchanger though.
  3. The heat exchanger is not smooth, but rather added may ribs to increase the surface area for heat exchange. The effect is 9.2% increase. The ribs' width, height and its number varies. It is very complicated, so it is likely being 3D printed even though the paper did not say anything about it.
  4. Another measure is "全流量氢逆流冷却" (Full Flow Hydrogen Reverse Flow Cooling, I don't know the professional term) to reduce the flow resistance in the exchanger. YF-79 is 3.0/MPa, Vinci is 3.5/MPa. That is a 14% reduction.
屏幕截图 2022-09-07 005034.jpg
 
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broadsword

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I believe the ribs are similar in concept to those found on typical air-conditioning heat exchangers where ribs or micro-fins are made on the surface of the inner diameter of the tubes. They maximize the surface area for more heat transfer.

Also, the tubes running around the shroud, if made semi-circle rather than circle, would also increase efficiency.
 
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