The Accident Investigation Team continues to make progress in examining the anomaly on September 1 that led to the loss of a Falcon 9 and its payload at Launch Complex 40 (LC-40), Cape Canaveral Air Force Station, Florida.
Since the incident, investigators from SpaceX, the FAA, NASA, the US Air Force and industry experts have been working methodically through an extensive fault tree to investigate all plausible causes. As part of this, we have conducted tests at our facility in McGregor, Texas, attempting to replicate as closely as possible the conditions that may have led to the mishap.
The investigation team has made significant progress on the fault tree. Previously, we announced the investigation was focusing on a breach in the cryogenic helium system of the second stage liquid oxygen tank. The root cause of the breach has not yet been confirmed, but attention has continued to narrow to one of the three composite overwrapped pressure vessels (COPVs) inside the LOX tank. Through extensive testing in Texas, SpaceX has shown that it can re-create a COPV failure entirely through helium loading conditions. These conditions are mainly affected by the temperature and pressure of the helium being loaded.
SpaceX’s efforts are now focused on two areas – finding the exact root cause, and developing improved helium loading conditions that allow SpaceX to reliably load Falcon 9. With the advanced state of the investigation, we also plan to resume stage testing in Texas in the coming days, while continuing to focus on completion of the investigation. This is an important milestone on the path to returning to flight.
Pending the results of the investigation, we continue to work towards returning to flight before the end of the year. Our launch sites at Kennedy Space Center, Florida, and Vandenberg Air Force Base, California, remain on track to be operational in this timeframe.
Cheers, Mike.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Also the SpaceX launch pad foomp still worries me*. I'm trying to think of why solid oxygen, as opposed to liquid, next to the helium COPV makes an ignition more likely. There is general thermodynamic reasoning ( see Gibb's free energy ) but still some specifics to explain. Now I get that oxygen just loves to combine with carbon, but why did a conflagration ( not detonation ) occur in this instance ? The best I can come up with ( FWIW ) is that with liquid oxygen at the COPV interface any ( nett ) energy release from C + O2 -> CO2 will rapidly diffuse away as kinetic energy within the liquid. So that release is not available to encourage others to go over the 'reaction hump'. But a solid oxygen layer could focally confine any hot spot and thus keep the heat in said small pocket, however initially small, for long enough to then kick off an exponential cascade. Once the reacting volume achieved a certain size then this would no longer matter, as surface area grows proportionally less than volume etc. In other words the trick is start things going.
{ In principle this is a similar problem to firing up a thermic lance. This is basically iron burning vigorously in pure oxygen at a relatively small interface ie. not the usual slow rust which takes ages. You get an extremely hot jet ~ 4000+ K and thus cut up whatever takes your fancy on this planet. }
I look forward to next month ! :-))
Cheers, Mike.
* I'm aware of the disclosure that COPV failure has been reproduced under the conditions of fuel loading. I don't think we should 'blame' anyone. As pointed out this is unprecedented simply because no one has done these vehicle designs before. I reckon they'll do a workaround, and maybe will involve some easing up on the propellant chilling. This is rocket science after all ..... ;-)))
Bear in mind that a proven reliable system ( like Soyuz say ) is only so because of much learned from failure. That gradually became, and still is, well over-designed. But that is not where SpaceX is at. They are pushing the margins to wring performance and there will be more hard calls to come upon what might be viewed as fine/fungible detail elsewhere. I think that collectively it is a confidence thing within the company, and in turn confidence in the company from their market.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Bear in mind that a proven reliable system ( like Soyuz say ) is only so because of much learned from failure. That gradually became, and still is, well over-designed. But that is not where SpaceX is at. They are pushing the margins to wring performance and there will be more hard calls to come upon what might be viewed as fine/fungible detail elsewhere. I think that collectively it is a confidence thing within the company, and in turn confidence in the company from their market.
Start-ups have always had this problem. Two current ones that come to mind are the sister SpaceX Hyperloop project in California, and Bransons involvement in a Super Concorde.
Also the SpaceX launch pad foomp still worries me*. I'm trying to think of why solid oxygen, as opposed to liquid, next to the helium COPV makes an ignition more likely.
I'm not convinced yet there was ignition before COPV failure, see the COPV failure table in this article NASA's list of COPV failures causes Spaceflight101.com article
SpaceX were filling this tanks very quickly. If solid oxygen is a cause (from say rapid fuelling), it could be a factor in the de-lamination of the COPV lining for example.
