The Boeing 787... Cool aircraft, but is it a bit too ambitious?
01-06-2007, 08:00 PM
#21
Gets Weekends Off
Joined APC: Nov 2006
Posts: 135
All,
While I appreciate the confidence in Boeing and hope they indeed are doing it all right, remember that they failed their fuselage cert test for the 787 because one of the fuselage barrels they were going to use was found to have voids in the composite matrix. The stuff is tricky, they have to really, really take the inspection methods seriously and this is a concern given the driven nature of the business.
I worry more than even about Airbus, however, because they are truly in dire straights. They cut corners when they were tops in the industry; I don't even want to imagine their attitude on safety when they are in a panic.
No weak-winged, pencil-whipped composite-winged A-380 for me, thanks.
Jetblaster
While I appreciate the confidence in Boeing and hope they indeed are doing it all right, remember that they failed their fuselage cert test for the 787 because one of the fuselage barrels they were going to use was found to have voids in the composite matrix. The stuff is tricky, they have to really, really take the inspection methods seriously and this is a concern given the driven nature of the business.
I worry more than even about Airbus, however, because they are truly in dire straights. They cut corners when they were tops in the industry; I don't even want to imagine their attitude on safety when they are in a panic.
No weak-winged, pencil-whipped composite-winged A-380 for me, thanks.
Jetblaster
01-06-2007, 08:07 PM
#22
Gets Weekends Off
Joined APC: Mar 2006
Position: Red Tail CRJ CA
Posts: 262
Originally Posted by Imeneo
Hello all again... I guess I've been thinking lately about the Boeing 787 as I've started my research in composite materials. Anyway from what I've studied composites are quite difficult to repair without compromising strength and toughness, they are not really as isotropic as metals (uniform in properties in all directions of the material), and are quite expensive when you get into exotic aerospace laminates.
It is my understanding that Boeing has done its own research on composites (probably with data obtained through miltary and space craft designs). However, if I understand correctly this will be the first time in aviation history where the entire fusalage of a commerical airliner will be made entirely of composites. Now that concerns me a little because not only is this a vastly different animal than say a fighter aircraft body (which undergoes extreme loading conditions, but is unpressurized and relatively easier to engineer IMHO because of its small size and singular usage). In a commerical aircraft fusalage you not only have the loading every other aircraft encounters, but also pressurization cycling... not to mention those large windows and doors that could lead to high stress concentrations. And yes, composites have been used as pressure vessels (gas canisters), but those are pretty simple cylindrical shapes with simple loadings.
Yes, the commercial aircraft manufacturing industry has used composite materials for years on the order of 10% - 30% composites... but these have been mostly used for non-load bearing parts like panel coverings etc. I believe airbus uses composite control surfaces with honeycomb interiors, but those have been under regulator scrutiny as of late.
My professor says that in all likelyhood Boeing has developed "advanced aerospace composites" that give favorable testing results, but as far as how they accomplish such a feat, he still remains clueless.
Still there is the matter of composite laminate damage testing, and how unless newer more riggorous techniques to test composite damge is developed and standardized in the aircraft industry we could see a great deal of problems with the Boeing 787. Micro cracking anywhere on the fusalage can lead to moisture intrusion and moisture weakening of the general area in between composite layer.
I guess from the airline standpoint, sure they'll be saving money by flying lighter, longer-range aircraft, but at what cost? Aircraft incursions with ground vehicles are not uncommon and if such ground equipment bumps into a 787, the resulting damage may be huge because I really don't think you can "patch" a composite material like you would a metal part, you have to replace the entire thing to maintain stuctural integrity. So an aircraft encountering a mild ground incursion would be written off or go through extensive repairs (replacing entire sections of the aircraft).
I'm surprised people haven't been concerned about these things before. This is a HUGE leap of faith on the part of Boeing in the usage of composite materials. I really hope they've got their bases covered.
It is my understanding that Boeing has done its own research on composites (probably with data obtained through miltary and space craft designs). However, if I understand correctly this will be the first time in aviation history where the entire fusalage of a commerical airliner will be made entirely of composites. Now that concerns me a little because not only is this a vastly different animal than say a fighter aircraft body (which undergoes extreme loading conditions, but is unpressurized and relatively easier to engineer IMHO because of its small size and singular usage). In a commerical aircraft fusalage you not only have the loading every other aircraft encounters, but also pressurization cycling... not to mention those large windows and doors that could lead to high stress concentrations. And yes, composites have been used as pressure vessels (gas canisters), but those are pretty simple cylindrical shapes with simple loadings.
