SpaceX’s Crew Dragon spacecraft static fire anomaly - THREAD 3

[OxCartMark]

My understanding is that valve seats tend to need the really precise tolerances that machining provides.

Leakage between the valve and its seat is one definite possibility but also as we're talking about 3D printing that would seem to bring up the possibility of porosity in the bulk material.

Grinding isn't the only way for the seat.  Assuming they'd be using a commercially made hardened ball then the seat could be "ballized", the ball could be pressed into it to create a flat hard spherical low void contact surface.  I've done this even on plastic seat automotive valves, millions.  Would this be aerospace practice when there's the possibility to spend more?  Dunno.

[Hog]

Valve lapping for engine cylinder head valves is pretty standard stuff.

Valve Lapping



Ballizing Process



Titanium powders for building titanium components using additive manufacturing. Back in the late 50's when Lockheed was designing/manufacturing the CIA's A-12 photorecon plane(Project Oxcart), which in its final derivation, after the 3 YF-12A Mach 3+ interceptor firing 3 AIM-47 air-air missiles, the 2 M-21 variants that would launch the supersonic D-21 drone(M-21=Mothership D-21=Daughtership) would be the SR-71(32 airframes built) which was a slightly longer, heavier recon plane that not only took pictures, but collected infra-red images, SLAR (Side Looking RADAR), electronic intelligence and various electronic defense systems.  The A-12's first flight was in April 12, 1962, the SR-71's first flight was Dec 22 1964.

Prior to the CIA A-12, titanium was primarily used only for high temp parts of jet engines, work with large casting/forgings was unheard of at the time. Titanium was considered a strategic material so it was stockpiled. When ALL the parts/materials/chemicals that went into supporting SR-71 mission ops was disposed of from the massive US Marine Corps warehouse, all of the precious billets, rods, sheets, corrugations of titanium also went to scrap, at scrap prices.  Some of the "cylinders" of TEB had begun top leak. Initially the guys who were disposing of the TEB (Triethylborane-used to start the J58 engines and also a shot was used anytime the throttles were raised up over the Military Power throttle detent into the afterburner range of throttle movement- as the SR-71 took its last bit of fuel onboard during inflight refueling, both J58's at Military Power couldn't keep up with the tanker, the pilot would then select minimum afterburner in one engine)  were simply opening the valves and letting it burn off until security reports put a stop to that.  It was a sad sight.



As it turns out the USSR at the time had large access to titanium, so the USA used shell companies to purchase  rutile ore, and have the ore shipped into the USA.  The ore would then be worked to produce the various titanium alloys Early batches proved of low quality. New tooling, handling, cutinmg, shaping methods had to be devised.  A commonly used felt marker, when used on this certain titanium alloy, would weaken the metal causing failure.  Alternate markers were used and a ban on the offending markers was instituted within Skunkworks.

Going from a metal that needed to be "snuck" into the country that if the wrong "Sharpie"(a North American brand name of felt tipped permanent marker) was used would render the metal unuseable, to using the same metal today in powder form, to "print" titanium parts on the surface of a desk using additive manufacturing.  My how technology has evolved.

attachments
a)A-12 flying
b)A-12s in storage

[OTV Booster]

...designing/manufacturing the CIA's A-12 photorecon plane(Project Oxcart)...

Definitely OT and maybe a personal intrusion, but I have to wonder if this is the genesis of OxCartMark.

Phil

[Rondaz]

Nield: fault tree nearly complete in investigation of Crew Dragon Static fire accident; also “tremendous amount” of work being done on COPVs and planning for load-and-go for crewed Dragon launches.

https://twitter.com/jeff_foust/status/1170019684990771201

[eeergo]

Interesting note in CNN's article from Bridestine:

[...] the updated emergency abort system "has not been qualified" and has not been tested. Musk said over the weekend that a spacecraft with the new abort system would arrive in Florida in October so it can undergo final testing.

http://edition.cnn.com/2019/09/30/tech/elon-musk-spacex-crew-dragon-nasa-timeline/index.html

So we can expect a similar (hopefully by setup, not by result) static fire, within the next month-ish.

