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Comment: Re:Awesome! (Score 1) 40

by cbhacking (#49524633) Attached to: NASA's Rocket Maker To Begin 3D Printing Flight-Ready Components

Makes sense. Even if Dragon 2 takes over completely from the initial Dragon, if SpaceX gets anywhere near the reusability out of it that they're aiming for (and, unlike the Falcon 9 first stage, Dragon 2 is designed from the start for safe landings and reusability) they won't need to manufacture that many of the rocket motors. Certainly not enough for economies of scale, at least not for the first revision or two. In the meantime, they (and ULA, and everybody else doing this) will be driving down the cost of this kind of manufacturing.

Comment: Re:Have we solved all human rights issues? (Score 1) 332

by cbhacking (#49521321) Attached to: Update: No Personhood for Chimps Yet

Indeed. Leaving aside the fact that things Medicaid and food stamps and emergency rooms that are obliged to treat you mean that even the most destitute Americans are already better off than a lot of the world, I've yet to see an American community - population in the thousands - who live in the following conditions:
  * Rough shacks (a trailer home is a mansion by comparison; I've seen outhouses bigger than some of these shacks)
  * No electricity
  * No running water (the luckier ones don't have to carry water very far)
  * No water sanitation (it probably comes out of a stream or lake)
  * No sewers (hope you can draw your water upstream of most of the community...)
I'm talking about people who literally live on top of trash dumps, or in shantytowns outside of cities. In some ways, the arguably-even-poorer people who live in the middle of nowhere actually have it better; they may not even have the leavings of civilization (in the sense of "city dwellers") to live on, but their population is low enough to be supported by well water and to grow or gather plant crops and to not shit where they eat.

Comment: Re:Awesome! (Score 4, Informative) 40

by cbhacking (#49515897) Attached to: NASA's Rocket Maker To Begin 3D Printing Flight-Ready Components

Yep. Some parts of the Merlin 1D are built additively, I think, but the *entire* SuperDraco thruster (which uses Hydrazine rather than cryogenic fuels like RP1/LOX) is printed. http://en.wikipedia.org/wiki/S...

It's really cool to see this technique taking off (pun not initially intended, but let's go with it). People think of 3D printing as making rough plastic parts, but it can be used to create extremely precise parts out of various metals, too.

Comment: Re:Property taxes? (Score 1) 536

by cbhacking (#49514149) Attached to: George Lucas Building Low-Income Housing Next Door To Millionaires

If they're renting (as most low-income people do), they won't be (directly) paying property tax.

I suspect Lucas doesn't actually expect to turn a profit on doing this, possibly not by a long shot. 200M isn't exactly pocket change, but he can easily afford to write off the whole thing if needed.

Comment: Re:Not a revenge plot (Score 1) 536

by cbhacking (#49514119) Attached to: George Lucas Building Low-Income Housing Next Door To Millionaires

It's pretty sad that "rich guy flips the bird to other rich people in revenge for not getting his way" pleases you more than "rich guy helps people get housing in one of the most expensive parts of the world". I mean, I enjoy the feel of a good "fuck you!" too, but if you like that *more* than what's essentially charity, well, that's kind of screwed up of you...

Comment: Re:Interstate Water Sharing system (Score 1) 669

by cbhacking (#49513411) Attached to: William Shatner Proposes $30 Billion Water Pipeline To California

Seems like a reasonable claim to me! Resource supply is one of the key determiners of land value, and always has been. If it rains on my land, and I catch that rain before it wanders onto somebody else's land, how is that not my water?

I mean, there's lots of arguments for (and against) communal ownership of natural resources, but the current (and, for as far back as I'm aware, historical) rule is that they are part of the land value. You're going to have a hell of a time overturning that view. Some things, like rivers, tend to get a bit complicated - it's really awkward if your upstream neighbor feels like using his water (immediately before it ceases to be his) as an arsenic dump - but taking ownership of the water falling from the sky or coming up through the ground has never, so far as I know, *not* been part of land property rights.

Comment: Re:Video from the barge (Score 1) 113

I'm not actually sure which of use that tweet backs up; I thought he meant "I estimate we have an 80% chance of at least one landing by year's end, because there are lots of launches between now and then and there's a pretty good chance at least one will succeed." It would be pretty awesome if what he meant was "By the end of the year, we'll have so much more launch practice that, even though each launch has less than 50% chance of recovery right now, by year's end it should be about 80%." I hope the latter is the case, but the two are very different statements and the latter is much more optimistic. I was hoping you could indicate which one was more accurate.

