SpaceX after they land their first stage?

[Nibb31]

Contrary to popular belief, SSME's weren't completely refurbished after each flight. They were designed for reusability, which is why they were so expensive. They were removed and rotated after each flight so that they could be serviced and tested, and then got a full refurbishment after X flights.

There is no reason to believe that Merlins will need to be fully refurbished after each flight. I'm more concerned with mechanical stress and fatigue on the tanks and legs. An invisible crumple in a cylinder can fragilise the structure. I think that even if they get the landing part fixed, it will be a while before they will be flying reused stages.

[cicatrix]

Although I like the idea of reusability I don't like the risks involved.

You have to check EVERYTHING before you attempt launching this thing again. It's not just the engine, you have to check every bolt, every welding seam, you have to sound the fuel tank for microscopic cracks and deformations, you have to keep in mind fatigue, etc. Wouldn't all these checks be finally nearly as expensive as building a new stage?

[Ralathon]

Although I like the idea of reusability I don't like the risks involved.

You have to check EVERYTHING before you attempt launching this thing again. It's not just the engine, you have to check every bolt, every welding seam, you have to sound the fuel tank for microscopic cracks and deformations, you have to keep in mind fatigue, etc. Wouldn't all these checks be finally nearly as expensive as building a new stage?

Yea I know right? All this maintenance that's being done on aircraft is way more expensive than just buying a new A-380 after every flight /s

They'll do all these expensive checks for the first few landed stages of course. But I reckon that after a while they'll bring it down to some routine checks with a intensive check every dozen or so flights. You don't do a complete check of every weld on an airliner either.

[Lukaszenko]

Although I like the idea of reusability I don't like the risks involved.

You have to check EVERYTHING before you attempt launching this thing again. It's not just the engine, you have to check every bolt, every welding seam, you have to sound the fuel tank for microscopic cracks and deformations, you have to keep in mind fatigue, etc. Wouldn't all these checks be finally nearly as expensive as building a new stage?

What posters are saying, is that this not necessarily be true. If it can be shown that the engines work reliably without this whole process after each flight (much like jet engines), then what reason is there to do it?

[cicatrix]

Yea I know right? All this maintenance that's being done on aircraft is way more expensive than just buying a new A-380 after every flight /s

They'll do all these expensive checks for the first few landed stages of course. But I reckon that after a while they'll bring it down to some routine checks with a intensive check every dozen or so flights. You don't do a complete check of every weld on an airliner either.

Yeah, but a rocket stage is subject to much heavier stresses and loads that any airliner. Besides, airliners crash from time to time exactly because something had been overlooked.

[Lukaszenko]

Yeah, but a rocket stage is subject to much heavier stresses and loads that any airliner.

Is that true? Jet engines operate at the extreme limits of material capability. You can't get much higher stresses than that. Yet they are considered much more reliable than reciprocating engines. I see no engineering reason why rocket engines can't be the same.

Besides, airliners crash from time to time exactly because something had been overlooked.

Very rarely is it because of outright material failure, and never is the solution "look at and test EVERYTHING, EVERY TIME". Nevertheless, crashes can never be fully eliminated, but this is no reason to make the whole concept of reusable airplanes (and rockets) prohibitively expensive.

[cicatrix]

Is that true? Jet engines operate at the extreme limits of material capability. You can't get much higher stresses than that. Yet they are considered much more reliable than reciprocating engines. I see no engineering reason why rocket engines can't be the same.

I'm not talking about engines, I mean the hull and its load bearing elements. Bending stresses are higher not to mention much higher temperature during reentry.

[AngelLestat]

Also another point.. After the launch and reentry.. you are igniting the engine again to land.. That is the last proof that all still works.

About vibration and structure streess... Its designed to stand that at a lot more.

You tell me that every time a 747 find turbulance they need to check all the airplane again? Also.. a 747 is much more complex than a rocket.

My washing machine every time that centrifuged is like an 12.5 earthquake, and after 3 years since start with these unusual shakes still works.

