justloveplanes
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Next Gen 787 Battery Containment

Sat Apr 20, 2013 5:12 pm

Now that the 787 Battery solution is approved, no doubt Boeing will be looking to make improvements.

Specifically, Boeing took a safe but expeditious route to contain future thermal incidents. The stainless steel cage, while reliable, is a significant factor in the 150 extra lbs imposed by the solution.

One obvious improvement is to construct a container made of lighter material, such as composites. It is a fairly easy application, in essence a simple pressure cell with some connections coming in and out. Question should be temperature resistance, though the box can conceivably replaced after a few incidents.

Other thoughts might include titanium, buttressed aluminum or composites with a metal pressure liner.
 
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Stitch
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RE: Next Gen 787 Battery Containment

Sat Apr 20, 2013 5:36 pm

I expect Boeing will stick with this new system going forward because if they make any other changes, they would have to certify that one, as well. There is also the spares / maintenance angle for operators with 787s with different containment systems (Mk. II and Mk. III+).
 
justloveplanes
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RE: Next Gen 787 Battery Containment

Thu Apr 25, 2013 4:35 pm

OK, how about this.....

Airplane as a rule consume for a person about 42.6 miles per gallon per person (not bad, see blog below)

http://truecostblog.com/2010/05/27/f...s-of-transportation-ranked-by-mpg/

assuming the 150 extra lbs for the battery containment is half a person, we are getting about 85 MPG for the battery solution extra on an airplane

at $3 gallon for Jet Fuel that is about $11 per thousand miles, and say 5000+ miles per day for a 787. So about $60 per day to fly around the battery upgrade. $1800 per month, about $20K a year.

So some incentive to go to a lighter battery housing.
 
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bikerthai
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RE: Next Gen 787 Battery Containment

Thu Apr 25, 2013 7:28 pm

For starter, by shear size reduction you can save some weight by integrating the steel box into the battery case itself.

Second . . . super plastic form diffusion bonded casing would provide both the stiffness/strength and thermal resistance

You can also do a composite box but you'll have to use a stainless skin insulation blanket between the battery cells and the containment box to handle the thermal protection.

bt
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nomadd22
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RE: Next Gen 787 Battery Containment

Thu Apr 25, 2013 9:24 pm

Quoting justloveplanes (Reply 2):
Airplane as a rule consume for a person about 42.6 miles per gallon per person (not bad, see blog below)

No. A person plus his share of the airplane structure, fuel and cargo averages 42.6 mpg. That's a far cry from the weight of an additional person costing 42.6 mpg. A passenger's share of the total weight for a loaded 789 is close to 2,000 pounds. You need to cut you estimate of cost for the extra weight by about 90%.
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twiga
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RE: Next Gen 787 Battery Containment

Wed May 01, 2013 12:05 am

Quoting bikerthai (Reply 3):
For starter, by shear size reduction you can save some weight by integrating the steel box into the battery case itself.

Probably for the next generation box with titanium. Advantage with keeping the present system for now is there is extra space in there for "safely experimenting", if they have to, with different Li-ion chemistries that might need a little more space say as discussed before. Only time will tell on the battery mods/ fix they have.

BTW on a picture I saw of the containment box it looks like they rounded the corners and used a slightly wide shallow corrugated profile -good move for a pressure vessel. On Boeings web page they had the disc opening at btween 16 to 18 psi so our speculation of about 16 psi was close.
 
JoeCanuck
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RE: Next Gen 787 Battery Containment

Thu May 02, 2013 1:14 am

Is the 150lbs total battery weight or in addition to the original battery weight?

Regardless, Boeing is no doubt working on different battery chemistries and maybe even enclosures but I suspect that anything with 'lithium' in the description, will require an enclosure at least this robust. The current batteries went through a very thorough series of tests and the root causes for the runaways is still unknown.

That lack of root cause will, for the foreseeable future, meant that everyone will be extra cautious about any lithium batteries, no matter how benign they might appear to be during testing.

[Edited 2013-05-01 18:21:54]
What the...?
 
