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#21
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Other questions about the Airbus planes
In article ,
John Smith wrote: Mike Ash wrote: That is indeed ridiculous. Even more funny is that those Airbus bashers don't seem to realize that a certain Boeing Dreamliner, should it ever fly, is built with a much higher percentage of plastic parts than any Airbus. It didn't occur to me that they would be Boeing partisans. I just figured they were anti-composites. If they are Boeing fans then that does indeed make it that much funnier. -- Mike Ash Radio Free Earth Broadcasting from our climate-controlled studios deep inside the Moon |
#22
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Other questions about the Airbus planes
"Brian Whatcott" wrote in message ... Private wrote: "a" wrote in message ... One has no idea how true this is, but for what it's worth, read on:. snip More at http://www.globalresearch.ca/index.p...t=va&aid=14025 Happy landings, Dear Anonymous Poster, the level of engineering insight of this URL is typified by this paragraph: "We do not know if Air France Flight 447 was brought down by a lightning storm, a failure of speed sensors, rudder problems or pilot error. What we do know is that its plastic tail fin fell off and the plane fell almost seven miles into the ocean killing everyone aboard." If you don't realize the level of insight offered in this paragraph, should you be spreading it? IMHO the quoted passage is a fair statement of what we currently suspect, hopefully further investigation will reveal more complete information. The link was offered to stimulate thought and discussion and with the qualifier "One has no idea how true this is, but for what it's worth, read on:" All pilots are (as always) encouraged to apply their own knowledge and experience to form their own conclusions. Happy landings, |
#23
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Other questions about the Airbus planes
"Mike Ash" wrote in message ... In article , Brian Whatcott wrote: Private wrote: "a" wrote in message ... One has no idea how true this is, but for what it's worth, read on:. snip More at http://www.globalresearch.ca/index.p...t=va&aid=14025 Happy landings, snip (And yes, I realize that there are certain differences between building a 600-pound glider and a 200,000-pound airliner, and between engineering something to be safe enough to carry a single dare-devilish pilot and carrying hundreds of paying passengers. But four decades ought to be enough to figure out how it works for the latter, and indeed things are moving that way.) snip I do not disagree with much of your post, and also have personally enjoyed many happy hours flying glass gliders and powered aircraft, but feel compelled to submit that in addition to the obvious weight differences, most gliders live in a (UV free) trailer or hanger, and IMHE few have accumulated over 5000 hours (500-2000 hrs is more average) vs. 50,000 hours for airliners. (I once flew in a 737-200 that had 70,000 hrs and a similar number of cycles.) On most small powered and glider glass aircraft the vertical stab is formed as an integral part of the fuselage vs. the airliner where the weak point of the assembly seems to be the point of attachment to the fuselage. I suspect you will also agree that in addition to the increased loading and much higher speeds, the consequence of structural failure of a commercial aircraft carrying large numbers of passengers is greater than that of a much slower glider carrying 1 or 2 flyers who are probably also wearing parachutes. The real point of the article was that the materials technology, service expectations and proper inspection procedures seem to still be under development and that we still have much to learn. Older glass gliders often display obvious deterioration of at least the gel coat and crashes have been caused by structural failure or lightning strikes. Happy landings, |
#24
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Other questions about the Airbus planes
Mike Ash wrote:
It didn't occur to me that they would be Boeing partisans. Look at the subject ;-) |
#25
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Other questions about the Airbus planes
While I certainly distance myself from any of this sensationalist
speculation, and do not in any way join the Airbus detractors, I do think the apparent similarity of the vertical stabilizer separation in the two accidents is worthy of investigation. I am also fully confident that it will be investigated, and determined as to whether the similarity is only an apparent one or not. This is significant even if we never determine what its contribution may have been in the causality of the Air France accident. |
#26
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Other questions about the Airbus planes
In article ,
