Looking at that track record, many engineers are scratching their heads. Engineers are trained to evaluate and mitigate risk. Every day, they build cars, trucks, airplanes, elevators, rockets, medical devices, and other products that have to control a package of energy. Sometimes that package is powerful, but engineers generally find a way to regulate it. In almost every case, they are successful in handling gasoline, rocket fuel, electricity, and, yes, lithium-ion batteries.
But in almost no case do they smack their hands together and say, "The risk is zero."
It's hard for most of us to imagine the external pressures that must have been brought to bear on Boeing staffers. For the past two-and-a-half months, Boeing has been deluged with press inquiries. Its story has been told in virtually every newspaper and radio broadcast. Its engineers and executives have lived on precious little sleep. And its stockholders have undoubtedly been breathing down the necks of management. So a public discussion of engineering risk probably hasn't come up high on the company's priority list.
For those reasons, it's much easier to say the risk is zero. That's what consumers want to believe about every product they touch, anyway. And it's what they usually believe when something goes wrong and they start phoning lawyers.
So the easy solution is for the company to say "zero." No risk. It's impossible. Fire can't begin, develop, or be sustained.
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!
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.
Having worked for over 30 years with some of the biggest names in industry mostly in startup operations, you're correct. When they are a modest size marvellous engineering happens...it's like one big family forging on to a promising future, then when they get bigger all sorts of cowboys (and cowgirls!) swagger into the organisation and create all sorts of mischief.
There's a recurring theme. At start up even branch plants need engineering people who know something about the product and technology with which they are dealing, then when the company grows a clutter of MBA's comes in throwing their weight around and invariably crowing that they don't need to know anything about the technology they only need to know how to manage people. Some of their braying would make any responsibly minded Engineer's hair curl since an MBA's understanding of the technology is so superficial it amounts to perilous innocence. There are exceptions of course who were engineers before they became MBA's but they are rarities.
Management and spin doctors in big corporations are the company's worst enemies and Boeing suffers mightily from this....just ask any Liaison Engineer who has worked for them at least those who have been on contract since they have experienced other companies as well...unhappily it's not only Boeing.
ScotCan, sounds like you've had similar experiences. My perspective was partly from the outside as a journalist, and partly from the inside, both working as a contractor and knowing others who worked at these places. There are also larger historical phases: the MBA/bean-counter plague was not always an inevitable point in a company's lifecycle.
Ann, There are countless anecdotes of MBA interference albeit indirectly in the engineering process.
One prime example was the gentleman who declared that a wing spar process would be shipped out to the lowest bidder since the process we were looking at only realized $5 per sq.ft. whereas the aircraft assembly area was (at that time) making $42 per sq.ft. When it was pointed out to him that the wing spar was the most vital part of the wing assembly and that's why the company manufactured it in house...to keep track of material, machining and QA...he said the outsource would look after that. When it was pointed out that the company assumed full responsibility for the wing construction again he argued that he ASSUMED the outsource would do the same...little did he know about engineering reality and yet he had the say-so to even suggest such things.
ScotCan, your example is a perfect one. I worked at companies in the late 80s where MBAs and the bean-counting, short-term-profitability concept they brought with them had a direct, negative effect on the company's product quality, performance, and time-to-market. And the arrogance...well, that was amazing. OTOH, I also worked at a company that eventually got sold and disappeared because it didn't have realistic budgets or product launch timelines, yet had one of the most innovative product ideas and engineering I've ever seen.
I think Warren has a good point about the 16-year-old's feeling of invulnerability and immortality. I remember (just barely). But I think this is a different problem, one that goes with increasing amounts of power, and other inevitabilities, as ScotCan points out.
I think your article stated it correctly. Marketers and managers use superlatives without care. Engineers should be immediately alert and be reminded to use metrics and quantitative realities they can defend. "how to lie with statitistics" is a prerequisite to every political debate.