[speedevil]

Interesting note in CNN's article from Bridestine:

[...] the updated emergency abort system "has not been qualified" and has not been tested. Musk said over the weekend that a spacecraft with the new abort system would arrive in Florida in October so it can undergo final testing.

http://edition.cnn.com/2019/09/30/tech/elon-musk-spacex-crew-dragon-nasa-timeline/index.html

So we can expect a similar (hopefully by setup, not by result) static fire, within the next month-ish.

Is this the in flight abort test - or are they in addition doing another ground test?

[eeergo]

Interesting note in CNN's article from Bridestine:

[...] the updated emergency abort system "has not been qualified" and has not been tested. Musk said over the weekend that a spacecraft with the new abort system would arrive in Florida in October so it can undergo final testing.

http://edition.cnn.com/2019/09/30/tech/elon-musk-spacex-crew-dragon-nasa-timeline/index.html

So we can expect a similar (hopefully by setup, not by result) static fire, within the next month-ish.

Is this the in flight abort test - or are they in addition doing another ground test?

Static fire = ground test. They need to qualify the redesigned abort system, presumably fixing the cause(s) of the recent anomaly, by doing at least an integrated test of it, equivalent to the one that concluded with an explosion. Apparently that will be done in KSC. IFA goes after that, in principle with the same capsule (ex-DM-3, IIRC).

[woods170]

(ex-DM-3, IIRC).

ex-DM-2 in fact.

[Ken the Bin]

(ex-DM-3, IIRC).

ex-DM-2 in fact.

That is correct.  DM-2 will be ex-DM-3.

[Bananas_on_Mars]

1 hour long interview with Benji Reed about Crew Dragon, by NASA Podcast "Houston we have a Podcast"

Released on september 27th, but the interview took place on August 20th.

[cferreir]

Interesting note in CNN's article from Bridestine:

[...] the updated emergency abort system "has not been qualified" and has not been tested. Musk said over the weekend that a spacecraft with the new abort system would arrive in Florida in October so it can undergo final testing.

http://edition.cnn.com/2019/09/30/tech/elon-musk-spacex-crew-dragon-nasa-timeline/index.html

So we can expect a similar (hopefully by setup, not by result) static fire, within the next month-ish.

Is this the in flight abort test - or are they in addition doing another ground test?

Static fire = ground test. They need to qualify the redesigned abort system, presumably fixing the cause(s) of the recent anomaly, by doing at least an integrated test of it, equivalent to the one that concluded with an explosion. Apparently that will be done in KSC. IFA goes after that, in principle with the same capsule (ex-DM-3, IIRC).

Aren't they using burst disk valves now for the LAS/Super Dracos? If so, any knowledge/speculation about how much work it takes to refurbish the system? Especially since the original design was not for expendable valves...etc..? Asking for a friend....

[kevinof]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

Interesting note in CNN's article from Bridestine:

[...] the updated emergency abort system "has not been qualified" and has not been tested. Musk said over the weekend that a spacecraft with the new abort system would arrive in Florida in October so it can undergo final testing.

http://edition.cnn.com/2019/09/30/tech/elon-musk-spacex-crew-dragon-nasa-timeline/index.html

So we can expect a similar (hopefully by setup, not by result) static fire, within the next month-ish.

Is this the in flight abort test - or are they in addition doing another ground test?

Static fire = ground test. They need to qualify the redesigned abort system, presumably fixing the cause(s) of the recent anomaly, by doing at least an integrated test of it, equivalent to the one that concluded with an explosion. Apparently that will be done in KSC. IFA goes after that, in principle with the same capsule (ex-DM-3, IIRC).

Aren't they using burst disk valves now for the LAS/Super Dracos? If so, any knowledge/speculation about how much work it takes to refurbish the system? Especially since the original design was not for expendable valves...etc..? Asking for a friend....

[woods170]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

That information is already outdated. Cargo D2 do not have Super Dracos at all. Outer mold line reflects this as well. The idea to convert flown CCP Crew Dragons to cargo D2 is under review. SpaceX has come to the conclusion that it is likely more expensive to convert a flown Crew Dragon to cargo D2 than do an all-new build of cargo D2.