"Private" wrote: "Mike Ash" wrote in message ... In article , Brian Whatcott wrote: Private wrote: "a" wrote in message ... One has no idea how true this is, but for what it's worth, read on:. snip More at http://www.globalresearch.ca/index.p...t=va&aid=14025 Happy landings, snip (And yes, I realize that there are certain differences between building a 600-pound glider and a 200,000-pound airliner, and between engineering something to be safe enough to carry a single dare-devilish pilot and carrying hundreds of paying passengers. But four decades ought to be enough to figure out how it works for the latter, and indeed things are moving that way.) snip I do not disagree with much of your post, and also have personally enjoyed many happy hours flying glass gliders and powered aircraft, but feel compelled to submit that in addition to the obvious weight differences, most gliders live in a (UV free) trailer or hanger, and IMHE few have accumulated over 5000 hours (500-2000 hrs is more average) vs. 50,000 hours for airliners. (I once flew in a 737-200 that had 70,000 hrs and a similar number of cycles.) On most small powered and glider glass aircraft the vertical stab is formed as an integral part of the fuselage vs. the airliner where the weak point of the assembly seems to be the point of attachment to the fuselage. I suspect you will also agree that in addition to the increased loading and much higher speeds, the consequence of structural failure of a commercial aircraft carrying large numbers of passengers is greater than that of a much slower glider carrying 1 or 2 flyers who are probably also wearing parachutes. All fine points. I understand that the circumstances are greatly different (thus my parenthetical above), but it seems that 40 years ought to be enough to move from the one to the other. And indeed, it seems that both Airbus and Boeing think this way as well. The real point of the article was that the materials technology, service expectations and proper inspection procedures seem to still be under development and that we still have much to learn. Older glass gliders often display obvious deterioration of at least the gel coat and crashes have been caused by structural failure or lightning strikes. Gel coat deterioration is largely inconsequential, as it's not structural and can be easily replaced. (Obviously it's not "inconsequential" for the poor glider owner who has to pay five figures for a refinish, but in terms of maintenance it's easy to spot and a known quantity for repair.) The lightning strike angle is an interesting one. I assume you're referring to that ASK-21 which exploded over the UK a few years back, and which we've seen some posts about from the passenger recently. I'm not aware of another such incident, but that's probably more because gliders are fair-weather beasts, not because they're usually immune to lightning. Are there any other incidents you know of? As for the structural failure angle, my (admittedly highly limited) understanding is that there basically isn't any other than that resulting from exceeding design limits or from manufacturing defects. My club has an Open Cirrus which is over 40 years old and it's built like a tank, and by all indications every bit as strong right now as it was when it was built. My understanding is that this is the norm for composite construction, as long as it's properly protected from the elements. An important thing is that it doesn't really fatigue the way metal does. Let's not forget that metal fatigue killed a bunch of airline passengers in the 50s and remains a significant (and occasionally deadly) concern today. No doubt there is much to learn, and maybe the Airbus was improperly designed, but my point is simply that a knee-jerk rejection of all composites (which is what the article seemed to be trying to do with its pejorative use of the word "plastic") is not the way to go. Again, my knowledge on the subject is quite limited, so if I'm wrong about any of the above, or just missing further important information, I would very much appreciate any correction! -- Mike Ash Radio Free Earth Broadcasting from our climate-controlled studios deep inside the Moon |
#27
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Other questions about the Airbus planes
Mike Ash wrote:
I particularly enjoy the derisive use of the word "plastic" to describe the vertical stabilizer. As an owner of a composite aircraft, I can tell you that I much prefer "plastic" to metal when given the choice. Yeah, when you exceed its strength it fails in a completely unforgiving manner, but composites make it a *lot* harder to get to that point in the first place. Perhaps there really is an engineering deficiency here, but to think that it's the fault of the material itself and that airliner engineering should just ignore new materials technology and stick to good ol' aluminum forever is silly. Glider makers figured out how great composites were forty years ago, it's about time for the rest to catch up too. (And yes, I realize that there are certain differences between building a 600-pound glider and a 200,000-pound airliner, and between engineering something to be safe enough to carry a single dare-devilish pilot and carrying hundreds of paying passengers. But four decades ought to be enough to figure out how it works for the latter, and indeed things are moving that way.) Gliders fly at lower altitudes, at lower speeds, in good weather conditions... Airliners fly in high altitude, high speed, low temperature, in thunderstorms... How good is composite when lightning strikes? Doesn't is explode or something? I don't think it will conduct electricity, does it? Please see that as questions, I really don't know much and I'm wondering. I'm not trying to reduce your opinion in anyway. Tom |
#28
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Other questions about the Airbus planes