Yes, the commercial aircraft manufacturing industry has used composite materials for years on the order of 10% - 30% composites... but these have been mostly used for non-load bearing parts like panel coverings etc. I believe airbus uses composite control surfaces with honeycomb interiors, but those have been under regulator scrutiny as of late.
My professor says that in all likelyhood Boeing has developed "advanced aerospace composites" that give favorable testing results, but as far as how they accomplish such a feat, he still remains clueless.
Still there is the matter of composite laminate damage testing, and how unless newer more riggorous techniques to test composite damge is developed and standardized in the aircraft industry we could see a great deal of problems with the Boeing 787. Micro cracking anywhere on the fusalage can lead to moisture intrusion and moisture weakening of the general area in between composite layer.
I guess from the airline standpoint, sure they'll be saving money by flying lighter, longer-range aircraft, but at what cost? Aircraft incursions with ground vehicles are not uncommon and if such ground equipment bumps into a 787, the resulting damage may be huge because I really don't think you can "patch" a composite material like you would a metal part, you have to replace the entire thing to maintain stuctural integrity. So an aircraft encountering a mild ground incursion would be written off or go through extensive repairs (replacing entire sections of the aircraft).
I'm surprised people haven't been concerned about these things before. This is a HUGE leap of faith on the part of Boeing in the usage of composite materials. I really hope they've got their bases covered.
Granted it has been a while since I took eng. materials in college and when we didnt cover composites in too much great depth (we were more concerned with metals, and things like annealing and quenching ect.) and most of out composites questions were answered with a simple "well it involves a comples math matrix and you'll cover it in grad school...." To answer the later question, yes you can patch composite and it usually cures with in 24 hours the basic process is to lay a base material such a fiberglass cloth or some other type of mesh and then mix the resin or other type of adhesive in. (almost like spackling a hole in a wall) Generally once complete the patch is usually stronger than the original material... As for ground strikes well my guess is since the fuselage on a 787 will most likely sit pretty high or much higher than the CRJ that I drive atleast.... the risks will be much lower... But Im sure the various MX departments at the airlines that will fly the 787 will be getting crash courses on how to patch a fuselage.... As for the pressure cycles Im sure that these materials will function every bit as well as the metals that they are replacing as ryane said they tested the A 700 far beyond what it actually experiences in flight..... So hope that helps answer some questions...
01-06-2007, 08:23 PM
#23
Che Guevara
Joined APC: Aug 2005
Posts: 6,408
I bet the composite parts are easy to replace as wholes. LIke how they make car doors absorb impact then in half an hour they can simply just replace the whole door. The composit could be absorbers on pressure points to keep the rest of the metal from fatigueing?(spelling)
01-07-2007, 11:20 AM
#24
Swearing at the FMA
Joined APC: Jun 2006
Position: MD-88 FO
Posts: 902
Originally Posted by Imeneo
Still there is the matter of composite laminate damage testing, and how unless newer more riggorous techniques to test composite damge is developed and standardized in the aircraft industry we could see a great deal of problems with the Boeing 787. Micro cracking anywhere on the fusalage can lead to moisture intrusion and moisture weakening of the general area in between composite layer.
I guess from the airline standpoint, sure they'll be saving money by flying lighter, longer-range aircraft, but at what cost? Aircraft incursions with ground vehicles are not uncommon and if such ground equipment bumps into a 787, the resulting damage may be huge because I really don't think you can "patch" a composite material like you would a metal part, you have to replace the entire thing to maintain stuctural integrity. So an aircraft encountering a mild ground incursion would be written off or go through extensive repairs (replacing entire sections of the aircraft).
I guess from the airline standpoint, sure they'll be saving money by flying lighter, longer-range aircraft, but at what cost? Aircraft incursions with ground vehicles are not uncommon and if such ground equipment bumps into a 787, the resulting damage may be huge because I really don't think you can "patch" a composite material like you would a metal part, you have to replace the entire thing to maintain stuctural integrity. So an aircraft encountering a mild ground incursion would be written off or go through extensive repairs (replacing entire sections of the aircraft).
01-07-2007, 12:05 PM
#25
Gets Weekends Off
Joined APC: Nov 2006
Posts: 423
Originally Posted by Pilotpip
PS: The little sticker on the Katana changes around 135 degrees. Do you really want to be doing touch and gos in that kind of heat?