[eeergo]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

That information is already outdated. Cargo D2 do not have Super Dracos at all. Outer mold line reflects this as well. The idea to convert flown CCP Crew Dragons to cargo D2 is under review. SpaceX has come to the conclusion that it is likely more expensive to convert a flown Crew Dragon to cargo D2 than do an all-new build of cargo D2.

Does that mean crewed D2 capsules are about to be declared non-reusable?

[rockets4life97]

Elon's "Tight is right, and long is wrong" design philosophy seems to have come directly from the experience with Dragon 2. I expect SpaceX is moving on from Dragon 2 as fast as possible given their contract commitments. If Dragon 2 was an internal project, I expect it would have already been cancelled or only flown a handful of times like FH looks destined to do.

[envy887]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

That information is already outdated. Cargo D2 do not have Super Dracos at all. Outer mold line reflects this as well. The idea to convert flown CCP Crew Dragons to cargo D2 is under review. SpaceX has come to the conclusion that it is likely more expensive to convert a flown Crew Dragon to cargo D2 than do an all-new build of cargo D2.

Does that mean crewed D2 capsules are about to be declared non-reusable?

That probably depends on how much work it will be to convince NASA that they can be reused for crew flights.

Also on whether private parties sign up for flights... but with the Bigelow deal now called off there doesn't seem to be much interest at the Dragon price point.

[woods170]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

That information is already outdated. Cargo D2 do not have Super Dracos at all. Outer mold line reflects this as well. The idea to convert flown CCP Crew Dragons to cargo D2 is under review. SpaceX has come to the conclusion that it is likely more expensive to convert a flown Crew Dragon to cargo D2 than do an all-new build of cargo D2.

Does that mean crewed D2 capsules are about to be declared non-reusable?

They are non-reusable within the scope of CCtCAP. For the six missions now contracted with NASA the baseline is a new spacecraft for each of those six crew rotation missions.

Reuse of Crew Dragon on non-NASA missions is likely. BUT there are currently NO non-NASA missions for Crew Dragon on contract. And it is not likely any will surface. SpaceX wishes to move on to SS+SH.

However, cargo D2 is another matter. Expect reuse of those capsules fairly early into the CRS-2 program.

[woods170]

Elon's "Tight is right, and long is wrong" design philosophy seems to have come directly from the experience with Dragon 2. I expect SpaceX is moving on from Dragon 2 as fast as possible given their contract commitments. If Dragon 2 was an internal project, I expect it would have already been cancelled or only flown a handful of times like FH looks destined to do.

Crew Dragon is quite a different experience for SpaceX than cargo Dragon (COTS and CRS-1) has been. CCP sees much more bureaucracy and much less "action" (for lack of a better word) than CRS-1. Courtesy of NASA not repeating the experience of COTS/CRS-1. COTS was deemed TOO successful by forces that control NASA's budget. It is one of the reasons why CCP was short-funded in its initial years. It was also the reason that US Congress wrote into law that the final phase of CCP -CCtCAP - was to use FAR contracting in stead of much more agile SAA contracting.

[Hog]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

That information is already outdated. Cargo D2 do not have Super Dracos at all. Outer mold line reflects this as well. The idea to convert flown CCP Crew Dragons to cargo D2 is under review. SpaceX has come to the conclusion that it is likely more expensive to convert a flown Crew Dragon to cargo D2 than do an all-new build of cargo D2.

Does that mean crewed D2 capsules are about to be declared non-reusable?

They are non-reusable within the scope of CCtCAP. For the six missions now contracted with NASA the baseline is a new spacecraft for each of those six crew rotation missions.

Reuse of Crew Dragon on non-NASA missions is likely. BUT there are currently NO non-NASA missions for Crew Dragon on contract. And it is not likely any will surface. SpaceX wishes to move on to SS+SH.

However, cargo D2 is another matter. Expect reuse of those capsules fairly early into the CRS-2 program.

I thought he was asking about Dragon-2 human capsules being re-used as Cargo non human capsules?

[Mike_1179]

They are not re-using the D2 for crew flights - Single crew flight only and then converted into cargo. A cargo D2 doesn't need refurbishment of the super dracos as it won't use them.

But if they need to perform a static fire of the integrated abort system as part of every capsule qualification flow, then you would have to go in and replace the burst disks at least once.

Will they need to verify performance of the integrated abort system each time?