Author Topic: Orion Discussion Thread 2  (Read 307059 times)

Offline sdsds

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Re: Orion Discussion Thread 2
« Reply #140 on: 10/22/2015 05:59 am »
NASA should have known about the cost differences well before they built the AVCOAT version.  The contractor would have bid manual labor for filling the holes, which if you have watched the video was very laborious (and not very consistent).  If cost was an issue they would have gone with the tiles to start.

By the "start" do you mean in 2006 when LM was awarded the Orion work? The timeline back then put a bit of pressure on them. Orion development was to be complete by the end of 2011, with crewed flight in 2014 (on Ares I, of course).

So the decision in 2006 to focus on the AVCOAT version may have been silly given a first test flight in 2014, but that wasn't the plan to start....
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Offline woods170

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Re: Orion Discussion Thread 2
« Reply #141 on: 10/22/2015 09:06 am »
http://www.nasa.gov/feature/nasa-applies-insights-for-manufacturing-of-orion-spacecraft-heat-shield

Heatshield made out of multiple pieces. We knew that but it's fun to look at it for the first time.

Yep... I attached an image from the link.

Heatshield tiles? Who would have thought? And so one of the main arguments for Avcoat (vs PICA) is chucked out the window.

Lets not forget that the decision to use AVCOAT over PICA was made long before something the size of Dragon used it as a heat shield.
The fact is AVCOAT will work just as well and it is good that NASA is making improvements to lower the cost and manpower needed to make the heat shield.
Emphasis mine: Your statement is partially incorrect.
The CEV was originally scheduled to fly with a PICA heatshield. NASA didn't switch to AVCOAT until April of 2009. The switch was primarily over mass considerations.

See here:
https://www.flightglobal.com/news/articles/nasa39s-orion-heat-shield-decision-expected-this-323585/http://www.nasa.gov/mission_pages/constellation/orion/orion-tps.html
http://www.collectspace.com/ubb/Forum39/HTML/000078.html
http://archive.floridatoday.com/content/blogs/space/2009/04/nasa-selects-apollo-era-heat-shield.shtml

SpaceX had chosen PICA for Dragon two months earlier (february 2009). See here:
http://www.businesswire.com/news/home/20090223005140/en/SpaceX-Manufactured-Heat-Shield-Material-Passes-High

Offline sdsds

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Re: Orion Discussion Thread 2
« Reply #142 on: 10/22/2015 09:18 am »
The CEV was originally scheduled to fly with a PICA heatshield.

Where do you get that? From one of the sources you yourself provide, the 2009 Florida Today article:
Quote
For more than three years, NASA's Orion Thermal
Protection System Advanced Development Project considered eight
different candidate materials, including the two final candidates,
Avcoat and Phenolic Impregnated Carbon Ablator, or PICA, both of
which have proven successful in previous space missions.
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Offline woods170

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Re: Orion Discussion Thread 2
« Reply #143 on: 10/22/2015 12:48 pm »
The CEV was originally scheduled to fly with a PICA heatshield.

Where do you get that? From one of the sources you yourself provide, the 2009 Florida Today article:
Quote
For more than three years, NASA's Orion Thermal
Protection System Advanced Development Project considered eight
different candidate materials, including the two final candidates,
Avcoat and Phenolic Impregnated Carbon Ablator, or PICA, both of
which have proven successful in previous space missions.

Look at the first link (FlightGlobal), it gives a good summary of the developments of the CEV/Orion TPS between 2006 and 2009.
The CEV proposal by LockMart featured segmented PICA. When LockMart was chosen as prime contractor the baseline for the TPS was set as PICA. Boeing received a contract to do the PICA-based TPS for the CEV, as a sub to LockMart. This all played out between 2006 and late 2008. Boeing even delivered to NASA a prototype of the segmented PICA in late 2007.
Orion was, through-out most of CxP set to get to CDR with a PICA heatshield. However, the continued mass-trouble associated with the Ares-1/Orion combination led to AVCOAT eventually being selected as a replacement because of mass-savings. That happened in april 2009, when CxP was already very much in dire-straits and CEV/Orion already had a good three years of development under it's belt.
When NASA chose the LockMart proposal voor the CEV, they inherently chose PICA as the TPS baseline. The switch to AVCOAT took place three years later.
« Last Edit: 10/23/2015 09:06 am by woods170 »

Offline sdsds

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Re: Orion Discussion Thread 2
« Reply #144 on: 10/22/2015 06:08 pm »
The switch to AVCOAT took place three years later.