01-07-2007, 05:26 PM
#26
Gets Weekends Off
Joined APC: Mar 2006
Position: Red Tail CRJ CA
Posts: 262
Originally Posted by ToiletDuck
I bet the composite parts are easy to replace as wholes. LIke how they make car doors absorb impact then in half an hour they can simply just replace the whole door. The composit could be absorbers on pressure points to keep the rest of the metal from fatigueing?(spelling)
01-08-2007, 07:43 AM
#27
Gets Weekends Off
Joined APC: Nov 2006
Posts: 135
Originally Posted by Space Monkey
Yes they are easy to replace as a whole but expensive since when dealing with composites (unlike metals) entire wings and fuselages are one piece items... so if you were going to replace the wing tip on a harrier (for example) and not do a cast repair then you would have to remove and replace an entire wing not just the affected area.... in the 787's case this would be even more extreme since the fuselage is built in large high volume legnth and area pieces so to do what you are talking about might mean removing and replacing an entire third of the fuselage at a time... the better answer is to patch, sand and blend with more composite... much cheaper.... as for using composite in high pressure areas.... well answering this question is much more compicated since there are several factors that go into this......but to make a very long answer short... the first issue is which material truely is stronger or more flexable and more suited to the job??? then if we do decide to put composite and another material together how do we attach them??? a piece of composite may or may not blend and adhere to other materials... if they will not adhere or blend to each other should be use some sort of bracing or plating to attach them???? and how strong is the bracing or plating also by the time we do this is it really that much stronger and whats the cost??? if there is any additional cost is the extra stregnth or benefit worth it??? and the list continues... if the composites turn out to be worth it then they will be used if not then stick to conventional materials.... Hope this helps answer the question... Back to my wine now.... It''s Yellow Tail Chardonnay tonight............
You must be incorrect, because the manner in which Airbus repairs composite material is much different than you describe.
See this picture: http://www.ntsb.gov/events/2001/AA587/AA587_15.jpg
On AA 587, when the aircraft came off the production line, Airbus discovered a large void in the attachment lug of the vertical fin. Since there was no "approved" way to repair composite and there was no criteria under which such a repair might be certified or what resultant stiffening of the lug might do to load distribution and the Fail Safe numbers for the Part 25 certification (simulating the failure of one lug and return to base on five remaining lugs), Airbus got creative.
You can see, rather than patching the composite with sand-and blend, as you outline, the Airbus method was to take a scrap of metal plate, slap it on the outside of the identified area, drill 21 metal bolts through the composite (with resultant breaking of continuous carbon strands and introducing metal into the midst of the carbon matrix with predictable heating-and-cooling differences in the metal and carbon materials now a serious consideration) and shove it out on the line.
Jetblaster
01-08-2007, 08:47 AM
#28
Gets Weekends Off
Joined APC: Mar 2006
Position: Red Tail CRJ CA
Posts: 262
Originally Posted by jetblaster
Spacemonkey,
You must be incorrect, because the manner in which Airbus repairs composite material is much different than you describe.
See this picture: http://www.ntsb.gov/events/2001/AA587/AA587_15.jpg
On AA 587, when the aircraft came off the production line, Airbus discovered a large void in the attachment lug of the vertical fin. Since there was no "approved" way to repair composite and there was no criteria under which such a repair might be certified or what resultant stiffening of the lug might do to load distribution and the Fail Safe numbers for the Part 25 certification (simulating the failure of one lug and return to base on five remaining lugs), Airbus got creative.
You can see, rather than patching the composite with sand-and blend, as you outline, the Airbus method was to take a scrap of metal plate, slap it on the outside of the identified area, drill 21 metal bolts through the composite (with resultant breaking of continuous carbon strands and introducing metal into the midst of the carbon matrix with predictable heating-and-cooling differences in the metal and carbon materials now a serious consideration) and shove it out on the line.
Jetblaster
You must be incorrect, because the manner in which Airbus repairs composite material is much different than you describe.
See this picture: http://www.ntsb.gov/events/2001/AA587/AA587_15.jpg
On AA 587, when the aircraft came off the production line, Airbus discovered a large void in the attachment lug of the vertical fin. Since there was no "approved" way to repair composite and there was no criteria under which such a repair might be certified or what resultant stiffening of the lug might do to load distribution and the Fail Safe numbers for the Part 25 certification (simulating the failure of one lug and return to base on five remaining lugs), Airbus got creative.
