"It's a misprint."
Posted on 07/16/2019 6:00:11 AM PDT by BenLurkin
... Crew Dragon’s explosion was unrelated to the spacecraft’s propellant tanks, Draco maneuvering thrusters, or SuperDraco abort engines. Rather, the cause lies in a more exotic and unanticipated chemical/material interaction between a plumbing valve, liquid oxidizer, and a helium-based pressurization system.
According to Hans Koenigsmann, SpaceX is approximately 80% of the way through what is known as the fault tree, ….SpaceX executive was fairly confident that the results presented on July 15th would be representative of the final conclusion.
The ultimate (likely) cause of Crew Dragon’s extremely energetic and destructive explosion centers around the spacecraft’s extensive SuperDraco/Draco plumbing and its associated pressurization system, which uses helium to keep the pressure-fed engines, propellant tanks, and feed lines around 2400 psi (16.5 megapascals).
... this method of pressurization means that there is direct contact between the pressurant (helium) and the oxidizer/fuel, thus requiring some sort of valve preventing the pressurized fluid from flowing into the pressurization system.
SpaceX’s understanding is that the high-speed slug of dense NTO was traveling so fast and at such a high pressure that, by impacting the titanium check valve, it quite literally broke the valve and may have chemically ignited the metal, thus introducing a slug of burning NTO into the liberated NTO system itself – effectively a match tossed into a powder keg.
... the solution – as SpaceX perceives it – is the same: instead of a mechanical check valve (simple but still not 100% passive), the barrier between pressurant and oxidizer (as well as fuel, most likely) will be replaced with something known as a burst disk. According to Koenigsmann, only a handful (~4) of those valves exist and thus need to be replaced by burst disks, a relatively fast and easy fix.
(Excerpt) Read more at teslarati.com ...
All the best fires are exotic.
Over the course of ground testing, a “check valve” separating the pressurization system and oxidizer leaked what SpaceX described as a “slug” of nitrogen tetroxide oxidizer (NTO) into the helium pressurization lines."
Looks like a simple ANTI-BACKFLOW VALVE would work................
A spark between dissimilar metals caused the Hindenburg fire.
Well, that’s a relief.
What’s the difference between a check valve and an anti-backflow valve?
*ping*
"It's a misprint."
As with anything new, you have to learn about the things that you didn’t know, and especially the things that you didn’t know that you didn’t know.
Spelling nomenclature. Same thing...............
You get what you pay for, and sometimes not even then. I don’t mind NASA contracting out to SpaceX, but if anyone believes that they are going to provide safe, reliable human space transportation at a fraction of the cost of previous NASA manned programs, well, reality check. Space is hard. Human space even harder. No free rides.
“Way over my head...”
Reads like it was intended to be. Wonder how much of this is horseclinton.
“The ultimate (likely) cause of Crew Dragon’s extremely energetic and destructive explosion centers around the spacecraft’s extensive SuperDraco/Draco plumbing and its associated pressurization system, which uses helium to keep the pressure-fed engines, propellant tanks, and feed lines around 2400 psi (16.5 megapascals).”
Look how they figured we need to know how many megapascals 2400 psi is. Overboard on the jargon.
Fill ‘er up, and put Point 22 megapascals in the tires.
It looks simple to Me.
Except that contains parts. The more parts the bigger chance of trouble.
At minimum a Check valve would have: A Case or Body, a Spring and a Ball.
A Rupture Disk has 1 moving part.
See My Post above for a Link with details and Pics.
LOL!!!
Whoever would you find to say that to today??
Methinks you're showing your age...
As with anything new, you have to learn about the things that you didn’t know, and especially the things that you didn’t know that you didn’t know.
...
According to some people on the SpaceX forums the potential explosiveness of NTO and titanium has been known since the 1960’s.
A spark between dissimilar metals caused the Hindenburg fire.
...
I’d like to see hydrogen airships make a comeback. Please invent the technology to make them safe.
There is a ‘tilted disk’ type of check valve, maybe that is what they are going to use.................
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