Author Topic: Starship/SuperHeavy orbital Flight Test LIVE  (Read 8967 times)

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Offline coppice

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #75 on: April 26, 2023, 12:54:50 pm »
How much explosive charge does a typical large rocket carry and what's left after it destructs? There are a lot of big, heavy metal components and it seems unlikely that they all just vaporize. The self destruct gets rid of all the fuel and oxidizer but there must be quite a few big heavy chunks raining down.
There's a reason most launch sites have a large expanse of sparsely populated land or sea to their east. Self-destructing the rocket is not about cleaning up the impact. Its about controlling where the impact happens. You don't need that much explosive. Rockets are generally destroyed while there is still considerable fuel on board. If the fuel is exhausted, blowing the thing up doesn't achieve that much. The explosive only needs to get the remaining fuel and oxidiser to mix and go pop.
 

Offline David Hess

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #76 on: April 26, 2023, 02:00:39 pm »
Is it true what David Hess wrote, that they are now suddenly abandoning completely the hydraulic steering and going for electronic? Its quiet a huge change.

This first launch was with a preliminary version of the ship. The others they have already assembled use electrically powered steering, and have numerous other substantial revisions. I think they learned a lot from building and ground testing this first one, so immediately they moved to building the second one they had already refined the design in numerous ways.

That is my understanding.  It came down to either removing this one for disassembly without learning anything, or launching it just to get it out of the way for the newer one, and at least launching it will provide data, which is what they did.

Now they know that the launch infrastructure needs to be significantly improved before launching the next one.

 

Offline Sal Ammoniac

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #77 on: April 26, 2023, 06:47:22 pm »
How much explosive charge does a typical large rocket carry and what's left after it destructs? There are a lot of big, heavy metal components and it seems unlikely that they all just vaporize. The self destruct gets rid of all the fuel and oxidizer but there must be quite a few big heavy chunks raining down.

It's actually not much explosive, typically just a linear charge to "unzip" the component. Aerodynamic stress does the rest.

Depending how high the failure occurs, some of the components will burn up in the atmosphere, others won't. Launches are usually directed over water so falling components won't impact land--rockets are launched eastward from KSC and southward from Vandenburg, for example. Notice to mariners is given well in advance to avoid these areas.

Shuttle SRBs came down on parachutes, while the Saturn V S-1C stage just fell into the ocean intact.
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Offline coppice

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #78 on: April 26, 2023, 06:55:17 pm »
Shuttle SRBs came down on parachutes, while the Saturn V S-1C stage just fell into the ocean intact.
The vast majority of rocket stages just fall out of the sky, either whole or in pieces. SpaceX are the first to start changing that.
 

Online wraperTopic starter

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #79 on: April 26, 2023, 10:53:52 pm »
Shuttle SRBs came down on parachutes, while the Saturn V S-1C stage just fell into the ocean intact.
Shuttle SRB "reuse" makes so much sense that it actually does not. It's just an empty shell that gets rescued (in SRB engine burns itself), taken apart into segments, stripped of paint, refurbished, refilled and assembled back. Literally it would be cheaper to just not reuse them. From what I read it was estimated to be about 3 times cheaper to just use brand new ones. Also this segmented construction is the reason why Challenger exploded.
 

Offline Sal Ammoniac

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #80 on: April 26, 2023, 11:18:40 pm »
Also this segmented construction is the reason why Challenger exploded.

The segmented construction was a contributor to the Challenger explosion, but the real cause was the poorly designed joints between the segments that would flex under load. That wasn't a major issue at the usual ambient temperatures at KSC, but when Challenger was launched the temperature was around 30F, and the rubber o-rings lacked resiliency and failed to contain the hot gases inside the segment. The joints were redesigned to prevent the issue that doomed Challenger and no further issues were encountered in over 100 subsequent flights.

The SRBs were segmented because it was impractical to transport full-length boosters from the Utah plant to KSC.
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Offline tszaboo

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #81 on: April 27, 2023, 08:25:06 am »
There is a lot of comparison to Nasa in this thread. I believe Nasa was first testing the launch abort systems for the Saturn V even before they launched it suborbital. Is there any abort systems on the Starship, other than the one we just saw demonstrated?
 

Offline David Hess

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #82 on: April 27, 2023, 11:46:47 am »
Also this segmented construction is the reason why Challenger exploded.

The segmented construction was a contributor to the Challenger explosion, but the real cause was the poorly designed joints between the segments that would flex under load. That wasn't a major issue at the usual ambient temperatures at KSC, but when Challenger was launched the temperature was around 30F, and the rubber o-rings lacked resiliency and failed to contain the hot gases inside the segment. The joints were redesigned to prevent the issue that doomed Challenger and no further issues were encountered in over 100 subsequent flights.

