Author Topic: SpaceX Dragon 2 Updates and Discussion - Thread 2  (Read 462189 times)

Offline gongora

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1360 on: 07/13/2018 04:00 PM »
What are we seeing in that photo of Dragon 2 with the Super Dracos?
Beyond the white or light grey ramps, as opposed to black, are those covers over the exhaust ports?
I wonder if they are to prevent water intrusion and were added when SpaceX went from land landing to ocean?
Notice two things from the HR version of that photo: (1) The exhaust ports are covered by something that is marked as "remove before launch", and (2) The color of the ramps is not grey, but silver.  That makes sense in the same sense as they silvered much of the tail portion of SpaceShip Two.  Reflecting heat away is more effective than absorbing it, at least for certain cases.

The silver material is NOT for heat reflection.

It is the same silver-colored material that is used to cover the primary heat shield on Cargo Dragon, as well as the primary heat shield on Crew Dragon. It is for moisture protection. Given that the exhaust ports for Super Draco are covered in the same material as the primary heat shield (PICA-X) you can expect the same application of silvery material for moisture protection.

PICA(-X) is known to absorb moisture (water) from the atmosphere. When absorbed into the PICA material the water negatively influences the performance of PICA as a heat shield material. It is therefore necessary to prevent PICA from absorbing moisture. That is why the PICA is covered in the silvery material as seen in the recent pictures.

More on this subject: https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1083&context=me_etds

Offline Nomadd

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1361 on: 07/13/2018 04:58 PM »
 I imagine little exploding steam pockets or increased thermal conductivity in your heatshield wouldn't be the most desirable thing in the world.

Offline woods170

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1362 on: 07/13/2018 09:03 PM »
I imagine little exploding steam pockets or increased thermal conductivity in your heatshield wouldn't be the most desirable thing in the world.

Yeah, that's basically it. PICA is a great heat shield material as long as you make sure it is prevented from behaving like a moisture sponge.

Offline jak Kennedy

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1363 on: 07/13/2018 09:53 PM »
What are we seeing in that photo of Dragon 2 with the Super Dracos?
Beyond the white or light grey ramps, as opposed to black, are those covers over the exhaust ports?
I wonder if they are to prevent water intrusion and were added when SpaceX went from land landing to ocean?
Notice two things from the HR version of that photo: (1) The exhaust ports are covered by something that is marked as "remove before launch", and (2) The color of the ramps is not grey, but silver.  That makes sense in the same sense as they silvered much of the tail portion of SpaceShip Two.  Reflecting heat away is more effective than absorbing it, at least for certain cases.

The silver material is NOT for heat reflection.

It is the same silver-colored material that is used to cover the primary heat shield on Cargo Dragon, as well as the primary heat shield on Crew Dragon. It is for moisture protection. Given that the exhaust ports for Super Draco are covered in the same material as the primary heat shield (PICA-X) you can expect the same application of silvery material for moisture protection.

PICA(-X) is known to absorb moisture (water) from the atmosphere. When absorbed into the PICA material the water negatively influences the performance of PICA as a heat shield material. It is therefore necessary to prevent PICA from absorbing moisture. That is why the PICA is covered in the silvery material as seen in the recent pictures.

More on this subject: https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1083&context=me_etds

In the vacuum of space wouldn't the water evaporate or boil off, even sublime? Although prevention always seems the first choice.

Offline matthewkantar

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1364 on: 07/13/2018 10:26 PM »
Water soaked into a material could do damage coming out, flashing into steam as mentioned above, or water could chemically damage the material. If they are ok with the weight of the paint to protect it, there must be a good reason.

Offline butters

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1365 on: 07/13/2018 10:37 PM »
I imagine little exploding steam pockets or increased thermal conductivity in your heatshield wouldn't be the most desirable thing in the world.

Yeah, that's basically it. PICA is a great heat shield material as long as you make sure it is prevented from behaving like a moisture sponge.

