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Here to there wrote:
On Tue, 26 Oct 2004 18:51:45 GMT, Pete wrote: But Molin didn't know he was putting more pressure on the tail than it could bear. Why he didn't -- and who's to blame for that -- is the subject of a bitter fight between Airbus and American. I thought that was one of the main advantages of fly-by-wire systems, to eliminate truly stupid actions of pilots. Sounds like Airbus shares a lot of blame for the crash. It's like an auto maker made a car that sheared off its wheels if the steering wheel was turned too quickly, and the maker's response was to tell drivers, "Don't do that!" Ummmmmm... so what exactly do you think will happen to a car if you turn the wheel rapidly while driving at more than a snail's pace? If it exceeds the available traction of the tires then I expect the car to start sliding and possibly spin out. As long as the car doesn't hit anything then I expect loss of tire rubber to be the most serious damage. Of course if there is an impact (even with something like a curb), then there are likely to be much more severe consequences. I'll give you a hint - you'll get the opportunity to find out either how expensive it is to replace your suspension, CV joints, etc, or how well your roof supports the weight of the car after it has flipped. Probably you'll discover all of those. BMW had a sales promotion event recently where they had us try out some of their cars on a large parking lot with a course laid out with cones. They actively encouraged aggressive driving and there were frequent incidents where control was lost resulting in the cars sliding and spinning. As far as I know there was no serious damage done to any of the vehicles other than loss of tire rubber (tires were replaced every 2-3 hours during the event). "Don't do that" is a perfectly reasonable approach. You can't make everything infinitely strong. But if there's a clear rule for what 'shouldn't be done' then it would seem prudent to build it into the firmware for the fly-by-wire system so that it can't be done. From what I've read, it wasn't the first officer's fault, really - he did exactly what he was trained to do. Unfortunately, his training was wrong. |
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On Tue, 26 Oct 2004 12:32:02 -0700, Peter wrote:
Here to there wrote: On Tue, 26 Oct 2004 18:51:45 GMT, Pete wrote: But Molin didn't know he was putting more pressure on the tail than it could bear. Why he didn't -- and who's to blame for that -- is the subject of a bitter fight between Airbus and American. I thought that was one of the main advantages of fly-by-wire systems, to eliminate truly stupid actions of pilots. Sounds like Airbus shares a lot of blame for the crash. It's like an auto maker made a car that sheared off its wheels if the steering wheel was turned too quickly, and the maker's response was to tell drivers, "Don't do that!" Ummmmmm... so what exactly do you think will happen to a car if you turn the wheel rapidly while driving at more than a snail's pace? If it exceeds the available traction of the tires then I expect the car to start sliding and possibly spin out. As long as the car doesn't hit anything then I expect loss of tire rubber to be the most serious damage. Of course if there is an impact (even with something like a curb), then there are likely to be much more severe consequences. Except that's not the way it frequently happens in real life. Rapid steering wheel movement at speed is one way that people manage to flip cars, even when they haven't hit obstacles or gone off the road. Around here, the tow trucks do a land office business in the winter when the local students decide to do donuts in the parking lots, and flip themselves. ;-) I'll give you a hint - you'll get the opportunity to find out either how expensive it is to replace your suspension, CV joints, etc, or how well your roof supports the weight of the car after it has flipped. Probably you'll discover all of those. BMW had a sales promotion event recently where they had us try out some of their cars on a large parking lot with a course laid out with cones. They actively encouraged aggressive driving and there were frequent incidents where control was lost resulting in the cars sliding and spinning. As far as I know there was no serious damage done to any of the vehicles other than loss of tire rubber (tires were replaced every 2-3 hours during the event). Were the drivers turning the wheels rapidly, all the way to the stops? According to the crash report, that seems to be essentially what the first officer was doing with the rudder as he attempted to recover from the turbulence. "Don't do that" is a perfectly reasonable approach. You can't make everything infinitely strong. But if there's a clear rule for what 'shouldn't be done' then it would seem prudent to build it into the firmware for the fly-by-wire system so that it can't be done. Well, perhaps, if it was a fly-by-wire system.... - Rich |
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Here to there wrote:
On Tue, 26 Oct 2004 12:32:02 -0700, Peter wrote: Here to there wrote: On Tue, 26 Oct 2004 18:51:45 GMT, Pete wrote: But Molin didn't know he was putting more pressure on the tail than it could bear. Why he didn't -- and who's to blame for that -- is the subject of a bitter fight between Airbus and American. I thought that was one of the main advantages of fly-by-wire systems, to eliminate truly stupid actions of pilots. Sounds like Airbus shares a lot of blame for the crash. It's like an auto maker made a car that sheared off its wheels if the steering wheel was turned too quickly, and the maker's response was to tell drivers, "Don't do that!" Ummmmmm... so what exactly do you think will happen to a car if you turn the wheel rapidly while driving at more than a snail's pace? If it exceeds the available traction of the tires then I expect the car to start sliding and possibly spin out. As long as the car doesn't hit anything then I expect loss of tire rubber to be the most serious damage. Of