Skylon

SpaceX Discussion Thread

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22 minutes ago, Ignath said:

said complete/near-complete loss of vehicle.

 

N2O4 running over the length of the entire vehicle is gonna destroy everything.

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Well, better to get the failures out when they are on the ground rather than in flight, I guess. 

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Is it just me, or did that explosion happen near the top of the capsule? 

Superdraco engine breaks off and shoots through the capsule like a bullet, exiting out of the docking ring? 

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36 minutes ago, MinimumSky5 said:

Is it just me, or did that explosion happen near the top of the capsule? 

Superdraco engine breaks off and shoots through the capsule like a bullet, exiting out of the docking ring? 

Next generation LES:

Launches you through the capsule instad of launching the capsule through the sky.

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Interesting that now both Boeing and SpaceX had a failure in their liquid propellant fueled LES system. Might have all went a little faster with the good old Solids.

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Course this capsule also took a swim, maybe salt water got into someplace it shouldn't have.

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Its great that this happened during a static fire and not in a real abort event.

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@sh1pman It’s great that no one was harmed, on the other hand, they had years of testing, this problem appearing now seems like it could be a big setback. 

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11 hours ago, Xd the great said:

N2O4 running over the length of the entire vehicle is gonna destroy everything.

Spoiler

too-much-nitro.jpg

 

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Posted (edited)
Spoiler

Dragons are for Targaryens only.

 

Edited by kerbiloid

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MxW35eA.jpgWIQlLU0.jpgoNplPlp.jpg

frames 1-3. Images taken from video posted by Astronut099 on Twitter, brought up here by @Arcturusvfx

vskiabb.jpg

Hm. Bit of a hard start there.

Was curious, so I plotted where the center of the explosion appeared to originate from.

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2 minutes ago, Cunjo Carl said:

MxW35eA.jpgWIQlLU0.jpgoNplPlp.jpg

frames 1-3. Images taken from video posted by Astronut099 on Twitter, brought up here by @Arcturusvfx

vskiabb.jpg

Hm. Bit of a hard start there.

Was curious, so I plotted where the center of the explosion appeared to originate from.

Hint, do not mess up the abort and self destruct systems. 

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13 minutes ago, magnemoe said:

Hint, do not mess up the abort and self destruct systems. 

Same control panel designer?

1*l8Y8QP76O-Eq7zxjmL70jg.png

(Ronald Reagan's finger in screengrab from "Land of Confusion" by Genesis)

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While Musk had said water didn't get in, what makes these Super Dracos different than all the others tested? Reentry? All it would take is a tiny expansion to make a leak someplace. You'd assume that before static firing these they'd pressure test them with something inert.

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11 hours ago, tater said:

Course this capsule also took a swim, maybe salt water got into someplace it shouldn't have.

Seems like a distinct possibility. MMH seems to be catalytic decomposed by low levels of chlorides of Ni and Fe, the components of the inconel the superdracos are printed from, and likely materials used in valves and pipes as well.

From: Survey- Monomethylhydrazine Propellant/Material Compatibility- DTIC

" Small amounts (0.003M) of disolved nickel and iron increased the decomposition rate of MMH by a factor of 10 at 100'C. "
"...the addition of 1 percent NH4Cl increased the rate of MMH decomposition at 200"C in Pyrex by a factor of 100 - a more pronounced effect than that observed with hydrazine."

Though inconel is corrosion resistant, it's definitely not corrosion proof- especially in the face of sea water and salty breeze.

Given this, I could totally imagine corroded metal surfaces kicking off a thermal runaway shortly after the lines were pressurized, but _before_ the MMH started flowing. This would make the most sense for an exposed valve surface like a face-shutoff valve used on the pintle injector in the Merlins. Any idea if this same system is used on the Dracos? It'd sure make sense to use it here, where simplicity and speed of startup are the top priorities.

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1 hour ago, tater said:

While Musk had said water didn't get in, what makes these Super Dracos different than all the others tested? Reentry? All it would take is a tiny expansion to make a leak someplace. You'd assume that before static firing these they'd pressure test them with something inert. 

Well, they had few successful tests on that same day before that last one where things went boom

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Just now, Cuky said:

Well, they had few successful tests on that same day before that last one where things went boom

I read they had tested the Dracos, but it was unclear if they had yet tested the Super Dracos.

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6 hours ago, tater said:

While Musk had said water didn't get in, what makes these Super Dracos different than all the others tested? Reentry? All it would take is a tiny expansion to make a leak someplace. You'd assume that before static firing these they'd pressure test them with something inert.

Maybe the inert test broke it...

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5 hours ago, Cunjo Carl said:

Seems like a distinct possibility. MMH seems to be catalytic decomposed by low levels of chlorides of Ni and Fe, the components of the inconel the superdracos are printed from, and likely materials used in valves and pipes as well.

From: Survey- Monomethylhydrazine Propellant/Material Compatibility- DTIC

" Small amounts (0.003M) of disolved nickel and iron increased the decomposition rate of MMH by a factor of 10 at 100'C. "
"...the addition of 1 percent NH4Cl increased the rate of MMH decomposition at 200"C in Pyrex by a factor of 100 - a more pronounced effect than that observed with hydrazine."

Though inconel is corrosion resistant, it's definitely not corrosion proof- especially in the face of sea water and salty breeze.

Given this, I could totally imagine corroded metal surfaces kicking off a thermal runaway shortly after the lines were pressurized, but _before_ the MMH started flowing. This would make the most sense for an exposed valve surface like a face-shutoff valve used on the pintle injector in the Merlins. Any idea if this same system is used on the Dracos? It'd sure make sense to use it here, where simplicity and speed of startup are the top priorities.

Yep, if i remember correctly it is a pintle injector.

Also, 3D printed, so that might be a problem.

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Looking at the link from @Arcturusvfx, it seems that SpaceX hasn't cleaned the capsule. With this, I decided to compare images to the landed Dragon 2 from DM1.

Spoiler

5JvTEDp.png

This frame from the Dragon landing shows one side of the Dragon being significantly darkened along with no hatches or windows.

Spoiler

q4HhfNx.png

While this picture shows the hatch side being much lighter.

GnhIUJo.png

Now the capsule here has a lighter side facing the camera and the burnt parts here matching the burnt parts on the recovery image of the hatch side.

My opinion is that the explosion didn't come from the SuperDracos. The explosion isn't centered on any engine pod (being centered at the area below and right of the hatch) and that the Dragon 2 is supposed to be able to operate after a catastrophic engine failure. (Scott Manley's take: https://twitter.com/DJSnM/status/1119860405461864448) The muffled audio also sounds like someone counting down with the explosion occurring after 9. Ignition would be later on and on the Dragon abort test, the sound suppression system would've started.

I found an interesting picture for the internals.

Dragon without a shell (from SpaceX's insta, https://www.instagram.com/p/BucYA72AYJ1/):

Spoiler

MBjmRZK.pngll

 

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Should the visible center of the hot gas cloud match the visible projection of the center of the explosion process?
We can see where the gas cloud breaks out through the weakest place of the hull, but not where the explosive has exploded.

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