We may not like the solution Boeing and FAA agreed upon. We may not perceive it as thorough or exhaustive or in our individual branding: safe. They are selling convenient cost-controlled air travel. We are buying or not.
Of course Boeing claims they have created a zero-risk solution. To declare anything else would admit known liability and inherent design flaw. Zero is their definition of significant figures. I'm impressed they gave as much disclosure as they did about the corrections implemented.
So flier beware and keep your will in order. And if you see something, say something. Smoke, particularly.
@charles, the minute an engineer hears this is more than upsetting; it absolutely goes against the grain of both training and experience. Most of us can relate to relegating a potential problem to "that's never gonna happen," only to have it happen in real life. Lessons like that should only have to be learnt once, and to have management proclaim there will be no more fires is the pinnacle of outrageousness and folly.
@dpccreating: absolutely. In fact, the same term came to mind to me, too, and it didn't involve Molly Brown.
I had a post written up to this point right after the article came out, but I killed it (my post.) There've been so many highly competent & experienced engineers on these 787 threads, I just shied away from being the first.
The correct solution is not fire avoidance. Unless you change chemistry or maybe do a major mechanical reconfig, the best you can do is Fire Control.
Manage risk to increase "probability of no fire" out to so many '9's.
Construct an onboard environment to handle the fire.
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.
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.
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.
The operative word is YET. True there were no injuries or fatalities from the two serieous battery failures aboard in service 787's. But there were also comparatively few in service flying hours for the aircraft. Given more time and other scenarios, combination of unpredictable events, who knows if the current battery design could have contributed to a more severe in flight problem. Fire and smoke on the ground, even on a taxi-way is bound to be less of a problem than in flight half way across the Atlantic.
To some extent this reminds me of the story about the first production run of the Xerox 914 copier. The units were fitted with a "scorch guard" pushbutton which, I've been told, was no more than a fire extinguisher trigger. As the story went, engineering wasn't ready to ship the unit as the toner affixing heater ran hot enough to cause the paper to burn if anything jammed. But sales and promotions insisted on meeting the announced deadline for starting shipments. So, the first units were shipped with onboard fire extingishers to buy time until the overheating problem could be solved. You don't want your new baby blamed for burning down other businesses. To say the least, you'd never sell another copier.
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!
As I have been around for some time I do recall that Li Ion batteries were used in Laptop which did have the noterity of catching fire and it was in the news. Since I have worked with a lot of different type of batteries, Lead, calcuim, NCL, Gel, They all have some enviornmental and physical conditions that would lead you to do a 40 year type of analisys as planes have change in ATM pressures, temperature, gravity, Electrical Stresses, Fire is not the only safety issue for 250 passengers and they should not be exposed to forced exiting for any safety issue, PLAN AHEAD.
One minor correction, the "more electric" aircraft architecture was really designed to avoid the use of engine "bleed air" which a previous generation of engineers had come to rely on as "free power" particularly on competitive commercial aircraft. If you really get down to splitting hairs though nothing is REALLY free. (The primary reason I'm correcting you is even some of the new aircraft architectures have shaft-driven hydraulic pumps but they're primarily there as a backup in case the entire electrical system were to go down.) Other than that I find that your analysis is pretty much "spot on".
The 787 goes further towards an "all-electric" plane like the F-16, but the purpose of the batteries isn't what you state. The aft battery (Boston fire) starts the auxilary power unit. The APU is a small gas turbine in the tail of most airliners and provides electrical power, HVAC, engine start, etc. on the ground as well as "hot standby" power during certain flight phases. The APU is shut down in flight. The battery is required to ground-start the APU away from external power or in a flight emergency. The forward battery (Japan incident) powers "essential" items like the glass cockpit as a last layer of power redundancy.
Both batteries exist on "legacy" aircraft...it has nothing to do with the higher electrical load on the 787. This is the first Li-Ion on an airliner although military aircraft have used them for awhile.
Adding to your and other's comments: The 65,000 gallons of fuel on a 747 have far more energy content (by weight and volume) than Li-Ion and of course the fule system has catastrophic failure modes. They've been mitigated to very acceptable levels but not zerop (TWA800 accident).
