131–140 of 159 posts
Earlier quoted context omitted.
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;
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…
From the "classic" era:
Mercury: 6 crewed flights. [1]
Gemini: 10 crewed flights. [2]
Apollo: 15 crewed flights (including Skylab and Apollo-Soyuz missions). [3][4][5]
Vostok: 6 crewed flights. [6]
Soyuz: 147 crewed missions (and counting). [7]
There have been four generations of Soyuz [8], so it's unclear whether it should be counted as one, four (or more?) spacecraft types. That doesn't include China's derivative,
Shenzhou: 11 crewed flights. [9]
Moving on to modern times, we have
STS: 135 crewed flights (counting orbital only). [10]
Dragon 2: 10 crewed flights and counting. [11]
Counting Apollo's LEM but not different Soyuz generations as a separate spacecraft gets us to 9, but out of those, it's STS and Soyuz which stand out as having accumulated most experience.
And all that's ignoring space stations, which arguably are spacecraft too and easily account for the bulk of time spent in space by humans [12][13]:
Salyut: 6 orbited, 34 crewed visits.
Skylab: 1 orbited, 3 crewed visits.
Mir: 1 orbited, 39 crewed visits.
Tiangong: 3 orbited, 10 crewed visits.
ISS: 1 orbited, 88 crewed visits.
[1] https://en.wikipedia.org/wiki/Project_Mercury#Crewed
[2] https://en.wikipedia.org/wiki/Project_Gemini#Missions
[3] https://en.wikipedia.org/wiki/List_of_Apollo_missions
[4] https://en.wikipedia.org/wiki/Skylab#Mission_designations
[5] https://en.wikipedia.org/wiki/Apollo%E2%80%93Soyuz
[6] https://en.wikipedia.org/wiki/Vostok_programme#Crewed_flight...
[7] https://en.wikipedia.org/wiki/List_of_Soyuz_missions
[8] https://en.wikipedia.org/wiki/Soyuz_(spacecraft)#Variants
[9] https://en.wikipedia.org/wiki/Shenzhou_(spacecraft)#Launch_r...
[10] https://en.wikipedia.org/wiki/List_of_Space_Shuttle_missions...
[11] https://en.wikipedia.org/wiki/SpaceX_Dragon_2#Crew_Dragon_fl...
[12] https://en.wikipedia.org/wiki/List_of_space_stations
[13] https://en.wikipedia.org/wiki/List_of_spaceflight_records#Du...
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> And when they were new, well, lots of delays and setbacks and costs as they kept accidentallying rockets trying to land them. They were launching just fine, it's just the landings where they blew up. This wasn't any sort of delay or major cost. Nobody else was landing rockets at all, they were just blowing them up intentionally. This is still the case today for all production orbital rockets other than SpaceX.
If I recall correctly they had their experience of them blowing up on the go up part, but that is old history now
>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 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…
Earlier quoted context omitted.
> The whole point of these two adages is that reusing an existing design is better than a new one. Yes, and that's put in doubt. Starship aims to improve on previous designs - in terms of affordability, that is, making human flights cheaper. This cheapness can't be realized with existing designs, so a new design becomes better in that regard. > SpaceX's REUSABLE rockets are great for a number of reasons yes, but by d…
None of this is put in doubt though. Your points about SpaceX's potential for future cost savings and efficiencies are hardly realized today - particularly when considering the length of time that has been spent without a capable manned vehicle. If, fast forward a decade or two and SpaceX is still using today's designs (albeit, upgraded) and actually realized massive savings - then we can talk. However, I'd bet they'…
Only during peacetime. During war (hot or cold) they often have a rather short service life before becoming obsolete.
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…
The newspace paradigm is downstream of costs coming way down. Now you can afford to iterate a few times - it’s much faster and you learn more by flying and testing against nature instead of recreating the environment perfectly on the ground and refining your analysis to the n’th degree. In this world, a good number of these laws are dated and miss the mark.
The old way is still more true in human spaceflight, because there are people on board. But even there, humans are now passengers with computer pilots, so you can do unmanned test missions that chip away at the old delays.
Earlier quoted context omitted.
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.
A better counterexample would be a crewed program that developed its own launch vehicle and still completed on time and within budget. If you treat the Falcon 9's development time as part of the overall project (which you should if you're maintaining it's a new vehicle per the adage), then you're looking at something like 15 years just to get a crew to orbit. Which is consistent with the rule.
Earlier 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.
Starship is likely to be similar. Super-Heavy (the launch portion of the combined vehicle) isn't likely to be scrapped for the crew version after the cargo Starship is ready.
Earlier quoted context omitted.
> What was the "determined" date to have them ready? How do you know they were late? Judging by Elon's estimates? Crew Dragon was approximately 3 years late, from the original planned launch date of 2017 to the actual date of 2020. Given that the contract for the missions were awarded in 2014, it's a miracle that things have proceeded at the pace they have. > You know of course that requirements for the rocket to lau…
Congress didn't pay SpaceX the agreed upon amounts for the first 3 years of the contract, and Crew Dragon was 3 years late. Coincidence?