Hi. I'm Henshaw of Rule 37. AMA.
Akin’s Laws of Spacecraft Design
21–30 of 159 posts
Re: Akin’s Laws of Spacecraft Design
#22This 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.
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 makes sense, as e.g. it's rather hard to pinpont. As for the overall idea for how much Starship development would cost - how do you know it's missed already or going to be missed?
Re: Akin’s Laws of Spacecraft Design
#23Hi. I'm Henshaw of Rule 37. AMA.
What work are you doing these days?
Re: Akin’s Laws of Spacecraft Design
#24Hi. I'm Henshaw of Rule 37. AMA.
What's the backstory, was there a situation where you were the blamee (or the blamer?)
Re: Akin’s Laws of Spacecraft Design
#25> 3. Design is an iterative process. The necessary number of iterations is one more than the number you have currently done. This is true at any point in time. I'm going to agilely build a space craft! /S
Funny thing is SpaceX is known for applying Agile to its aerospace engineering workflows. Boeing etc. are much slower because they use waterfall.
Oh, I'm pretty sure someone(s) manages a massive GANTT chart over on the SpaceX side.
Re: Akin’s Laws of Spacecraft Design
#26By the way, since you need to apply thrust from any direction to maneuver flexibly in 3D space (without wind or gravity), wouldn't spherical/disc(saucer) shaped spacecraft be the most efficient?
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…
Plus, without deflector shield voodoo, a skinny tube design minimize your cross sectional area and how much debris you will impact.
Re: Akin’s Laws of Spacecraft Design
#27Hi. I'm Henshaw of Rule 37. AMA.
What's a line of blame?
Re: Akin’s Laws of Spacecraft Design
#28Earlier quoted context omitted.
It could be argued that Dragon has already proven this wrong. Falcon 9 was developed in the form it was specifically to launch Dragon. SpaceX's original next rocket was going to be a Falcon 5 until they got the Dragon contract from NASA. Yes, the original Dragon was a cargo vehicle rather than a human spaceflight vehicle, but both Falcon 9 and Dragon were developed with the intention of eventually human rating.
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.
Re: Akin’s Laws of Spacecraft Design
#29Re: Akin’s Laws of Spacecraft Design
#30This 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.
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, given that Crew Dragon was developed by a private company and is quite modern judging by performance, I think it's a good result.