China's Space Program News Thread

[taxiya]

What's the propellant used by LM-8? There's no condensation from cryogenics like LOX, but there's no orange fumes from hypergolics.

First stage LOX/Kerosene, second stage is LOX/LH2.

 

[Temstar]

So if Long March 8 is more or less identical to Long March 722HO how come they're splint up into two rocket family like that?

Is it just Long March 8 has reusability in mind while Long March 7 doesn't? Would there ever be any consideration for Long March 8R with four boosters or 3rd stage?

 

[Temstar]

Here's the chief designer for Long March 8 saying starting 2022, assuming production rate keeps up the requirement is for 30 Long March 8 launches a year.

 

[Tam]

Extended mission involved?

To study NEO in preparation of the Zheng He mission.

 

[Quickie]

Why would they go for such an unorthodox nozzle configuration the weight distribution is just weird on one side you have two engines and the other side have one not to mention the two sides that doesn't have any engines at all, a Soyuz style one longmarch 6 core and four long march 6 boosters configuration makes way more sense

First of all, the LM-6 has nothing to do with LM-8, see #6332 for details. There is no LM-6 core or booster. LM-6 is an off-shoot specific purpose vehicle.

The off-center for LM-8R reusable variant is: 1. a have-to-do choice. 2. It is not really a problem either.

1. YF-100 is rated at 65% down-throttling. In test, it has been claimed to go as deep as 50%. LM-8 has totally 4 YF-100, turning off all three will give 25% of lift-off thrust with one YF-100 in full thrust, with the last engine running at 50%, we get 12.5% thrust. This is the maximum allowed thrust for landing. There is no other way than this before a YF-100 variant that can do deeper throttling at 20%-30%.

2. off-center TVC control just need the engine's TVC being slightly compensated when restarted. This is not difficult, the recent SpaceX SN8 test has demonstrated it. Note, CNSA had this idea in LM-8R without waiting for SpaceX to demonstrate it, I say this to prevent some SpaceX fans to claim the credit.

I think Eprash was implying the LM-8 core stage has only one engine, with the other missing. I was skeptical but taking a second look at the pictures, it does seem like this LM-8 rocket has only one engine in its first core stage.

 

[Dante80]

Neither I nor CNSA is claiming credit or tried to. I said "prevent SpaceX fan".

Besides, your example of Atlas 411 is nothing unique of off center TVC control. At take off, a lot of rockets do so. What was talked about originally was "off center vertical landing". It is unique issue of its own.

Not that unique either (see the third Clipper Graham test in 1996 - all four RL-10s put to +/-8 gimbal on purpose while landing). I'm not trying to argue with you btw. It's just that Spaceflight and rocketry is my niche. And - as in most things in life - evolution relies on derivative (even if unconnected) action.

In other news,

 

[Dante80]

In other news, it may have come as a footnote but the launch of Haisea-1 is an important milestone (even when treated as a secondary payload). Not only are we talking about a first Chinese commercial SAR sat, but also, the first miniature one. CETC has been doing some extremely impressive work on this front, and given the specifics of the satellite, further miniaturization in combination with rapid deployment is going to be a hot topic in remote imaging.

 

[taxiya]

So if Long March 8 is more or less identical to Long March 722HO how come they're splint up into two rocket family like that?

Is it just Long March 8 has reusability in mind while Long March 7 doesn't? Would there ever be any consideration for Long March 8R with four boosters or 3rd stage?

The numbering of 7 and 8 is not much of specific or technical reason. Earlier on CZ-3 and CZ-4 had the similar story, where CZ-4 was an alternative solution for CZ-3 (hypergolic 3rd stage instead of LH2/LOX), but later got its own number. To be precise, 722HO is renamed to be CZ-8, they are the same thing, it is only a numbering change.

CZ-7 has reusability in mind too. But everything depends on CZ-8R's successful verification of bundled landing. CZ-8R is the pioneer program for all possible reusable rocket development or modification.

There will never be CZ-8 being three stages. Three stage is only within CZ-7 series, CZ-8 is the two stage variant. I highly doubt there will be a CZ-8 with 4 boosters either, because CZ-7 basic (2 stages) variant has 4 boosters. High takeoff lift/mass is good for LEO which is not CZ-8's designed target area.

 

[taxiya]

Not that unique either (see the third Clipper Graham test in 1996 - all four RL-10s put to +/-8 gimbal on purpose while landing). I'm not trying to argue with you btw. It's just that Spaceflight and rocketry is my niche. And - as in most things in life - evolution relies on derivative (even if unconnected) action.

In other news,

Our conversation so far is not about who is more technically competent in the subject, but rather that you seem to keep missing my point, twice.

Look, I said "It is unique issue of its own.", I did not say "unique to any specific rocket". I did put SpaceX SN8 and CZ-8R forward when I talked about the issue. That issue certainly includes your new example "Clipper" or any other experiment for that matter. But it was never my point to make CZ-8R look unique.

 

[taxiya]

Please, Log in or Register to view URLs content!

Chief designer of CZ-8 talked about "launching a small (down-sized) rocket experimenting VTVL in 2021". According to his word, it is not really small, it is still still 3.35 in diameter. As I understand it, it may be a single core stage. Since YF-100 can not be throttled down enough and Thrust-Mass ratio without boosters are too high, they may put some dead weight on it. The purpose is apparently test everything in near real-life before launching CZ-8R in its full setup.