China's Space Program News Thread

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FairAndUnbiased

FairAndUnbiased

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anzha said:
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3D printing doesn't make sense for large rocket components. Throughput and cost is far too high and the mechanical properties are shit. A cylinder is literally the simplest shape for extrusion.

Most cold engine parts are better machined in solid blocks, again for mechanical strength. The only parts that should be 3D printed are small, highly complex refractory parts that would otherwise be made with powder metallurgy.
 
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anzha

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FairAndUnbiased said:
only the injector and parts of the combustion chamber (what I said about small refractory components typically made from powder metallurgy) are 3-D printed. There is no contradiction here.
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Not Aerojet, but being tested at NASA's Marshall Center:

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There are plenty of others. Perhaps the technology has moved on from where you think it is?
 
FairAndUnbiased

FairAndUnbiased

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anzha said:
Not Aerojet, but being tested at NASA's Marshall Center:

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There are plenty of others. Perhaps the technology has moved on from where you think it is?
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The technology is fundamentally limited by being low throughput, especially for large parts. You can even see this if you pay for 3-D printing services vs. machining services: for 3-D printing the low run number unit cost is low, but it doesn't keep getting lower by much as you increase volume. for machining, the low run number unit cost is high, but as you get to very high run numbers, the unit cost becomes very low.

the biggest cost savings in 3-D printing is in not needing specialized tooling for prototype and low volume production. Once you get to the mass production stage, only parts that are made using even more difficult techniques (like powder metallurgy) are worth it.

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3-cost-vs-quantity.png
 
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anzha

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FairAndUnbiased said:
The technology is fundamentally limited by being low throughput, especially for large parts. You can even see this if you pay for 3-D printing services vs. machining services: for 3-D printing the low run number unit cost is low, but it doesn't keep getting lower by much as you increase volume. for machining, the low run number unit cost is high, but as you get to very high run numbers, the unit cost becomes very low.
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I understand what you are saying. For very large runs of CNC does have better economies of scale. I agree.

However, I suspect the idea being pursued is the total number of rockets built by a firm is not high enough to get that economy of scale you are rightly pointing out exists for large production runs. Therefore, if the company doesn't have to buy all that specialized tooling, then the conjecture I suspect is, they have a net win.

You do have valid points. These folks are relatively small and new. Well, not Aerojet, but in general. They very well may fail. The 3d metal printing when I used it was not ready for rocketry. However, it's been a while and there's always a chance the technology has moved on. Or the new kids[*] have found new ways of doing things.

Just a thought.

*. I'm not quite to the point of yelling at the kids to get off my lawn. ;)
 
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taxiya

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A paper by CASC propulsion institute (6th) summarizing additive fabrication in rocket engines both domestical and abroad.

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5-7 are either YF-100 or YF-115. 8-10 are likely YF-130, YF90 or YF-135 as it is heavy rocket engine. 11 and 12 are an unknown engine for commercial launcher and seems to be open cycle as it has component exhaust pipe. Most of their statuses are under testing, but two are in flight application. All of them except 7 are for turbo-pomps. There is one term that I don't know for sure, 离心轮. The other term 泵叶轮 is pump blade. Anyway, they are all the high speed rotating disk-blade driving the pump of 480t engine.

There are other applications in CZ rockets. There are also list of application outside of China. From my understanding, China's application of 3D printing in rocket engines is far ahead of the other countries if you compare the kind of components used.

This institute is also 3D printing combustion chamber of a new engine, but I lost the link so can't show the photo.
 
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taxiya

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anzha said:
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This application is on their LT-5 engine that was used in their recent jump test. It has been discussed in this thread if I remember correctly.

It is impressive by a startup company, but to be honest it is far less so compared to what CASC has done so far. See my other post #10,188. CASC is far ahead of everyone including NASA, SpaceX and this Launcher's LOX pump is merely 7.8t engine compared to 480t YF-130. Maybe this (under impressiveness) is the reason that other member was sceptical of its application on large engine (1st stage >80t).
 
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