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SpaceX Discussion Thread


Skylon

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:o

Low visibility, they say.

Make life easier for astronomers, they say.

And here we are, with the perspective of tens of thousands of nearly invisible satellites above our heads - some of which will be spy birds. :ph34r:

How many?

And which ones?

Wouldn't you love to know?

:unsure:

 

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So far block 5 is doing ok on the refurbs.

Probably won't see 24h turnaround. Still quite a way to go from 50 days to 7-14 though! Also that chart needs updating.

 

 

Edited by RCgothic
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Alright, I have a question about the appearance of the rocket exhaust, and could use some education:

1) At launch, what is the composition of all those billowing clouds?  Is the rocket kicking up that much dust from around the launch pad?  Or is it imperfectly-burned LF/Ox?  Or is it a whole lotta condensed water vapor from the exhaust? A combination of the three?  Something else?

2) At low altitudes, the exhaust is a bright yellow flame, and then around Max-Q it's more of a transparent orange, and then at MECO, it's almost invisible.  Why is that? Is it because the exhaust expands more at higher altitude, so there's not such a concentration of light-emitting hot/burning gasses in the plume?

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11 minutes ago, zolotiyeruki said:

Alright, I have a question about the appearance of the rocket exhaust, and could use some education:

1) At launch, what is the composition of all those billowing clouds?  Is the rocket kicking up that much dust from around the launch pad?  Or is it imperfectly-burned LF/Ox?  Or is it a whole lotta condensed water vapor from the exhaust? A combination of the three?  Something else?

2) At low altitudes, the exhaust is a bright yellow flame, and then around Max-Q it's more of a transparent orange, and then at MECO, it's almost invisible.  Why is that? Is it because the exhaust expands more at higher altitude, so there's not such a concentration of light-emitting hot/burning gasses in the plume?

1) is mostly water vapour from the pad sound suppression system and possibly some dust being kicked up of the pad.

2) A more expanded exhaust is cooler so it isn't as bright.

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13 minutes ago, zolotiyeruki said:

Alright, I have a question about the appearance of the rocket exhaust, and could use some education:

1) At launch, what is the composition of all those billowing clouds?  Is the rocket kicking up that much dust from around the launch pad?  Or is it imperfectly-burned LF/Ox?  Or is it a whole lotta condensed water vapor from the exhaust? A combination of the three?  Something else?

2) At low altitudes, the exhaust is a bright yellow flame, and then around Max-Q it's more of a transparent orange, and then at MECO, it's almost invisible.  Why is that? Is it because the exhaust expands more at higher altitude, so there's not such a concentration of light-emitting hot/burning gasses in the plume?

1) At launch they spray lots of water onto the exhaust to reduce noise, large rockets are so load the vibrations can damage the rocket and stuff on the pad, secondary use is to cool the flame trench. 
See the huge water tower nearby who is used for this. 

2) correct, guess you also have the air react to the flame from the rocket and get heated up, you also has a bit of not fully burned fuel who continue to burn in contact with oxygen. 

 

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5 minutes ago, zolotiyeruki said:

 

1) At launch, what is the composition of all those billowing clouds?  Is the rocket kicking up that much dust from around the launch pad?  Or is it imperfectly-burned LF/Ox?  Or is it a whole lotta condensed water vapor from the exhaust? A combination of the three?  Something else?

It's mainly a normal water cloud which forms because they spray a lot of water underneath the rocket during take off, this water decreases shockwaves and heat from the engines.
There will be some dust as well, but I think the land landings gives an idea how big that cloud could get, I don't think you can see any dust because of the water cloud.
 

7 minutes ago, zolotiyeruki said:

2) At low altitudes, the exhaust is a bright yellow flame, and then around Max-Q it's more of a transparent orange, and then at MECO, it's almost invisible.  Why is that? Is it because the exhaust expands more at higher altitude, so there's not such a concentration of light-emitting hot/burning gasses in the plume?

At low altitudes the exhaust encounters a lot of oxygen from the air around the rocket and the exhaust is kept at atmospheric pressure by the air so the exhaust products can continue to burn, so it's bright.
At higher altitude the exhaust encounters less oxygen and the exhaust quickly expands so it doesn't burn as much anymore. In space you only see the dark sooth that would burn at lower altitudes.

Haha I love the three similar answers :P .

One thing I want to add is the shape of the flame of the first stage, there are these 8 visible flames on the outsides of the plume. I think that's where the exhaust from different engines collides together and with the surrounding air so it becomes higher pressure and with more oxygen again. But I'm not sure.

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