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starship? but ........ROTFL ! :-)



 
 
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  #11  
Old March 4th 20, 12:08 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 2,083
Default starship? but ........ROTFL ! :-)

In article ,
says...

On 2020-03-02 12:29,
wrote:

I think Musk is crazy because:
1) is trying to do something better than Saturn 5
2) Saturn 5 was scrapped about 50 years ago by NASA



Technology has advanced a bit since the 1960s.
What is being "displayed in public" at BocaChica doesn't represent the
real developmenht in my opinion.


I'll take that opinion with a grain of salt since you're not an expert
in the field. As someone with an aerospace engineering degree, I see a
rapid design, build, test cycle that can't be hidden from the public
because they're building in view of a road.

Consider that the Raptor engines are being developped in a serious and
private environment and are being tested with no hystericals.


Yes, they're being test fired at their existing facilities in McGregor
Texas. But they've actually reactivated the old vertical test stand so
that they can test Raptor vertically (in addition to the two horizontal
test cells they've been using):

https://twitter.com/spacex/status/1233080513516077058

The glorified beer kegs build publicly at Boca Chica gives SpaceX wants
to test very inexpensively some construction techniques with steel that
it has no experience with. So the failure of "SN1" teach SpaceX more
about how to weld steel. Maybe they will find a way to do steel, maybe
they will conslude it can't be done and switch back to more modern
materials.


Yeah, because no one in aerospace has ever figured out how to weld
stainless steel into liquid fuel propellant tanks. /s

https://en.wikipedia.org/wiki/Atlas_(rocket_family)

From above:

The first successful test launch of an SM-65 Atlas missile was
on 17 December 1957.[1] Approximately 350 Atlas missiles were
built.

The Atlas boosters would collapse under their own weight if not
kept pressurized with nitrogen gas in the tanks when devoid of
propellants. The Atlas booster was unusual in its use of
"balloon" tanks. The rockets were made from very thin stainless
steel that offered minimal or no rigid support. It was pressure
in the tanks that gave the rigidity required for space flight.
In order to save weight they were not painted and needed a
specially designed oil to prevent rust.

Note that when working with composites, small flaws in laying up the
fibre that leave air bubbles can be "fatal" to the structure. So I
suspect that SpaceX is at the same stage with learning to do flawless
welds. If you have seen close up pictures, you will see welds havce a
lot of arrows and markings along the welds.


Yes. These are prototypes. You calling them "glorified beer kegs"
shows your lack of knowledge about how engineering prototypes are often
built.

Jeff

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  #12  
Old March 6th 20, 01:24 PM posted to sci.space.policy
Dean Markley
external usenet poster
 
Posts: 455
Default starship? but ........ROTFL ! :-)

On Thursday, March 5, 2020 at 4:43:56 PM UTC-5, JF Mezei wrote:
On 2020-03-03 11:36, David Spain wrote:

I suspect that isn't really correct. I'd have to double check but AFAIK
there isn't tons of security around the McGregor test site.


But MUSK isn't staging shows like he does at Boca Chica knowing geeks
have cameras 7/24 pointed to it, knowing the press will report on every
bowel movement seen there. (or explosive vomiting :-)

The engine development has been much more "normal", out of the limelight
and PR games. And one should not underestimate the success just because
it has been quiet. Engines are a BIG item in any rocket especially
since Raptors are not only brand new, but also based on new fuel.





I think you are confusing failure with progress and are too skeptical.


With composites, the key to avoiding any flaw that can lead to
structural failure is the process. The process must not introduce flaws
to start with. (as opposed to detecting and getting any bubbles out
before it si cured).


If steel welds have flaws that result in total failure, then the key is
to find a welding process that does not introduce flaws. Welding outdoos
near the beach isn't likely to be something that Musk knows will ever
work, but still builds the beer kegs knowing they will fail. Good show.
I have to imagine that SpaceX is working elsewhere on a perfect welding
process (robots etc).


With each "failure" you learn an incredible amount of information that
can be put to practical use almost immediately. Instead of crying
"fail!" after each RUD I say "progress!".


But if you know that welding the rings by hand outdoors will always have
imperfections, then continuuing to do so becomes a side show to
entertain the space geeks because you are working elsewhere on a real
solution.

Off the shelf rolls of steel is cheap. And the beer keg building
exercises may be more focused towards training a workforce than to build
test items. And this exercise may also train the workforce on detecting
welding imperfections (a process that will still be needed even if you
get robots to do perfect welds).


I suspect you just do not understand manufacturing techniques. You do not train a workforce by building defective items. You do know that welding stainless steel is an established practice? And that such welds and be inspected using X-ray equipment?

You seem to make it clear that you do not approve of Elon Musk or his techniques. That's fine but there are other experts here that keep pointing out to you facts that you keep ignoring. If you are going to argue with experts, you'd better know something about the topics.
 




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