China's Space Program Thread II

[Wrought]

Thanks for clarifying.

I believe it falls under the jurisdiction of the Emergency Management Ministry alongside firefighting, disaster relief, and related activities.

 

[by78]

More high-resolution images of the successful VTVL test of iSpace's SQX-2Y technology verification rocket.

 

[by78]

 

[nativechicken]

It's interesting and surprising that no other company/country has been able to develop and operationalise a reusable rocket like space X, who has been doing so for almost a decade now. I wonder why it's the case. Would have thought that many companies/countries would have developed a similar rocket by now giving the advantages

The gravity well of the Earth requires the rocket to have a maximum and minimum thrust adjustment range of 20:1
SpaceX achieved this thrust level through 9 Merlin 1D engines with a variable thrust ratio of 40%.
Considering the evolution of technology, for the first time, the rocket could only reach the mid size rocket level, with a takeoff weight of 500-700t and a transport capacity of around 15-20 tons (hydrocarbon based rockets).
This limits the weight of the arrow body and the minimum thrust of the engine.
The secret to the true success and leadership of SpaceX in reusing rockets is that the Merlin 1 series engine only has a thrust of 36-85t, which, combined with the self weight of the F9 stage 22-25t, can easily achieve vertical landing.
Other companies are unable to achieve vertical takeoff and landing rockets due to the lack of engines and rocket bodies with appropriate thrust.
Most shelf engines have a thrust of over 100t, with a 50% throttle of 50t, while the 3-meter diameter arrow weighs only 14-22t. Vertical landing is very difficult.
Moreover, the engine can only use hydrocarbon based fuels (liquid oxygen kerosene, liquid oxygen methane), and cannot use ambient temperature and hydrogen oxygen fuels. In addition, the development cycle of the engine is about 5 years, and the mature rocket body requires a research and development cycle of 7-10 years.
That's why SpaceX is currently the only company with reusable rockets, and China has so many private rocket companies because between 2000 and 2010, China modified a 60t methane engine based on YF77 for technical verification. Then the technology spreads to private rocket companies.
The reason why CZ8R cannot come out is because the thrust of YF100 is too high. Previously, only 65% of the engine was throttled, with a minimum thrust of 78t, while the recovered bundled mass was 30-35t.
Now YF100 has basically solved the 30% throttling problem (it has been tested and reported in the literature). To achieve a 20% throttle, the CZ8R can achieve a biased power landing, and to achieve a 10% throttle, it can achieve a dual engine landing.

 

[nativechicken]

You need several technologies to get this to work. You need engines which can throttle down enough, you need advanced control systems, and then you need to have the recovery ships like SpaceX is doing.

The engine thrust and arrow body must match.
There are many details constraints here.
The reason why China's aerospace industry is very powerful is that if you truly understand the secrets of reusable rockets, see the various preparations in China's aerospace industry over the past 8 years, and then take a look at various aerospace science jokes on Weibo and Zhihu. Take a look at the words and phrases （只言片语）of real experts on NSF. Only then can you understand NASA's fear.

 

[Paulo R Siqueira]

 

[Michael90]

they still haven't needed to produce more Merlin engines despite them being the world's largest launch provider by far.

Is Space X really the world's largest launch provider BY FAR?
You mean they launch more than anybody else BY A WIDE MARGIN?
I think they maybe ahead but not BY A WIDE MARGIN as you claim?

 

[Dragon of War]

One big issue with making rockets reusable, is what do you do with the engine production facility while it's idle to keep worker skills up to date. To keep the engine production facility operational you need to have a minimum amount of engines being produced all the time. Notice how SpaceX has stopped Merlin engine production two years ago to focus on Raptor and they still haven't needed to produce more Merlin engines despite them being the world's largest launch provider by far.

For countries with much more reduced launch requirements this would mean having your own engine factory would be uneconomic.

You make a valid point about the challenges of maintaining engine production facilities during idle times. China's approach to addressing this concern could leverage their substantial domestic launch demand, which would provide a consistent flow of work for their engine factories. This could potentially make it more economically viable for them to maintain and further develop their engine production capabilities, ensuring a steady supply of engines while keeping worker skills up to date.

 

[gelgoog]

Is Space X really the world's largest launch provider BY FAR?
You mean they launch more than anybody else BY A WIDE MARGIN?
I think they maybe ahead but not BY A WIDE MARGIN as you claim?

SpaceX alone launches about as many rockets as China. The other US launch providers are negligible. Those SpaceX launches are all made with the Merlin engine and the Falcon family of rockets. China on the other hand is using multiple types of rockets and engine types and most of the launches are still made with other Long March 2 and 3 rockets.

As SpaceX ramps up Starlink, they will need a huge amount of mass to be launched further increasing their advantage.

If anything I think Starship is a mistake, since there is no real requirement for its launch capacity. The Falcon is a great rocket design though.

 

[ZeEa5KPul]

One big issue with making rockets reusable, is what do you do with the engine production facility while it's idle to keep worker skills up to date. To keep the engine production facility operational you need to have a minimum amount of engines being produced all the time.

Do it the Apple way: planned obsolescence.

If anything I think Starship is a mistake, since there is no real requirement for its launch capacity. The Falcon is a great rocket design though.

This is a case where supply will create its own demand.