China's Space Program News Thread
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So since Long March 5's success this year I've been looking up its stats, and particularly the engines and it soon jumped out at me that YF-100 engine is a goddamn work of art. Oxygen-rich staged combustion is already hard enough but on top of this YF-100 has variable mix ratio and variable thrust.
It's little wonder than they took this engine and made Long March 6 by building a 3.35m core with one YF-100, then Long March 7 with a 3.35m core with two YF-100. Then they basically took four Long March 7 core, added nose cones to them and made them into boosters for Long March 5.
So that brings us to Long March 8R:
Notice how it lands with one engine firing on the core. The Long March 8 core is basically identical to Long March 7, 3.35m diameter with two YF-100. The two "boosters" that remain attached are not actually solid fuel, but instead liquid fuel 2.25m (Long March 1 diameter) rockets powered by a single YF-100 - basically the "boosters" are Long March 6 core, but made skinnier and longer.
Then it occurred to me: those aren't boosters at all, that whole contraption is actually just a single rocket stage with four YF-100 engines split into three separate stacks instead of crammed into a single tube. By firing 1/4 engine at launch at landing it allows you to throttle a single YF-100 low enough to land the whole thing safely, like how Falcon lands with 1/9 engines firing.
So why not design a new 5m first stage using tooling from Long March 5 and put four YF-100 on the bottom? Well because the core is already done from Long March 7 and is mature and the "boosters" can be made with Long March 1 tooling based on the work done on Long March 6 core. They basically came up with a way to build a more powerful first stage with enough engines to work for stage recovery by playing lego with existing parts.
It's little wonder than they took this engine and made Long March 6 by building a 3.35m core with one YF-100, then Long March 7 with a 3.35m core with two YF-100. Then they basically took four Long March 7 core, added nose cones to them and made them into boosters for Long March 5.
So that brings us to Long March 8R:
Notice how it lands with one engine firing on the core. The Long March 8 core is basically identical to Long March 7, 3.35m diameter with two YF-100. The two "boosters" that remain attached are not actually solid fuel, but instead liquid fuel 2.25m (Long March 1 diameter) rockets powered by a single YF-100 - basically the "boosters" are Long March 6 core, but made skinnier and longer.
Then it occurred to me: those aren't boosters at all, that whole contraption is actually just a single rocket stage with four YF-100 engines split into three separate stacks instead of crammed into a single tube. By firing 1/4 engine at launch at landing it allows you to throttle a single YF-100 low enough to land the whole thing safely, like how Falcon lands with 1/9 engines firing.
So why not design a new 5m first stage using tooling from Long March 5 and put four YF-100 on the bottom? Well because the core is already done from Long March 7 and is mature and the "boosters" can be made with Long March 1 tooling based on the work done on Long March 6 core. They basically came up with a way to build a more powerful first stage with enough engines to work for stage recovery by playing lego with existing parts.
They must play Kerbal
Extended mission involved?
Yes, I hear it was going to visit a NEO but this piece of news didn't say. It may still be up in the air.
A correction, the 2.25m single YF-100 stage is the booster of CZ-7, nothing to do with CZ-6. The whole family is from CZ-7.
This CZ-8 is essentially CZ-722HO in the early plan. The first 2 stands for 2 stages, the second 2 stands for two boosters, HO is LH2/LOX upper (2nd) stage. All boosters are 2.25m single YF-100, all core stage is 3.35m two YF-100.
For comparison, the two successful CZ-7 launches were of CZ-724, the failed recent launch was of CZ-734HO.
CZ-6 was not really in the plan (the new generation rocket family), it is more or less IMO an offshoot by 8th academy. It's early conception includes an alternative of CZ-7 booster (2.25m), but later deemed unfit. However a CZ-7 core (3.35m 2 YF-100) would be too powerful for its lower target payload, so they came up with the 3.35m core with one YF-100 which is unique to CZ-6 and has no other application.
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