Boeing either has incredible hubris, or has a truly innovative solution to the problem. Which one will be interesting....
That's the first I've ever heard about using batteries as the primary start energy for the APU. Normally, commercial aircraft run off of external power when on the ground, and that same externally-supplied power is what is used to "kick over" the APU (which is a small gas turbine, usually in the tailcone, which produces power which, among other things, supports starting the main gas turbines in the engine nacelles).
I've never heard that they were using the battery system to provide starter energy for the APU, and abandoning the long-time practice of using ground power.
I do know, as a fact, however, that the primary purpose of the batteries is, in fact, exactly as I described it. The argument has always been about "parasitic losses." Parasitic losses are losses which serve no purpose... such as running a generator unit or hydraulic pump even when it's not being used. The entire argument for the transition from hydraulic to electrical, especially combined with "battery storage," has been to reduce the requirement for the power being tapped off the engines on a continual basis. The idea is, you take a little bit of power, which is used to charge the batteries... and you discharge the batteries (in "lump amounts") as needed.
This is the same thing you see with hybrid vehicles, by the way. I worked on the battery system which went into the "New Bus for London" (the big red double-decker buses which were unveiled just prior to the last Olympics in London). This vehicle had a small engine in the right rear corner, which could run the vehicle at "constant speed" with just a tiny bit of excess power available... with that excess going to charging the battery tray. When you'd brake, "regenerative braking" would drive power back into the battery pack, and when you wanted to accelerate, you'd dump a lot of energy out of the battery pack.
This worked out really well in this application. The vehicle is significantly more fuel-efficient.
Of course, we were talking about a vehicle riding at street level, with multiple exits, and the ability to off-load the vehicle very quickly if necessary, as well as having the battery pack very robustly designed, fully vented, water-cooled, and with both ballistic and shock/vibration protection designed into the enclosure... all in a compartment with no other hardware adjacent, separate from the habitable spaces of the vehicle.
Don't get me wrong... I LOVE this technology. I just recognize the issues... MAJOR issues... with it.
My aerospace activity was all related to auxiliary equipment related to the engines... so I'm pretty familiar with big commercial gas turbine design, even if I wasn't directly responsible for the engines themselves. A big part of that was understanding the startup processes for commercial aircraft, since our equipment was directly dependent on that and was crucial to that as well.
In other words, I'm not tossing out "academic" experience... I'm talking about what the engine and aircraft manufacturers communicated to me and my team as how they do these things. That's my source of info about "what these batteries are used for."
But, at least on these issues, my knowledge is, admittedly, second-hand.
Your comments are accurate, but not in the context of the 787. Here's a good link that explains my earlier comments: http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:7a78f54e-b3dd-4fa6-ae6e-dff2ffd7bdbb&plckPostId=Blog:7a78f54e-b3dd-4fa6-ae6e-dff2ffd7bdbbPost:5e8acfbf-0e5f-4354-a6f3-f19ec0ac6556
You're right about ground power from a cable or "start cart". But that's not always available at the far corner of the maintenance or overnight parking ramp. The more important thing is twin-engine aircraft have a requirement called ETOPs to fly over water or isolated areas. The higher levels of ETOPS certification require a cold-start APU (cold in both the literal and figurative sense). In case of a double failure of both engines the APU needs to be started on a stand-alone basis after being cold-soaked to -70C in flight...not an easy requirement!
The batteries are definitely not used as a "reservoir" floating on the main bus or to handle parasitic losses as you describe with ground vehicles.
My knowledge is second-hand too...just from working with avionics, as an "aerogeek", and a private pilot. So, I could stand corrected but everything I've seen from Boeing, NTSB, FAA, etc. support the Avweek link.
I hate to keep arguing with you... but this is the only reason that the aviation business has moved away from hydraulic systems to electrical system, for, say, actuating the gear, or the flaps, or the control surfaces in some cases.