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Francoflier
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RE: Next Gen 787 Battery Containment

Thu May 02, 2013 4:35 am

You would think that the ultimate goal of Boeing (and Airbus) engineers would be to come up with a battery that doesn't spontaneously combusts in flight rather than coming up with ever smarter and lighter armoured boxes...

With all the extra weight of the containment system, I suspect the weight advantage of the Li battery is completely nullified anyway?
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JoeCanuck
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RE: Next Gen 787 Battery Containment

Thu May 02, 2013 6:47 am

Quoting francoflier (Reply 7):
With all the extra weight of the containment system, I suspect the weight advantage of the Li battery is completely nullified anyway?

This could end up being a good thing for the development for batteries. With essentially unbroachable containment, new battery chemistries can be tried out, without having to worry about the fear of fire.

Unless they go to NiCd's, any new battery will need this type of containment to get certified, for a very long time to come.

With the grief that comes from certification and a fleet wide grounding, I don't think anybody is going to be in a rush to pioneer new battery technology in aircraft again.

You can bet they'll stay with NiCd on the 777x.
What the...?
 
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Stitch
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RE: Next Gen 787 Battery Containment

Thu May 02, 2013 12:40 pm

Quoting francoflier (Reply 7):
You would think that the ultimate goal of Boeing (and Airbus) engineers would be to come up with a battery that doesn't spontaneously combusts in flight rather than coming up with ever smarter and lighter armoured boxes...

With all the extra weight of the containment system, I suspect the weight advantage of the Li battery is completely nullified anyway?

Well one hasn't yet (the JTSB have determined that no part of NH692's battery caught fire and the NTSB have determined that on JL8 it was the plastic in and around the battery cells that caught fire, not the battery itself) so...  

Seriously, I expect that there will eventually be a cathode chemistry change to a more stable formula which would then allow Boeing and Airbus to be able to scale-back the containment system (and therefore reduce the weight).

And yes, while the new containment system and battery weight as much as a NiCad without the containment system, the Li-Ion battery still offers benefits in terms of system performance over the NiCad.
 
bellancacf
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RE: Next Gen 787 Battery Containment

Thu May 02, 2013 3:55 pm

I presume (perhaps mistakenly) that Boeing and others are still interested in battery-assisted planes like the SUGAR Volt project. What does this containment requirement with its accompanying weight do to these ideas?
 
twiga
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RE: Next Gen 787 Battery Containment

Tue May 07, 2013 10:42 pm

Quoting JoeCanuck (Reply 8):
This could end up being a good thing for the development for batteries. With essentially unbroachable containment, new battery chemistries can be tried out, without having to worry about the fear of fire.
Quoting Stitch (Reply 9):
Seriously, I expect that there will eventually be a cathode chemistry change to a more stable formula which would then allow Boeing and Airbus to be able to scale-back the containment system (and therefore reduce the weight).
And yes, while the new containment system and battery weight as much as a NiCad without the containment system, the Li-Ion battery still offers benefits in terms of system performance over the NiCad.

I fully agree with both of the above posts. Forgive me for a longish answer, with a summary to keep things in context . If not interested in the summary/ rationale, please simply "jump" to the conclusion and questions at the end.

In order to predict the future of a/c batteries and containment, I think we need to first review (1) - the past philosophy/ history on a/c batteries in general, and (2a) - Boeings battery issue, (2b) - Boeings battery system fix, and then move forward to (3) - next generation containment. Safety parameters listed provide some context for these discussions.

(1) - Past philosophy/ history on a/c batteries. I presume there have been battery fires before with both lead acid and NiCad batteries without containment - and I presume (because I don't know) there was no loss of airplane or life. Therefore this element would fit in the Safety Category of Hazardous 1:10^7 hrs (1 in 10 million) and not the worst Safety Category of Catastrophic 1:10^9 hrs (1 in 1 billion) where there could be loss of airplane and life. To further clarify this conclusion - according to AC 23.1309-1E, "Hazardous" is a failure condition defined as 'extremly remote' and those failures not anticipated to occur to each airplane during its total life, but may occur a few times when considering the total operational life of all airplanes of this type. There is more to this but sufficient here for this discussion.

