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SpaceX (general discussion)

Flyaway

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Can someone enlighten me on several points?
Space shuttle had some of the slowest re-entry speeds ever for a space vehicle, correct?
Allegedly the temperature it endured at re-entry was some 1500 degree Celsius. It was aluminum with a lot of ablative shielding.

SpaceX's Starship is all steel, with allegedly no ablative shielding to be used for re-entry? Will it get any other kind of cover? At one point I read about fairly simple ceramic tiles?

What re-entry temperature, at its maximum, is expected for Starship? Will it somehow be below 1300 degree Celsius? If I am not mistaken, most steel alloys melt at close to such temperatures.
It will have a heat shield that’s what the tiles on the test vehicles have been.
 

Archibald

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"a lot" I would say.

It's a new world we live in.

I was telling (more or less) the same thing to the wife and 7-years-old-kid at breakfast this morning. "You will certainly see spaceships going to Mars"
The wife thought we parents may not live to see it - or that we would be old or senile before that happened; to which I answered "Darling - not in 2050 or 2060, but in 2030 or even before" (we are both around 40).

Nice way of starting the day, really.
 

Deino

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"a lot" I would say.

It's a new world we live in.

I was telling (more or less) the same thing to the wife and 7-years-old-kid at breakfast this morning. "You will certainly see spaceships going to Mars"
The wife thought we parents may not live to see it - or that we would be old or senile before that happened; to which I answered "Darling - not in 2050 or 2060, but in 2030 or even before" (we are both around 40).

Nice way of starting the day, really.


I had almost exactly the same conversation with my family today ... but I'm already at 51! :(
 

sferrin

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Can someone enlighten me on several points?
Space shuttle had some of the slowest re-entry speeds ever for a space vehicle, correct?
Allegedly the temperature it endured at re-entry was some 1500 degree Celsius. It was aluminum with a lot of ablative shielding.

SpaceX's Starship is all steel, with allegedly no ablative shielding to be used for re-entry? Will it get any other kind of cover? At one point I read about fairly simple ceramic tiles?

What re-entry temperature, at its maximum, is expected for Starship? Will it somehow be below 1300 degree Celsius? If I am not mistaken, most steel alloys melt at close to such temperatures.
EyfE585WEAcFXcJ.jpg


And enough air gap between the stainless and the tiles that the area didn't frost up on the free fall:

vlcsnap-2021-05-06-04h42m52s693.png
 

TomcatViP

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The tiles are poor thermo conductor. If they are used to block heat to enter the airframe, they also block the outside atmosphere from heating up the inside cold that the steel surface let go through (frosting with ambiant air). That's why you only have frost on the stainless steel surface and none on the tiles themselves.
;)
 

sferrin

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Don't know how far those mounts embed into the tiles. They're obviously still testing different mounting methods. (Compare the lower set to the upper.) Poor heat transfer is a nice bonus but the primary characteristic is heat resistance. If were all about insulation they could just use foam. ;)

5udiaji21je61.jpg
 

Michel Van

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They test two systems isolation
floam were heatshield is glued to SN
blanked who pinned on surface then covert mit heatshields

by the way
the results of Starship bingo are in: SN15 C 7
 

Archibald

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The landing was not as bad as SN10, but it wasn't perfect by any mean - black marks, a fire, and it nearly landed outside the concrete pad.
Doesn't matter, however: SN16 should correct that and definitively validate the complete flight profile.

Pretty amazing to think all this flight test program is mostly because Mars atmosphere is such a giant PITA...

"Hey, look at me, the Mars atmosphere !
I'm just thick enough to burn you if you don't wear a heatshield.
BUT I'm just thin enough to not brake you enough and let you crash head on into the solid ground.
I managed to get the worst of both Earth landings and Moon landings, all by myself !
You can't be a fully-propulsive LM nor a Shuttle glider: find yourself an hybrid of these two..."