[Lukaszenko]

I'm not talking about engines, I mean the hull and its load bearing elements. Bending stresses are higher not to mention much higher temperature during reentry.

I doubt a hull experiences higher stresses than engine parts. Even if it did, you're saying that we can make this that operates at the limits of material capability, but we can't make what amounts to a tube with a couple tanks?

I'd even venture to say that a rocket's hull is simpler and experiences similar, if not lower stresses than an airplane's.

[cicatrix]

I doubt a hull experiences higher stresses than engine parts. Even if it did, you're saying that we can make this https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQ1bNIq0TVZcglqb7n2kP-RCpLDGr6dOgMbFl0OYDIsdgtP6R2B that operates at the limits of material capability, but we can't make what amounts to a tube with a couple tanks?

I'd even venture to say that a rocket's hull is simpler and experiences similar, if not lower stresses than an airplane's.

oooookay, I'm convinced... somewhat.

[Nibb31]

I doubt a hull experiences higher stresses than engine parts.

A hull that it basically a very thin aluminium tube that supports multiple tanking/detanking cycles, several tons of vertical load, thermal cycles varying from cryo fuel loading to hypersonic friction, aerodynamic loads, and landing empty at potentially non-vertical angle.

It's much more complex than an airplane's airframe and with much tougher weight constraints.

[Dkmdlb]

Besides, airliners crash from time to time exactly because something had been overlooked.

Rarely. Like incredibly rarely. It's like 1 crash for millions of flying hours. If that same applies to rockets, SpaceX will probably never lose a rocket.

[Kerbart]

Yea I know right? All this maintenance that's being done on aircraft is way more expensive than just buying a new A-380 after every flight /s

Part of the reason that A-380 is so expensive is because it is designed to be used for multiple decades. The useage profile is also different. If airlines were tasked with "get my cargo up to 35'000 feet and you don't have to worry what happens with it after that, and let's do that only four times per year" they might decide to use an entirely different design that indeed features one-time useage, just because it fits their business better.

The reality is that NASA is a large, schizophrenic government organization. At the very top (congress) decisions are not made based on rational business decisions (the business being getting as much Science possible with available Funds <-- see what I did there?) but based on congressmen who want to be re-elected and want to get some of that juicy tax money to land in their state.

And then at a lower level you have day-to-day management who has to pick up the pieces and is left with a set of ever-changing long-term goals ("let's go to moon! NO! Mars! NO! ARM! NO! the moon! Mars! Mars! Mars!"), discouragement of succesful long running missions ("it's eating up our budget") and because this is all tax money "failure is not an option" leading to conservative overdesigned missions that take forever to get off the ground.

And then there's SpaceX with clear fixed goals and a different mindset as they don't have answer to congress. Failure is an option and SpaceX can afford what NASA can't: the time tested approach of "throw spaghetti against the wall and see what sticks." Which short turn gives you failures, but longer term gives you tons of data and the ability to avoid your mistakes. The only way NASA can trust their engines is by expensive certification and overengineering. The way SpaceX will trust their engines is by having a track record of dozens and dozens of launches.

To go back to an airplane analogy: do you want a SpaceX pilot with 15,000 hours of actual experience, or do you want the NASA pilot who has never flown before but can show he's up to the task with an impressive portfolio of written tests he passed?

[Lukaszenko]

......very thin aluminium tube...

...which is still as thick as it needs to be to cope with the known and understood stresses + a safety factor, which I understand from what Elon says is actually much higher than normal. I mean yeah it's a challenge to get the best combination of everything, but I doubt is as impossible as some people make it out to be.

[Kryten]

Part of the reason that A-380 is so expensive is because it is designed to be used for multiple decades. The useage profile is also different. If airlines were tasked with "get my cargo up to 35'000 feet and you don't have to worry what happens with it after that, and let's do that only four times per year" they might decide to use an entirely different design that indeed features one-time useage, just because it fits their business better.