(2a) - Boeings battery issues. Boeing advised their battery was designed for the 1:10^7 hr (1 in 10 million) event as in the "Hazardous" category above. They also advised they had at least 3 or 4 layers of redundancies built in and all these related to the battery cells, charging, monitoring, etc and no mention of the blue battery case. So I think its safe to assume, that based on the thiness of the metal this was not intended as "containment" in the strict sense of safety, other than a convenient box to package and carry the cells, and furthermore this didn't figure in their 1:10^7 metric for safety, which in this case only took into account the 3 or 4 layers of redundancies described above. Now with two battery burning events occuring in 50,000 hrs or 1 in 25,000 hrs this fell far short of the 1:10 million design event. Recognizing from a statistical point of view 2 data points are virtually useless, but try and convince the public of that because perception is everything, and from a common sense point of view something happening this frequently when it's not supposed to, has to raise red flags - hence the grounding.

(2b) - Boeings battery system fix. Involved Battery Modifications and Containment and these two items have been discussed in great detail on many posts. Without knowing the root cause Boeing used the shotgun approach to improve the safety of the Battery. This was a very logical systematic approach aimed at every possible cause and can only lead to a much improved and safer battery with a high possibility of actually nailing the root cause, but there are no guarantees - hence the containment vessel. The containment vessel which totally isolates the battery and any future burning issues, is constructed with 1/8 inch thick stainless steel and vented to outside the a/c. It is engineered with known conditions to a FS of 3. (Factor of Safety). This containment vessel is independent of layers of redundancies as is required for a/c systems e.g. deployment, or retraction of landing gear system, but equivalent to the structural design of the landing gear metal framework. Just as a bridge, building including skyscrapers in NYC are designed for a FS of 2. So my speculation is, although Boeing made significant modifications to the Battery, their strategy for quick FAA approval was to place total safety reliance of 1:10^7hrs (1:10 million) or more on the containment vessel. To do otherwise without root cause, despite the battery mods, could have resulted in a much longer grounding, because of loss of trust by the regulators in the way the initial safety metric of 1:10 million was developed being based on the combined effects of 3 or 4 layers of redundancies for the battery. Now this strategy sets the stage for next generation batteries/ containment.

(3) - Next generation batteries/ containment. The 1/8 inch thick stainless steel containment vessel reportedly adds approx. 75 lbs/ battery or making the battery plus containment equivalent to a Ni-Cad battery. Going to 1/8 inch thick titanium would reduce the weight by about 25 to 30 lbs /battery. As discussed by others this containment vessel provides some additional space sufficient to experiment "safely" with other less volatile Li-ion chemistries, which may require say 10% more space than the current modified battery. I believe Li- ion batteries are here to stay - its only a natural progression which has to start somewhere, and it would surprise me if Boeing wasn't already seriously investigating alternative chemistries because it will take at least 2 years, with current and yet to be produced aircraft, to verify/ test their battery mod/ fix with 1 million hours of service - at least with the containment they have a safe way of verifying. It also wouldn't surprise me if the regulators insist on battery containment when using Li-ion chemistries.

Conclusion
Looking down the road perhaps 1 to 3 years, once safe Li-ion chemistries are developed and proven, as someone else posted, they would likely shrink the containment by integrating it into the battery case to save further weight. Obviously outside venting will be part of the system to release pressure and heat build up from battery malfunction issues. If titanium was used for this integrated battery case it would further reduce the added 75 lbs/ battery weight by about 50 to 55 lbs/ battery, or for a total increase of weight of 20 to 25 lbs/ battery to the origional battery prior to issues. This is still 50 to 55 lbs/ battery less than going back to NiCad.

Question
The question is and somebody else can do the math. If they went to an integrated titanium battery case with an a/c reduction in weight of 100 to 110 lbs what would the total $ savings be for say, 1,500 aircraft over a period of 20 years. Back of the envelope tells me around $5 billion or $170,000 per a/c per year. And I don't know how 110 lbs translates - small pax or freight? Probably pax, nobody is going to adjust for 40 or 50 lbs of fuel. Conclusion something is likely going to change sooner than later - its called progression. One final question, over the last 3 months Boeing invested significant resources on Li-ion issues, hundreds of engineers, 200,000 hrs, involving many experts form around the world - with this significant R and D investment in Li-ion would it now be wise to even remotely consider going back to NiCad? This question is only aimed at the so called "bus and train riders", who are actually much bigger risk takers than they think.
 
