55
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Accepted
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 ...
- 6,153
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: ...
- 6,862
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 ...
- 4,538
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 ...
- 8,429
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 ...
- 12.6k
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..."
...
- 174k
19
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 ...
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16
votes
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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. ...
- 121k
16
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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 ...
- 2,291
16
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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 ...
- 2,994
16
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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?
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 ...
- 20.6k
15
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, ...
- 149k
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 ...
- 9,125
14
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 ...
- 260
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 ...
- 71.8k
11
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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 ...
- 48.4k
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 ...
- 165k
10
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 ...
- 12.5k
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 ...
- 17.6k
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 ...
- 48.4k
9
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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 ...
- 48.4k
9
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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 ...
8
votes
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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 ...
- 165k
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 ...
- 47.4k
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 ...
- 71.8k
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 ...
- 7,708
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 ...
- 174k
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 ...
- 58.3k
6
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 ...
- 81
6
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Why does Blue Origin land the crew capsule separate from the booster?
There's 2 major reasons: safety and practicality
Safety: If you look at the history of booster landings it is not a proven technology, the reliability is not good enough for safety. Don't get me ...
- 19.2k
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