Mars atmosphere reminds me of Omar Sy (and Fred Testot) "Super connard" running joke

View: https://www.youtube.com/watch?v=0YAAi-L4c4I
 

sferrin

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The landing was not as bad as SN10, but it wasn't perfect by any mean - black marks, a fire, and it nearly landed outside the concrete pad.
Where were the black marks?
From a slight skid on the landing. Each of the feet have a black skid mark next to them. Hardly worth mentioning (Falcon 9 does the same thing). As for it not being a perfect landing, compared to whos?
 

merriman

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The landing was not as bad as SN10, but it wasn't perfect by any mean - black marks, a fire, and it nearly landed outside the concrete pad.
Where were the black marks?
From a slight skid on the landing. Each of the feet have a black skid mark next to them. Hardly worth mentioning (Falcon 9 does the same thing). As for it not being a perfect landing, compared to whos?
any landing your can walk.... (honestly! Do I have to finish that?) Box that thing up and barge it over to Hawthorne -- mission accomplished!
 

Josh_TN

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Has their been any discussion of the fire yet? Presumably it was a methane leak?
 

Archibald

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Yes it is huge. The length of a 787 and the span of a swept Tu-22M Backfire.

When you think about it, those flights are like some crazy whacky Soviet pilot
-taking off vertically on a Backfire
-stopping midair at 30 000 feet
-flipping into horizontal flight briefly
-going back to vertical to land on its tail

Something never done before by aircraft or rockets (except DC-X maybe ?)
 

Grey Havoc

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Michel Van

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SpaceX just flow a Flacon 9 booster B1051 for ten time !
it landed Save, follow reuse payload faring for second time (for moment unclear if they are recoverd)

Good news for the French Starlink goes this may in Beta phase for France (also oversea territories ?)

next flights 15 May another Starlink
in July and Oktober launch of Falcon Heavy for the US Space Force
both cases disposal Core stage and booster landing on Drone ships
 

Archibald

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Ok for a second flight, but if it survives...

View: https://www.youtube.com/watch?v=lFmhRLiYho0
 

Michel Van

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SN15 is soon lifted on Pad B
odd, the Nosecone in his cage is rolled back to production site
 

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SN15 is soon lifted on Pad B
odd, the Nosecone in his cage is rolled back to production site
I was wondering too what this was but now I wonder if they weren't testing exposure of sidelined ready to go Starships during the boosted recovery.
 

Michel Van

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NC02 return to production site into High bay and attach to big crane.
on Video below, i notice that Base of Teststand has attachment points
Seems that test stand is not complete and something will be add on in High bay

preparation for Launch Tower stacking begins as they assemble a monster of heavy crane on site

View: https://www.youtube.com/watch?v=gpkd6-8Akxo
 

Dragon029

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SN15 is soon lifted on Pad B
odd, the Nosecone in his cage is rolled back to production site
I was wondering too what this was but now I wonder if they weren't testing exposure of sidelined ready to go Starships during the boosted recovery.
The nosecone was a test article for verifying nosecone strength and how well it'd fare against maximum dynamic pressures during ascent.
 

Michel Van

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more confusion
NC03 got free of it cage and put on stand in production site
anything related to Test configuration is removed

now had SpaceX tested NC03 or not ?
 

Dragon029

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more confusion
NC03 got free of it cage and put on stand in production site
anything related to Test configuration is removed

now had SpaceX tested NC03 or not ?
The nosecone structural test article was indeed tested (there was a period about a week ago where gas it appeared to be pressurised and at one stage there were reports of some mild warping of the steel rings) - the rumour is that it passed with flying colours.
 

Michel Van

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SpaceX issue new Flight plans at FCC

one is Suborbital test were Superheavy goes over Gulf of Mexico and Land on platform (Phobos or Demios) 20 miles from coast
The orbital flight test Starship/Superheavy with booster landing 20 miles of coast on platform.
Starship will go across the Gulf of Mexico north of Cuba further over Atlantic
and end 60 km north of Island of Kauaii, Hawaii, into pacific ocean !
just water landing, no platform

source: https://apps.fcc.gov/els/GetAtt.html?id=273481&x=
via Scott Manley on Twitter
 

WilliamMook

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Can someone enlighten me on several points?
Space shuttle had some of the slowest re-entry speeds ever for a space vehicle, correct?
Allegedly the temperature it endured at re-entry was some 1500 degree Celsius. It was aluminum with a lot of ablative shielding.

SpaceX's Starship is all steel, with allegedly no ablative shielding to be used for re-entry? Will it get any other kind of cover? At one point I read about fairly simple ceramic tiles?

What re-entry temperature, at its maximum, is expected for Starship? Will it somehow be below 1300 degree Celsius? If I am not mistaken, most steel alloys melt at close to such temperatures.
1620952269060.png
Altitude versus time


1620952752611.png
The Shuttle versus Gemini and Apollo are shown here -- altitude versus velocity.