Ah, thanks! That makes sense from Lockheed Martin's perspective. From NASA's perspective, though, wouldn't the decision have been "made" at the PDR milestone rather than at the contract award?

Here's a quote (with emphasis added) from a different flightglobal article:
Quote
Lockheed wants to use the Phenolic Impregnated Carbon Ablator developed by NASA Ames and used for Lockheed's cometary-dust capturing Stardust capsule, which returned to Earth in January. McKenzie says: "We have baselined for the TPS the Stardust capsule material."

Ames researchers expect that whichever potential TPS option is selected at the Orion PDR, it will be ablative.
https://www.flightglobal.com/news/articles/orion-rises-208901/

The article also mentions some bit about how the heat shield would have to be ejected so the landing airbags could be deployed. My how times have changed!
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Offline Lars-J

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Re: Orion Discussion Thread 2
« Reply #145 on: 10/22/2015 11:32 pm »
For those who are curious, here is a picture of the Boeing heat shield prototype, built with PICA: (image from 2007)

source: http://www.collectspace.com/ubb/Forum39/HTML/000078.html

Offline woods170

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Re: Orion Discussion Thread 2
« Reply #146 on: 10/23/2015 09:35 am »
The switch to AVCOAT took place three years later.
Ah, thanks! That makes sense from Lockheed Martin's perspective. From NASA's perspective, though, wouldn't the decision have been "made" at the PDR milestone rather than at the contract award?
NASA chose the LockMart proposal for the CEV. Proposals are rather complete at such stages including initial material choices for all major parts of a design.
However, that does not mean that the material originally proposed ends up being the material actually used.
When going into development many of the initial choices will be researched thru risk-reduction studies.
This also applied to the CEV heatshield. The risk-reduction studies were done by NASA Ames. They studied a range of TPS candidate materials. But from day 1, the LockMart-chosen PICA and NASA-heritage Avcoat were placed in the roles of leading candidate and back-up. Why was Avcoat in the back-up role? Answer: flight experience on Apollo.
What happened in late 2008 and early 2009 is that the two materials switched places. Avcoat became leading with PICA being the back-up. This was the result of not just the risk-reduction studies but also other contributing factors such as the earlier mentioned mass considerations.

On a different note:
Although the above-linked NASA presentation suggests that SpaceX chose PICA for Dragon based on the work done by NASA, that is not entirely correct. The basic choice for PICA had already been made by SpaceX at that time. The results from the NASA study only served to re-confirm the the soundness of the initial choice of PICA for Dragon.
« Last Edit: 10/23/2015 11:57 am by woods170 »

Offline b0objunior

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Re: Orion Discussion Thread 2
« Reply #147 on: 10/29/2015 03:14 am »
Great video about the Orion heatshield by an engineer at NASA. He explains in detail the road to EFT-1 and what's ahead for the EM missions.

Offline vulture4

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Re: Orion Discussion Thread 2
« Reply #148 on: 11/15/2015 07:25 pm »
What about the airbags? Weren't they deleted to fit the payload capacity of the Ares I? Why couldn't they be replaced when the SLS became the LV?

Offline woods170

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Re: Orion Discussion Thread 2
« Reply #149 on: 11/16/2015 09:14 am »
What about the airbags? Weren't they deleted to fit the payload capacity of the Ares I? Why couldn't they be replaced when the SLS became the LV?
The airbags were deleted in an early DAC of Orion. The DAC's had been all but completed by the time Orion was repurposed to fly on SLS.
It is not exactly easy to fit things back into a design that has evolved considerably from the original design.
« Last Edit: 11/16/2015 09:15 am by woods170 »

Offline vulture4

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Re: Orion Discussion Thread 2
« Reply #150 on: 11/16/2015 04:33 pm »
What about the airbags? Weren't they deleted to fit the payload capacity of the Ares I? Why couldn't they be replaced when the SLS became the LV?
The airbags were deleted in an early DAC of Orion. The DAC's had been all but completed by the time Orion was repurposed to fly on SLS.
It is not exactly easy to fit things back into a design that has evolved considerably from the original design.
Land recovery was originally chosen because it reduced cost and risk. I would have thought the decision to abandon it would be reconsidered when the reason for the decision went away. Maybe I am just naive.