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RE: Next Gen 787 Battery Containment

Wed May 08, 2013 2:11 am

Quoting twiga (Reply 11):
The question is and somebody else can do the math. If they went to an integrated titanium battery case with an a/c reduction in weight of 100 to 110 lbs what would the total $ savings be for say, 1,500 aircraft over a period of 20 years. Back of the envelope tells me around $5 billion or $170,000 per a/c per year.

My back of the envelope math comes to a different result. I cannot figure how you come to a $170,000 saving per a/c per year.

Let's take some very rough numbers: 100 lbs containment reduction, average 787 flying weight 400,000 lbs. A direct relationship between weight and fuel burn.

Then the 100 lbs saving means 1/4000 less fuel burn. And it means that a 787 burns fuel per year worth 4000 x $170,000 = $680 million.

$680 million, that is roughly 500 million kg fuel these days. If we assume a fuel burn of 5,000 kg per hour, then it means that every 787 shall fly 100,000 hours per year.

That meas that every 787 shall fly 100,000 / 365.25 = 274 hours each day.

Which is obviously not possible. I think your estimate is a factor 20 off scale. Making the potential per plane/year saving $8,500 instead of $170,000.

Now fuel burn on a plane isn't entirely weight related. It is in fact drag related. Roughly half of the drag is related to lift generation. So in reality we can cut the potential $8,500 saving in half.

Well over four grand is still sort of money. But eleven dollars and 63 cent a day isn't what makes or breaks 787 profitability.
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twiga
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RE: Next Gen 787 Battery Containment

Wed May 08, 2013 5:50 am

Quoting prebennorholm (Reply 12):
Quoting twiga (Reply 11):The question is and somebody else can do the math. If they went to an integrated titanium battery case with an a/c reduction in weight of 100 to 110 lbs what would the total $ savings be for say, 1,500 aircraft over a period of 20 years. Back of the envelope tells me around $5 billion or $170,000 per a/c per year.
My back of the envelope math comes to a different result. I cannot figure how you come to a $170,000 saving per a/c per year.
Quoting prebennorholm (Reply 12):
Which is obviously not possible. I think your estimate is a factor 20 off scale. Making the potential per plane/year saving $8,500 instead of $170,000.
Now fuel burn on a plane isn't entirely weight related. It is in fact drag related. Roughly half of the drag is related to lift generation. So in reality we can cut the potential $8,500 saving in half.
Well over four grand is still sort of money. But eleven dollars and 63 cent a day isn't what makes or breaks 787 profitability.

I spent about 10 minutes doing this and used a totally different approach. Right or wrongly I used a "revenue" approach. As posted the basic costing was for 1,500 aircraft over a 20 yr period with a weight saving of 100 to 110 lbs. Following are my assumptions.
1)-As alluded to in my post the 100 to 110 lb weight saving would transalate into to 1 extra pax. (right now they are removing 1 pax for the extra 150 lb, they could be clever and make some adjustment for the extra 40 or 50 lbs to accomodate that extra pax)
2)-Each airplane would fly on average 345 days/ yr
3)-Each airplane would fly one 10 hr flight/ day and the pax revenue for that 10 hr flight would be $475. (if an a/c made say 4 shorter flights/ day revenue would be higher) (Vancouver to LHR costs about $1,150 return)
4)-Admin costs would be the same whether you carried 250 pax or 251 pax (2 flight crew, same # flight attendants etc)

Total Revenue = 1,500 a/c x 1-10hr flight/ day x 345 days/ yr x 20 yrs x $475 /10hr flight = $5.175 B
Revenue/ a/c / year = $5.175 B/(1,500 x 20) = $172,500/ yr (forgot to subtract fuel cost for 1 pax/ yr)
Savings/ yr = Revenue/ yr - fuel costs for 1 pax/ yr = $172,500 - $8,500 = $164,000 savings/ yr/ airplane or $4.92 Billion for 1,500 a/c for 20 years

Anyway thats my back of the envelope and its vastly different than yours, so which of my assumptions is that wild and what part of the math did I get wrong? If you gave this problem to 5 accountants I'm sure you would get 5 quite different answers but I don't think any of them would come anywhere near $4,250 savings/ yr/ airplane.
 