1620952868074.png
Temperature versus velocity. IRBM sustains a temperature of 5,000 Kelvin, an ICBM sustains a temperature of 6,500 Kelvin, orbital re-entry 7,000 Kelvin, Lunar Return 9,500 Kelvin, and Mars Return 14,000 Kelvin.

1620953156049.png
AOTV intercepts the Earth and exits back to orbit at orbital velocity. This is a maneuver a tenker sent from Mars or the Moon would do which takes less effort than lifting it from Earth.

Orbital speed at Earth's surface is 7.905 km/sec and escape speed at Earth's surface is 11.180 km/sec is fixed by Earth's radius and surface gravity. Apollo capsules that came back from the Moon travelled at about 10.850 km/sec whilst orbital vehicles whether Apollo, Gemini, Mercury or the Shuttle, travelled at 7.650 km/sec at a vacuum perigee altitude of 60 km where aerocapture occurred. Gemini was a pure ballistic entry wilst Apollo had some lift and Shuttle had a lot of lift. In fact lift to drag got better as the Shuttle slowed down, extending the period of time it had to slow, thus lowering g forces and lower thermal loads. Apollo and Gemini used ablative thermal protection system. This acts like wax coating on an old style milk carton. When you throw such a thing in the fire the wax has to burn off beore the cardboard catches fire. Same for Apollo and Gemini thermal protection. Space Shuttle tiles were NOT ablative. They were highly thermally insulating and could withstand high temperatures and still maintain low temperatures on the opposite side. There were several types of tiles on the Shuttle depending on the thermal load they were exposed to.







1620954130526.png

A stainless steel substructure with a ceramic coating applied by plasma deposition covered by a zirconium infused paint followed by a high temperature ablative plastic that can be sanded, seems to be the approach SpaceX is using to sustain a brief re-entry thermal pulse of up to 14,000 Kelvin for a Mars return re-entry.
 

WilliamMook

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Well...

It's a new world we live in.

Anyone know the build rate on Raptor engines?
They are constrained by the availability of turbopumps from Barber and Nichols who are one of the few companies authorised to build such things in the USA for qualified USA buyers.

1620954702513.png

1620955141512.png

 

Dragon029

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Can someone enlighten me on several points?
Space shuttle had some of the slowest re-entry speeds ever for a space vehicle, correct?
Allegedly the temperature it endured at re-entry was some 1500 degree Celsius. It was aluminum with a lot of ablative shielding.

SpaceX's Starship is all steel, with allegedly no ablative shielding to be used for re-entry? Will it get any other kind of cover? At one point I read about fairly simple ceramic tiles?

What re-entry temperature, at its maximum, is expected for Starship? Will it somehow be below 1300 degree Celsius? If I am not mistaken, most steel alloys melt at close to such temperatures.
I didn't see this question before and William gave some good data but it should be pointed out that Starship *does* have shielding, just not ablative. You can see on the recent Starship prototypes large black patches on their windward sides (remembering the Starship re-enters in a horizontal orientation). These tiles are a derivative of the TUFROC technology used for the X-37B's heatshield, where a structure comprised of ceramic-ceramic composites are used in layers to provide different mechanical and thermal properties. Unlike with the Space Shuttle, the vast majority of Starship's tiles will be identical hexagons, allowing for things like space tiles to be carried during interplanetary missions. Also unlike the Space Shuttle, Starship's heatshield tiles are mechanically, not adhesively attached, with each tile attaching via 3 clip pins.
1620959395963.png

In the image above you can see some of the tiles and pins, as well as how there's a couple different sizes of hexagon tile (which will be used in patterns for covering the 3D-curved surface of the nosecone). Some areas like the flap edges and flap fairings will need specialised tiles, but they'll be in the minority.
Below is a render showing how the tiles are expected to cover half of Starship's surface, as well as the top of the flaps:
1620959617348.png
 

Flyaway

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View: https://twitter.com/djsnm/status/1392960208771575813


And of course the landing is targetted and controlled, but there will be no landing barge, I'm, not sure if that means they'll tow it back or sink it. Given that it's [Starship] gone through reentry there's lots of value in looking at it. (assuming it doesn't break up)

View: https://twitter.com/elonmusk/status/1393083299526889473


We need to make sure ship won’t break up on reentry, hence deorbit over Pacific
 
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