China's Space Program News Thread

[silentlurker]

You guys may laugh at it now but SSO reusable rockets are the future. The first automobiles and planes were also unimpressive. Look at where they are now.

I don't think there's a single SSTO reusable rocket on Earth right now.

 

[siegecrossbow]

I don't think there's a single SSTO reusable rocket on Earth right now.

Starship may pave the way to that.

 

[taxiya]

You are dead wrong about that. The Raptor engine is the first full-flow staged combustion engine that has flown. That *is* a big thing. It was attempted in the past both in the Soviet Union and the USA but it never went past bench testing because of its design complexity. In some cases the prototypes exploded on the test stand in other cases they never went past subscale tests. It also works on LOX/Methane and is actually the first launcher engine using that fuel combination. Which again has been talked about for decades but never actually been used. It is futile to compare it with the SSME or RD-0120 on specific impulse because it will never have the same specific impulse because of the fuel combination they chose. The fuel was specifically chosen to have a combination of higher storage density than hydrogen and higher Isp than kerosene. So it will have Isp between both fuels. No it is not less advanced, it is in fact more advanced than the SSME. It uses a more advanced engine cycle, it uses channel wall nozzle, it doesn't need those stupid resonance chambers, it is superior overall. You could argue that the RD-0120 has some design advantages in that it is lighter weight because it is a single shaft engine. But it still uses a less advanced combustion cycle. The RD-0120 was in fact more advanced than the SSME because of the single shaft-design, no resonance chambers, and channel wall nozzle. Which proves some people on Youtube who say the Soviet Union never could do LOX/LH2 engines properly are in fact totally incorrect. They were late at the game but they in fact did it better.
The Soviets basically did an engine better than the SSME and did an oxygen rich LOX/Kerosene staged combustion engine for the same vehicle (Energia). A much greater achievement in propulsion technology than the Shuttle. But also part of the reason why they went bankrupt I guess. USA after the oil crisis and Nixon taking the dollar off the gold standard and getting into fiat currency had to nerf the Shuttle program so it used solids instead of LOX/Kerosene stages. The Shuttle was a case study on how not to do cost cutting.



Well, sure, but the ability to launch larger payloads more cheaply, by at least an order of magnitude, is strategically and militarily significant. It means all sorts of things you wouldn't launch can be launched. Like a high resolution satellite constellation which covers the entire Earth, or a space based long wave radar network, or even programs like Brilliant Pebbles ABM might return to the table.

I have no interest in debating in length with a fanxxx, so here comes the short answers.

The SSME and RD-0120 were still the most powerful engines much much better in the job, highest specific impulses. That IS a big thing that Raptor will NEVER get close because of the character of H2, rule of physics. No amount of texts can get around that.

The larger and cheaper REMAINS to be seen, I will ignore "pie in the sky" argument. And even IF that pie becomes reality, it means NOTHING in market (China and Russia) it has no access, nor to countries (many who do not line up with the west) that have no access to US payload or European payload that uses American made screws and nuts. It just means NOTHING as far as my original point concerns "SpaceX is not a trouble to China". So don't try to drag the subject away.

 

[silentlurker]

Starship may pave the way to that.

I recall reading somewhere the physical limits of chemical reactions and the rocket equation means the max a SSTO can do at peak effeciency is barely reach orbit. So unless someone finds a big breakthrough in physical chemistry or we move past chemical fuel SSTO reusables will probably be overshadowed by multi-stage reusables.

 

[gelgoog]

...
The SSME and RD-0120 were still the most powerful engines much much better in the job, highest specific impulses. That IS a big thing that Raptor will NEVER get close because of the character of H2, rule of physics. No amount of texts can get around that.
...

The larger and cheaper REMAINS to be seen, I will ignore "pie in the sky" argument. And even IF that pie becomes reality, it means NOTHING in market (China and Russia) it has no access, nor to countries (many who do not line up with the west) that have no access to US payload or European payload that uses American made screws and nuts. It just means NOTHING as far as my original point concerns "SpaceX is not a trouble to China". So don't try to drag the subject away.

It does not matter. What matters is low mass fraction. If you get really high Isp with a really low density fuel you need really heavy tanks which decrease your payload to orbit. That is why LOX/LH2 is typically reserved for second stages. Also, LOX/LH2 is not the uber alles of high Isp, you got ion propulsion, which is in use today, or nuclear thermal rockets, which have been bench tested and proven to work. While LOX/LH2 has an Isp of at best 480 ion propulsion can reach 3200 and nuclear thermal 900.
So I don't know why the fixation with hydrogen.

