[ExI] spacex landing on boat

[John Grigg]

This makes me think of so many classic science fiction films from the
1950's, where the spaceships land just like that!  :  )

https://www.youtube.com/watch?v=TdSxDNnqRlo

https://www.newscientist.com/article/2190418-elon-musk-reveals-starship-test-rocket-that-looks-like-1950s-sci-fi/

On Fri, Jan 1, 2021 at 10:46 AM spike jones via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

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> *…*> *On Behalf Of *Dan TheBookMan via extropy-chat
>
> *Subject:* Re: [ExI] spacex landing on boat
>
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> On Dec 31, 2020, at 2:32 PM, spike jones via extropy-chat <
> extropy-chat at lists.extropy.org> wrote:
>
> I share this Twitter user’s attitude about how cool this is, but disagree
> with his comment on impossible.  It was generally agreed by about the late
> 1990s that it is possible to land a rocket feet first.
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> https://twitter.com/i/status/1343959265988411394
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> spike
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> >…I think his statement — ‘Still kinda hard to believe this was considered
> *impossible* 5 years ago’ — is vague enough to border on being meaningless.
> He doesn’t say by whom and even when you say ‘generally’ it’s unstated who
> you mean. I gather you mean by experts in the field and not, say, the
> general public or even educated members of the general public…
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> Ja, not by 5 yrs ago.  By then the consensus of the people in the biz I
> think would have been the feet first landing is possible.  There were
> credible papers being presented in that direction as much as 30 yrs ago by
> guys who understood control loops, structural dynamics, performance of
> thrust vector control, all the elements.
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> I might be flattering myself here (but hey, somebody hasta do it) and I am
> watching for my own confirmation bias.  But I give a lotta credit to the
> big advances made in fiber optic angular accelerometers.  I thought that
> whole concept was just wicked cool first time I heard of it, and they were
> returning astonishing numbers: their speed in feeding back info to central
> processors in the control loop was mind-blowing, and they were handing it
> accurate numbers.  Working on that gyro accelerometer was one of the most
> exciting projects I ever did.
>
>
>
> The structural dynamics modeling advanced some, materials not so much
> really (we were using good old 6061 alloy for nearly everything the whole
> time) the actuator tech advanced some.  But it was the calculation end of
> it, getting the signals from the accelerometers enough times per second,
> deciding what to do and getting it done before the booster had time to get
> squirrelly, that was what got this done.  I looked over the control models
> and thought around 2000 or 2001 that someone would manage the feet first
> lander.  I didn’t know it was only 15 yrs off.  I mighta guessed at least
> 20.
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> >…By the way, I was thinking of how back before SpaceX accomplished this I
> thought it was very high risk…
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> You were right: it was a crazy high risk project.  Those landings are
> still high risk: I wouldn’t be surprised if they lose a rocket about every
> 10 flights.
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>
> >… Am I wee too cautious or was SpaceX just lucky? Dan
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> I am willing to credit the guys at SpaceX.  Their controls guys are just
> on it.  I bet they enjoy going to the conferences these days: the ordinary
> controls proles would surely treat them with a lotta respect.
>
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> I had an idea: go see if I could get a job at SpaceX trimming the hedges
> or cleaning the restrooms, get a SpaceX badge, go to the controls
> conferences, act like a bigshot, then when the SpaceX guys don’t know who I
> am, act like it’s so secret I don’t even know what I am doing.
>
>
>
> spike
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