SpaceX Starship : Texas Prototype(s) Thread 8 : Discussion

[spacexfanatic]

Are we really on this again?  Give it a rest!  SpaceX blows stuff up - it’s what they do.  They also build rockets and go to space, which is something no one else is doing on anything like this scale.

Enjoy the ride!


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Progress is slower so we try to fill the space in between two attempte launches.
PS: it's done for me no more SX methodology critics.

I would say the process - as visible as SpaceX is allowing it to be, is tremendously entertaining, and is inspiring a generation of kids into engineering.  Pretty damned valuable side effect of their approach.

Analyzing everything to death is slower and more expensive than build test break, and part of what they are doing is educating an engineering workforce in the problems and solutions and approaches needed to get to a minimum viable product quickly.  Building these rockets + figuring out what needs attention and what doesn't - the 50's-70's agile engineers who might have had the right mindset are long gone and I doubt analysis heavy approaches would get to a workable result as fast or as cheaply.  Just look at glacial progress of every big aerospace and Nasa R&D program of last 25 years - SpaceX has comprehensively proven that that is an inefficient way to do development.

The scale up in production itself has a lot of value further down the track - so not really a problem breaking rockets at the moment when they only cost a few weeks.

For me it make a lot of sense.

[Lemurion]

Part of the problem is that we’re only seeing half of the picture. Sure we see SN4 and SN5 but what we’re not seeing in the same discrete fashion are the steps they are making towards mass production. They are both learning what they can build and how they can build them. It’s not wasteful to apparently duplicate effort when the otherwise identical looking ship managed to retire a production issue we never really saw.

There’s a lot going on, and I don’t know that we’re always interpreting it correctly because we as observers do seem to be focused on the ships.

[Starforces]

It's not "How do we design and make this so it won't fail" but "how cheap and quick can I get away with".  The welders know how to weld, they know how to work metal, and the engineers (I'm quite sure) know how to design a puck.  The problem is doing it now, fast & cheap all while having to work around in non-pristine conditions.

Did they shuck a puck?  Yepper, they sure did.  Did they shuck a second one?  Nope.  Did somebody make a mistake for SN3?  Sure;  either by not speaking up or by overlooking something.  Will that same mistake happen again?  Not likely.

And, how many since the start of the year?  Say 1 per month?

I got no complaints and think they are doing fine - as fine or better as the Gemini, Mercury, and Apollo folks did back in the day.  Spx is iterating fast and finding just exactly where the borders are on Cheap & Fast & Good-enough.

That is a recipe for death. It means building everything to 80% and what you end up with is a rocket that "just about almost works... most of the time". My fear is not that Starship will fail. My fear that Starship will become a compromise rocket like the shuttle, and that would be a far worse outcome.

[sferrin]

OMG could we take all the concern-trolling to another thread? 

[kessdawg]

Any tenuous relationship between this thread topic, the specific prototypes under construction, has been gone for pages.  Please move discussion to appropriate thread.

[Zpoxy]

The power slide take off sounds scary.  Perhaps they will tilt the take off mount over a degree or so to get the Raptor directly under the centre of gravity.
I doubt side thrusters at the top will have the grunt to provide compensation.
I'm picking SN4 and 5 won't fly and they will wait for the material change and associated new thrust structure design.  Pure speculation.

No, they won't.

[Alvian@IDN]

I have created a new thread here, for those of us who want to continue a debate. From now on, let's talk more about what this thread should have been, and also the next important milestone for Texas Prototype, which is more appropiate 

https://forum.nasaspaceflight.com/index.php?topic=50772.0

[tssp_art]

 You'd think off center ballast wouldn't help since fuel weight will be decreasing, but they'll only have 30 tons of fuel for the low level hop, so a few off to the side anvils might help with the sliding/angle.

This is actually an interesting question.

Would a couple of mass simulators hanging off the unused engine mounts help in a single engine hop?
Would it make it a more accurate and useful test?

.

I think using additional mass to shift the center of mass can make it a better test, but placing the additional mass depends on what you're trying to accomplish. Hanging it in place of the missing Raptors will test the ships characteristics in an abnormal situation (unless they plan on always landing this way which I doubt). But I think we're all aiming for a successful hop to test out some of the basics - and in that case the extra mass should probably be placed to put the center of mass over the single engine. I know that the actual center of mass at liftoff will migrate toward the dry center of mass as fuel gets burned so the optimum placement ought to be somewhere in between - depending on where the experts (definitely not me) think it will mitigate the most risk

Of course the weight of the single raptor itself will help shift the center of mass in the right direction. We're just talking about an inexpensive and relatively easy way to maybe mitigate a bit more risk. They may well plan on doing that and we may never know if they do. But it's a good enough thought that someone EM follows might want to suggest it.


Edit: spelling

[capoman]

 You'd think off center ballast wouldn't help since fuel weight will be decreasing, but they'll only have 30 tons of fuel for the low level hop, so a few off to the side anvils might help with the sliding/angle.

This is actually an interesting question.

Would a couple of mass simulators hanging off the unused engine mounts help in a single engine hop?
Would it make it a more accurate and useful test?

.

I think using additional mass to shift the center of mass can make it a better test, but placing the additional mass depends on what you're trying to accomplish. Hanging it in place of the missing Raptors will test the ships characteristics in an abnormal situation (unless they plan on always landing this way which I doubt). But I think we're all aiming for a successful hop to test out some of the basics - and in that case the extra mass should probably be placed to put the center of mass over the single engine. I know that the actual center of mass at liftoff will migrate toward the dry center of mass as fuel gets burned so the optimum placement ought to be somewhere in between - depending on where the experts (definitely not me) think it will mitigate the most risk

Of course the weight of the single raptor itself will help shift the center of mass in the right direction. We're just talking about an inexpensive and relatively easy way to maybe mitigate a bit more risk. They may well plan on doing that and we may never know if they do. But it's a good enough thought that someone EM follows might want to suggest it.


Edit: spelling

Why bother? This is a landing mode they may need to test anyway, so why skew the results with counterweights? One question I still haven't seen answered is can thrusters counteract off center thrust in this scenario, especially hot thrusters that are expected to in the production design?

[Chris Bergin]

Thread is going off the rails due to some people liking the sound of their own voice over the community's wish to read about what is guided by the thread title.

Boo, sir. BOOO.

New thread always helps refocus people

New thread:
https://forum.nasaspaceflight.com/index.php?topic=50773.0