They've moved away from direct hydraulic to electrically-powered devices for the EXACT reason I described. You can store up electrical energy, over time, and discharge it "on demand," reducing parasitic loses and thus improving overall fuel efficiency.
There is ZERO DOUBT about what I'm describing. This is hard fact.
There's quite literally no other reason to move from a hydraulic system to an electrical system, is there?
I'll concede that your point about "remote self-starting" COULD be accurate... though every airport I've ever deal with would just roll out a "start cart" to the aircraft, and I've never seen a commercial airliner have to start itself. The "in-flight restart" scenario does seem quite a bit more likely... and I know this is a real requirement, in fact. But normally, to do this, they'd switch of other in-flilght systems (lighting, entertainment, heating, etc). Today's aircraft use a lot more batteries than older ones, because they're supporting a far, far higher electrical load... including the various "replaced hydraulics" I mentioned previously.
I'm worried that maybe you think I'm stating a direct paralle between the passenger bus (which uses stored electrical power for MOTIVE FORCE) and the aircraft (which uses stored electrical power for momentary high-demand actions like, for example, deploying flaps or landing gear).
But the POINT remains the same, and I'm absolutely clear on this... the reason for switching from hydraulic to electrical power is to permit you to burn less fuel throughout the flight, by slowly charging the batteries and rapidly discharging them in burst to do brief "high demand" operations, rather than having a perpetual load on the engines capable of supplying that full load at any given instant, and serving only as losses the rest of the time.
That's the argument which was at the core of the 787's overwhelmingly electrically-driven design... all in the name of improving fuel efficiency.
This isn't a "debatable" point... so... you can take my word for it, or reject what I'm telling you... but I'm not going to bother to restate this another time.
Totally agree the swich from bleed air and hydraulics over to electrics is fuel burn. BTW, during revenue service before the grounding, airlines reported fuel burn bettered spec by 1-2%, which as you know is huge in the airline biz.
Other reasons for moving away from hydraulics are one less system to maintain, less weight, easier system integration into the airframe, better "coupling" to software control (and thus other systems), easier monitoring and maintenance, more environmentally-friendly, etc. Of course a leaky hydraulic fitting seems way easier to detect and fix than an error code on the maintenance console and the difference between hydraulics and electrics ought to add more reliability through "diversity".
I'm open to being wrong as I know you have a lot of knowledge too. I could very well be misinterpreting the Avweek link. Also as a "sparky", the battery capacity seems a drop in the bucket compared to total electrical load. There may be other battery banks that do what you describe....of course the LAST thing Boeing wants to do at this point is say..."oh, you know there's much larger batteries on the 787" ! :)
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.
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.
I, (email@example.com), have recently been in contact with Boeing with details of a system that is able to prevent thermal runaway by monitoring the cells and detecting any physical instability including swelling or ballooning of one or more of the cells in a lithium-ion battery pack. By implementing this means of detection we were able to successfully develop a viable solution that is able to prevent the onset of thermal runaway and combustion before it ever occurs.
You can't claim that there's a "new" battery management algorithm which somehow "magically" prevents any risk of what is, frankly, a matter of natural laws. Batteries, like all real physical objects, do not behave in "binary, digital" ways.
People have been developing battery-management systems (BMS) for as long as there have been batteries. The BMS is at the core of EVERY battery installation out there. Your iPhone has a "BMS on a chip" to prevent overcharging of the device (which would result in battery overheating, and thus failure).
To claim that there is a "new" ELECTRONIC MONITORING SYSTEM which somehow can overrule the basic laws of physics is.. naive, at best. The ability to bypass cell blocks which are showing signs of deterioration is a RISK REDUCER... and it's one which has been in use for many, many years. This is a large part of what any BMS system does, after all.
You can "reduce risk" by the use of this sort of monitoring and bypassing scheme. But every major battery manufacturer already does this, and I doubt, very much, that Boeing bought a battery system without a very robust BMS system as part of it.
