> 41. There's never enough time to do it right, but somehow, there's always enough time to do it over Same for software!!!
Most of them apply to software as well
Akin’s Laws of Spacecraft Design
121–130 of 159 posts
Re: Akin’s Laws of Spacecraft Design
#122> 8. In nature, the optimum is almost always in the middle somewhere. Distrust assertions that the optimum is at an extreme point. This rings true in politics as well.
Isn't a Pareto optimal solution always at the edge of the feasible space?
Yet, it is usually in middel of the repsective dimensions, not on the extreme ends of either.
Re: Akin’s Laws of Spacecraft Design
#123Earlier quoted context omitted.
Falcon 9 (plus Dragon) is the definitive counterexample. The jury on Starship remains out.
I'd consider development of Crew Dragon to be rather fast - because, in the condition of a private development, it wasn't done before. Comparing to other spacecraft developments, in late 1950-s there was a race, USA vs. USSR, to put a man in space "soonest", and it took Soviets ~3.5 years from the launch of the Sputnik to send Gagarin to orbit. So, just a few short years... and a large government backing. Still, give…
I think the difference between the “private” development of Dragon and the “government” development of Mercury is exaggerated.
Like Dragon, the Mercury capsule was (mostly) designed and (entirely) built by a private contractor, McDonnell Aircraft.
Like Mercury, Dragon was designed and built with input and strict oversight from NASA, including a contingent permanently on-site with the contractor. NASA always had total visibility and the final say on everything.
There are some important differences in the contracting models of the two programs, but a lot of the “private”/“commercial” framing of the ISS crew/cargo programs is just leftover vibes from the 2000s when ”harnessing the dynamic private sector” was the way to frame a new program that you wanted to get funded.
Re: Akin’s Laws of Spacecraft Design
#124Earlier quoted context omitted.
Falcon 9 (plus Dragon) is the definitive counterexample. The jury on Starship remains out.
Far from being a counterexample, Falcon 9 is a great example of the adage's truth. It flew for 10 years before being used for human missions.
Human-rating the then-new Falcon 9 launch vehicle was part of SpaceX’s award for Commercial Crew starting in 2011, and the launch vehicle did not delay the program, so I think it counts. Falcon 9 had flown twice when NASA made the initial award, it certainly wasn’t a proven launch vehicle and it’s easy to imagine it tanking the whole program if it went differently.
Re: Akin’s Laws of Spacecraft Design
#125>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.
That's for the cost estimate, not time.
Re: Akin’s Laws of Spacecraft Design
#126Hi. I'm Henshaw of Rule 37. AMA.
Well, you can tell us about the event/project that led you to coin that rule and how it panned out...
It's been long enough that my memories are fuzzy, but I believe it was this:
The project was highly successful from an R&D perspective, but it never flew in space for a variety of reasons. SOme of those were related to a lack of funding and/or national commitment to spacecraft servicing, and some were due to us not executin the program as expeditiously as we probably should have.
Re: Akin’s Laws of Spacecraft Design
#127Earlier quoted context omitted.
What's a line of blame?
I took it to mean clearly delineated responsibilities (i.e. who gets blamed when a part / aspect doesn't work). If there are unclear boundaries between responsibilities, things will fall through the gaps when one group assumes another will take care of something.
Correct!
Re: Akin’s Laws of Spacecraft Design
#128Hi. I'm Henshaw of Rule 37. AMA.
What work are you doing these days?
I'm the lead roboticist on this:
https://www.darpa.mil/program/robotic-servicing-of-geosynchr...
Re: Akin’s Laws of Spacecraft Design
#129>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.
I understood it as:
better_time = estimated_time * 3;
better_cost = estimated_cost * 10;Re: Akin’s Laws of Spacecraft Design
#130Earlier quoted context omitted.
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 i…
There was a joke running round the European car manufacturers a couple of decades ago that the European Space Agency literally couldn't hire rocket scientists because they'd all been poached to work on drive-by-wire systems. I don't know how true it actually was, but the point is that in a lot of cases it's not just going to be the same standards, it's literally the same individuals.