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dpccreating
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Iron
Unsinkable
dpccreating   3/20/2013 8:45:46 AM
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The certainly of Boeings statement resonantes with another famous transportation failure where statements of "Unsinkable" quickly proved incorrect!

Its another compartmentalized design where cascade failures were completely missed.

naperlou
User Rank
Blogger
traveling with danger
naperlou   3/20/2013 10:58:55 AM
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Chuck, you make an excelent point.  One thing you mention is how engineers "...control a package of energy."   We have become very good at this.  It was not long ago that automobiles routinely burst into flame when in a bad accident.  Remember the Pinto?  With the level of requirements engineers face and the tools available, society has become used to products being safe.  This is a good thing, but perhaps we don't always appreciate how far we have come.  The fact is that, even with the problem of the 787 battery there have been no fatalities associated with this.  It is a testament to the level of engineering that goes into products today.

warren@fourward.com
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Platinum
Re: Unsinkable
warren@fourward.com   3/20/2013 3:18:41 PM
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There was a time when I thought I could do anything, but I was only 16 at the time.  Boeing's whole attitude about its achievement of perfection reminds me of a 16 year old. 

I had a year of law school (just to prove I wanted to be an engineer instead of a professional lier), and the one thing I remember is to never claim to be an expert at anything.  Boeing is setting themselves up for a lot of trouble to claim the perfect battery supply- especially a type that has never been truly conquered.  They would have been better served with a large dose of humility and respect for the challenge.  Back off on the claims, Batman!

Ann R. Thryft
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Blogger
Re: Unsinkable
Ann R. Thryft   3/20/2013 4:19:23 PM
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I'm sorry to say, this reminds me of several very large technology companies and industry leaders--IBM, Microsoft, Intel, Apple--that get to a point where they seem to believe their own PR, become arrogant, and behave as if they think they're invulnerable and not subject to the laws of the universe like the rest of us. Boeing is only the latest in a much-too-long line.

Charles Murray
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Blogger
Re: traveling with danger
Charles Murray   3/20/2013 6:48:53 PM
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You're right, naperlou. There were no fatalities and no significant damage to the plane. It's easy to forget that. The idea of of a fire on board an aircraft, however, is understandably scary and elicits a strong reaction from the public.

GTOlover
User Rank
Platinum
Re: traveling with danger
GTOlover   3/21/2013 9:34:10 AM
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The public drives automobiles that are more likely to kill you than airplanes. But I think the ability to familarize and control a car is why the public accepts (though likes improvements) to this risk.

An airplane, few can understand its complexity and even fewer can control the plane. Even slight risks are hyperized and published! I disagree with Boeings pronouncement of "no fire", but they have to equally hyperize and publish their confidence in what they deem as a significant reduction in the risk of catastrophic failure. Hopefully they continue to investigate and revise the designs even if this fix is accepted.

In the end, will the plane land safely if an 'event' occurs? Boeing seems to think the answer is yes.

CLBrown
User Rank
Iron
"Danger, Danger..."
CLBrown   3/21/2013 9:49:45 AM
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1 saves
Like all engineers, I've come to despite "marketing-speak," which inevitably makes life harder for us (and results in us getting blame for things we had no say over, naturally).

 

I've worked in aerospace, automotive, consumer products, lithium-ion battery manufacturing, and currently work for a company which makes flywheel-based UPS systems.   So, I do have a bit of insight into this topic, as (clearly) does the author.

 

All lithium-ion battery chemistry, without exception, has a very high-energy oxygen bond which is at the core of its functionality.   There are some chemistries...  patent protected (though, naturally, in mass production for Chinese "official, non-commerical" use without any benefits coming back to the US-based inventors) with stronger oxygen bonds, which are much safer.  But since I know what US based businesses own the patents for that chemistry, and since I know Boeing isn't using that chemistry...  I know that Boeing's batteries will release oxygen whenever they become too hot, or for any other reason begin to decompose.

 

This is the real pitfall of Li-Ion batteries.  Some people think that their batteries "explode" but this is not really the case.  What happens is that they burn... very hot... and in a self-sustaining fashion.  They produce their own oxygen, after all... you can't drown them, smother them, or even extinguish them by exposure to vacuum.  Yes, Li-Ion batteries will continue to burn, even in space.

 

The only way to extinguish this sort of fire is to (a) allow it to burn itself out (which, in practical terms, means partitioning your battery systems in a pretty dramatic fashion... so that a fire in one cell won't cause a fire in any adjacent cells), or (b) extinguishing by removal of energy (ie, dousing it with liquid nitrogen, for example).

 

Remember, all a battery is, though, is a means of storing energy.    You don't really NEED all that much storage of energy in an aircraft in operation.  Historically, these aircraft have used power tapped off the main engines to drive on-board systems...  electrical generators, hydraulic pumps, etc.

 

But, today, we're seeing more and more "electrical-i-zation" of these aircraft.  The reasoning behind this, on one level, seems very reasonable.  After all, for generators, hydraulic pumps, etc, strapped to the turbine's gearbox, they are operating at all times, and thus always act as a parasitic load, VERY SLIGHTLY reducing the propulsive output of the main engines versus the fuel consumed for that propulsive output.   In other words...  these burn extra fuel, all the time.