Which is why SpaceX probably isn't thrilled about splashing down. Not sure if any of the flight-proven Dragon 1 missions have used flight-proven heatshields.

Online envy887

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1366 on: 07/13/2018 11:31 PM »
What are we seeing in that photo of Dragon 2 with the Super Dracos?
Beyond the white or light grey ramps, as opposed to black, are those covers over the exhaust ports?
I wonder if they are to prevent water intrusion and were added when SpaceX went from land landing to ocean?
Notice two things from the HR version of that photo: (1) The exhaust ports are covered by something that is marked as "remove before launch", and (2) The color of the ramps is not grey, but silver.  That makes sense in the same sense as they silvered much of the tail portion of SpaceShip Two.  Reflecting heat away is more effective than absorbing it, at least for certain cases.

The silver material is NOT for heat reflection.

It is the same silver-colored material that is used to cover the primary heat shield on Cargo Dragon, as well as the primary heat shield on Crew Dragon. It is for moisture protection. Given that the exhaust ports for Super Draco are covered in the same material as the primary heat shield (PICA-X) you can expect the same application of silvery material for moisture protection.

PICA(-X) is known to absorb moisture (water) from the atmosphere. When absorbed into the PICA material the water negatively influences the performance of PICA as a heat shield material. It is therefore necessary to prevent PICA from absorbing moisture. That is why the PICA is covered in the silvery material as seen in the recent pictures.

More on this subject: https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1083&context=me_etds

In the vacuum of space wouldn't the water evaporate or boil off, even sublime? Although prevention always seems the first choice.
It probably wouldn't have time to evaporate in the event of a late abort requiring a near-orbital velocity entry.

Offline cppetrie

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1367 on: 07/13/2018 11:37 PM »
I imagine little exploding steam pockets or increased thermal conductivity in your heatshield wouldn't be the most desirable thing in the world.

Yeah, that's basically it. PICA is a great heat shield material as long as you make sure it is prevented from behaving like a moisture sponge.

Which is why SpaceX probably isn't thrilled about splashing down. Not sure if any of the flight-proven Dragon 1 missions have used flight-proven heatshields.
They have not.

Offline deadman719

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1368 on: 07/14/2018 02:56 AM »
Quote
spacex Crew Dragon arrived in Florida this week ahead of its first flight after completing thermal vacuum and acoustic testing at @NASA’s Plum Brook Station in Ohio

https://www.instagram.com/p/BlJVBidF4I2/

Edit to add: higher-res photo

Anyone have insight as to why the window on the right side has a plate instead of a glass? 

Respectfully,
Rob
Covers for transport? There appear to be covers over every opening to seal out debris. Seems likely they’d cover the glass to prevent debris from damaging the glass in transit.

I thought that at first. If it was for protection during shipment, why would the left window have plastic taped over the window while the right one appears to have a bolted-in-place panel?

The window at the right is not actually a window. It is a cover-plate to fill in the void between the outer-shell panels where there could be a window (per design) but where there is not actually a window on this particular vehicle. The pressure shell underneath doesn't have the window frame welded into it at that location.

The DM-1 vehicle carries only two windows, one each left and right of the crew hatch. There is no need to carry more given that the vehicle is un-crewed and the two windows present are enough to satisfy window qualification requirements on this mission.

Thanks Woods! Window qualification never entered my thoughts.

Regarding the window frame: would the lack of a frame and window at two of the window locations result in different load/stress distribution through the pressure shell? I'll admit, this is way outside my swim lane!

Offline russianhalo117

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1369 on: 07/15/2018 04:29 PM »
Quote
spacex Crew Dragon arrived in Florida this week ahead of its first flight after completing thermal vacuum and acoustic testing at @NASA’s Plum Brook Station in Ohio

https://www.instagram.com/p/BlJVBidF4I2/
So, where are we in the flow to DM-1?
Arrival to CCAFS Area 59, to either DPF (DSCS Processing Facility) or NPF (Navistar Processing Facility), which SpaceX is actively leasing for Dragon-2 crew and cargo processing.