And no BMS system can PREVENT failures. It only reduces the "occurance" number... it can't reduce it to zero. Severity remains high... detection risk remains high... all you can do is handle "occurance" and you do that by having extra banks of cells beyond what you "really" need, and having the ability to switch off banks, or modules, IF you detect electrical or thermal precursors to failure.
And that's something that was already part of the system on the Dreamliner... and on the Chevy Volt... and on and on and on...
I have not claimed that this is just a new battery management algorithm.
I assume from your reference to 'the system that is already incorporated in the Dreamliner and Chevy Volt etc.' that you are referring to a typical battery management system which at best only monitors voltage, temperature, and current conditions of the battery. These devices although offering some protection are still unable to detect instability at an early stage and are unable to detect the deformation such as the ballooning or swelling of the battery cells that occurs prior to and during the condition known as "Thermal Runaway".
The system I refer to is able to detect and protect at an early stage from the potential dangers caused by the volatile nature of lithium-based battery cells by measuring and monitoring any changes, in a 3 dimensional space, the physical dimensions of one or more of the battery cells within the pack. This dimensional deformation which leads to ballooning or swelling of any of the unstable cells within a battery pack is detected before Thermal Runaway and combustion of any cell occurs.
My objection to your statement is not that you haven't implemented an additional level of detection... though "volumetric" detection is notoriously unreliable, since cells vent at different rates, different cans will deform in different ways, etc...
My objection is that you seem to be claiming that "detection" and "block-switch-off" can be sufficient to eliminate this concern. It can't. The cells still decay, with use or with "abuse," and still produce oxygen as the principle byproduct of that decay.
Unless you're also implementing a liquid nitrogen "spray cool" process as part of your system, along with a multiply-redundant detection/control hardware solution... I won't be comfortable with the use of these devices in large quantities in aerospace applications.
Li-Ion batteries are great devices... but they have real, unavoidable drawbacks.
Ultimately, my point is that, in order to save a tiny amount in terms of fuel economy, they've compromised the safety of the aircraft, and thus of all the passengers, crews, and people along the flightpaths... plus, they're adding other costs into the system (such as, perhaps, your own system?) just to deal with the added risks of these systems... which, I strongly suspect, more than offset the "fuel economy" savings.
1. The system we have developed is capable of detecting minimal changes in any dimension of any size or shape battery cell with extreme accuracy.
2. There is oxygen expelled from the positive electrode of Lithium-ion cells only if the temperature exceeds a certain value. However our system detects instability before this temperature rise.
3. The system does include levels of security by way of multiple redundant hardware/software and as it is able to detect any unstable cells at an early stage of instability a gas such as Halon 1301 provides an effective suppressant preventing any further temperature increase. Liquid nitrogen would really not be ideal as a coolant in this situation!
4. Our system is designed to minimise the drawbacks and make Lithium-ion a safe technology.
5. The system was originally designed for improved safety within the electric vehicle market. I am unable to comment on the economic decisions made by the aviation industry in their choice of battery technology, I can however say that our system is not only cost effective but most of all makes Lithium-ion battery technology much safer.
They should have backpedalled to a less finicky, more extinguishable battery technology until they get their act together. I can't imagine that they could easily overcome Lion's overtemp/undertemp restrictions in the environs of a commercial aircraft.
I am in agreement with VGM's comments on the histories of batteries / battery technologies. I was involved with USN and USAF aircraft, specifically as an aircraft electrician (AF) and, for a short time, worked in battery charging and testing work centers. Li-ion was not much on the horizon at that time. We were using lead acid and Ni-Cad at that time (1966-1970's). Some were large: an 80 lb Nicad is a handfull, even when it is at normal temperatures.
