China's Space Program Thread II

[gelgoog]

Actually it is quite common for the colors to be like that. Rockets and spacecraft typically either are kept bare metal/composite or painted. White is quite common as paint in most cases since it is reflective. And black coatings are typically used close to engines. If you paint them white, then the engine exhaust will smoke them over and it will look dirty.

You could change the shape. The capsule does not need to have that kind of shape. But designing a new shape requires extensive wind tunnel testing, which I doubt a small private company has good access to. This is not a subsonic or supersonic wind tunnel. This is a Mach 20+ tunnel. US company Sierra Nevada Corporation also copied the Soviet BOR-4 spacecraft design to make the Dreamchaser spacecraft. Yet that does not seem to be an issue.

It can take many years to develop a new airframe design for atmosphere reentry regime. About as much as to make an engine. Like 5-10 years. A capsule is easier. But the Dragon-2 is not exactly a traditional capsule design. It is somewhere in between a traditional capsule and a winged reentry vehicle.

 

[tacoburger]

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So what do you guys think of propellant crossfeed for falcon heavy like configurations of central core+side boosters? It's basically just the side boosters pumping fuel into the central booster during launch. Spacex was thinking about doing it for the falcon heavy, which would have given it a "hefty" performance boost according to Spacex engineers, although they ultimately abandoned the idea due to 1) The falcon heavy already being of the of the most powerful rockets in service, there wasn't that much point in boosting it's performance by a few percentage points 2)They decided to run full speed towards Starship, rather than spending more time and effort on the falcon heavy.

The issues is this is a "new" technology, never done before and will properly be hard to actually do, considering the difficulties of pumping hundreds of litres of fuel every second during the stresses launch, disconnection issues during stage separation, especially if you want your rockets to be resuable. Back of the envelope calculations suggests that it could give a rocket 10-15% more payload, but this has never done before and the calculations were made by random people in their spare time, which means that the performance boost could easily be more modest, especially when you consider how much more weight will have to installed in the pumping system.

But Spacex was seriously considering doing it before chasing the holy grail of a fully reusable rocket, so I think there should be a decent performance increase. And I think there's merit in China seriously investing into this technology. There's more than a dozen private rocket companies doing/copying the falcon heavy configuration and CALT are doing the CZ-5G. Most of the small private rocket companies probably won't be building a Starship tier rocket anytime soon, so a 5-15% increase in performance in a workhorse rocket will be well worth it, especially since most of their rockets are so much weaker and needs that performance boost.

And of course, the CZ-5G will benefit greatly too. Not as the first version of course. Again, the issue is that is it worth it to invest in this technology, instead of just throwing everything into the development of the LM9? I think yes, the CZ-5G will probably be China's only crewed lunar capable rocket for some time, development issues of the LM9 means that it easily won't be flying until mid 2030s no matter how much money you throw at it, so squeezing as much payload as you can out of the CZ-5G is the best way to get China's lunar crewed program and lunar base program the best chances it needs to succeed. If CALT does develop this technology, I hoped that they actually give out the design/technology of this system to their private rocket companies, literally all of them are working on a falcon heavy rocket configuration and if it works as intended, it will greatly boost the total payload capacity of the entire industry.

So thoughts? Should CALT develop this for a 5-15% boost on the CZ-5G or just run straight for the LM9?

 

[H2O]

All the design freedom in the world and they ended up with a me too design? Yes physics will dictate a lot of the design but not to this extent.

It's pure laziness on the company's part. Engineers are told what they can and cannot do by the boardroom (as long the physics supports it). That's the problem with corporations, the bottom line will dictate behavior. If the "similarities" in design don't negatively affect the bottom line then this behavior will never change.

 

[taxiya]

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So what do you guys think of propellant crossfeed for falcon heavy like configurations of central core+side boosters? It's basically just the side boosters pumping fuel into the central booster during launch. Spacex was thinking about doing it for the falcon heavy, which would have given it a "hefty" performance boost according to Spacex engineers, although they ultimately abandoned the idea due to 1) The falcon heavy already being of the of the most powerful rockets in service, there wasn't that much point in boosting it's performance by a few percentage points 2)They decided to run full speed towards Starship, rather than spending more time and effort on the falcon heavy.

