231–240 of 253 posts
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>I'd be very interested in what they are saying if --and only if-- they had access to Boeing and FAA design and test data. This kind of walled garden horseshit is what ensures no transparency in government contracts.
Just wowndering. Are you the kind of person who would consider convicting someone without looking at the evidence?
While I can't dispute anything that is being said I think it is unfortunate that this is playing out the way it is. I can't dispute it because there's virtually no reliable publicly-available information on the design of this battery pack. I think it is unbecoming of an engineer or scientist, particularly of prominence, to voice such opinions without access to design data from the source. Before I could even begin to…
So Musk lays down his ideas for good battery design and is backed up by a guy from MIT. Seems fairly solid. Boeing guy says something like "I design battery cells not to fail, then assume they will. I then design battery so if one cell fails others won't. Then I assume they will and design for that." What we know is that the cells fail, then batteries fail, then noxious smoke blows into the cabin, so if what he says…
While I can't dispute anything that is being said I think it is unfortunate that this is playing out the way it is. I can't dispute it because there's virtually no reliable publicly-available information on the design of this battery pack. I think it is unbecoming of an engineer or scientist, particularly of prominence, to voice such opinions without access to design data from the source. Before I could even begin to…
I'm going to disregard the bits about wings and the general engineering attitude at Boeing. It is simply not relevant. Musk has one very important justification to make the statement he did: that battery caught fire. That alone is proof positive that he is right. If the charger should fail, is it then permissible that the batteries catch fire? If not then they are fundamentally unsafe. For that reason alone this is a…
I'm just surprised there isn't more damage from the fire! I use similar chemistry batteries (although much smaller) in RC planes (they are very energy dense for their weight). When they are damaged (normally through charging incorrectly but in some cases through puncture / crash damage) they burn extremely rapidly and very violently for their size. The damage in the photographs of the 787 is not on the scale i was ex…
I'm just surprised there isn't more damage from the fire! I use similar chemistry batteries (although much smaller) in RC planes (they are very energy dense for their weight). When they are damaged (normally through charging incorrectly but in some cases through puncture / crash damage) they burn extremely rapidly and very violently for their size. The damage in the photographs of the 787 is not on the scale i was ex…
This is a bit off-topic, but I have been considering retrofitting my roomba with Li-ion batteries but am a bit concerned about the fire risk (partly because I don't want to loose the roomba, but mostly since it is in my apartment.) Is there anything that comes to mind that I should particularly look out for or consider?
I understand the charging strategy for A123 is much simpler to implement than for Li-Ion (may not even need a micro controller) but i'm not 100% confident in that statement!
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It was an engineer, Roger Boisjoly, who repeatedly warned about the safety of the o-rings, particularly in low temperatures. The decision to launch the shuttle came from management not the engineers. http://www.space.com/14522-roger-boisjoly-shuttle-challenger...
Feynman was on the accident investigation committee, and was critical to exposing crucial facts and making sure they made it into the report. Feynman even wrote an additional report to add to the committee's work. http://www.ralentz.com/old/space/feynman-report.html Bolsjoy's ordeal is now in the curriculum of many engineering ethics courses.
[1] http://abclocal.go.com/kgo/story?section=news/local/peninsul...
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Sounds like you only know people with Civil PEs, then. There are different examinations and qualifications for different disciplines. Source: my wife is a Naval Architecture PE.
Yeah that's the only kind of PE I've met. As a profession they do not impress. These guys are incapable of imagining anything they haven't done before a hundred times, let alone doing it and putting their seal on it.
Earlier quoted context omitted.
This is a bit off-topic, but I have been considering retrofitting my roomba with Li-ion batteries but am a bit concerned about the fire risk (partly because I don't want to loose the roomba, but mostly since it is in my apartment.) Is there anything that comes to mind that I should particularly look out for or consider?
May be worth exploring the differences between "safer" cells such as LiFe / A123 vs the riskier Li-ion & LiPo types. I understand the charging strategy for A123 is much simpler to implement than for Li-Ion (may not even need a micro controller) but i'm not 100% confident in that statement!
While I can't dispute anything that is being said I think it is unfortunate that this is playing out the way it is. I can't dispute it because there's virtually no reliable publicly-available information on the design of this battery pack. I think it is unbecoming of an engineer or scientist, particularly of prominence, to voice such opinions without access to design data from the source. Before I could even begin to…
Boeing batteries are overheating. Tesla batteries are not overheating. There are sufficiently similar requirements on their performance and safety that any layman can conclude there is something wrong with Boeings design. The problem here is that the engineers at Boeing are not clowns. The problem here is that you think that is what is being alleged. It isn't: an enormous and old company like Boeing can have an entre…
So since all of the variables to prevent thermal runaway are know, it should make no difference how closely together they are placed. However in this case there is either a problem with the charging software---which isn't adequately performing and preventing the condition that is causing the batteries to overheat OR the batteries themselves (although in good working order) are not performing within the correct performance envelope that the software has been developed to use.
Screaming that placing the cells too close together is bogus. You laptop has cells placed equally close together as do all Tesla vehicles---and they can burn and explode just like the ones on the 787---yet that is a very rare occurrence. Because all of the charging parameters are known. Same applies to the Boeing batteries, but something is not performing according to plan.
In space, the parameters are completely different. Fire is the absolute worst case scenario in space and everything that can be done to mitigate the chance of one will be taken. Which is why the batteries on the SpaceX vehicles are spaced out they way they are. Yes, they know all of the parameters for the batteries, but the logistics of changing a battery in space are much different than those of an aircraft.
Boeing's fault in all of this is that something is not performing according to spec---and they knew that due to all of the battery swaps the Japanese airlines were doing. At that point they should have grounded and figured out the problem. But past Elon, others have already stepped up and criticized Boeings move to lions in the first place. Nickel cadmium batteries would have weighed 40 pounds more and have barely 1/1000th of a chance of thermal runaway that lithium ion batteries do. They don't charge as fast, but they are still well within the performance envelope needed by the 787.