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zeke
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RE: Next Gen 787 Battery Containment

Wed May 08, 2013 7:11 am

Quoting prebennorholm (Reply 12):

I did it a slightly different way, I assume an aircraft flies 2x7 hr sectors a day. As a benchmark, an A330-300 at max weight costs around 225kg of additional fuel for each 1000 kg increase in AUW for a 7 hr sector. Lets say the 787-8 burns less fuel, and this number is 200 kg per 7 hr sector, that would be 400 per day (2x7 hrs sectors) to carry an extra 1000 kg in AUW over 2x7 hr sectors.

Fuel is about $900 per 1000 kg. http://www.iata.org/publications/eco...-monitor/Pages/price-analysis.aspx

Looking at 150 lbs, it equates (150/2.2042)/1000 x 400 = 27 kg/day or 9.9t/year = $8942
Looking at 50 lbs, it equates (50/2.2042)/1000 x 400 = 9 kg/day or 3.3t/year = $2890

Dropping 100 lb would save around $6000 per year, $16.43 a day, or $1.17 per hour.
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dynamicsguy
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RE: Next Gen 787 Battery Containment

Wed May 08, 2013 10:49 am

Quoting twiga (Reply 13):
Anyway thats my back of the envelope and its vastly different than yours, so which of my assumptions is that wild and what part of the math did I get wrong?

The assumption that every flight is operated at the edge of the payload/range curve and you need to offload a passenger to meet the mission. For almost every mission you have the ability to add the extra fuel to fly the extra weight, so the incremental cost of the box is only for that fuel.
 
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bikerthai
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RE: Next Gen 787 Battery Containment

Wed May 08, 2013 6:33 pm

Alas, the decision on whether Boeing will update the battery containment system does not rest with how much fuel the airlines will save. It will depend on how much under the guarantee weight the 787 will be. If the 787 gets into weight issue, Boeing may decide to put investments in weight saving design changes somewhere else. Boeing's calculation for cost per weight saved is much different than how airlines calculation. Shrug.

bt
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twiga
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RE: Next Gen 787 Battery Containment

Thu May 09, 2013 12:44 am

Quoting justloveplanes (Reply 2):
at $3 gallon for Jet Fuel that is about $11 per thousand miles, and say 5000 miles per day for a 787. So about $60 per day to fly around the battery upgrade. $1800 per month, about $20K a year.
Quoting prebennorholm (Reply 12):
Which is obviously not possible. I think your estimate is a factor 20 off scale. Making the potential per plane/year saving $8,500 instead of $170,000. Now fuel burn on a plane isn't entirely weight related. It is in fact drag related. Roughly half of the drag is related to lift generation. So in reality we can cut the potential $8,500 saving in half. Well over four grand is still sort of money. But eleven dollars and 63 cent a day isn't what makes or breaks 787 profitability.
Quoting zeke (Reply 14):
Dropping 100 lb would save around $6000 per year, $16.43 a day, or $1.17 per hour.

Above we have three posts that have all focused on fuel burn as the primary consideration for airplane economics. And realizing that these are all "back of the envelope" calculations there is quite a variation in the annual cost savings per airplane - $4,500/yr, $6,000/yr and $20,000/yr, a max variation of approx 4.5 times. All significantly different than mine of $170,000/yr. From this focus on "fuel" it gives the impression that they build airplanes to carry fuel. I thought they built airplanes to carry pax, and that should be the main and primary focus on economics - and granted fuel and fuel burn is a very important consideration, and is part of the overall equation, but not the only one. My number was primarily based on revenue and to be fair, an adjustment of say 25 to 30% of pax fair, should have been made for fuel, which brings the number for savings down to around $125,000/yr or $3.75 B for 1,500 a/c over 20 yr. When airlines evaluate new aircraft to upgrade their fleets, the overall economics involves evaluating (among other items) both revenue from pax, and expenses from fuel burn. Why do the analysis above only consider one side of this equation - that is the fuel and fuel burn? If you were the CEO of an airline company and your accountants/ economists were tasked to evaluate the purchase of 100 new aircraft, would you be happy if they told you they only studied fuel burn and fuel, and forgot to look at the pax side of the equation? Whether its one extra pax or 5 extra pax its all part of the same equation and the principles involved - the changes just involve a multiple.