The issues is this is a "new" technology, never done before and will properly be hard to actually do, considering the difficulties of pumping hundreds of litres of fuel every second during the stresses launch, disconnection issues during stage separation, especially if you want your rockets to be resuable. Back of the envelope calculations suggests that it could give a rocket 10-15% more payload, but this has never done before and the calculations were made by random people in their spare time, which means that the performance boost could easily be more modest, especially when you consider how much more weight will have to installed in the pumping system.

But Spacex was seriously considering doing it before chasing the holy grail of a fully reusable rocket, so I think there should be a decent performance increase. And I think there's merit in China seriously investing into this technology. There's more than a dozen private rocket companies doing/copying the falcon heavy configuration and CALT are doing the CZ-5G. Most of the small private rocket companies probably won't be building a Starship tier rocket anytime soon, so a 5-15% increase in performance in a workhorse rocket will be well worth it, especially since most of their rockets are so much weaker and needs that performance boost.

And of course, the CZ-5G will benefit greatly too. Not as the first version of course. Again, the issue is that is it worth it to invest in this technology, instead of just throwing everything into the development of the LM9? I think yes, the CZ-5G will probably be China's only crewed lunar capable rocket for some time, development issues of the LM9 means that it easily won't be flying until mid 2030s no matter how much money you throw at it, so squeezing as much payload as you can out of the CZ-5G is the best way to get China's lunar crewed program and lunar base program the best chances it needs to succeed. If CALT does develop this technology, I hoped that they actually give out the design/technology of this system to their private rocket companies, literally all of them are working on a falcon heavy rocket configuration and if it works as intended, it will greatly boost the total payload capacity of the entire industry.

So thoughts? Should CALT develop this for a 5-15% boost on the CZ-5G or just run straight for the LM9?

CZ-5DY (I have not seen G yet) is enough for the initial moon landing mission (Apollo sized) before 2030. There is no need to squeeze it by the risky "cross feeding" which isn't any easier than what CZ-9 would face.

Why would anybody gives out some excellent tech for free to anybody? If it is good, what is the point of not using it themselves? It doesn't make any sense.

 

[tacoburger]

CZ-5DY (I have not seen G yet) is enough for the initial moon landing mission (Apollo sized) before 2030. There is no need to squeeze it by the risky "cross feeding" which isn't any easier than what CZ-9 would face.

If you're trying to set up a moon base, every kg of payload you can squeeze into a single mission is good. It's not like launching a typical one and done satellite, if you got 5% extra payload to spare, just chuck in some extra food, water, oxygen as spares for the base. Also there's a lot you can do with an improved heavy lift rocket, mega-constellations, extremely heavy sats etc etc

Why would anybody gives out some excellent tech for free to anybody? If it is good, what is the point of not using it themselves? It doesn't make any sense.

Because it benefits the entire industry as a whole? NASA gave Spacex all the documents it had on space-docking and orbital refuelling experiments for this very reason. The merlin engine is based off an old NASA design that NASA made public. Hell, the entire the entire academia system runs on this principle, there's hundreds of extremely influential and ground-breaking papers published every day for free or for a minor fee. One famous example, stable diffusion wouldn't have been created without a series of now famous A.I research papers on deep learning neural networks published for free, and it wouldn't have beaten other A.I art models if it had been locked away like DALL-E, instead it's free to use and the team behind it are worth 1 billion because of this.

Or other examples like RISC-V, free and open source.

 

[taxiya]

If you're trying to set up a moon base, every kg of payload you can squeeze into a single mission is good. It's not like launching a typical one and done satellite, if you got 5% extra payload to spare, just chuck in some extra food, water, oxygen as spares for the base. Also there's a lot you can do with an improved heavy lift rocket, mega-constellations, extremely heavy sats etc etc

CZ-5DY isn't for moon base, CZ-9 is. China isn't setting up the base before 2030, therefor CZ-9 isn't needed before 2030. All your advice to CZ-5DY are CZ-9's missions. Squeexing CZ-5DY is a wasteful risky work.