 

They don't burn MUCH fuel, though, really.  But...  in our "make it green" world, today...  saving a single droplet of fuel is considered a benefit.  And this will certainly save quite a few droplets.

 

So... they generate power from the turbines, and store it in battery banks, where it ca be drawn on as needed.  Much of the formerly-hydraulically-driven hardware (fuel pumps, for example) are now electrically-driven (which, of course, results in the "fun" task of routing live electrical wiring through a tank filled with jet fuel...  essentially refined kerosine).

 

So, Boeing decided to "go green" on the 787.  They replaced way too much of aircraft's formerly hydraulic hardware with electrical hardware.  They did the math...  but the math assumed that the batteries were "black boxes" rather than what they are...  VOLITILE CHEMICAL ENERGY STORAGE DEVICES.

 

And this, as it always proves to be, was a horrific misconception on the part of those who did this.

 

Remember...  the fuel used by an internal combustion system is simply "chemical storage of energy in a volitile form."   The "fossil fuels" we use are, when you really get down to it, just chemically-stored solar energy, aren't they?  Batteries are just a different way of storing energy in chemical form.  And the more energy you pack into a small area, the more volitile it's going to be.

 

This...  I hate to have to say it this way, considering that we're talking about BOEING...  this isn't rocket science, guys!  Pack a lot of energy into a small volume, it's going to release a lot of energy when something inevitably starts to go wrong.

 

The Dreamliner is an example of the "green" marketing buzz overtaking basic FMEA analysis, and a thorough consideration of actual REAL costs and benefits.

 

Oh, it'll fly...  but it's going to be a nightmare to operate.  It "looks inexpensive" to operate, on paper... but there are a whole series of issues that nobody has really thought through yet.  (Fuselage maintenance is another area that they've largely ignored, I think...  there's a lot to be said for the riveted-sheet-metal skins conventional aircraft use!)

 

The final version of this aircraft, which will be in the air in ten years, will be a far cry from the version we see today.  I reallly expect to see "retro" retrofitting (conversion to hydraulics) for a lot of the on-board systems, and I suspect that due to fuselage maintenance issues which I'm convinced will be a massive issue as these aircraft age, few of the original fleet will even be operational at that point, versus "conventional construction" aircraft which can fly for quite a few decades in safety.

 

Of course...  if anyone wants to debate the issues I'm raising, please, by all means, feel free.   I'm sure that there arer people out there with greater knowledge than my own on any one of the topics I've raised here... so, let's hear it! 

VM
User Rank
Iron
Batteries in Airplanes
VM   3/21/2013 9:51:10 AM
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I am somewhat surprised that in all of the discussion about lithium batteries burning up (a phenomena already well know to the model airplane community), little mention has been made of the fact that a similar issue exists for nicad batteries.

I remember - about 40 years ago - reading an article in a Canadian flight safety magazine about a CF jet having a fire (thankfully on the tarmac) after a number of short hops between airports.  The final report cited overheating and eventual catastrophic self discharge of the nicad battery used to self-start the aircraft.

A quick search on the internet reveals that this issue (with nicads) is now commonly understood.

The big difference of course is that lithium burns.....

It is also intertesting to note that the model aircraft community did (and maybe still does) advocate the use of surplus metal ammo cases to charge batteries that are rather minscule when compared to what is being used by Boeing.

So the issue is far from new.  Maybe a little too much  of a we know better attitude.

vgm

ChasChas
User Rank
Platinum
Part of the job.
ChasChas   3/21/2013 9:51:25 AM
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1 saves
 

Alan Mulally had to say what he said in order to keep his job.

Management told him that this must not happen again. And if you cannot make it not happen, we will find someone who can.

After a few months, Alan could not say that we have a very good possible fix.

No, he had to say the problem is solved and will never happen again.

He wasn't talking to Engineers.

Ratsky
User Rank
Platinum
Reliability
Ratsky   3/21/2013 9:52:34 AM
The lead-in to this article reminds me that few (it seems these days) engineers have a fundamental understanding of reliability concepts.  To me, the worst terminology ever invented has to be "mean time between failures"/"mean time to failure."  The numbers generated for these reliability measures as generated by the usual methodologies are totally misunderstood unless one appreciates the classic "bathtub curve" of failure rates over life.  The rate starts out relatively high due to "infant mortality" then levels off to a flat rate FOR THE DESIGN LIFE, then begins to rise rapidly after that ("wearout" phase).  MTBF or MTTF is only the failure rate during the flat design life portion of the curve.  Unfortunately, the convention analysis is usually summed up in a report as the MTTF/MTBF, often shown in the misleading form "product life is x million hours" which is patently untrue. Once REALITY sets in, and the product begins to show failures, if the EXPERIENCED failure rate is significantly worse than the prediction, the prediction is shown INVALID, OR (same thing in the long run) there is an unanticipated wearout mechanism in the design.  Those whose training did not include the underpinnings of reliability analyses invariably do not account for wearout mechanisms at all, but only quote the calculated MTTF/MTBF as gospel.

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