The SRBs were segmented because it was impractical to transport full-length boosters from the Utah plant to KSC.

The ultimate cause has always been disputed, and NASA directed the blame elsewhere:

https://www.nasa.gov/pdf/382045main_19%20-%2020090730.11.STS%20Problem%202003.pdf
 

Offline asmi

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #83 on: April 27, 2023, 03:03:51 pm »
The SRBs were segmented because it was impractical to transport full-length boosters from the Utah plant to KSC.
I would imagine that the safety aspect was also important as SRB is basically a LOT of highly-explosive material with some moderator to control burning, and so if something goes sideways during transportation, it will be one hell of explosion. Splitting it in segments limits potential damage.

Offline coppice

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #84 on: April 27, 2023, 03:48:53 pm »
The SRBs were segmented because it was impractical to transport full-length boosters from the Utah plant to KSC.
I would imagine that the safety aspect was also important as SRB is basically a LOT of highly-explosive material with some moderator to control burning, and so if something goes sideways during transportation, it will be one hell of explosion. Splitting it in segments limits potential damage.
The fuel is solid. Its not volatile. It burns ferociously once ignited, but like many high energy combustible or explosive materials its pretty hard to get started. One of the nice things about solid fuel rockets for things like air-to-air attacks is you want them to sit around for years unused with minimal risk and maintenance, and they do.
 

Offline Sal Ammoniac

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #85 on: April 27, 2023, 04:14:13 pm »
The SRBs were segmented because it was impractical to transport full-length boosters from the Utah plant to KSC.
I would imagine that the safety aspect was also important as SRB is basically a LOT of highly-explosive material with some moderator to control burning, and so if something goes sideways during transportation, it will be one hell of explosion. Splitting it in segments limits potential damage.

There was a transportation incident involving SRB segments back in May 2007. A train carrying eight segments derailed in Alabama. The segments were tossed around, but none ignited and there was no disaster. After inspection, all eight segments were used on shuttle flights.
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Offline james_s

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #86 on: April 27, 2023, 05:43:49 pm »
I'd imagine it would be pretty spectacular if and accident resulting in a fire ignited a complete assembled SRB being transported horizontally on the ground. Of course they're massive things so I'm not even sure how you'd transport an assembled one, the logistics of that alone support the segmented approach.
 

Offline asmi

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #87 on: April 27, 2023, 07:28:28 pm »
The fuel is solid. Its not volatile. It burns ferociously once ignited, but like many high energy combustible or explosive materials its pretty hard to get started. One of the nice things about solid fuel rockets for things like air-to-air attacks is you want them to sit around for years unused with minimal risk and maintenance, and they do.
That is still more dangerous than with liquid rockets, which are simply transported unfueled and therefore these is zero chance of explosive accident.

Offline coppice

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #88 on: April 27, 2023, 07:37:00 pm »
The fuel is solid. Its not volatile. It burns ferociously once ignited, but like many high energy combustible or explosive materials its pretty hard to get started. One of the nice things about solid fuel rockets for things like air-to-air attacks is you want them to sit around for years unused with minimal risk and maintenance, and they do.
That is still more dangerous than with liquid rockets, which are simply transported unfueled and therefore these is zero chance of explosive accident.
That rather ignores the bulk transport of the fuel and oxidiser, which are potential disasters throughout the supply chain. There is no escape from hazard when high energies are involved. Solid fuels is comparatively benign.
 

Online tautech

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #89 on: April 27, 2023, 07:59:03 pm »
Before and after.  :o

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Some stuff seen @ Siglent HQ cannot be shared.
 

Offline Sal Ammoniac

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #90 on: April 27, 2023, 08:16:13 pm »
The fuel is solid. Its not volatile. It burns ferociously once ignited, but like many high energy combustible or explosive materials its pretty hard to get started. One of the nice things about solid fuel rockets for things like air-to-air attacks is you want them to sit around for years unused with minimal risk and maintenance, and they do.
That is still more dangerous than with liquid rockets, which are simply transported unfueled and therefore these is zero chance of explosive accident.