I think you need to take a closer look at China's space program's time plan, milestones including rocket's road-map before making the suggestion. Those are available in this thread.

Because it benefits the entire industry as a whole? NASA gave Spacex all the documents it had on space-docking and orbital refuelling experiments for this very reason. The merlin engine is based off an old NASA design that NASA made public. Hell, the entire the entire academia system runs on this principle, there's hundreds of extremely influential and ground-breaking papers published every day for free or for a minor fee. One famous example, stable diffusion wouldn't have been created without a series of now famous A.I research papers on deep learning neural networks published for free, and it wouldn't have beaten other A.I art models if it had been locked away like DALL-E, instead it's free to use and the team behind it are worth 1 billion because of this.

Or other examples like RISC-V, free and open source.

China isn't US or the west as a whole. The whole industry means nothing if it does not serve the purpose of the People whose asset (CNSA's rocket tech) is in the hand of the State. Giving state property to private company (part of that industry) is a crime of stealing.

 

[YISOW]

CZ-5DY isn't for moon base, CZ-9 is. China isn't setting up the base before 2030, therefor CZ-9 isn't needed before 2030. All your advice to CZ-5DY are CZ-9's missions. Squeexing CZ-5DY is a wasteful risky work.

I think you need to take a closer look at China's space program's time plan, milestones including rocket's road-map before making the suggestion. Those are available in this thread.


China isn't US or the west as a whole. The whole industry means nothing if it does not serve the purpose of the People whose asset (CNSA's rocket tech) is in the hand of the State. Giving state property to private company (part of that industry) is a crime of stealing.

CZ-5DY is just for early stage of go to the moon

 

[discspinner]

this suggests first launch of LM9 is ~ 2030 at around 44:15

 

[Taiban]

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[by78]

The YF-102V engine has recently completed four full ignition tests. The LOX/Kerosene engine features a 3D printed thrust chamber.

【YF-102V完成4次整机点火 直径超过400mm的3D打印全不锈钢推力室】2023年元旦前后，航天六院首台大推力开式循环液氧煤油高空发动机完成4次整机点火，稳态参数平稳，燃烧效率等关键参数达到国际先进水平，标志着我国首台新型液液燃烧喷注器、我国最大尺寸全3D打印的全不锈钢结构推力室关键技术取得重大突破。该型推力室由西安航天动力研究所自主研究设计，从方案论证、图样设计、缩比燃烧试验到整机热试，仅仅用时十个月，实现了创新驱动、快速研制，为我院“八年九机”之一的发展奠定基础，燃烧技术迈出了“虚拟世界多次迭代、物理世界一次成功”关键一步。

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发动机推力室瞄准高性能、变推力、低成本的研制目标，院、所领导明确了发展思路：设计是龙头，创新驱动发展。设计师通过方案比较，大胆创新。在研究手段上，利用“数字仿真+试验验证”相结合的方式，建立了喷嘴燃烧仿真模型，开展高压缩比模拟试验，为参数选取提供依据，快速突破液液高效燃烧、可靠冷却等关键技术；在设计方面，采用数字化结构设计和优化，减少设计生产反复；在制造方面，在结构拓扑优化基础上，选用一体化3D打印技术，提高产品结构可靠性，显著降低研制成本；在试验方面，突破传统研制思路，优化流程。

推力室是液体火箭发动机中结构最为复杂、制造加工要求最为苛刻的核心组件，研制周期长，生产成本高。直径超过400mm，推力室集成国内外最先进的设计、制造和试验技术，同类型的热力组件国内尚属空白，没有经验，没有成功案例！喷注器烧蚀如何解决，如何验证？燃烧不稳定性重大风险如何避免？高性能如何实现？攻关组采用了一系列独创的新型技术，基于仿真、模拟试验结果，凭扎实的专业知识，掌握了液氧煤油高效稳定燃烧核心技术，实现推力室结构功能一体化、复杂结构集成化，短短十个月就完成推力室研制，开创出一条创新发展之路。大胆进行风险分析，提出合理的试车参数，保证了推力室热试一次成功，实现了“零”的突破和跨越。（西安航天动力研究所）