I'm not convinced yet there was ignition before COPV failure
Same here. I was hypothecating beyond the first moment of intimate contact b/w the carbon and the oxygen, however that came about. My Gibb's reference was one interpretation on general reasoning. Gibbs free energy takes some account of circumstance ie. pressure and volume. In the setting of chemical reactions, a Gibbs differential yields an estimate of spontaneous reactivity eg. hypergolics. The anti-intuitive bit here is that things can burn even if they are very cold in everyday terms. There is still energy release ( heating ) from lattice tearing lattice too ...... I'm thinking quite microscopically here. I appreciate their problem of having to generate an explanation that only spans a quite short time interval.
Cheers, Mike.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Quote:October 28, 4:00pm
)
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
http://www.theverge.com/2016/
)
http://www.theverge.com/2016/11/5/13533900/elon-musk-spacex-falcon-9-failure-cause-solved
Richard
Interesting.
)
Interesting.
Successful launch of GOES-R
)
Successful launch of GOES-R weather satellite from cape this evening.
Here is a pic from the back yard.
assume that is the Atlas
)
assume that is the Atlas 5-b?
nice pic btw
Great shot. Well done !
)
Great shot. Well done ! :-)
Also the SpaceX launch pad foomp still worries me*. I'm trying to think of why solid oxygen, as opposed to liquid, next to the helium COPV makes an ignition more likely. There is general thermodynamic reasoning ( see Gibb's free energy ) but still some specifics to explain. Now I get that oxygen just loves to combine with carbon, but why did a conflagration ( not detonation ) occur in this instance ? The best I can come up with ( FWIW ) is that with liquid oxygen at the COPV interface any ( nett ) energy release from C + O2 -> CO2 will rapidly diffuse away as kinetic energy within the liquid. So that release is not available to encourage others to go over the 'reaction hump'. But a solid oxygen layer could focally confine any hot spot and thus keep the heat in said small pocket, however initially small, for long enough to then kick off an exponential cascade. Once the reacting volume achieved a certain size then this would no longer matter, as surface area grows proportionally less than volume etc. In other words the trick is start things going.
{ In principle this is a similar problem to firing up a thermic lance. This is basically iron burning vigorously in pure oxygen at a relatively small interface ie. not the usual slow rust which takes ages. You get an extremely hot jet ~ 4000+ K and thus cut up whatever takes your fancy on this planet. }
I look forward to next month ! :-))
Cheers, Mike.
* I'm aware of the disclosure that COPV failure has been reproduced under the conditions of fuel loading. I don't think we should 'blame' anyone. As pointed out this is unprecedented simply because no one has done these vehicle designs before. I reckon they'll do a workaround, and maybe will involve some easing up on the propellant chilling. This is rocket science after all ..... ;-)))
Bear in mind that a proven reliable system ( like Soyuz say ) is only so because of much learned from failure. That gradually became, and still is, well over-designed. But that is not where SpaceX is at. They are pushing the margins to wring performance and there will be more hard calls to come upon what might be viewed as fine/fungible detail elsewhere. I think that collectively it is a confidence thing within the company, and in turn confidence in the company from their market.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Bear in mind that a proven
)
Start-ups have always had this problem. Two current ones that come to mind are the sister SpaceX Hyperloop project in California, and Bransons involvement in a Super Concorde.
Hyperloop
Concorde Mk2
Waiting for Godot & salvation :-)
Why do doctors have to practice?
You'd think they'd have got it right by now
Mike Hewson wrote:Great shot.
)
I'm not convinced yet there was ignition before COPV failure, see the COPV failure table in this article NASA's list of COPV failures causes Spaceflight101.com article
SpaceX were filling this tanks very quickly. If solid oxygen is a cause (from say rapid fuelling), it could be a factor in the de-lamination of the COPV lining for example.
... and nice photo!
AgentB wrote:I'm not
)
Same here. I was hypothecating beyond the first moment of intimate contact b/w the carbon and the oxygen, however that came about. My Gibb's reference was one interpretation on general reasoning. Gibbs free energy takes some account of circumstance ie. pressure and volume. In the setting of chemical reactions, a Gibbs differential yields an estimate of spontaneous reactivity eg. hypergolics. The anti-intuitive bit here is that things can burn even if they are very cold in everyday terms. There is still energy release ( heating ) from lattice tearing lattice too ...... I'm thinking quite microscopically here. I appreciate their problem of having to generate an explanation that only spans a quite short time interval.
Cheers, Mike.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal
Mike Hewson wrote:AgentB
)
I found the rather interesting original NASA article about COPVs and a failure will cause catastrophic damage https://ston.jsc.nasa.gov/collections/trs/_techrep/SP-2011-573.pdf