The reality is that NASA is a large, schizophrenic government organization. At the very top (congress) decisions are not made based on rational business decisions (the business being getting as much Science possible with available Funds <-- see what I did there?) but based on congressmen who want to be re-elected and want to get some of that juicy tax money to land in their state.

And then at a lower level you have day-to-day management who has to pick up the pieces and is left with a set of ever-changing long-term goals ("let's go to moon! NO! Mars! NO! ARM! NO! the moon! Mars! Mars! Mars!"), discouragement of succesful long running missions ("it's eating up our budget") and because this is all tax money "failure is not an option" leading to conservative overdesigned missions that take forever to get off the ground.

And then there's SpaceX with clear fixed goals and a different mindset as they don't have answer to congress. Failure is an option and SpaceX can afford what NASA can't: the time tested approach of "throw spaghetti against the wall and see what sticks." Which short turn gives you failures, but longer term gives you tons of data and the ability to avoid your mistakes. The only way NASA can trust their engines is by expensive certification and overengineering. The way SpaceX will trust their engines is by having a track record of dozens and dozens of launches.

To go back to an airplane analogy: do you want a SpaceX pilot with 15,000 hours of actual experience, or do you want the NASA pilot who has never flown before but can show he's up to the task with an impressive portfolio of written tests he passed?

NASA doesn't build launch vehicles, NASA doesn't build engines, NASA doesn't arrange launches. The current US orbital launch providers are Lockheed Martin, Orbital Sciences, and United Launch Alliance; all private companies. Please get some basic knowledge about the subject before trying to pontificate about it.

[AngelLestat]

NASA doesn't build launch vehicles, NASA doesn't build engines, NASA doesn't arrange launches. The current US orbital launch providers are Lockheed Martin, Orbital Sciences, and United Launch Alliance; all private companies. Please get some basic knowledge about the subject before trying to pontificate about it.

Is the same.. All the design (with some exceptions), manufacture procedures and quality checks are imposed by nasa.

Also those companies are corporations, at those levels they gain contracts thanks to politician connections. They haven´t enoght risk to lose a contract or enter in bankruptcy for excessive cost.

By other hand if spacex does not do anything with the best efficiency, then they die and can not compete.

------------------------------------

Going back to my washing machine analogy.. what is more trusted? a new one that I buy today and I never test it, or my old one with the 12.5 earthquake in each wash.

[Frozen_Heart]

TBH if SpaceX thinks that they can reuse the stage economically then I trust their judgment over that of random forumers.

The engines have been proven that they can fire more than once and I'm sure that they will be destructively tested to see what their limits are.

The structure and tanks will also be tested until they collapse. And even when they are reused they'll be checked in the same way as an aircraft.

And those saying re-entry will damage them too much... they aren't re-entering from orbital velocity and don't have much heating at all.

The first few landed stages need to just be tested repeatedly until they break, both as a whole, and as components. After that assuming that landed stages have been found to still be viable, they should be allowed to fly.

[Kryten]

Is the same.. All the design (with some exceptions), manufacture procedures and quality checks are imposed by nasa.

None of the designs have anything to do with NASA, and NASA can only impose quality checks on launches for NASA. That applies to SpaceX just as much as it does to any other company.

[Nibb31]

Is the same.. All the design (with some exceptions), manufacture procedures and quality checks are imposed by nasa.

Also those companies are corporations, at those levels they gain contracts thanks to politician connections. They haven´t enoght risk to lose a contract or enter in bankruptcy for excessive cost.

By other hand if spacex does not do anything with the best efficiency, then they die and can not compete.

News: SpaceX is a corporation too. In fact, they employ 3500 people, which makes them bigger than ULA, and their biggest customer is the US Government.

[Rakaydos]

Ula's been in buisness since the apollo days. In that time, they have optimized for the government requisition process- the goverment puts out a list of requirements, and whoever can meet those specific requirements for the lowest bid gets to build it. This leads to specialized designs that are just enough for the job at hand, as defined by people who dont design rockets themselves.