I know little about aircraft and the industry, and even less about economics, but just thought there might be a common sense approach. Ah well it was worth a try. One final question - how much C02 would be saved? No I don't want any involvement in this - too much exposure to the firing squad.  wink 

Quoting bikerthai (Reply 16):
Alas, the decision on whether Boeing will update the battery containment system does not rest with how much fuel the airlines will save. It will depend on how much under the guarantee weight the 787 will be. If the 787 gets into weight issue, Boeing may decide to put investments in weight saving design changes somewhere else. Boeing's calculation for cost per weight saved is much different than how airlines calculation. Shrug.

Perhaps you are right and all the above is just nonsense.

[Edited 2013-05-08 18:18:50]
 
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zeke
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RE: Next Gen 787 Battery Containment

Thu May 09, 2013 1:36 am

Quoting bikerthai (Reply 16):
If the 787 gets into weight issue, Boeing may decide to put investments in weight saving design changes somewhere else. Boeing's calculation for cost per weight saved is much different than how airlines calculation.

What do you mean by if ?

Boeing will do the bare minimum it needs to, it is a business, not a charity.

Quoting twiga (Reply 17):
Why do the analysis above only consider one side of this equation - that is the fuel and fuel burn?

Because most aircraft are not operated at the maximum limits, the example I gave was for 2x7 hr sectors, giving about 14 hrs a day utilization which is about normal for a widebody. A 7 hr sector is not anywhere near the maximum range for the 787, so payload is not going to be offloaded. The only additional direct cost will be fuel. The battery mod is not taking up a passenger seat or cargo space.

Quoting twiga (Reply 17):
If you were the CEO of an airline company and your accountants/ economists were tasked to evaluate the purchase of 100 new aircraft, would you be happy if they told you they only studied fuel burn and fuel, and forgot to look at the pax side of the equation?

When looking at new aircraft, we look at they type across a network, various routes, various loads, various times of the year. Everything comes into play. Most routes however for a 787 will not involve maximum range.
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dynamicsguy
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RE: Next Gen 787 Battery Containment

Thu May 09, 2013 8:53 am

Quoting twiga (Reply 17):
Above we have three posts that have all focused on fuel burn as the primary consideration for airplane economics.

No, the focus on fuel burn is because for this question that is the main additional cost and I can't see any other significant saving it would bring. You are right that in any analysis of the economics needs to consider other aspects of the operational costs and revenue, but your assumption that a passenger will in all cases be offloaded to offset the weight of the fix is flawed and would only apply for the very small proportion of flights flown at the edge of the aircraft's capability. I can't see how your proposed titanium box would reduce other costs - if anything they would drive up non-recurring development and certification costs and production costs, and would probably be neutral for maintenance costs.

Your original proposition was regarding the impact of the weight:


Quoting twiga (Reply 11):
The question is and somebody else can do the math. If they went to an integrated titanium battery case with an a/c reduction in weight of 100 to 110 lbs what would the total $ savings be for say, 1,500 aircraft over a period of 20 years.
 
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bikerthai
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RE: Next Gen 787 Battery Containment

Thu May 09, 2013 1:19 pm

Quoting zeke (Reply 18):
Quoting bikerthai (Reply 16):
If the 787 gets into weight issue, Boeing may decide to put investments in weight saving design changes somewhere else. Boeing's calculation for cost per weight saved is much different than how airlines calculation.

What do you mean by if ?

Boeing will do the bare minimum it needs to, it is a business, not a charity.