In our NiCad battery shop we had a large trash can nearly full of water. The procedure was to pick up an thermal run-away Ni-Cad and drop it in there (also aprons, face shields, and heavy thermal protective gloves). This was on a USN ship, and ships move, so think about moving around with a heavy battery that is overheating, on a moving deck and possibly a wet floor. This in a shop full of calibrated test equipment made to evaluate the condition of the battery systems. If you don't have full control over batteries in that environment in a more sophisticated fashion than a water bath, we need to think acknowledge the risks and reliability and how we deal with them. The water barrel is not much of an option at FL 380 (38,000' in the air). And this was not the dark ages, it was 1988.
All battery systems have their problems, plus most of them are heavy and contain aggressive electrolytes and various other toxic materials. Overheating these compounds does not help the situation, especially in a confined area.
Just my $0.02 worth; it's about learing curves: (1) Boeing and the PR flacks (trying to paint the prettiest face on it) pressured by the accounting department, and (2) would be how we get smarter when newer technologies enter operating environments. At the bottom of all this is how risk fits into both the discussions: probability of really getting to Zero risk is as unlikely as it will be expensive.
Just because they may have come up with a way to stop or contain a fire, it doesn't mean that the aircraft will be safe. The electrical system will still be compromised and that could be a bigger danger, especially with a fly-by-wire aircraft. It's like the containment dome at a nuclear power plant; if a problem develops, it might prevent a radiation leak but that won't restore power.
"The entire argument for the transition from hydraulic to electrical, especially combined with "battery storage," has been to reduce the requirement for the power being tapped off the engines on a continual basis. The idea is, you take a little bit of power, which is used to charge the batteries... and you discharge the batteries (in "lump amounts") as needed."
It doesn't matter if the power is being "tapped off the engines on a continual basis", the load on the engines and its effect on fuel consumption is only a function of the current being drawn, assuming the voltage being generated must be at fixed constant value.
The sizing of the generators depends on the peak current load that must be handled, but only the actual electrical load being delivered by the engine at any given moment, whether the load is constant, variable or intermittent, will affect fuel usage. No load, essentially no additional fuel usage except to cover minimal constant losses within the generator due to windage, bearing friction, etc.
It's an interesting development. The publicity factor with a safety related issue always bears the potential to outweight the utility, and I know that with lithium-ion's reputation their will be no shortage of executives taking the opportunity to staid the concern. Mr McNerney himself will be keen to see the Dreamliner's presence in news ahead of the A350, given the latter has marginally better specifications. I've had the pleasure of working on the topical laminates for both jets during testing and I have to say, the budgetary restraints continued to lapse on either side as the project continued. Everything is related to appearances and neither side wants to be outdone in even the most remote aspect of test and dev, given the possible reprecussions the media has motivation to slant a certain way. I was at http://www.ventec-usa.com while the match-up was unfolding and there were optimisation concerns from both parties which at one point I thought would never be settled
Now it's almost 18 months since Dream's commercial introduction, and with the A350 hurtling towards us from beyond the horizon, it's about time there was a united front for all disciplines in all departments at Boeing! Although I'm certain the engineers have done a fantastic job despite the on-going pressure which to be frank, has been there since conception.
If those folks at Boeing wanted to be a bit more accurate they could have claimed that there would never be a fire from whatever cause they had removed from the list of potential causes, which it seems that they have done. But there are always other failure modes that can cause problems, and getting rid of all of the possible failure modes is a HUGE effort, perhaps not even possible. On top of that, just one bullet fired from the ground could, if it impacted the battery box, cause a number of failure modes. That is more of a problem with military aircraft, but none-the-less it is another potential cause. In this day and age we do have those who do that sort of thing, like crashing planes int buildings.
On the other side, it is a wonderful thing to be invincible, and quite traumatic to lose one's invincibility. Perhaps we have some folks like that at Boeing.
Your point is well taken, William K. If they made their claims with regard to one possible cause, it would be easier to accept. But when they still haven't nailed down the cause of the Logan Airport fire, how can they definitively say there can't be another fire?
Five years ago, optical heart rate tracking seemed like an obvious successor to the popular chest straps used by many fitness buffs, but the technology has faced myriad engineering challenges on its way to market acceptance.
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