SpaceX, meanwhile, is taking a Silicon Valley approach- build a better mousetrap and the world will arrive at your door. By setting their own specs, they can build a rocket that makes sence to rocket engineers.

[Kryten]

Ula's been in buisness since the apollo days.

It's actually more than four years younger than SpaceX.

[AngelLestat]

None of the designs have anything to do with NASA, and NASA can only impose quality checks on launches for NASA. That applies to SpaceX just as much as it does to any other company.

Really? So why they have the nasa´s glenn research center, nasa's Ames Research Center, Nasa Langley Research Center, George Marshall Space Flight Center, and some others that they may have.

Where is being develope the SLS??

Of course as I said.. there are some exceptions. Spacex is very different, they paid them to make a job, and is all done inside spacex under their own control.

News: SpaceX is a corporation too. In fact, they employ 3500 people, which makes them bigger than ULA, and their biggest customer is the US Government.

Yeah I use the word "corporation" as a way to distinguish company levels. We can not compare Boing earnings and history vs Spacex.

Spacex is a new company so all the examples that I did applied to them.

[Kryten]

Really? So why they have the nasa´s glenn research center, nasa's Ames Research Center, Nasa Langley Research Center, George Marshall Space Flight Center, and some others that they may have.

To develop and build spacecraft. You know, the things that are the reason launch vehicles exist in the first place.

Where is being develope the SLS??

Lockheed Martin, Boeing, Orbital ATK and Aerojet Rocketdyne. NASA is only acting as a systems integrator, and even then that something doesn't apply to any other LV built in the last 40 years.

EDIT: AngelLestat, do you know what SpaceX's first contract was? Or why their rocket is named Falcon?

[AngelLestat]

To develop and build spacecraft. You know, the things that are the reason launch vehicles exist in the first place.

So you are saying that they dont develope launch systems?

Lockheed Martin, Boeing, Orbital ATK and Aerojet Rocketdyne. NASA is only acting as a systems integrator, and even then that something doesn't apply to any other LV built in the last 40 years.

EDIT: AngelLestat, do you know what SpaceX's first contract was? Or why their rocket is named Falcon?

Really? I just read that these are the ones involve with the developement:

The SLS Program at NASA’s Marshall Space Flight Center in Huntsville, Ala., has been working closely with the Orion Program, managed by NASA’s Johnson Space Center in Houston, and the Ground Systems development and Operations Programâ€â€the operations and launch facilities at NASA’s Kennedy Space Center in Cape Canaveral, Fla. All three programs are managed by the Explorations Systems Development Division within the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington.

The other SLS agency partners include NASA’s Ames Research Center in Moffett Field, Calif, which is responsible for physics-based analysis; NASA’s Glenn Research Center in Cleveland, which is responsible for omposites research and payload fairing development; NASA’s Goddard Space Center in Greenbelt, Md., which is responsible for payloads; NASA’s Langley Research Center in Hampton, Va., which is responsible for wind tunnel testing; NASA’s Michoud Assembly Facility, which will manufacture and assemble the SLS core and upper stages, as well as the main propulsion system; and NASA’s Stennis Space Center, which is responsible for J-2X and RS-25 testing.

http://www.nasa.gov/pdf/664158main_sls_fs_master.pdf

But as you said.. they never develope launchers...

About spacex first contract I know, In fact I said that spacex is paid to do that job.. but its design, develope, built and check is all on them.

[Kryten]

So you are saying that they dont develope launch systems?

They can act as a systems integrator, but SLS is the first occasion of this since the Saturn V. They have nothing to do with anything ULA is flying.

Really? I just read that these are the ones involve with the developement:

They have contracts for the first stage, second stage, boosters and engines respectively. NASA just intends to puts it together.

About spacex first contract I know, In fact I said that spacex is paid to do that job.. but its design, develope, built and check is all on them.

So you don't know. NEWSFLASH: Falcon 1's development was done under the 'small launcher' section of DARPA's Force Applications and Launch from the CONtinental US program, and it received three non-competed launch contracts from the DoD as support for the same contract.