Also Falcon 9 family is already cheaper than any other rocket on the market in payload to orbit. Even if Starship fails the rest of the industry will have to compete against it.

Like I said cheaper launch by an order of magnitude makes many uses of space that wouldn't be possible, become possible, so it is of strategic significance, and no just because the Chinese market is isolated it doesn't mean it doesn't matter. The Qing also thought they didn't need to modernize vs the west and look at what happened.

Reusable rockets are a big thing.

Compare the Raptor with the YF-100 engine. It has about twice the thrust, better Isp, throttles deeper, and will likely end up with a better thrust-to-weight ratio. This means each Raptor engine can easily replace more than two YF-100 engines on a first stage application. The SSME has about the same thrust, and less than half the thrust-to-weight ratio and a huge tank that weighs a ton so they have to discard it in flight.

 

[Temstar]

Isn't this the first launch of a Stainless Steel Rocket? That by itself is very impressive. The Rocket attempting to land is impressive too. This is to certify the first rocket made out of steel and that means a lot to cost savings. SpaceX must be commended for its innovation.

No stainless steel rocket is actually very old tech. The first Atlas rockets (and the original ICBM) were made out of thin stainless steel "balloon" tanks.

Here's a Mercury-Atlas showing the stainless construction.

 

[silentlurker]

Also, LOX/LH2 is not the uber alles of high Isp, you got ion propulsion, which is in use today

Not sure why you're bringing this up in the context of rocket launches, ion propulsion creates an absolutely tiny amount of thrust, only useful for accelerating in space over hours or days.

 

[ZeEa5KPul]

Yeah... I thought I was in "China's Space Program News Thread." Guess I thought wrong.

 

[taxiya]

It does not matter. What matters is low mass fraction. If you get really high Isp with a really low density fuel you need really heavy tanks which decrease your payload to orbit. That is why LOX/LH2 is typically reserved for second stages. Also, LOX/LH2 is not the uber alles of high Isp, you got ion propulsion, which is in use today, or nuclear thermal rockets, which have been bench tested and proven to work. While LOX/LH2 has an Isp of at best 480 ion propulsion can reach 3200 and nuclear thermal 900.
So I don't know why the fixation with hydrogen.

Also Falcon 9 family is already cheaper than any other rocket on the market in payload to orbit. Even if Starship fails the rest of the industry will have to compete against it.

Like I said cheaper launch by an order of magnitude makes many uses of space that wouldn't be possible, become possible, so it is of strategic significance, and no just because the Chinese market is isolated it doesn't mean it doesn't matter. The Qing also thought they didn't need to modernize vs the west and look at what happened.

Reusable rockets are a big thing.

Compare the Raptor with the YF-100 engine. It has about twice the thrust, better Isp, throttles deeper, and will likely end up with a better thrust-to-weight ratio. This means each Raptor engine can easily replace more than two YF-100 engines on a first stage application. The SSME has about the same thrust, and less than half the thrust-to-weight ratio and a huge tank that weighs a ton so they have to discard it in flight.

hmm, now you are trying to shift the goal post, that is not honest of you. Did I saying anything refuting these things that you are trying to stuff into the conversation? Did I even mention anything related to these "new" points of yours?

Now you finally joined my ignore list.

 

[Arcgem]

What SpaceX is doing with reusable rockets does have significant implications for China's future in space.

If space does become a large avenue for commerce, then SpaceX will corner the launch industry the same way TSMC cornered the chip industry. Any Chinese company doing business in space would have to fly American to be competitive, with all the strings that come attached. No building your own satellites, no Chinese-made parts, etc.

This would essentially be Semiconductors 2: Electric Boogaloo where any Chinese company could be shut out of the market if it gets too uppity.

Even discounting the commercial side, remember that SpaceX is launching payloads for the military. If payloads to space get 10 times cheaper for the US, that is 10 times more US assets in space, assuming constant budget.

Strategically, this leaves China with several options:

1: Give up on matching the US in space power, with all the national security risks that entails.
2: Try to brute-force it by subsidizing more costly rockets, draining resources while stunting domestic growth.

Then there is 3: Realize where the ball is headed now and ensure domestic alternatives remain competitive on the world stage, including reusability.