Offline Dante80

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Re: Orion Discussion Thread 2
« Reply #151 on: 11/16/2015 09:18 pm »
Land recovery was originally chosen because it reduced cost and risk. I would have thought the decision to abandon it would be reconsidered when the reason for the decision went away. Maybe I am just naive.

You are not. Its simply a fact of Orion moving too much along to change it now, while at the same time never having the funding to change the design a lot in the first place.

If ESA was not making the trunk, Orion would be in big funding trouble by now.

Offline b0objunior

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Re: Orion Discussion Thread 2
« Reply #152 on: 11/19/2015 10:57 pm »
NASA has made another change to the EM-1 spacecraft, but it was predictable. They will ''paint'' it in a metallic finish for temperature control. I like the way it looks, reminiscent of Apollo.

http://www.nasa.gov/feature/engineers-refine-thermal-protection-system-for-orion-s-next-mission
« Last Edit: 11/20/2015 05:17 am by b0objunior »

Offline jacqmans

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Re: Orion Discussion Thread 2
« Reply #153 on: 11/24/2015 05:57 pm »
some new pictures made public by ESA
Jacques :-)

Offline jacqmans

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Re: Orion Discussion Thread 2
« Reply #154 on: 11/24/2015 05:58 pm »
Jacques :-)

Offline okan170

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Re: Orion Discussion Thread 2
« Reply #155 on: 11/24/2015 06:35 pm »
These are also available on NASA's Orion Flickr page!

Offline woods170

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Re: Orion Discussion Thread 2
« Reply #156 on: 11/25/2015 11:52 am »
These are also available on NASA's Orion Flickr page!
Correct. And their source is NASA, not ESA. The latter just re-issued them thru it's own channels.
« Last Edit: 11/25/2015 11:52 am by woods170 »

Offline Mark S

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Re: Orion Discussion Thread 2
« Reply #157 on: 11/26/2015 01:27 pm »
The NASA article states that a metallic coating will be bonded to the backshell tiles:

"For these future Orion missions, a silver, metallic-based thermal control coating will also be bonded to the crew module’s thermal protection system back shell tiles."

When they say "a coating", it makes me think that each tile will be individually silvered during the manufacturing process. But the renderings make it look like a silver film is applied in large sheets to the backshell. And actually the graphics make it look like more substantial metallic sheets are riveted to the backshell, not just a film or coating.

So does anyone know if this reflective coating will be "painted" on the tiles individually, applied as a film to the backshell, or installed as heavier panels secured mechanically to the backshell?

Thanks.

Offline woods170

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Re: Orion Discussion Thread 2
« Reply #158 on: 11/26/2015 01:43 pm »
The NASA article states that a metallic coating will be bonded to the backshell tiles:

"For these future Orion missions, a silver, metallic-based thermal control coating will also be bonded to the crew module’s thermal protection system back shell tiles."

When they say "a coating", it makes me think that each tile will be individually silvered during the manufacturing process. But the renderings make it look like a silver film is applied in large sheets to the backshell. And actually the graphics make it look like more substantial metallic sheets are riveted to the backshell, not just a film or coating.

So does anyone know if this reflective coating will be "painted" on the tiles individually, applied as a film to the backshell, or installed as heavier panels secured mechanically to the backshell?

Thanks.

There is no mass budget for installing panels over the backshell TPS. Besides such panels would invalidate the primary function of the backshell TPS.
The primary function of this coating is for thermal protection while in space, more specific to prevent over-heating when the backshell TPS is exposed to the sun for prolonged periods.
Given that the backshell tiles are black I can see where this is coming from.
This coating therefore must be lightweight, be able to provide thermal regulation and not interfere with the primary TPS role (and backup MMOD protection role) of the backshell TPS tiles.

Well, guess what: that's exactly what led to the Apollo CSM backshell being taped with strips of metallic-coated Kapton.
So, my guess is that a (Kapton?) film will be applied over the backshell TPS, much like was done on the Apollo CSM. It will burn-off easily upon re-entry with the remains being easily removable in support of post-flight assessment of the condition of the TPS.

Offline Raj2014

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Re: Orion Discussion Thread 2
« Reply #159 on: 11/28/2015 10:36 am »
Good images of the CM with the new coating added. There was a video released by ESA showing an antenna extending from the ESM and Jim said it will be part of the Orion spacecraft. Yet there are images not showing the antenna. Could someone confirm this, please? It is confusing on which images and videos are accurate.   

 

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