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Akin's Laws of Spacecraft Design (2011) [pdf]

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Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#81

The last and most important slide is missing. "Ignore all the advise above and do the right thing Subtext: This will take multiple lifetimes to accomplish" This is particularly important considering that some of the advice is at odds with each other and engineering is an unending juggling of tradeoffs. It's also by far the hardest to achieve both technically and socially but worth striving for.

I believe that might be Law 16:

“The previous people who did a similar analysis did not have a direct pipeline to the wisdom of the ages. There is therefore no reason to believe their analysis over yours. There is especially no reason to present their analysis as yours.”

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#82

Earlier quoted context omitted.

> I wonder how Elon / SpaceX folks would respond to these laws esp. #39 (avoid designing launch vehicles). Perhaps, based on specific context, let the Law's vote! > Law 11: Sometimes, the fastest way to get to the end is to throw everything out and start over. > Law 16: The previous people [...] did not have a direct pipeline to the wisdom of the ages. There is therefore no reason to believe their analysis [was optim…

> > I wonder how Elon / SpaceX folks would respond to these laws esp. #39 (avoid designing launch vehicles) SpaceX has designed 3 (four if you include Falcon 1) launch vehicles: Falcon 1, Falcon 9, Falcon Heavy and Starship. The first three run the same engine family and are arguably in the same vehicle family. SpaceX has absolutely embraced avoiding designing new launch vehicles (and even major components) until the…

The capsule (?) for humans riding to the ISS looks reminiscent of the 1960s too

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#83

Earlier quoted context omitted.

> > I wonder how Elon / SpaceX folks would respond to these laws esp. #39 (avoid designing launch vehicles) SpaceX has designed 3 (four if you include Falcon 1) launch vehicles: Falcon 1, Falcon 9, Falcon Heavy and Starship. The first three run the same engine family and are arguably in the same vehicle family. SpaceX has absolutely embraced avoiding designing new launch vehicles (and even major components) until the…

The capsule (?) for humans riding to the ISS looks reminiscent of the 1960s too

> capsule (?) for humans riding to the ISS looks reminiscent of the 1960s too

Dragon 2 [1] looks like the Apollo and Gemini craft for the same reason it resembles Soyuz 3 [2]. Crewed disposable atmospheric reëntry vehicles launched in cylinders and soft landed or splashed down under parachutes are going to look similar.

[1] https://upload.wikimedia.org/wikipedia/commons/4/4e/Iss071e0...

[2] http://www.spacepatches.nl/soyuz/soyuz3.html

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#84
post #44

I’m Henshaw (#37). AMA.

Tell us. What inspired you to say this?

I was a grad student in Dave Akin's lab from 1994-2003. Like many labs, we had a journal club. Once a week (Wednesday, I think) somebody would give a presentation over lunch on a paper they'd read. We would get takeout Chinese and eat while discussing the paper.

On this particular Wednesday the presentation was on a failed spacecraft program. It's been a long time, but I think it was probably this paper:

https://llis.nasa.gov/llis_lib/pdf/1009464main1_0641-mr.pdf

which is the initial failure analysis of the Mars Climate Orbiter (1999), which famously crashed into Mars during its orbital insertion burn because JPL specifications were in metric, but Lockheed wrote code in imperial units, and as a result there was a failure to properly convert between newtons and pounds. One fact of note was that the the team responsible for spacecraft navigation had already observed anomalous trajectory data but their reports were ignored because they didn't follow program guidelines for filling out the paperwork to document the observations, so the insertion burn went ahead heedless of what the spacecraft's behavior was trying to tell them.

Ultimately, the loss of mission was a result of unclear responsibility for ownership of the orbital maneuvering software, including the mission requirements that traced to the software, the development of the software derived from those requirements, tests to validate the software, and reports from users of the software that it was behaving unexpectedly.

I was trying to be funny, and turned the statement around from "clear lines of responsibility" to "clear lines of blame".

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#85

Earlier quoted context omitted.

That's not a good example, but for a different reason: the N95 outsold the original iPhone. The original iPhone was a promising proof of concept. It got the form factor and the interface right, but the actual device was underwhelming. It had no 3G, no GPS, no third-party apps, and a weak camera. iPhone 3G added all the features competitors already had (apart from a good camera) and became a much bigger commercial suc…

The N95 outsold the IPhone because it had a good camera and was cheaper, and got even cheaper with the phone companies subsidy. But I'd be surprised if Apple didn't have a beefier profit with the IPhone compared to Nokia with the N95.

