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SpaceX Discussion Thread

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3 minutes ago, Spaceception said:

Don't have anything useful to add, so here (Not mine, from the KSP facebook)

51174325_10161489285945235_1081309607915

Someone should change to audio of the raptor engine video to yeet.

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16 minutes ago, Spaceception said:

Don't have anything useful to add, so here (Not mine, from the KSP facebook)

51174325_10161489285945235_1081309607915

"Bory Truno"

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27 minutes ago, NSEP said:

"Bory Truno"

I honestly didn't notice that until after I posted it.

 

I can't wait for an update on that test fire though.

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26 minutes ago, Spaceception said:

I honestly didn't notice that until after I posted it.

 

I can't wait for an update on that test fire though.

I assume it was a Merlin. A long Raptor fire would likely get some sort of post.

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33 minutes ago, tater said:

I assume it was a Merlin. A long Raptor fire would likely get some sort of post.

Unless there was a problem.

1 hour ago, Spaceception said:

Don't have anything useful to add, so here (Not mine, from the KSP facebook)

51174325_10161489285945235_1081309607915

What is the rationale on preferring BE-4 over Raptor? BE-4 has a little more absolute thrust, but it has lower TWR, much lower thrust/area, and lower chamber pressure.

Or is the lower chamber pressure why it would be preferred?

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1 hour ago, sevenperforce said:

Unless there was a problem.

A 6 minute burn that doesn’t end with a bang can’t be too much of a problem ;) 

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2 hours ago, NSEP said:

"Bory Truno"

Bory Truno, Jeff Who and Melon Musk walk into a bar...

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13 minutes ago, sh1pman said:

Bory Truno, Jeff Who and Melon Musk walk into a bar...

“Ouch!”

Cuz when someone yelled “Duck!” they looked at the pictures of Donald and Daisy on the wall.

(E: ya, I know, that joke was pretty Daffy)

Erm, back on topic. I hope we hear official words about that 6 minute test soon

Edited by StrandedonEarth
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3 hours ago, Spaceception said:

Don't have anything useful to add, so here (Not mine, from the KSP facebook)

51174325_10161489285945235_1081309607915

Rhb5lua.gif

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18 minutes ago, StrandedonEarth said:

Erm, back on topic. I hope we hear official words about that 6 minute test soon

Seems unlikely this long after the test. They have tested Merlins and subscale Raptors many, many times with no official notice at all. Given the posts about a few second test ther other night (2, actually), I'd only expect some word if it was in fact Raptor, otherwise we likely hear nothing.

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On 2/4/2019 at 1:45 PM, CatastrophicFailure said:

 

 

 

Unless I made a mistake, that much thrust over two seconds would be sufficient to accelerate a 5 tonne male elephant to over 450 m/s.

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13 minutes ago, Jaelommiss said:

Unless I made a mistake, that much thrust over two seconds would be sufficient to accelerate a 5 tonne male elephant to over 450 m/s.

I got 46 m/s.

F=ma

116000 kg = 5000 kg * a

116000/5000 = 23.2 m/s^2 = a

46.4 m/s after two seconds.

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27 minutes ago, Jaelommiss said:

Unless I made a mistake, that much thrust over two seconds would be sufficient to accelerate a 5 tonne male elephant to over 450 m/s.

This is Elon''s baby, and he wants to call the first StarShip the Heart of Gold. That is a reference to The Hitchhikers Guide to the Galaxy. So if you want to equate a StarShip engine's thrust output to an animal, the correct animal to use would be a sperm whale. So going by your numbers, that test would have accelerated a 45 tonne sperm whale to over 50 m/s!

As I was writing this, cubinator posted:

9 minutes ago, cubinator said:

I got 46 m/s.

F=ma

116000 kg = 5000 kg * a

116000/5000 = 23.2 m/s^2 = a

46.4 m/s after two seconds.

Erk. kg =/= N. Force is measured in Newtons, in the SI system. Kilograms would need to be multiplied by 9.8N/kg to get Newtons, which explains the nearly factor of 10 difference.

Relevant quote:

Spoiler

From the book, after the Heart of Gold's infinite improbability drive was activated (not sure how to insert a name into a quote when not quoting from the forum):

Quote

“Another thing that got forgotten was the fact that against all probability a sperm whale had suddenly been called into existence several miles above the surface of an alien planet.

And since this is not a naturally tenable position for a whale, this poor innocent creature had very little time to come to terms with its identity as a whale before it then had to come to terms with not being a whale any more.