"Mike Ash" wrote in message ... snip something to be safe enough to carry a single dare-devilish pilot and snip Gel coat deterioration is largely inconsequential, as it's not structural How do we know for sure? snip As for the structural failure angle, my (admittedly highly limited) understanding is that there basically isn't any other than that resulting from exceeding design limits or from manufacturing defects. EXACTLY my point. snip No doubt there is much to learn, and maybe the Airbus was improperly designed, but my point is simply that a knee-jerk rejection of all composites (which is what the article seemed to be trying to do with its pejorative use of the word "plastic") is not the way to go. Again, my knowledge on the subject is quite limited, so if I'm wrong about any of the above, or just missing further important information, I would very much appreciate any correction! I think we are in substantial agreement, I particularly liked your original reference to "a single dare-devilish pilot" and am reminded of the final words (and on his gravestone) of Otto Lilienthal. http://en.wikipedia.org/wiki/Otto_Lilienthal His statement "Sacrifices must be made" pretty much sums up the history of all aviation development, during which most advances have been accompanied by the loss of (lots of) both blood and money. IMHO, The use of the term 'plastic' is probably improper and certainly overly general but it is common usage, and while I do agree that precise language is an important goal, I try not to get too fixated on semantics. Composites offer significant opportunities for improved aircraft performance, but the use of these materials is complicated by the variability of the materials and difficulty of quality control.in both manufacturing and maintenance. It seems that better inspection procedures for QC need to be developed and implemented and this will be of increased importance as composite use increases and the fleet ages. We went through a similar period in the development of metal airframes. Happy landings, |
#29
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Other questions about the Airbus planes
In article ,
"Private" wrote: I think we are in substantial agreement, I particularly liked your original reference to "a single dare-devilish pilot" and am reminded of the final words (and on his gravestone) of Otto Lilienthal. http://en.wikipedia.org/wiki/Otto_Lilienthal His statement "Sacrifices must be made" pretty much sums up the history of all aviation development, during which most advances have been accompanied by the loss of (lots of) both blood and money. Yes, it seems to me that we are in agreement as well. How unusual. IMHO, The use of the term 'plastic' is probably improper and certainly overly general but it is common usage, and while I do agree that precise language is an important goal, I try not to get too fixated on semantics. Normally I would consider it to be completely unimportant. However in this particular case, it's clearly being used as a pejorative. I don't care all that much about his use of the word "plastic", it's merely indicative of the overall attitude that composites are bad and people who use them are stupid. In other words, "plastic" is a symptom, not the disease. I've heard glider people refer to composite aircraft as "plastic" from time to time and that doesn't bother me at all, because the intent is not the same. Composites offer significant opportunities for improved aircraft performance, but the use of these materials is complicated by the variability of the materials and difficulty of quality control.in both manufacturing and maintenance. It seems that better inspection procedures for QC need to be developed and implemented and this will be of increased importance as composite use increases and the fleet ages. We went through a similar period in the development of metal airframes. The incremental use of composites in airliners, starting with small bits here and there and working up, seems like the proper way to do things here. I don't expect, or want, the airline industry to drop aluminum and start doing everything in composites. An evolutionary approach as is being done now will get us there in the end with a minimum of surprises. -- Mike Ash Radio Free Earth Broadcasting from our climate-controlled studios deep inside the Moon |
#30
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Other questions about the Airbus planes
In article ,
Tom Duhamel wrote: Gliders fly at lower altitudes, at lower speeds, in good weather conditions... Airliners fly in high altitude, high speed, low temperature, in thunderstorms... Don't think airliners fly higher. It's true that *on average* they do, and they certainly collect *vastly* more time at FL360 than gliders do, but gliders *do* collect time there. The current glider altitude record, set in a composite glider, is over 50,000ft. I don't think low temperatures or pressures have been seen to do anything bad to the structure. A fellow did tell me once that a rapid descent can do bad things to the gelcoat due to the temperature change, but that's a separate issue, and I don't know if an airliner would even use that sort of coating. For speeds, that's really just a matter of increased structural strength and stiffness, which means using more stuff or different shapes. The question is how the composites tolerate load, which is well known. They won't change their characteristics suddenly just because they're moving. How good is composite when lightning strikes? Doesn't is explode or something? I don't think it will conduct electricity, does it? This one is a completely open question to me. No, they don't conduct electricity as far as I know. In the one famous case of a glider getting hit by lightning, the lightning traveled along metal control rods. The rods superheated the air inside the wings, blowing the glider to bits. Obviously this is not a desirable outcome for an airliner carrying 300 people and no parachutes. I can only assume that the smart engineers working on this stuff have figured out a way to stop this from happening, but I have no idea at all what that way would be. -- Mike Ash Radio Free Earth Broadcasting from our climate-controlled studios deep inside the Moon |
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