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Akin’s Laws of Spacecraft Design

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Re: Akin’s Laws of Spacecraft Design

#31
post #22

Earlier quoted context omitted.

That's still going to be late and over-budget.

Late comparing to what? Maybe SpaceX will not make it ready for NASA's return to the Moon flights as it was planned. However those dates don't look too serious to me - what's the justification for them? I suspect they were specified fully understanding they can easily slip right. Over-budget - what's the planned budget? I suspect Elon Musk himself doesn't have pre-approved specific budget to develop Starship, which m…

[deleted]

Re: Akin’s Laws of Spacecraft Design

#32
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.

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.

Re: Akin’s Laws of Spacecraft Design

#35
post #20

Earlier quoted context omitted.

Both were late, and I wouldn't say that Falcon was built expressly for humans. It spent a decade proving itself before it flew with people. That's not a _new_ launch vehicle.

> 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…

> 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 launch people are different from the rocket to launch only cargo?

I'm well aware of the differences. I work in this industry. That said, SpaceX made the wise decision to cut their teeth and prove their design on cargo first. That's not a new launch vehicle by definition. They were launching rockets regularly for years before they put people on the pointy end. Most other human-rated rockets in recent history have _only_ launched humans. I'm neglecting older, converted ICBMs like Redstone and Titan. The only standout from this list is probably Soyuz (the R-7 derivative launch vehicle), which has been kept going through sheer inertia.

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

I suspect that Starship will be years behind schedule before it even launches cargo. I suspect that it will miss NASA's planned lunar landing date, but it won't be at fault because other parts of the program will suffer even worse schedule slips. I understand that people are hopeful that this really will revolutionize spaceflight, and I count myself in that group too! Reality has a way of intruding eventually though. I want SpaceX to build, fly, and trash as many unmanned Starships as it takes to make it reliable. That will cause some level of delay because they'll find something new in the testflights that will necessitate a redesign before it kills someone.

Re: Akin’s Laws of Spacecraft Design

#37
Number 13. Design is based on requirements. There's no justification for designing something one bit "better" than the requirements dictate.

Isn't that the margin for error? I want to go up in a ship that's a little better than the absolute minimum.

Re: Akin’s Laws of Spacecraft Design

#38

Number 13. Design is based on requirements. There's no justification for designing something one bit "better" than the requirements dictate. Isn't that the margin for error? I want to go up in a ship that's a little better than the absolute minimum.

Then specify that in the requirements.

Re: Akin’s Laws of Spacecraft Design

#39

Earlier quoted context omitted.

Both were late, and I wouldn't say that Falcon was built expressly for humans. It spent a decade proving itself before it flew with people. That's not a _new_ launch vehicle.

A decade is a short period of time by human-rated-spaceflight standards.

So? Falcon wasn't a human spaceflight program during that time, and it was also over-schedule and over-budget anyway.

The advice isn't "no new launch vehicles should ever be invented ever", it's "if you want your human spaceflight program to be on time and on budget, don't include a new launch vehicle in the plan"

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