Starship SN8

Watching the incredible maneuvers Starship made, I got to wondering what computer systems were onboard to make all those real-time calculations. I thought surely it must be some new specialized, super fast supercomputer! Nope!

”SpaceX uses an Actor-Judge system to provide triple redundancy to its rockets and spacecraft. The Falcon 9 has 3 dual core x86 processors running an instance of linux on each core. The flight software is written in C/C++ and runs in the x86 environment. For each calculation/decision, the "flight string" compares the results from both cores. If there is a inconsistency, the string is bad and doesn't send any commands. If both cores return the same response, the string sends the command to the various microcontrollers on the rocket that control things like the engines and grid fins.

The microcontrollers, running on PowerPC processors, received three commands from the three flight strings. They act as a judge to choose the correct course of actions. If all three strings are in agreement the microcontroller executes the command, but if 1 of the 3 is bad, it will go with the strings that have previously been correct. The Falcon 9 can successfully complete its mission with a single flight string.

The triple redundancy gives the system radiation tolerance without the need for expensive rad hardened components. SpaceX tests all flight software on what can be called a table rocket. They lay out all the computers and flight controllers on the Falcon 9 on a table and connect them like they would be on the actual rocket. They then run a complete simulated flight on the components, monitoring performance and potential failures.

SpaceX engineers perform what they call "Cutting the strings" where they randomly shut off a flight computer mid simulation, to see how it responds.

Dragon uses a similar triple redundant system for its flight computers.”

I’m not sure if the same systems are on Starship...maybe it has a quad-core! Lol
 
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They lay out all the computers and flight controllers on the Falcon 9 on a table and connect them like they would be on the actual rocket. They then run a complete simulated flight on the components, monitoring performance and potential failures.

SpaceX engineers perform what they call "Cutting the strings" where they randomly shut off a flight computer mid simulation, to see how it responds.
All aerospace companies do this. At my company we call this a hilsim (Hardware In the Loop Simulator). It’s all the bits without the actual fuselage and wing and stuff (but all the control surface servos are there of course). We feed an aircraft mission elements (flight plans, etc.) and air data and trick the systems into thinking it’s flying. We use this to find faults in code, induce failures, use telemetry to observe equipment behavior in failure states...

... all manner of things you don’t want to do to an actual aircraft because cost is a thing.
 
Watching the incredible maneuvers Starship made, I got to wondering what computer systems were onboard to make all those real-time calculations. I thought surely it must be some new specialized, super fast supercomputer! Nope!

The microcontrollers, running on PowerPC processors, received three commands from the three flight strings. They act as a judge to choose the correct course of actions. If all three strings are in agreement the microcontroller executes the command, but if 1 of the 3 is bad, it will go with the strings that have previously been correct. The Falcon 9 can successfully complete its mission with a single flight string.

Triple-redundancy is used in aircraft flight systems and also for your car's driver-assistance features.
I don't think it is too compute-intensive for modern processors. You could probably run on your phone. :)
 
Triple-redundancy is used in aircraft flight systems and also for your car's driver-assistance features.
I don't think it is too compute-intensive for modern processors. You could probably run on your phone. :)

They were doing it on fighter planes in the 70s with the computers they had then.
 
I was a metrology engineer at SpaceX... when they test the flight computers they are hooked up to the Iron Maiden (really). The Iron Maiden simulates multiple failures to test the error trapping and recovery process of their flight algorithms. They have huge posters of Eddie in the avionics testing lab... pretty cool stuff...oh, and they have massive 3D printers that turn out various pieces for rocket motors. They “print” turbo pumps out of titanium...it was a fun gig till it wasn’t.
 
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They got way more out of that than Elon predicted beforehand. That was amazeballs.
Why taking risks for any habited ground building and not blow up the engine at high altitude from the control room before it actually hits the ground ?
 
Why taking risks for any habited ground building and not blow up the engine at high altitude from the control room before it actually hits the ground ?

It was only when it was close to the ground that the problem became apparent. Not sure if you know, but these rockets are intended to land and be reused.
 
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It was only when it was close to the ground that the problem became apparent. Not sure if you know, but these rockets are intended to land and be reused.
I know, but from the images it seems quite obvious something is going wrong with the exhaust quite early at stopping the boosters one by one. Well anyway it's none of my business whatever are my personnel opinions about Musk and his clique. IMHO certain domains should not be left prey to private investors whatever be the country.
 
Why taking risks for any habited ground building and not blow up the engine at high altitude from the control room before it actually hits the ground ?
What certain domain? Musk and his clique?
I don’t think you realize how barren that whole area actually is. Just because places have names doesn’t mean they’re inhabited, and if you don’t think the EPA and a dozen environmental groups aren’t up their ass every day you’re nuts.
If they had positive control, and they did, they could choose to fly to any point they felt it was unsafe and invoke range rules. Other than one engine failing the ship did everything it was supposed to right up until the last moment. That pad was located and set up for exactly what we saw.
 
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I know, but from the images it seems quite obvious something is going wrong with the exhaust quite early at stopping the boosters one by one. Well anyway it's none of my business whatever are my personnel opinions about Musk and his clique. IMHO certain domains should not be left prey to private investors whatever be the country.

If there wasn’t what, an 11 year gap for flights following grounding the shuttles?, if the SLS was making any progress, if ULA, Boeing etc didn’t cost a subsidized fortune and have no innovations, there would be no market for private enterprise in manned space flight. Musk thought he could do it better, faster and cheaper, and so far he’s been rather correct. There are 2 Dragon capsules currently docked at the ISS right now, Falcon’s have been reused 7x and making it look almost routine.... all on like 1/10th the budget/assistance of anyone else.

In my book those guys are quite the success story
 
Yeah, i don't know how anyone could take issue with Elon or Space X. They've shattered every timeline for advancements in space travel and will be the absolute biggest reason we step foot on Mars, much less possibly colonize it. It's truly amazing what he and his teams have accomplished.
 
Yeah, i don't know how anyone could take issue with Elon or Space X.
There’s always at least one, and the reason is rarely well conceived, well thought out, or well informed. More typically it’s fueled by misguided emotion, a complete lack of pragmatism and loaded with obtuse politics that, if followed to logical conclusion, ends in medieval agrarianism of the 13th century.
 
What certain domain? Musk and his clique?
I don’t think you realize how barren that whole area actually is. Just because places have names doesn’t mean they’re inhabited, and if you don’t think the EPA and a dozen environmental groups aren’t up their ass every day you’re nuts.
If they had positive control, and they did, they could choose to fly to any point they felt it was unsafe and invoke range rules. Other than one engine failing the ship did everything it was supposed to right up until the last moment. That pad was located and set up for exactly what we saw.
Well, it's an opinion I have, nothing more nothing less. I understand now that technically speaking things did thus happen close to alright. Personnally I'm just pissed because this guy intends to send a few 42000 satellites in space (ie about twice the quantity we shoot up there since the sixties), polluting for eternity our worldwide common property "the nightly skyview" that has been relatively untouched since birth of humanity All that just to have one or maybe 2 generations of humanity profit from a thing called internet. I - but just me - cannot see how anybody can be proud of such a person who's just doing this for his personal profit. This guy personalises for me the extreme extend of abuse of natural ressources for his own cupid and stupid neoliberalist interest; financed for a big part by taxes. I know this might hurt the thoughts of some people and hereby excuse myself for that. As I said it's just an opinion. So yes for me it is and remains : "Musk and his clique". I'm sorry.
 
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