probes
17th May 2012, 21:26
Thought I'd ask about the Polish government plane crash here, not to upset the pros up there. A new guy to investigate technical aspects, a US professor (the link from rumorous news):
Binienda specializes in fracture mechanics, a highly technical field that analyzes how and why materials break under stress. His focus is the lightweight stuff – aluminum, titanium and exotic polymers –used in aviation and aerospace. He often works with NASA and jet engine manufacturers. He is no stranger to aircraft structures.
The wing-tree impact became the target of his inquiry. It didn't make sense to Binienda that, after a collision that severed a third of the wing, the jet would be able to climb almost 100 feet in altitude before crashing, as the Russian investigators had concluded. Robbed of lift and momentum, the damaged plane should drop like a stone.
To study the wing-tree impact, Binienda created a computer model using a software program called LS-DYNA (http://www.lstc.com/products/ls-dyna). He and other engineers routinely use LS-DYNA to simulate complex fracture situations with lots of rapidly changing conditions, like when a loose, high-speed chunk of insulating foam bashed into the space shuttle Columbia's (http://www.google.com/url?sa=t&rct=j&q=ls-dyna%20columbia&source=web&cd=1&ved=0CCQQFjAA&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload% 3Fdoi%3D10.1.1.76.5872%26rep%3Drep1%26type%3Dpdf&ei=lAGbT879Ls_wggfX1fCVDw&usg=AFQjCNHtGlA2k58y6iAkYDBis-tmvffPvQ&cad=rja) wing during a 2003 launch, fatally damaging the orbiter.
With LS-DYNA and information from the crash reports, Binienda could input the strength, density and other properties of the wing and the tree. That allows a computer to calculate the impact forces and create a second-by-second, realistic 3-D animation (http://www.youtube.com/watch?v=fbJ29pGJLNU) of what happened.
Even when Binienda intentionally under-represented the wing's strength and over-estimated the tree's, the simulations still showed the wing slicing off the treetop while suffering only minor damage. The tree impact couldn't have broken the wing, his model showed. Something else must have done that, and something else must have snapped off the treetop. (For the latter, Binienda suspects it was the powerful backwash from the jet's engines as they passed overhead.)
Binienda's simulation also showed that, for the wing tip to have landed where it did, the break must have happened at a higher altitude and closer to the runway than where the birch tree was located.
Binienda's computer modeling of the tree impact is an unconventional approach to an aircraft crash analysis, said Greg Phillips (http://viterbi.usc.edu/aviation/bios/phillips.htm), a veteran former NTSB investigator who's now an aviation safety instructor at the University of Southern California. Still, "it sounds like the guy has all the credentials that would certainly set off the alarms that we really need to listen hard to this."
Whether the birch tree fractured the wing or not is a moot point, said Paul Czysz, an aircraft design expert and professor emeritus at St. Louis University's Parks College of Engineering, Aviation and Technology (http://parks.slu.edu/). "If that tree didn't do it, there are about 50 others in front of it that could have," said Czysz, who thinks pilot over-confidence caused the crash. "The fact that he hit the tree that far from the end of the runway means that unless he got that airplane up right away, he was dead. And very few pilots have the reactive skills to get that airplane up."
So someone has to be wrong. How can an investigation be so totally controversial about hard evidence? After all, it's not a Hollywood crime (about which someone had mentioned 'twas really hard to prove the guy had committed suicide because of the knife in his back).
Binienda knows his high-profile position raising doubts about the crash's official cause could jeopardize his professional reputation.
"If they show that I made an obvious error, it would be a tremendous blemish on my career," he said. But "if I would hesitate to look for truth just because of my career, that would be a pretty bad scientific approach. I hope at a minimum I can bring people to ask questions, and at the end they will do the investigation and show that my work was incorrect or correct. Either way, I don't mind."
graphics:
http://media.cleveland.com/science_impact/photo/29cgcrashjpg-767747a599d80284.jpg
Binienda specializes in fracture mechanics, a highly technical field that analyzes how and why materials break under stress. His focus is the lightweight stuff – aluminum, titanium and exotic polymers –used in aviation and aerospace. He often works with NASA and jet engine manufacturers. He is no stranger to aircraft structures.
The wing-tree impact became the target of his inquiry. It didn't make sense to Binienda that, after a collision that severed a third of the wing, the jet would be able to climb almost 100 feet in altitude before crashing, as the Russian investigators had concluded. Robbed of lift and momentum, the damaged plane should drop like a stone.
To study the wing-tree impact, Binienda created a computer model using a software program called LS-DYNA (http://www.lstc.com/products/ls-dyna). He and other engineers routinely use LS-DYNA to simulate complex fracture situations with lots of rapidly changing conditions, like when a loose, high-speed chunk of insulating foam bashed into the space shuttle Columbia's (http://www.google.com/url?sa=t&rct=j&q=ls-dyna%20columbia&source=web&cd=1&ved=0CCQQFjAA&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload% 3Fdoi%3D10.1.1.76.5872%26rep%3Drep1%26type%3Dpdf&ei=lAGbT879Ls_wggfX1fCVDw&usg=AFQjCNHtGlA2k58y6iAkYDBis-tmvffPvQ&cad=rja) wing during a 2003 launch, fatally damaging the orbiter.
With LS-DYNA and information from the crash reports, Binienda could input the strength, density and other properties of the wing and the tree. That allows a computer to calculate the impact forces and create a second-by-second, realistic 3-D animation (http://www.youtube.com/watch?v=fbJ29pGJLNU) of what happened.
Even when Binienda intentionally under-represented the wing's strength and over-estimated the tree's, the simulations still showed the wing slicing off the treetop while suffering only minor damage. The tree impact couldn't have broken the wing, his model showed. Something else must have done that, and something else must have snapped off the treetop. (For the latter, Binienda suspects it was the powerful backwash from the jet's engines as they passed overhead.)
Binienda's simulation also showed that, for the wing tip to have landed where it did, the break must have happened at a higher altitude and closer to the runway than where the birch tree was located.
Binienda's computer modeling of the tree impact is an unconventional approach to an aircraft crash analysis, said Greg Phillips (http://viterbi.usc.edu/aviation/bios/phillips.htm), a veteran former NTSB investigator who's now an aviation safety instructor at the University of Southern California. Still, "it sounds like the guy has all the credentials that would certainly set off the alarms that we really need to listen hard to this."
Whether the birch tree fractured the wing or not is a moot point, said Paul Czysz, an aircraft design expert and professor emeritus at St. Louis University's Parks College of Engineering, Aviation and Technology (http://parks.slu.edu/). "If that tree didn't do it, there are about 50 others in front of it that could have," said Czysz, who thinks pilot over-confidence caused the crash. "The fact that he hit the tree that far from the end of the runway means that unless he got that airplane up right away, he was dead. And very few pilots have the reactive skills to get that airplane up."
So someone has to be wrong. How can an investigation be so totally controversial about hard evidence? After all, it's not a Hollywood crime (about which someone had mentioned 'twas really hard to prove the guy had committed suicide because of the knife in his back).
Binienda knows his high-profile position raising doubts about the crash's official cause could jeopardize his professional reputation.
"If they show that I made an obvious error, it would be a tremendous blemish on my career," he said. But "if I would hesitate to look for truth just because of my career, that would be a pretty bad scientific approach. I hope at a minimum I can bring people to ask questions, and at the end they will do the investigation and show that my work was incorrect or correct. Either way, I don't mind."
graphics:
http://media.cleveland.com/science_impact/photo/29cgcrashjpg-767747a599d80284.jpg