You are very correct. It's all in the business case. When competing with Airbus, the bare minimum is always a moving target.

What I mean is Boeing is always looking for performance improvement and weight is only a part of it. At the beginning of a program they will be willing to spend lots more R&D and Engineering money to reduce weight. When a program is more mature, they still will spend money to get weight off, though not as much money. This is because there are always things that changes that would put weight back on (new system, cost savings initiatives).

So if you can cheaply remove weight from another system like overhead bins (strictly for example), you will do it and have extra weight buffer to absorb unforeseen weight increase like the battery weight . . . you just don't wait for the additional weight to hit you and then react . . . that is just not good business.

bt
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JoeCanuck
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RE: Next Gen 787 Battery Containment

Thu May 09, 2013 8:19 pm

They chose the quick and dirty way of containment, not worrying about weight, for the sake of getting the planes back into service. There are other, lighter materials which would serve just as well as containment, and Boeing is no doubt working on those as well.

As mentioned, there is titanium, a lighter but significantly more expensive prospect. There is a laminated approach, using ceramic, steel and aluminum. There are also very high temperature composites which are both strong, and chemical and fire resistant. Some formulations of silicone can withstand crazy temperatures, (shuttle tiles being an example), and might make a good, light lining for the box, and cell dividers.

This containment can be developed behind the scenes and introduced later in the production process and even as a retrofit.
What the...?
 
twiga
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RE: Next Gen 787 Battery Containment

Thu May 09, 2013 10:42 pm

Quoting zeke (Reply 18):
Because most aircraft are not operated at the maximum limits, the example I gave was for 2x7 hr sectors, giving about 14 hrs a day utilization which is about normal for a widebody. A 7 hr sector is not anywhere near the maximum range for the 787, so payload is not going to be offloaded. The only additional direct cost will be fuel. The battery mod is not taking up a passenger seat or cargo space.

Agree - what you say makes a lot of sense. See my fuller reply below last quote, because its a simmilar theme.

Quoting zeke (Reply 18):
When looking at new aircraft, we look at they type across a network, various routes, various loads, various times of the year. Everything comes into play. Most routes however for a 787 will not involve maximum range.

Agree - When making large purchases they would have teams of professionals including economists involved for months studying all the things you mentioned and more to make these important decisions.

Quoting dynamicsguy (Reply 19):
No, the focus on fuel burn is because for this question that is the main additional cost and I can't see any other significant saving it would bring. You are right that in any analysis of the economics needs to consider other aspects of the operational costs and revenue, but your assumption that a passenger will in all cases be offloaded to offset the weight of the fix is flawed and would only apply for the very small proportion of flights flown at the edge of the aircraft's capability. I can't see how your proposed titanium box would reduce other costs - if anything they would drive up non-recurring development and certification costs and production costs, and would probably be neutral for maintenance costs.

Agreed - And you were the first one in your previous post to point out the "flaw" of applying the revenues and savings across the entire range of operation, whereas in reality it would only apply to that upper narrow band of operation where you have full pax and full fuel loads for long range operations. In fact the methodology I used would give similar results to the fuel analysis approach, if it is applied to 5% of the upper band of operation. As follows $125,000 x 5% = approx $6,000/ ac/ yr. So we are all now agreed.   
 
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bikerthai
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RE: Next Gen 787 Battery Containment

Mon May 13, 2013 1:14 pm

Quoting JoeCanuck (Reply 21):
They chose the quick and dirty way of containment, not worrying about weight,

Quick and dirty is the key word. Note that all the parts that were built required NO TOOLING. All the other option you and others have described (me included) require tooling (either forming or curing tools) which require long lead both in terms of design and fabrication.

bt
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HAWK21M
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RE: Next Gen 787 Battery Containment

Tue May 14, 2013 9:35 am

Quoting JoeCanuck (Reply 21):
They chose the quick and dirty way of containment, not worrying about weight, for the sake of getting the planes back into service. There are other, lighter materials which would serve just as well as containment, and Boeing is no doubt working on those as well

I feel the weight issue will be tackled with other materials over time....currently the pressure was to get the B787 flying.
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