Comment: Re:Understatement of the year... (Score 1) 113

Not clear whether or not you realize this, so to give you the benefit of a doubt:

A) In orbital launch booster rocketry terms, that's a pretty damn small fireball.
B) At the time he sent that tweet, nobody (Musk included) had seen the video from the barge. I doubt he even had the video from the airplane, probably just the telemetry data that showed touchdown followed by a loss of telemetry.

Comment: Re:Video from the barge (Score 1) 113

Explode when it crashes, there's a difference. SpaceX has demonstrated powered vertical landings on their test vehicles, there were no explosions.

Hydrazine is nasty stuff, but you don't need very much of it (a few second's worth, maybe) and the *entire point* is to avoid the crash, so what happens in the event of a crash is much less important.

Comment: Re:Video from the barge (Score 4, Interesting) 113

by cbhacking (#49490061) Attached to: An Engineering Analysis of the Falcon 9 First Stage Landing Failure

Nitpick: The first attempt ran out of hydraulic fluid (for the guidance fins), not out of propellant for the RCS thrusters.

The rest of what you say is generally true, although a larger target *would* help. The advantage of a larger target is that, while you still have to zero your horizontal velocity, you don't have to zero it anywhere terribly precise. You can pick an optimal set of thrusts that results in the correct orientation and velocities (horizontal and vertical) without worrying overmuch *where* that series of thrusts has you touching down. Both attempts so far clearly demonstrate the ability to do an excellent good job of targeting a (relatively) tiny barge, but currently, if the rocket would come down even 100' (30m) to one side of its target spot, it needs to induce a horizontal momentum (which requires leaving a vertical attitude as well, it can't just translate sideways) and then null that momentum at the right moment (and fix its attitude). That's hard.

To clarify for the person who keeps misunderstanding my posts: they should, of course, plan for the barge-level of landing precision. They should aim for a precision of inches, and within a year, they may get it... 90% of the time. Stuff goes wrong, though, and (especially early in the testing of such a system) it behooves them to use a larger landing area so that there's some margin for error. I'd say their land attempt (possibly next CRS launch, in a couple months) has a very good chance of being their first success.

Comment: Re:Doesn't look close (Score 1) 113

by cbhacking (#49489831) Attached to: An Engineering Analysis of the Falcon 9 First Stage Landing Failure

The thrusters aren't even supposed to be needed there, actually. They're only supposed to fire in very short bursts, not a continuous stream like in the video. As for the legs holding up, just one of them supported the whole rocket for a few seconds; all four should have had no trouble. We know a hell of a lot more than just that it crashed. To claim otherwise is to embrace ignorance.

There is literally no point at all to living in a world where you are only concerned with the things that you absolutely know. You don't absolutely know *ANYTHING*, you could be a simulation in some advanced being's AI-run world, along with everything the program running you has ever simulated observing. The only way to achieve anything difficult is to analyze the differences between failures and successes, and a part of that analysis is to determine how close you came to success.

But then, you probably already knew that and are just a naysayer...

Comment: Re:Video from the barge (Score 1) 113

by cbhacking (#49489751) Attached to: An Engineering Analysis of the Falcon 9 First Stage Landing Failure

I'm not trying to fix the wrong problem, I'm trying to add a backup for the fix. Shit happens. Parts will fail, valves will stick, unexpected winds or waves will occur.

I thought the fact that the primary goal was to correct the problem that caused the excessive lateral velocity was so bloody obvious that it didn't need saying, but I guess I forgot I'm on the Internet. The purpose of my idea was not "fuck it, fixing a little problem is hard, let's do something much more complicated", it's "shit happens. What can we do to survive the likely error modes?"

Comment: Re:Holy Stiction, Batman! WTF is hysteresis? (Score 1) 113

by cbhacking (#49489725) Attached to: An Engineering Analysis of the Falcon 9 First Stage Landing Failure

A) You've mastered "dictionary", "bookshelf", and "somewhere", but an eight-letter word is too big for you?

B) Welcome to the Internet. You probably got here using "the blue e", right? Tip: highlight (whoops, big word) the scary word with your mouse, right-click on it, and click the option that will search or define the word for you! No need to go over to your bookshelf at all, and you get to avoid looking like a lazy ignoramus (sorry, is that one too long?) at the same time!

Seriously, I get that you're probably joking, but that is a really stupid thing to complain about. Definitions don't belong in a summary, especially not a summary delivered through the biggest inter-connected information network humanity has ever created.

"I got everybody to pay up front...then I blew up their planet." "Now why didn't I think of that?" -- Post Bros. Comics

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