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56 votes
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Why do the Russians use these fence-like interstage fairings?

It's all to do with ullage in the fuel tanks. Newton's laws of motion mean that when a rocket is no longer firing and no force is being applied, the rocket receives no acceleration. It continues at ...
Brian Tompsett - 汤莱恩's user avatar
44 votes
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When did the concept of "stages" enter rocketry?

The first multistage rocket is much older then one might think. Its from the 14th century CE. Huolongchushui or fire dragon issuing from the water (Chinese: 火龙出水; pinyin: huolóngchushui; literally: ...
Polygnome's user avatar
  • 6,956
43 votes
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Why not keep the engine for multi-stage rockets?

There are some major challenges with this. For starters, the engines of the first stage produce far too much thrust for the last stage, which would require extra structural mass to allow the rocket to ...
Nathan Tuggy's user avatar
  • 4,567
31 votes
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Is the failure to separate Starship from the Super Heavy booster a "dumb failure" and does it tell something about the project reliability?

It is far too early to say for sure exactly what happened during the Starship launch. And, to my knowledge, SpaceX have not provided any explanation so far. That said it is highly likely that SpaceX ...
Slarty's user avatar
  • 9,800
23 votes

Why not keep the engine for multi-stage rockets?

Nathan's answer is good and cover almost everything but let me add a last bit: An engine nozzle can be optimized for only one given altitude ambient pressure. This has a great impact on the rocket ...
Antzi's user avatar
  • 12.7k
21 votes

Why are stages not connected by the engine nozzle? Why are interstages used?

There is a misunderstanding in your question "The engine bell(s) already support the entire compressional stress generated by the weight of the stages above it when the engine is firing..." ...
Organic Marble's user avatar
21 votes

Wouldn’t Super Heavy flip following stage seperation, even without help from its 3 lit engines?

Aerodynamics don't matter. Staging takes place at an altitude of roughly 74 km, in an atmospheric pressure of about 4 Pa (0.004% of surface pressure). Even at the speed Super Heavy is going, that's ...
Mark's user avatar
  • 15.4k
20 votes

Why was the Polyus mounted backward?

The service module of Polyus was too fragile to withstand heavy laser payload above it during the launch. I've found the answer at buran.ru (in Russian). www.buran.ru/htm/str163.htm According to ...
Heopps's user avatar
  • 9,071
18 votes

Apollo 11 mission report shows velocity well below escape velocity thousands of km on the way to the Moon

As @Rikki-Tikki-Tavi points out escape velocity is the velocity you would need at (or near) the surface of Earth to make out out of Earth orbit. Of course, just like anything thrown up into the air, ...
uhoh's user avatar
  • 148k
16 votes
Accepted

Why does Blue Origin land the crew capsule separate from the booster?

It would be extremely unstable. There are 2 things that weight a lot on an empty rocket, the capsule and the engine. With the two of them on opposite sides, the rocket would become extremely unstable. ...
PearsonArtPhoto's user avatar
  • 121k
16 votes
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Why did Amazonas5 2nd stage ignite before 1st stage separation?

The initial exhaust from the upper stage fires at the first stage and is deflected and exits through the openings in the interstitial fairings, as shown in the markup of a Proton rocket below: The ...
Josh King's user avatar
  • 2,469
16 votes

When did the concept of "stages" enter rocketry?

I would mention works of Konstantin Tsiolkovsy. I think that he was first, who proposed to use multistage rockets for space flights. His most important work, published in May 1903, was Exploration ...
Pavel Bernshtam's user avatar
16 votes
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Why are stages not connected by the engine nozzle? Why are interstages used?

The answer is a bit more nuanced than Organic Marble presents it. It makes sense to make a force balance to see what bits of engine can take which amount of force. First, let's look at the chamber. It ...
Sanchises's user avatar
  • 280
16 votes

Is the failure to separate Starship from the Super Heavy booster a "dumb failure" and does it tell something about the project reliability?

The quoted article from the Italian source looks like there a combination of poor word choice, limited technical background and possibly even a bit of truth. First problem is that at time of writing ...
GremlinWranger's user avatar
15 votes
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Could Falcon 9 push the second stage a little longer after MECO and before separation?

After the first stage engines are shut down, the only way for the second stage to extract energy from the first stage is to push away from it, which is how the separation already works. Attempting to ...
Erin Anne's user avatar
  • 12.4k
12 votes
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What are the disadvantages of pneumatic stage separation systems?

