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Akin’s Laws of Spacecraft Design

spacecraft.ssl.umd.edu

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Re: Akin’s Laws of Spacecraft Design

#111

Post by sethrin »

tw04 wrote: post #105

> Design is based on requirements. There's no justification for designing something one bit "better" than the requirements dictate. I’m not sure the early Apollo astronauts would agree.

The phrase associated with Apollo was, "waste anything but time." Achieving arbitrarily high levels of quality takes time, for pretty much any process. Those F1 engines were mostly handmade, which you can see among other places in the imperfect machining of this F1 injector plate[0]. The attitude at NASA towards risk was not "avoid it at all costs": what they were doing was inherently risky. NASA's goal is to manage risk.

[0] https://web.archive.org/web/20230522164734im_/https://cdn.ge...

Re: Akin’s Laws of Spacecraft Design

#112

Post by hliyan »

avmich wrote: post #4

This is definitely the wisdom of ages, but some points do show some age. 39. (alternate formulation) The three keys to keeping a new human space program affordable and on schedule: 1) No new launch vehicles. 2) No new launch vehicles. 3) Whatever you do, don't develop any new launch vehicles. Recent SpaceX developments, Starship in particular, put some doubts on this one.

I think this comment is an artifact of its time, kind of like Knuth's "premature optimization" or Spolky's "never, ever rewrite from scratch". They are mostly valid under the circumstances the author uttered them, but by no means universally applicable, and certainly not to be turned into religious commandments.

P.S. any engineer who counters my request to take perf into consideration with "premature optimization is the root of all evil" is immediately asked to complete the remainder of the quote. Failing to do so usually results in me ejecting the person from the meeting!

Re: Akin’s Laws of Spacecraft Design

#113

Post by Animats »

jameshart wrote: post #61

I don’t feel like a field that has in its entire history only produced a handful of actual successful designs at all can possibly rate this kind of ‘world weary cynicism’ style of writing. Nobody has the experience or ability to be able to say ‘trust me I’ve built a few spaceships, this is the hard won truth of how it is’. There are exactly nine spacecraft that humans have ever flown in. Only the Mercury/Gemini/Apoll…

> But ‘trust me I have been teaching people to design spacecraft for decades’ doesn’t really count for much when during those decades no new spacecraft designs were actually getting made and launched.

That's an excellent point. Not until Space-X started launching Falcon-9 boosters was there a significant US advance since the Space Shuttle, for which design began in 1969. The Russians are still launching Soyuz. China has been developing and flying new boosters, and is now flying the Long March 7 and 8, with the Long March 9 in development. NASA, though...

Re: Akin’s Laws of Spacecraft Design

#114

Post by rzimmerman »

jameshart wrote: post #61

I don’t feel like a field that has in its entire history only produced a handful of actual successful designs at all can possibly rate this kind of ‘world weary cynicism’ style of writing. Nobody has the experience or ability to be able to say ‘trust me I’ve built a few spaceships, this is the hard won truth of how it is’. There are exactly nine spacecraft that humans have ever flown in. Only the Mercury/Gemini/Apoll…

Absolutely. A lot of back-patting and inside jokes about 40 years of building expensive space systems that often failed. Self-aggrandizing crap about how “space is hard”. Space was hard in the 60s when you had to invent microprocessors to get off the ground. It’s well understood and should be common and cheap now (at least for Earth orbiting systems). This old boys club nonsense might feel fun but space is changing, access is becoming easy, and anyone that tries to spend 10 years and a billion dollars on a project won’t last long.

Re: Akin’s Laws of Spacecraft Design

#115

Post by jiveturkey »

jameshart wrote: post #61

I don’t feel like a field that has in its entire history only produced a handful of actual successful designs at all can possibly rate this kind of ‘world weary cynicism’ style of writing. Nobody has the experience or ability to be able to say ‘trust me I’ve built a few spaceships, this is the hard won truth of how it is’. There are exactly nine spacecraft that humans have ever flown in. Only the Mercury/Gemini/Apoll…

Yup. It especially rubs the wrong way for the last point, #45.

> If you screw up the engineering, somebody dies

So, shouldn't something like cars get this level of diligence then? Coal-fired power plants maybe? Nursing home care??? Spaceflight deaths, even on a log scale graph, don't even make it on the chart vs any of those others.

It's far more about the perceptional impact to the program as a whole, if someone dies, many billions will have been wasted and many thousands will lose their jobs.

Still, it's fun and I've used it for a decade now. I really like #41.

> 41. There's never enough time to do it right, but somehow, there's always enough time to do it over.

Never mind that it's in direct contradiction to some of the other laws. I still love it.

Re: Akin’s Laws of Spacecraft Design

#117

Post by quartesixte »

jiveturkey wrote: post #115
jameshart wrote: post #61

I don’t feel like a field that has in its entire history only produced a handful of actual successful designs at all can possibly rate this kind of ‘world weary cynicism’ style of writing. Nobody has the experience or ability to be able to say ‘trust me I’ve built a few spaceships, this is the hard won truth of how it is’. There are exactly nine spacecraft that humans have ever flown in. Only the Mercury/Gemini/Apoll…

Yup. It especially rubs the wrong way for the last point, #45. > If you screw up the engineering, somebody dies So, shouldn't something like cars get this level of diligence then? Coal-fired power plants maybe? Nursing home care??? Spaceflight deaths, even on a log scale graph, don't even make it on the chart vs any of those others. It's far more about the perceptional impact to the program as a whole, if someone die…

>So, shouldn't something like cars get this level of diligence then?

They do. At least the, "engineering of the vehicle itself and then manufacturing it" part.

A lot of Aerospace designing, testing, and manufacturing is built off the foundation the automotive world laid down. Heck, one of the key standards, the SAE standard, is called such because it literally stands for Society of Automotive Engineers.

Cars may be involved in a lot of deaths every year. But rarely do people die because their car spontaneously combusted/fell apart while someone drove it.

Re: Akin’s Laws of Spacecraft Design

#118

Post by bladewolf47 »

Modified3019 wrote: post #101

>29. (von Tiesenhausen's Law of Program Management) To get an accurate estimate of final program requirements, multiply the initial time estimates by pi... I discovered this when my father would come up with some project me and my siblings had to do, such as scrape, sand, prime and paint the house (which thinking back very likely had lead paint). It would inevitably take roughly 3 times longer than he wanted it to ta…

The later half of the rule also scales the estimate up by an order of magnitude, would imply tasks taking 30x longer. Guess that makes you quite optimal at those tasks.

Re: Akin’s Laws of Spacecraft Design

#120

Post by hoseja »

Modified3019 wrote: post #101

>29. (von Tiesenhausen's Law of Program Management) To get an accurate estimate of final program requirements, multiply the initial time estimates by pi... I discovered this when my father would come up with some project me and my siblings had to do, such as scrape, sand, prime and paint the house (which thinking back very likely had lead paint). It would inevitably take roughly 3 times longer than he wanted it to ta…

Maybe it should be e actually? At least I'd pattern-match e into such a relationship.
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