course if there is an impact (even with something like a curb), then there are likely to be much more severe consequences. Except that's not the way it frequently happens in real life. Rapid steering wheel movement at speed is one way that people manage to flip cars, even when they haven't hit obstacles or gone off the road. Around here, the tow trucks do a land office business in the winter when the local students decide to do donuts in the parking lots, and flip themselves. ;-) In real life, parking lots unfortunately have many things you can impact such as curbs, potholes, posts, etc. In the absence of those there aren't all that many models of cars that can be flipped on a flat parking lot. That was one of Nader's original complaints about the Corvair and VW Beetle - due to an unusual rear suspension design it was possible to flip these. There are also some vehicles that are relatively narrow with a high center-of-gravity, but most cars will not flip when driven on a flat surface regardless of the control inputs. I'll give you a hint - you'll get the opportunity to find out either how expensive it is to replace your suspension, CV joints, etc, or how well your roof supports the weight of the car after it has flipped. Probably you'll discover all of those. BMW had a sales promotion event recently where they had us try out some of their cars on a large parking lot with a course laid out with cones. They actively encouraged aggressive driving and there were frequent incidents where control was lost resulting in the cars sliding and spinning. As far as I know there was no serious damage done to any of the vehicles other than loss of tire rubber (tires were replaced every 2-3 hours during the event). Were the drivers turning the wheels rapidly, all the way to the stops? Yes, the wheels were turned rapidly and the cars did spin out of control - but there was no indication that any even came close to flipping over. According to the crash report, that seems to be essentially what the first officer was doing with the rudder as he attempted to recover from the turbulence. "Don't do that" is a perfectly reasonable approach. You can't make everything infinitely strong. But if there's a clear rule for what 'shouldn't be done' then it would seem prudent to build it into the firmware for the fly-by-wire system so that it can't be done. Well, perhaps, if it was a fly-by-wire system.... Yes, this accident was on the A300 without FBW - my comment was just agreeing that this should be an advantage of the FBW systems. My reading of the reports on the accident is that while the co-pilot's actions may have been the proximate 'cause' of the tail's failure, the fault was not the co-pilot's but rather with the training which failed to indicate that such use of the rudder could cause structural failure. Whether that's the fault of Airbus or American remains to be determined - sounds like there's still plenty of finger-pointing going on. |
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![]() "Peter" wrote In the absence of those there aren't all that many models of cars that can be flipped on a flat parking lot. That was one of Nader's original complaints about the Corvair pppplease everyone note: That was true for pre 63, only. -- Jim in NC --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.782 / Virus Database: 528 - Release Date: 10/23/2004 |
#5
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Hi!
Morgans wrote: "Peter" wrote In the absence of those there aren't all that many models of cars that can be flipped on a flat parking lot. That was one of Nader's original complaints about the Corvair pppplease everyone note: That was true for pre 63, only. Have you ever heard about the "Moose Test"? MB A class failed that test and had to get electronic stability control to pass that test. brgds -- Gunter Herrmann Naples, Florida, USA |
#6
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In article ,
Morgans wrote: "Peter" wrote In the absence of those there aren't all that many models of cars that can be flipped on a flat parking lot. That was one of Nader's original complaints about the Corvair pppplease everyone note: That was true for pre 63, only. The 63 and 64 Corvairs were the primary subject of Nader's _Unsafe At Any Speed_. The 65 Corvairs added a stabilizer to the suspension. And the primary complaint about the original suspension was not that it caused the cars to flip, but that it tended to cause the outside wheel to tuck under during sharp cornering, leading to a sudden breakaway skid with no warning creep. It could also lead to a rollover if something as minor as a pothole tripped that wheel as it entered such a skid, but that wasn't the primary failure mode. _Consumers' Reports_ once rated a small Suzuki SUV Not Acceptable because of its tendency to tip, which they speculated could lead to rollover accidents. It's the rarity of that phenomenon that made it newsworthy. Virtually all real-world rollover accidents involve the wheels being tripped by a curb or other obstruction. -- Randy Hudson |
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Randy Hudson wrote:
It's the rarity of that phenomenon that made it newsworthy. Virtually all real-world rollover accidents involve the wheels being tripped by a curb or other obstruction. You've obviously not watched any good documentary on the subject. Police car chases in Los Angeles almost always involve some spectacular roll over. British spies are almost always involved in some form of car chase which involves some roll over. Heck, in a recent documentary about british spies, the spy was in a fancy sports car (aston martin if I recall correctly) on smooth ICE in iceland and the car flipped and slid for a while on its roof, until the spy pressed the "eject passenger seat" button which causes the case to bounce back into right side up condition, showing just how easy it is for a car to flip. It is possible that there might be something special about gravity in the Los Angeles area that makes it much easier for cars to flip over. I haven't personally witnessed any such accidents where I live (except in documentaries at the he movie theatre or TV). |