The separation between stages has to be hefty enough and quick enough so as to avoid recontact between the stages. This can happen (and has happened) if for example the stage separation occurs while ...
David Hammen's user avatar
  • 75.3k
11 votes
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Why do Soviet and Soviet-derived rockets hot-stage instead of using ullage motors?

Paraphrasing parts of an answer to a different question, hot-staging has a few advantages: It's less complex than staging using ullage motors since fewer parts are involved (whole rocket motors and ...
DarkDust's user avatar
  • 12.6k
11 votes

Why are stages not connected by the engine nozzle? Why are interstages used?

It is important at stage separation to remove as much as possible weight from the upper stage. The interstage weight does not count after separation, but any enhancement of the upper stage engine ...
Uwe's user avatar
  • 49.2k
10 votes

Which rockets have their upper stages separating at(around) 100 km?

It depends on your definition of a stage. Soyuz' boosters cut off and separate at ~40km, but the core stage cuts off well above the Karman line, around 175km altitude. This article refers to the ...
Russell Borogove's user avatar
10 votes

For Starship, using B9 and later, how will separation work if the Hydraulic Power Units are no longer needed for the TVC System?

Starship does not use a hydraulic / pneumatic stage separation system. Starship's stage separation is inspired by the satellite deployment system used on Falcon 9 launches of Starlink v1 and v1.5 ...
Jörg W Mittag's user avatar
9 votes

When did the concept of "stages" enter rocketry?

Important new ideas are often thought by more than one person of a single nation. See this page about multistage rockets. In the 14th century the idea was developed in China and Korea using solid ...
Uwe's user avatar
  • 49.2k
9 votes

Reliability of explosive bolts and redundant initiators

I found a document about that theme: Apollo Spacecraft & Saturn V Launch Vehicle Pyrotechnics / Explosive Devices Some cites: More than 210 pyrotechnic devices per Apollo Mission. All ...
Uwe's user avatar
  • 49.2k
9 votes

Could Falcon 9 push the second stage a little longer after MECO and before separation?

Look at it a different way. If the two stages separated in a non-violent manner - i.e., one didn't "push" away from the other - then they would continue side by side (or end to end) as ...
manassehkatz-Moving 2 Codidact's user avatar
8 votes
Accepted

Did the Saturn V interstage ring burn up in the atmosphere?

The first stage and the interstage ring both did fall uncontrolled after stage separation, landing somewhere in the Atlantic ocean. Stage separation occurs at about 2400 m/s and 67km altitude. That's ...
Russell Borogove's user avatar
8 votes

Which explode in spaceflight more often, nuts or bolts?

For Apollo: more nuts than bolts, but vastly more non-threaded connectors Table I of Apollo Experience Report: Spacecraft Pyrotechnic Systems, NASA Tech Note D-7141, lists all of the pyrotechnics ...
DrSheldon's user avatar
  • 48.1k
8 votes

Multistaging and its issues

Stage separation by design is typically slightly propulsive. The goal however is not to add a significant amount of momentum to the part of the vehicle that still matters. It is instead to ensure that ...
David Hammen's user avatar
  • 75.3k
8 votes

Is the failure to separate Starship from the Super Heavy booster a "dumb failure" and does it tell something about the project reliability?

Now, what perplexes me is that I would assume (in my technical ignorance of the subject) that a basic function such as firing the pyrotechnics to separate two stages should be one of the most reliable ...
Machavity's user avatar
  • 7,935
7 votes

What were the space shuttle’s emergency procedures for an SRB or ET separation failure?

Referencing the Ascent Checklist Ascent Cue Card: There were no procedures for failed SRB separation, and nothing the crew or ground could do about it. 1 The ET separation sequence2 could be halted ...
Organic Marble's user avatar
7 votes

Reliability of explosive bolts and redundant initiators

I know of at least one NASA pyrotechnic failure, although it was arguably not really the fault of the pyros themselves. It occurred on the Skylab 1 launch in 1973, the then-unmanned space station ...
Phil Karn's user avatar
7 votes
Accepted

Reliability of explosive bolts and redundant initiators

Sometimes they can do their job a little too well, or blow out some stuff when they're not supposed to, but I've never heard of one failing. They are normally used in a redundant pair fired close to ...
Mark Adler's user avatar
  • 58.2k

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