Offline woods170

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1370 on: 07/15/2018 06:31 PM »
I imagine little exploding steam pockets or increased thermal conductivity in your heatshield wouldn't be the most desirable thing in the world.

Yeah, that's basically it. PICA is a great heat shield material as long as you make sure it is prevented from behaving like a moisture sponge.

Which is why SpaceX probably isn't thrilled about splashing down. Not sure if any of the flight-proven Dragon 1 missions have used flight-proven heatshields.
They have not.
Correct. Every single re-used cargo Dragon had a brand new primary heat shield installed.

Offline tyrred

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1371 on: 07/17/2018 10:46 AM »
From twitter there have been 16 D2 parachute tests till June 26 2018.
https://twitter.com/spacex/status/1011703684454014976?lang=en

How many test articles can we confirmed for these tests?

Offline woods170

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1372 on: 07/17/2018 11:22 AM »
From twitter there have been 16 D2 parachute tests till June 26 2018.
https://twitter.com/spacex/status/1011703684454014976?lang=en

How many test articles can we confirmed for these tests?

At least three:

- the re-purposed cargo Dragon drop test vehicle
- the "brick"
- the re-purposed pad-abort Crew Dragon test vehicle

Offline yg1968

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1373 on: 07/17/2018 07:56 PM »
Mike Pence will visit Cape Canaveral next month for a big space update

Quote
Pence, who chairs the National Space Council, will confirm a new launch date for the first private crew missions and announce which crew capsules each of the four selected astronauts will ride in to the International Space Station.

We will get an update by VP Pence on commercial crew on August 3rd. See the link above.

Online Comga

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1374 on: Today at 05:17 AM »
Mike Pence will visit Cape Canaveral next month for a big space update

Quote
Pence, who chairs the National Space Council, will confirm a new launch date for the first private crew missions and announce which crew capsules each of the four selected astronauts will ride in to the International Space Station.

We will get an update by VP Pence on commercial crew on August 3rd. See the link above.

Pence?
"big space update" next month?
Is this "Celebrity Apprentice Astronaut"?
Spiro Agnew didn't announce that Armstrong would command Apollo 11.....
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Nomadd

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1375 on: Today at 05:42 AM »

Spiro Agnew didn't announce that Armstrong would command Apollo 11.....
Why would the governor of Maryland announce the Apollo 11 crew?

Offline Coastal Ron

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1376 on: Today at 06:21 AM »
Mike Pence will visit Cape Canaveral next month for a big space update

Quote
Pence, who chairs the National Space Council, will confirm a new launch date for the first private crew missions and announce which crew capsules each of the four selected astronauts will ride in to the International Space Station.

We will get an update by VP Pence on commercial crew on August 3rd. See the link above.

The article also says:
Quote
Pence, who chairs the National Space Council, will confirm a new launch date for the first private crew missions and announce which crew capsules each of the four selected astronauts will ride in to the International Space Station.

From what I've been reading with the GAO report, and hearing as scuttlebutt, it may be premature to announce launch dates for either Commercial Crew provider.

It really sounds like they are trying to package up a bunch of things since Pence (and maybe Trump) plan to attend the launch of the Parker Solar Probe. Standard PR.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1377 on: Today at 09:37 AM »
Well, since the DM-1 Dragon is in pre-launch flow at the Cape, I think it's about time for a firm date for SpaceX's uncrewed mission at least.
Failure is not only an option, it's the only way to learn.
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Offline theonlyspace

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1378 on: Today at 10:36 AM »
With the forth parachute added why couldn't crew dragon make a land landing in the southwest desert as Starliner is doing?

Online docmordrid

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Re: SpaceX Dragon 2 Updates and Discussion - Thread 2
« Reply #1379 on: Today at 12:25 PM »
It did in a recent parachute test, and the touchdown looked quite mild. Not likely they want to do that operationally though.

DM

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