#8
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![]() "Peter" wrote in message ... Here to there wrote: On Tue, 26 Oct 2004 12:32:02 -0700, Peter wrote: Here to there wrote: On Tue, 26 Oct 2004 18:51:45 GMT, Pete wrote: But Molin didn't know he was putting more pressure on the tail than it could bear. Why he didn't -- and who's to blame for that -- is the subject of a bitter fight between Airbus and American. I thought that was one of the main advantages of fly-by-wire systems, to eliminate truly stupid actions of pilots. Sounds like Airbus shares a lot of blame for the crash. It's like an auto maker made a car that sheared off its wheels if the steering wheel was turned too quickly, and the maker's response was to tell drivers, "Don't do that!" Ummmmmm... so what exactly do you think will happen to a car if you turn the wheel rapidly while driving at more than a snail's pace? If it exceeds the available traction of the tires then I expect the car to start sliding and possibly spin out. As long as the car doesn't hit anything then I expect loss of tire rubber to be the most serious damage. Of course if there is an impact (even with something like a curb), then there are likely to be much more severe consequences. Except that's not the way it frequently happens in real life. Rapid steering wheel movement at speed is one way that people manage to flip cars, even when they haven't hit obstacles or gone off the road. Around here, the tow trucks do a land office business in the winter when the local students decide to do donuts in the parking lots, and flip themselves. ;-) In real life, parking lots unfortunately have many things you can impact such as curbs, potholes, posts, etc. In the absence of those there aren't all that many models of cars that can be flipped on a flat parking lot. That was one of Nader's original complaints about the Corvair and VW Beetle - due to an unusual rear suspension design it was possible to flip these. There are also some vehicles that are relatively narrow with a high center-of-gravity, but most cars will not flip when driven on a flat surface regardless of the control inputs. I'll give you a hint - you'll get the opportunity to find out either how expensive it is to replace your suspension, CV joints, etc, or how well your roof supports the weight of the car after it has flipped. Probably you'll discover all of those. BMW had a sales promotion event recently where they had us try out some of their cars on a large parking lot with a course laid out with cones. They actively encouraged aggressive driving and there were frequent incidents where control was lost resulting in the cars sliding and spinning. As far as I know there was no serious damage done to any of the vehicles other than loss of tire rubber (tires were replaced every 2-3 hours during the event). Were the drivers turning the wheels rapidly, all the way to the stops? Yes, the wheels were turned rapidly and the cars did spin out of control - but there was no indication that any even came close to flipping over. According to the crash report, that seems to be essentially what the first officer was doing with the rudder as he attempted to recover from the turbulence. "Don't do that" is a perfectly reasonable approach. You can't make everything infinitely strong. But if there's a clear rule for what 'shouldn't be done' then it would seem prudent to build it into the firmware for the fly-by-wire system so that it can't be done. Well, perhaps, if it was a fly-by-wire system.... Yes, this accident was on the A300 without FBW - my comment was just agreeing that this should be an advantage of the FBW systems. My reading of the reports on the accident is that while the co-pilot's actions may have been the proximate 'cause' of the tail's failure, the fault was not the co-pilot's but rather with the training which failed to indicate that such use of the rudder could cause structural failure. Whether that's the fault of Airbus or American remains to be determined - sounds like there's still plenty of finger-pointing going on. 1:The FACS should have prevented flight control inputs aggressive enough to damage the A/C. 2: The Rudder limiter should not have allowed the rudder to go stop to stop several times. Ralph Nesbitt Professional FD/CFR/ARFF Type |
#9
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Peter wrote:
In real life, parking lots unfortunately have many things you can impact such as curbs, potholes, posts, etc. In the absence of those there aren't all that many models of cars that can be flipped on a flat parking lot. That was one of Nader's original complaints about the Corvair and VW Beetle - due to an unusual rear suspension design it was possible to flip these. There are also some vehicles that are relatively narrow with a high center-of-gravity, but most cars will not flip when driven on a flat surface regardless of the control inputs. That is especially true if the road surface is wet or snow covered. Yes, the wheels were turned rapidly and the cars did spin out of control - but there was no indication that any even came close to flipping over. Just because a car is spinning, doesn't mean it is out of control. Is your plane out of control if you spin it? If so how do you stop the spin with out hitting the ground? -- Chris W Not getting the gifts you want? The Wish Zone can help. http://thewishzone.com "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin, 1759 Historical Review of Pennsylvania |
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Chris W wrote:
Peter wrote: Yes, the wheels were turned rapidly and the cars did spin out of control - but there was no indication that any even came close to flipping over. Just because a car is spinning, doesn't mean it is out of control. And I neither wrote nor implied anything to the contrary. But in the case I was describing the cars were both spinning and out of control. |
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