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SpaceX Dragon CRS-6 Launch Webcast

nasa.gov

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Re: SpaceX Dragon CRS-6 Launch Webcast

#91

Post by spectrum1234 »

tsotha wrote: post #81
baq wrote: post #51

Earlier quoted context omitted.

the original, yes. now they've got experience and say they've got 80% odds for landing one first stage by the end of the year.

How can that make sense? Until they actually get a successful landing they can't be sure they don't have a problem that causes a failure 100% of the time.

Musk is a mastermind/strategic/INTJ personality. Much of someone skill of someone like this it often from making assumptions based on hunches. It could just be a hunch. And that's totally fine.

Re: SpaceX Dragon CRS-6 Launch Webcast

#92

Post by swamp40 »

david-given wrote: post #65
ggonweb wrote: post #60

Looks like Falcon landed fine, but excess lateral velocity caused it to tip over post landing -@elonmusk https://twitter.com/elonmusk/status/588082574183903232

Scott Manley did precisely this in KSP the other day, trying to replicate the barge landing: https://www.youtube.com/watch?v=C9I55o8hQgs Admittedly, he also replicated all the other possible failure modes too. Turns out landing on barges is hard.

I wonder how much of the rocket is steel?

Perhaps a barge full of Tesla batteries and electromagnets could grab and hold it as it comes in?

Re: SpaceX Dragon CRS-6 Launch Webcast

#93

Post by erobbins »

dandelany wrote: post #55
delibes wrote: post #16

That stage 2 engine nozzle really glows hot! Looks hot enough to melt, but holding together impressively. Also, the exhaust into the vacuum looks like a messy grey cloud, not the bright cone I might have expected. Very cool. Or hot.

> That stage 2 engine nozzle really glows hot! Yes! Amazingly, although the nozzle looks just like a bell-shaped piece of sheet metal, it in fact uses "regenerative cooling" which means the nozzle is full of small pipes which wind back and forth like a radiator. The rocket fuel is passed through these pipes before combustion, resulting in a heat exchange which is doubly beneficial, keeping the nozzle (relatively) coo…

I thought the 2nd stage engine's nozzle extension was radiatively cooled? First stage engines are regen for sure.

Re: SpaceX Dragon CRS-6 Launch Webcast

#94

Post by ufmace »

mikeash wrote: post #78
Cshelton wrote: post #14

Earlier quoted context omitted.

If it's successful I hope they'll show a quick replay for stage 1. Probably reasons why they don't want to show it live...

From what I understand, the reason they don't show it live is because they don't have enough bandwidth to transmit live video from the barge. They get a frame every second or two, and lots of telemetry, but not video.

Which is probably because they don't want to show it live. If they wanted to, I'm sure they could find a way to get enough bandwidth to it.

Their PR is very well-run, and not only will they not show a live video for something that they aren't sure is going to go right, they'll also have a plausible technical excuse for why they can't do it.

Not that I have anything against running your PR well, just admiring it.

Re: SpaceX Dragon CRS-6 Launch Webcast

#95

Post by TeMPOraL »

michaelmcmillan wrote: post #35

T+17m: Not a successful landing today. That sucks. Source: http://www.reddit.com/r/spacex/comments/32jnyd/rspacex_crs6_... Edit: "Looks like Falcon landed fine, but excess lateral velocity caused it to tip over post landing" @elonmusk

Pretty standard Kerbal landing - vertical ok, but too much lateral.

Re: SpaceX Dragon CRS-6 Launch Webcast

#96

Post by Crito »

TeMPOraL wrote: post #95
michaelmcmillan wrote: post #35

T+17m: Not a successful landing today. That sucks. Source: http://www.reddit.com/r/spacex/comments/32jnyd/rspacex_crs6_... Edit: "Looks like Falcon landed fine, but excess lateral velocity caused it to tip over post landing" @elonmusk

Pretty standard Kerbal landing - vertical ok, but too much lateral.

Just have to put those legs on struts sticking out the sides to give it a wider base!

Re: SpaceX Dragon CRS-6 Launch Webcast

#97

Post by tsotha »

smeyer wrote: post #83
tsotha wrote: post #81

Earlier quoted context omitted.

How can that make sense? Until they actually get a successful landing they can't be sure they don't have a problem that causes a failure 100% of the time.

Presumably they've tried to estimate that probability and factored it into the 20% probability of not succeeding. (I don't know though, since I haven't seen the calculation.)

Still... you can't assign a probability to something that is, by definition, unknown.

  "This is just a complete guess..."

Re: SpaceX Dragon CRS-6 Launch Webcast

#98

Post by mikeash »

ufmace wrote: post #94
mikeash wrote: post #78

Earlier quoted context omitted.

From what I understand, the reason they don't show it live is because they don't have enough bandwidth to transmit live video from the barge. They get a frame every second or two, and lots of telemetry, but not video.

Which is probably because they don't want to show it live. If they wanted to, I'm sure they could find a way to get enough bandwidth to it. Their PR is very well-run, and not only will they not show a live video for something that they aren't sure is going to go right, they'll also have a plausible technical excuse for why they can't do it. Not that I have anything against running your PR well, just admiring it.

I don't buy it. I'm sure Musk (and many others) would like nothing more than to watch the event live. Just having the stream doesn't mean they'd have to show it to anybody. It could be kept private. The fact that they don't have a stream at all means it must be pretty hard. Certainly it can be solved, but it's hard or expensive enough that other things take priority.

(Note that the seeming ease with which they send live video back from the rocket during the launch tells us nothing. It's relatively easy to receive high-bandwidth data from a rocket above the horizon to a tracking station with a big dish that it can point at the rocket.)

Re: SpaceX Dragon CRS-6 Launch Webcast

#99

Post by dandelany »

erobbins wrote: post #93
dandelany wrote: post #55

Earlier quoted context omitted.

> That stage 2 engine nozzle really glows hot! Yes! Amazingly, although the nozzle looks just like a bell-shaped piece of sheet metal, it in fact uses "regenerative cooling" which means the nozzle is full of small pipes which wind back and forth like a radiator. The rocket fuel is passed through these pipes before combustion, resulting in a heat exchange which is doubly beneficial, keeping the nozzle (relatively) coo…

I thought the 2nd stage engine's nozzle extension was radiatively cooled? First stage engines are regen for sure.

You're correct for the last generation of engines - Merlin 1C Vacuum was radiatively cooled. However I haven't found any confirmation one way or the other for the 1D Vacuum engine, which they're using currently. It's possible they haven't made this info public yet due to ITAR.

Re: SpaceX Dragon CRS-6 Launch Webcast

#100

Post by lutorm »

justin66 wrote: post #87
nine_k wrote: post #77

Earlier quoted context omitted.

Being fired for low performance is okay — if you feel you're continually perform poorly, you should start to look for another job well ahead of this moment. California is not a particularly saturated market for software developers. Not following the legally required procedure is bad, though.

> Being fired for low performance is okay The problem is that companies following the "fire at least 10% every year in every department" Jack Welch philosophy tend to let some good people go. It's a management philosophy that just assumes that there's no such thing as a really good team, full of worthwhile players. Its an attitude that works better in professional sports, where hyper-competitiveness is more often an…

It's not appropriate for me to comment on company HR policy. All I'm going to say is that my impression of the atmosphere on the software team is not at all "a bunch of coworkers trying to outdo one another to make the cut".
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