This is a complete record of its thoughts from the moment it began its life till the moment it ended it.

Ah … ! What’s happening? it thought.

Er, excuse me, who am I?

Hello?

Why am I here? What’s my purpose in life?

What do I mean by who am I?

Calm down, get a grip now … oh! this is an interesting sensation, what is it? It’s a sort of … yawning, tingling sensation in my … my … well I suppose I’d better start finding names for things if I want to make any headway in what for the sake of what I shall call an argument I shall call the world, so let’s call it my stomach.

Good. Ooooh, it’s getting quite strong. And hey, what’s about this whistling roaring sound going past what I’m suddenly going to call my head? Perhaps I can call that … wind! Is that a good name? It’ll do … perhaps I can find a better name for it later when I’ve found out what it’s for. It must be something very important because there certainly seems to be a hell of a lot of it. Hey! What’s this thing? This … let’s call it a tail – yeah, tail. Hey! I can can really thrash it about pretty good can’t I? Wow! Wow! That feels great! Doesn’t seem to achieve very much but I’ll probably find out what it’s for later on. Now – have I built up any coherent picture of things yet?

No.

Never mind, hey, this is really exciting, so much to find out about, so much to look forward to, I’m quite dizzy with anticipation …

Or is it the wind?

There really is a lot of that now isn’t it?

And wow! Hey! What’s this thing suddenly coming towards me very fast? Very very fast. So big and flat and round, it needs a big wide sounding name like … ow … ound … round … ground! That’s it! That’s a good name – ground!

I wonder if it will be friends with me?

And the rest, after a sudden wet thud, was silence.

 

 

Edited by StrandedonEarth
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8 hours ago, cubinator said:

I got 46 m/s.

F=ma

116000 kg = 5000 kg * a

116000/5000 = 23.2 m/s^2 = a

46.4 m/s after two seconds.

As has been pointed out, you can't directly use kgf as a stand in for Newtons. There's a hidden factor of g.

F=ma

116,000kgf = 5,000kg*a

116,000kg*g = 5000kg*a

1,137,960N = 5000kg*a

a = 1,137,960N / 5000kg

N= kg*m/s/s

So a= 1,137,960 (kg*m/s/s) / 5000kg

a = 227.592 m/s/s

For constant mass,

v=u+at = 0+227.592m/s/s *2s = 455.184m/s

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https://www.traditionaloven.com/building/masonry/concrete/convert-tonne-metric-t-concrete-to-kilonewton-kn-for-concrete.html

From this, 116 metric ton is 1138kN, or 1.138MN

Capable of giving the 5 ton elephant 227.6 meter per second square acceleration.

So a 2 second burn can kill the elephant and accelerate it to 455.2m/s from rest. 

Goddamn units. Why cant everyone use SI units?

Edited by Xd the great

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2 hours ago, Xd the great said:

Capable of giving the 5 ton elephant 227.6 meter per second square acceleration.

227.6 / 9.8 = 23.22g. Yeah, that would turn an elephant to paste.

I used a 45ton figure for a sperm whale, because it's a nice even factor of 9 elephants.

So 23.22/9 = 2.58g. Not extreme by human standards, but I don't think sperm whales are built to withstand that, even if they can handle a dive to over 1km depth. But at least it won't turn to paste...

 

Edited by StrandedonEarth

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17 minutes ago, StrandedonEarth said:

I used a 45ton figure for a sperm whale, because it's a nice even factor of 9 elephants.

So 23.22/9 = 2.58g. Not extreme by human standards, but I don't think sperm whales are built to withstand that, even if they can handle a dive to over 1km depth. But at least it won't turn to paste...

 

Yeah, sperm whales cannot withstand that, given that they are so big...

Ants can survive a fall at most heights on Earth.

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32 minutes ago, Xd the great said:

Yeah, sperm whales cannot withstand that, given that they are so big...

Ants can survive a fall at most heights on Earth.

It's easier to give an aquatic creature a G tank. Plays hell with the mass budget though.

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2 hours ago, Rakaydos said:

It's easier to give an aquatic creature a G tank. Plays hell with the mass budget though.

Well, first you need to acquire a Bird of Prey, then you need to go back to actually find some whales from a time before they all went extinct due to people accelerating them to demonstrate silly arguments of thrust. -_-

Might want to pick up some elephants while you’re there...

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It's Saturday! If there will be no delays, almost everyone will be able to watch it :D

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Just now, Barzon Kerman said:

Watch what?

DM-1.

 

Also:

 

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