Akin’s Laws of Spacecraft Design

Falcon 9 (plus Dragon) is the definitive counterexample. The jury on Starship remains out.

Only if instantaneous large accelerations in arbitrary directions is amongst your primary performance requirements. You'd need to have thrusters ready to fire in arbitrary directions as well. A spherical (specifically) spacecraft would also have more heat dissipation challenges.

> 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 definition, those are not NEW launch vehicles.

I don't know how good definition can exclude reusable rockets from being new. Was Shuttle ever new? Delta Clipper? Reusable Falcon-9? Falcon Heavy? I think this is not a good definition, if, according to it, reusable rockets can't be new.

> And when they were new, well, lots of delays and setbacks and costs as they kept accidentallying rockets trying to land them.

Do you know the difference between designing and using? In software it's rather clear, and nobody would expect a half-written program to function according to specs. Neither it's the case in aerospace - while Falcon reusability was being designed and tested, nobody should expect it to perform flawlessly as when used "in production". Not cheap, agree (actually, quite cheap by aerospace standards, but still not some typical household-sized money), but I'd argue that was rather quick - just a few years to put reusable first stage into production starting from announcing the idea and building the first "Grasshopper". So, while 39[a] may stand here, your comment doesn't provide a good justification to it.

> If anything, SpaceX's entire business model is EMBRACING that adage, not disproving it or an exception to it.

SpaceX benefited immensely from using proven solutions, but the results they are showing are still disproving the idea of this law. The ambitions of SpaceX are high compared to the rest of the world launching industry, but so are the results, and we also have genuine "firsts", like putting the reusable first stage into production, or flying reusable spacecrafts to space station, TKSes and Shuttles notwithstanding.

Let me try to explain again my main point: SpaceX aims to make human spaceflight significantly cheaper, and the opinion is that it can't be done without radical redesign from scratch. It was attempted several times in the past, with e.g. Shuttle and Energiya, and it still isn't done today, but if you want to risk being put on the "you're currently here" list of SpaceX achievements(1), which were doubted and then happened, I'd at least propose you to think from the basic assumptions and find out why SpaceX won't actually achieve cheaper human spaceflight this time.

(1) In Russian that list looked like this before reusable Falcon: https://meduza.io/impro/0ZWeCgCXA4nsWv7dj7CHbSIrsURgOh-qpiUh...

The space between things in space is quite large, so you're going in a single direction for a while. The thrust from the spacecraft is also used to exploit gravitational energy (slingshoting around planets) for the most part, from my understanding.

In Sci-fi, it's generally understood that very fast crafts (0.1c and up) will need to reverse and apply thrust opposite their direction to slow down for a very large part of the voyage (up to more than half) - so could be a good idea to be able to flip around and apply thrust the other way too.

> Both were late

What was the "determined" date to have them ready? How do you know they were late? Judging by Elon's estimates?

> I wouldn't say that Falcon was built expressly for humans

You know of course that requirements for the rocket to launch people are different from the rocket to launch only cargo? There were cases when non-human-rated rocket became human rated (at least Proton), but these days it's better to plan ahead, like teams working on Arian-5 (and also Dream Chaser, not a rocket) do. I'd assume Flacon-9 developed from the beginning in such a way so at least human-rating would be possible - if not built-in already.

> It spent a decade proving itself before it flew with people. That's not a _new_ launch vehicle.

I'd agree regarding Falcon-9. Starship is another story.