Ah, but you still have to transport the liquid fuel and oxidizer, which isn't without its own hazards, especially for hypergolics like hydrazine and nitrogen tetroxide.
"That's not even wrong" -- Wolfgang Pauli
 

Offline Dundarave

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #91 on: April 27, 2023, 08:24:08 pm »
There was a reference earlier in the thread regarding the failures and successes of the Russian rocket programs, and I wanted to bring attention to these four PDF books by Russian academician Boris Chertok for those interested:

https://history.nasa.gov/SP-4110/vol1.pdf
https://history.nasa.gov/SP-4110/vol2.pdf
https://history.nasa.gov/SP-4110/vol3.pdf
https://history.nasa.gov/SP-4110/vol4.pdf

They describe the Russian rocket and space program from the beginning in amazing personal detail from a high-ranking insider.  Lots of incredible screwups that make for great comparisons.
 
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Offline coppice

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #92 on: April 27, 2023, 08:29:28 pm »
Ah, but you still have to transport the liquid fuel and oxidizer, which isn't without its own hazards, especially for hypergolics like hydrazine and nitrogen tetroxide.
Transporting hypergolics must be a nightmare. They seem like something you would restrict to places where the alternatives have serious problems, like control thrusters. In reality there are large vehicles driven entirely by them.
 

Offline David Hess

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #93 on: April 27, 2023, 09:39:47 pm »
Transporting hypergolics must be a nightmare. They seem like something you would restrict to places where the alternatives have serious problems, like control thrusters. In reality there are large vehicles driven entirely by them.

Hypergolics have the advantages of easy ignition, easy storage, and high performance.  It took a long time for solid fuels to reach useful levels of performance and cryogenic fuels are difficult to store.

As far as safety, solid fuels have the disadvantage of not being able to throttle, shut-off, or restart, except for hybrid rockets which have the disadvantages of both and more.
 

Offline David Hess

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #94 on: April 27, 2023, 09:41:39 pm »
Transporting hypergolics must be a nightmare. They seem like something you would restrict to places where the alternatives have serious problems, like control thrusters. In reality there are large vehicles driven entirely by them.

I do not think hypergolics are any more dangerous to transport than many industrial chemicals.  They are sure a hazard if spilled, but so are a lot of things.
 

Offline tom66

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #95 on: April 27, 2023, 10:29:16 pm »
Shuttle SRBs came down on parachutes, while the Saturn V S-1C stage just fell into the ocean intact.
Shuttle SRB "reuse" makes so much sense that it actually does not. It's just an empty shell that gets rescued (in SRB engine burns itself), taken apart into segments, stripped of paint, refurbished, refilled and assembled back. Literally it would be cheaper to just not reuse them. From what I read it was estimated to be about 3 times cheaper to just use brand new ones. Also this segmented construction is the reason why Challenger exploded.

There were quite a few things worth reusing.

The SSRBs featured a pair of APUs which used onboard hypergolic fuel to provide hydraulic and backup electrical power.  They also had actuation and control systems to ensure thrust was directly correctly, and a set of gyros to stabilise the thruster during flight. These were all rated for 20 flights before requiring replacement.  And, of course, you have the casing of the SSRBs; the rockets weighed 91 tonnes dry, so certainly not negligible material there to dispose of every time. 
 

Offline AlbertL

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #96 on: April 27, 2023, 10:35:01 pm »
Before and after.  :o



Someone pointed out that SpaceX has taken us from expendable rockets on reusable launch pads, to reusable rockets on expendable launch pads!
 
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Offline rdl

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #97 on: April 28, 2023, 04:35:46 am »
As long as you ship the hydrazine and nitrogen tetroxide separately they're no more hazardous than many other industrial chemicals. They are not hypergolic with themselves.
 

Online wraperTopic starter

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #98 on: April 28, 2023, 09:28:40 am »
As long as you ship the hydrazine and nitrogen tetroxide separately they're no more hazardous than many other industrial chemicals. They are not hypergolic with themselves.
Depends on what you mean by hazardous. Many industrial chemicals like Phosgene are very toxic like hydrazine. They may not necessarily explode but cause fatal accidents nonetheless. Potentially spilling hundreds of tons of very toxic chemical is not the best idea.
« Last Edit: April 28, 2023, 09:31:00 am by wraper »
 

Offline iMo

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Re: Starship/SuperHeavy orbital Flight Test LIVE
« Reply #99 on: April 28, 2023, 09:53:37 am »
There is a lot of comparison to Nasa in this thread. I believe Nasa was first testing the launch abort systems for the Saturn V even before they launched it suborbital. Is there any abort systems on the Starship, other than the one we just saw demonstrated?
That is an interesting point.. One of the serious issues with the Space Shuttle was its abort system.. Actually none, in reality. The capsules like in those "standard rockets" are easy to abort and land them without killing the astronauts inside. How it should work with the Starship?
Readers discretion is advised..
 


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