They definitely didn't. Apple was starting from scratch in the market, and the original iPhone did a whole bunch of things it shouldn't have, making it needlessly expensive to build for the hardware it included. This is partly why Nokia initially dismissed it, as soon as it was on the market, teardowns showed that it was basically an amateurish prototype that was pushed to production, internally much worse than you'd expect from a mature company that was used to building consumer electronics. The N95 could be sold for less because it was legitimately a lot cheaper phone to build.

Then only a year later the iPhone 3G came out, and it was a rough wake-up for Nokia. Because that one was actually a well-built sane design.

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#86

Earlier quoted context omitted.

I had to look up the N95. Yeah, Wikipedia goes to pains to rattle off things that made it better than the iPhone, but then I looked at a photo of the device and it was clear why the iPhone "won".

I has a Nokia N95. The phone itself was great. The problem was the dearth of apps. Nobody developed anything for windows mobile OS. Maybe Ballmer was not so crazy when he was running around on stage screaming “Developers, developers, developers”.

N95 didn't use Windows mobile. It used Symbian, and the reason there were so few apps was that the development experience was downright horrible.

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#87

What's the story with the Avro C102 (per law 20)? What's the connection with "A bad design with a good presentation is doomed eventually. A good design with a bad presentation is doomed immediately"? I'm intrigued.

Two references come to mind – the first is that the Avro C102 was beat by the de Havilland Comet, which was an example of a bad design with a good presentation. It had a series of mysterious hull losses that were eventually attributed metal fatigue accumulating around a square cut-out in the hull.

https://en.wikipedia.org/wiki/De_Havilland_Comet#Comet_disas...

The second, more depressingly, is that the Avro C102 was cancelled to redirect resources to the Avro Arrow: Canada's mythical last jet fighter, of which only a handful were produced before the program was (painfully) cancelled, and Avro wound up. IIRC, the Canadian government was the main-to-sole bankroller of the project, and ballistic missiles became increasingly more important.

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#88
post #40

> "Trellis coded modulation got this rate up to 50 kilobaud by the 1990s" Not quite, and an interesting story that fits these engineering maxims better than you might think. An analog channel with the bandwidth and SNR characteristics of a landline phone line has (IIRC) a Shannon capacity of 30-something kbit/s, which was closely approached with V.34, which used trellis coded modulation plus basically every other cod…

> if your ISP-side modem directly outputs digital audio, the downstream channel capacity is significantly higher But why is it higher? It's still an analog channel (the last mile from the ISP to your house), right? Doesn't it get filtered? So isn't it still subject to the Shannon-Nyquist limit? Here's an ASCII drawing of which parts are digital vs analog as I understood your explanation: Rest of world Telco ISPmodem…

Yes, the actual bandwidth of the last-mile analog line was much, much higher. Hence why we eventually got 8mbit ADSL or 24mbit ADSL 2.0+ running across it. Or even 50-300mbit with VDSL in really ideal conditions.

Though the actual available bandwidth was very dependent on distance. People would lease dedicated pairs for high bandwidth across town (or according to a random guy I talked to at a cafe: just pirate an unused pair that happened to run between their two buildings). But once we start talking between towns, the 32kbit you could get from the digital trunk lines was almost always higher than what you could get on a raw analog line over the same distance.

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#89
post #12

> The biggest commercial success is not the best technical design: Nokia N95 versus the first generation iPhone That’s not a good example. Neither is Beta vs VHS. The most they illustrate is a different law I am coining right here: Canyon’s Law of Design Optimization: you will inevitably choose to optimize for different metrics than your customers would wish. Don’t try to convince them they are wrong.

I had to look up the N95. Yeah, Wikipedia goes to pains to rattle off things that made it better than the iPhone, but then I looked at a photo of the device and it was clear why the iPhone "won".

This was the (juvenile) nerd take back then https://maddox.xmission.com/c.cgi?u=iphone/

(Nokia E70 not N95, but still)

Re: Akin's Laws of Spacecraft Design (2011) [pdf]

#90
when I was at JPL, Akins laws (html version) were linked on the front page of the wiki. still one of the best (funniest) sources of engineering tips I’ve come across.

My favorite is still Mar’s law:

> Mar's Law) Everything is linear if plotted log-log with a fat magic marker.

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