# Tag Info

42

Long March 11 is a cold-launched rocket, based on a concept popular with military rockets. A gas charge is generated by the launch platform (often using a chemical gas generator) to eject the rocket from the launch platform before engine ignition. This saves the launch platform from having to manage hot exhaust gases, and reduces wear and tear on the launch ...

19

That's unburned $\mathrm{N}_2\mathrm{O}_4$. The zeroth and first stages of the Long March use $\mathrm{N}_2\mathrm{O}_4$ and $\mathrm{UDMH}$. The Dnepr uses the same propellants. I doubt that the red gas you see is from the cold launch system. That system uses a black powder mortar.

14

From Spaceflight101: For Shenzhou Missions, a stretched version of the typical Long March fairing is used ... Four aerodynamic stabilizers are attached to the upper part of the fairing that is part of the Launch Escape System in a escape scenario, those would deploy to stabilize the vehicle while flying under the Launch Abort Engines. The Fairing’s ‘wings’...

11

TLDR the main purpose of the grid fins is to steer the spent 1st stage away from populated areas when it's falling to the grond. CZ-4B targets SSO and is mostly launched from T-SLC (Taiyuan Satellite Launch Center). China currently operates 4 SLCs, T(Taiyuan), J(Jiuquan), X(Xichang) and W(Wenchang). While J-SLC launches into the desert and W-SLC into the ...

10

Is it possible theoretically to know where and when the Long March 5B will be landed approximately? Yes! Take it from Jonathan McDowell @planet4589's tweet: The EU SST prediction is narrow enough that we can start to talk about location now! In particular, none of the orbits within the predicted window cross the northwestern US or the mid Atlantic seaboard....

8

It's pretty rare to see popular news articles get technical details right, and this is no exception. The grid fins referred to in earlier QAs here are, as Polygnome notes, not maneuverable; they just act as passive stabilizers during LES aborts for the shroud-enclosed Shenzhou spacecraft. (See also this QA regarding the Soyuz grid fins.) The new article ...

5

You need to rephrase your question... Give a time frame? From right after launch, can we predict where it will re-enter? No. Too many variables. (Height and density of earth's atmosphere). Right the second before it hits the Earth? Yes. In between? It depends, and it gets more accurate the closer to re-entry it gets. Side note: Not landing, that is what ...

5

Would this then be regarded as a single-stage-to-orbit, and a survivor of astronaut Don Petit's tyranny? No, Long March 5B uses strap-on boosters. From a certain level of abstraction, there's little difference between a two stage rocket and a one-stage rocket with strap-on boosters. I believe the core stage engines are ignited at liftoff, but it's hard ...

5

Yes, it is now. The rocket has fallen down now and the approximate location where it fell is known. According to the China Manned Space Agency (as reported on their official website and quoted by multiple news agencies worldwide): The debris of the last stage of the Long March-5B Y2 carrier rocket reentered the atmosphere at 10:24 a.m. on Sunday (Beijing ...

5

According to the paper from the 64rd International Astronautical Congress, Beijing, China The Development of the LOX/LH2 Engine in China; IAC-13, C4.1, 1x18525, the nozzle was welded from spiral-shaped elements. So the spiral pattern is here by design. The spirals are "dump-cooled", an old Rocketdyne idea described in this 1966 NASA Technical Note TN D-...

5

Those falling particles seem to be parts of a protective sheet that shields the opening around the interstage lattice between first and second stages. Only the Long Marches launched from Taiyuan and Jiuquan during colder times of the year have such cover. The following are a few examples to illustrate the presence and absence of the sheet in different times ...

5

No. The 4 Soyuz boosters are RP1/LOX, this is a design that goes back to the R-7 that launched Sputnik 1. Thousands have been launched. Liquid boosters are a less common design than solids, but have been produced in greater numbers.

4

A Honda Civic is a two axle vehicle. It can tow a trailer. When it's towing a trailer, Civic-plus-trailer is functionally a three axle vehicle. There's no essential difference between a spacecraft with propulsion and a rocket stage. In this case, Long March 5 is a two-stage rocket because it's designed and built separately from the YZ stage. Long March ...

4

This comment is too long to fit as a comment, so I'll write it as a partial answer. Was this really as close as call as they make it out to be if it fell just off the west coast of Africa? Definitions of "just missed" and "close call" are subjective, but we can think about the sensitivity of the final state to the initial state. A ...

4

@uhoh pointed to a tweet by LaunchStuff that shows images of what appear to be several Chinese notices to airmen (NOTAMs). (Weirdly, I can't find the originals of those; they don't seem to be in the international airman notification system, nor the corresponding system for notices to mariners) They show three danger areas, one of which is near Guam: Note ...

4

Is there anything meaningful to this difference [?] It shows that it's a much smaller stage with a hat. The height of the Chinese booster includes its top cone. A quick measurement on the pictures gives its height as 4.5m, leaving a useful height of 23 m. The stage is smaller, so the contribution of the engines to its height is larger. The length of the ...

4

A controlled reentry comes at a cost. China and SpaceX are apparently betting that the added cost of a controlled reentry vastly outweighs the cost of debris from an uncontrolled reentry resulting in significant damage. Suppose a chunk of debris kills a cow. Nobody will have a cow over this. People will have a cow if a chunk of debris kills a person. But ...

3

These are fixed fins, therefore they provide passive aerodynamic stabilization of the launcher at the cost of adding some drag and weight. The booster-less Long March 3A mounts four similar fins on the core stage. The Long March 3A Series Launch Vehicle User's Manual (which covers the 3B) includes block diagrams of the guidance and control systems which show ...

2

Before we get into potential causes of the delay, I think it's important to say that the key focus of replacing CZ-2,3,4 wasn't to prevent booster on village syndrome it was to; To design a series of launch vehicles rather than one launcher made for a specific mission, so that to enhance China’s capability of entering the space. To apply the advanced ...

2

From to @TildalWave's comment So the color at the exhaust actually shows how well it is mixed with hydrazine at fuel / oxidizer injectors and the efficiency of the engine? I don't mean these first few seconds, but also later on. And another funny thing, dinitrogen tetroxide is apparently completely white at -196°C and below and gets darker red as ...

1

No. The Energia used kerolox strapons.

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