You can see, rather than patching the composite with sand-and blend, as you outline, the Airbus method was to take a scrap of metal plate, slap it on the outside of the identified area, drill 21 metal bolts through the composite (with resultant breaking of continuous carbon strands and introducing metal into the midst of the carbon matrix with predictable heating-and-cooling differences in the metal and carbon materials now a serious consideration) and shove it out on the line.
Jetblaster
well as we can see the A-300 went down shortly there after... Oddly enough I was still in college when that happened... and that was one semester before I was in eng. mat. class... too funny.. but what this does show is how technology and methods are almost constantly changing.... but I can remember at one point the answer to repairing composites was to trash and replace the entire component.
01-09-2007, 08:36 PM
#29
Line Holder
Joined APC: Oct 2006
Position: Cessna 210 Turbo
Posts: 50
Well, I'm no engineer, like some of you folks are, but I certainly do understand what you are talking about.
I had only been flying for 26 years when AA 587 went down, and we all know that was the FO's fault, right????
That being said, I'm going to give Boeing the benefit of the doubt. They have a lot riding on the 787 and they know the score. While they are not "betting the company" on the 787 as they were with the 747, there remains a ton of responsibility riding on this aircraft.
It's easy for a "professor" to make a comment, and, he might be right, but...
Could the 787 be the next "Comet"? One doesn't know. However, I'd like to give Boeing the credit to say that it will perhaps be the next 707, and the 707 was not an airplane to sneeze at. It changed the face of commercial aviation.
So may the 787.
Only time will tell.
I had only been flying for 26 years when AA 587 went down, and we all know that was the FO's fault, right????
That being said, I'm going to give Boeing the benefit of the doubt. They have a lot riding on the 787 and they know the score. While they are not "betting the company" on the 787 as they were with the 747, there remains a ton of responsibility riding on this aircraft.
It's easy for a "professor" to make a comment, and, he might be right, but...
Could the 787 be the next "Comet"? One doesn't know. However, I'd like to give Boeing the credit to say that it will perhaps be the next 707, and the 707 was not an airplane to sneeze at. It changed the face of commercial aviation.
So may the 787.
Only time will tell.
01-09-2007, 09:29 PM
#30
Banned
Joined APC: May 2006
Posts: 1,192
Whats up with airbus?
Wasn't airbus the company who's niche was to make thing people wanted but other couldn't?
Tha a300 was the first widebody 2 engine jet. Airbus burst on the scene with that thing while everyone was making 3 engine and 4 engine jets.
Same goes for the a-319 series. Yes we all know about the one that went lumberjacking but that was proven to be pilot error because air frances' star captain wanted to show off somethig he had little time in. Anyway the a320 was shown to be another industry changer.
I'm just wonder why is airbus not doing this anymore. They need to get back to their roots and make things that people will buy because they are innovative not just cheaper. What airbus needs to do is come out with a new narrowbody that will blow away the 80-150 seat market. Make it dirt cheap to operate and it will blow away boeing again.
I used to HATE boeing because they became the evil company that put the hard working real american heartland companies out of business. They felt they were entitled to all the defense contracts and that people just assumed they would buy their airplanes because they were boeing. They became the ford of the sky, now it seems they finally learned their lesson. Maybe getting their asses handed to them for the last decade by airbus and lockheed has finally humbled them back to the way they were when they were on top for the right reasons.
Wasn't airbus the company who's niche was to make thing people wanted but other couldn't?
Tha a300 was the first widebody 2 engine jet. Airbus burst on the scene with that thing while everyone was making 3 engine and 4 engine jets.
Same goes for the a-319 series. Yes we all know about the one that went lumberjacking but that was proven to be pilot error because air frances' star captain wanted to show off somethig he had little time in. Anyway the a320 was shown to be another industry changer.
I'm just wonder why is airbus not doing this anymore. They need to get back to their roots and make things that people will buy because they are innovative not just cheaper. What airbus needs to do is come out with a new narrowbody that will blow away the 80-150 seat market. Make it dirt cheap to operate and it will blow away boeing again.
I used to HATE boeing because they became the evil company that put the hard working real american heartland companies out of business. They felt they were entitled to all the defense contracts and that people just assumed they would buy their airplanes because they were boeing. They became the ford of the sky, now it seems they finally learned their lesson. Maybe getting their asses handed to them for the last decade by airbus and lockheed has finally humbled them back to the way they were when they were on top for the right reasons.
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