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Accident at Cape
On 9/1/2016 11:06 AM, JF Mezei wrote:
As you have probably heard, a Falcon 9 had an "anomaly" with large sound and lots of smoke. SpaceX confirmed loss of rocket and payload that was about to do a firing test. SpaceX seems perplexed, so apparently there will be no quick answers to this accident. If the cause involved something as simple as the false operation of a destructive charge, surely we would know by now. The Falcon 9 fuel and oxidizer (and the handling thereof) are certainly nothing new to the space industry. Yes, oxygen can be dangerous stuff, but folks have been loading LOX into rockets for decades now, and I can recall no similar launch pad accidents. Can anyone else cite a similar incident? This may seem farfetched but... Can we confidently exclude some sort of foul play? |
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Accident at Cape
JF Mezei wrote:
Also, consider some defect INSIDE the rocket away from avionics panel. But when explosion occured, avionics panel was first to blow, hence from camera's point of view, explosion appears to originate there. (imagine an electrical fire brewing some distance from panel and eventually get hot enough to cause the thing to go "boom". The problem with your thesis is that the explosion was right around the fueling station, not up by the avionics tray. At the end of the day, without any indication of what telemetry showed, the images are worthless. We just know it happened somewhere near top of second stage. I suspect that telemetry all looks normal. If it didn't, they'd be narrowing in on the cause. So what you really need is a fault tree that shows all the stuff that might cause something like this that would NOT affect telemetry. Does the payload use hydrazine ? If it had leaked slowly, would it not eventually drop to the top of stage 2? Would hydrazine self ignite once in contact with pure O2 ? If it was something like that from the payload I would have expected the payload to explode once the LOX tank in the second stage ruptured. That doesn't appear to have happened (the payload explosion doesn't happen until the payload bay hits the ground). -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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Accident at Cape
JF Mezei wrote:
On 2016-09-10 18:08, Fred J. McCall wrote: If it was something like that from the payload I would have expected the payload to explode once the LOX tank in the second stage ruptured. That doesn't appear to have happened (the payload explosion doesn't happen until the payload bay hits the ground). Fair enough. So if explosion was first seen near LOX storage and filling transfer pipe, what fuel would have burned ? Well, that is sort of the $64 question. Say O2 leaked inside the rocket once tank got full (pipe fitting gets cold enough that fitting gets loose, starts to spray liquid O2 on something. If that something contains plastic, or wiring insulation, rubber, woudln't it self ignite ? That fire could then cause some electrical malfunction and go kaboom. It takes relatively high temperatures to get 'auto-ignition'. But that would likely send some telemetry alarm before going kaboom, right ? If wiring was involved I would expect some sort of telemetry noise, at the very least. Large leaks should show some pressure fluctuations and spontaneous ignition requires fairly large volumes of atomized propellants. I guess SpaceX needs to precisely corelate the timing of any video with timing of any telemetry they got. Did event happen 2ms before visible explosion, or 1ms after ? (aka: precurson to visible explosion, or a side effect of explosion). If there are no telemetry anomalies, this won't help. I still think they're going to have to lock a bunch of smart guys in a room and come up with a fault tree of all the possible things that would explain what happened that wouldn't show telemetry signs. Then they're going to have to go through video to try to thin that tree. This is going to take a while, but they've got a few months before they can return to flight anyway... -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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JF Mezei wrote:
Are there any drawings that show the structures and systems located at the top of Stage2, as well as those that would be found on a payload that is mated to the top of stage2 ? I'm sure there must be some. Whether you can find them or not is a different matter. For payload see the Falcon 9 User's Guide. From a stress point of view, would this test exercise be the first time the stage2 is fully fueled in vertical position? Probably, since there's no reason to do so otherwise. Could it be as simple as a defect in the LOX rank which ruptured due to extreme cold and/or pressure? (I take it there are scenarios which would kill sensors or telemetry transmitters before they can report loss of pressure in LOX tank? You've got a chicken and egg problem here. Killing a sensor would presumably show up on telemetry, -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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Accident at Cape
JF Mezei wrote:
On 2016-09-11 19:51, Fred J. McCall wrote: You've got a chicken and egg problem here. Killing a sensor would presumably show up on telemetry, This is why schematics become important. What was located near the site of explosion? You mean drawings, right? 'Schematics' are just electrical. It's a privately developed vehicle. They have them and you do not. If LOX tank ruptured next to avionics board that gathers all sensor data for transmission (or even antenna), it could have litterally frozen telemetry before it could send anything. In which case someone would have noticed. Since we don't know whether SpaceX recorded any telemetry, then we really don't know what could have happened. But we do know, if you were paying attention. “We are currently in the early process of reviewing approximately 3,000 channels of telemetry and video data covering a time period of just 35-55 milliseconds,” SpaceX spokesman Phil Larson said in a statement. You are also confused. WE don't need to know what happened. They do. (for instance, if no anolany is send out prior to explosion, biut at time of explosion, there is telemetry emitted to show proble (LOX tank pressure, probably loss of contact with payload module etc) this would show that lack of problem report prior to explosion was not due to telemetry tramsmission failure. But total lack of telemetry could mean that there was nothing to report prior to explosion and at explosion, telemetry was knocked out first. Uh, you seem to be under the impression that TM only reports anomalies. It doesn't. It constantly reports thousands of items on the state of the vehicle. If it suddenly stopped prior to the explosion, I'm pretty sure someone would have noticed. Question: obviously, SpaceX will analyse its logs, photos, videos. But for such an accident at the Cape, is there also a formal government investigation ? I believe it is the FAA that does them ? or would it be air force because it was on air force property or NASA because Nasa is in charge for space flight ? No. SpaceX owns the investigation. The vehicle wasn't in flight so the Feds have no jurisdiction. -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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Accident at Cape
"Jeff Findley" wrote in message
... In article , says... Question: obviously, SpaceX will analyse its logs, photos, videos. But for such an accident at the Cape, is there also a formal government investigation ? I believe it is the FAA that does them ? or would it be air force because it was on air force property or NASA because Nasa is in charge for space flight ? No. SpaceX owns the investigation. The vehicle wasn't in flight so the Feds have no jurisdiction. While that may be technically true, considering USAF and NASA are both customers of SpaceX, it does not hurt to keep them both "in the loop" so to speak. Jeff Also, since I believe technically USAF still OWNS the pad, I'd be surprised if they don't have some sort of jurisdiction. -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net |
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Accident at Cape
Jeff Findley wrote:
In article , says... Question: obviously, SpaceX will analyse its logs, photos, videos. But for such an accident at the Cape, is there also a formal government investigation ? I believe it is the FAA that does them ? or would it be air force because it was on air force property or NASA because Nasa is in charge for space flight ? No. SpaceX owns the investigation. The vehicle wasn't in flight so the Feds have no jurisdiction. While that may be technically true, considering USAF and NASA are both customers of SpaceX, it does not hurt to keep them both "in the loop" so to speak. I answered the question that he asked. Under FAA rules the launch provider owns the investigation if there is no loss of life, injury, or outside property damage. This is the way it's done and it's why NASA managed Space Shuttle investigations (which had other people brought in due to loss of life). ATK managed the investigation when their rocket exploded. As to the board (of approximately 20 people) involved in the investigation, there is ONE NASA seat, ONE USAF seat, and virtually all the voting seats are SpaceX people. So they're 'in the loop' but have no say. -- "Adrenaline is like exercise, but without the excessive gym fees." -- Professor Walsh, "Buffy the Vampire Slayer" |
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