Posts Tagged ‘safety’
Bodies In Motion: Exploring the Human Limits of Future Travel
The limits of travel are defined not by what vehicles can do, but by what vehicles can do to us. So how much can we take?
As the crew headed north, they received instructions from a Jacksonville controller, first to climb to 26,000 feet, then 39,000. “Three nine zero bravo alpha,” the first officer acknowledged. It was her last transmission. A few minutes later, the Learjet leveled out and the controller issued another routine instruction. No one radioed back. The controller tried to reach the crew five more times in the next four and a half minutes.
When a flight crew is unresponsive, the FAA asks that the nearest military jet make a visual assessment—in this case, it was an F-16 pilot on a test run out of nearby Eglin Air Force Base. Coming even with the Learjet, the test pilot reported that both of the plane’s engines were running. By all indications, the Learjet was in perfect working order. But the test pilot also reported a disturbing detail: The Learjet’s windows were opaque, as if covered from the inside with condensation or ice.
"You can create a system to do whatever you need it to do. But can you keep a person conscious and alive inside it?"It was becoming clear that in the minutes after Bellegarrigue’s last transmission, the cabin had lost pressure and all its oxygen began to escape. Within as little as eight seconds, the crew and their passengers most likely began to experience hypoxia—lack of oxygen in the bloodstream—that impaired their most basic motor and cognitive functions. They may not have even been aware that there was a problem, but within a few minutes of the breach, they were probably dead.
Yet the plane continued on, because a plane does not need its occupants to be comfortable in order to operate. It does not even need them to be breathing.
Corporeal Limits
Humans are flimsy. Our bones snap after a fall of only a few feet. Our flesh ignites at the operating temperature of the average wood-burning stove. The highest human settlements are no more than 19,520 feet up, and none of us can stay alive long past 26,000.
Machines, meanwhile, can take a lot. The wings of a Boeing 777, for instance, can bend as much as 24 feet from their resting position, and any turbulence powerful enough to bend them that far will damage the passengers long before it damages the airplane. In 1997, United Airlines Flight 826, en route from Tokyo to Honolulu, encountered a sudden gust of “clear air turbulence” that crushed passengers into their seats and flung them at the ceiling. The turbulence killed one passenger and injured 70 others. But the pilot was able to return the plane itself safely to Tokyo.
This is the fundamental limit of all forms of travel. “You can create a system to do whatever you need it to do,” says Michael Planey, a former U.S. Air Force engineer and now a consultant for commercial airlines. “But can you keep a person conscious and alive inside it? That’s the challenge.”
How we'll move from place to place in the future will be determined by what passengers can withstand. How fast can the body accelerate? How long can it sit in one place? How many can we pack into a vehicle? Right now we have only a rough sense of these corporeal limits.
Scarce Data
Much of what we know is drawn anecdotally from the violent, often accidental experiences of airmen and astronauts. In 1966 a test pilot named Bill Weaver managed to eject when his SR-71 Blackbird broke apart at Mach 3.18. His systems officer was killed, but at 78,000 feet Weaver survived more than 2,000 mph of air resistance, revealing that a human can in fact withstand incredible shock at a very high altitude, at least when protected by a pressurized suit.
"Comfort is difficult to quantify. We look primarily at safety."In 1960, Air Force captain Joseph Kittinger established as-yet-unbroken records for the highest parachute jump (102,800 feet) and the fastest human free-fall through the atmosphere (614 mph). And between 1947 and 1954, Air Force colonel John Stapp, part of the Aero Medical Laboratory of the Wright Air Development Center, subjected himself to repeated tests on a rocket sled that zipped across what is now Edwards Air Force Base. During one run on his “human decelerator,” Stapp went from 630 mph to a complete halt in just a few hundred feet, experiencing 46 Gs of deceleration.
But standardized data about human tolerances is hard to come by. J.D. Polk, NASA’s chief of space medicine, knows a great deal about the strain of space travel—his astronauts have endured hours of waiting at the launch pad and lived for months in a weightless environment—but even he can’t quite name the breaking point of a human being. That’s because engineers can’t test humans the way they can other components of a spaceship. In designing a space shuttle, “you can stress a part until it breaks,” Polk says. “The human body is the only system in engineering that you can’t take to failure.”
Military and NASA researchers don’t really investigate human comfort, at least not in the way that a commercial traveler might hope. They aren’t attempting to engineer conditions that will convince the traveler to fly a particular airline or buy a particular car. That distinction was highlighted during the Iraq war, when Baghdad International Airport became one of the few places in the world where civilians regularly encountered the discomfort of military efficiency. Rather than the usual long, low approach to the runway, commercial pilots instead had to drop from as high as 35,000 feet in a hard spiral “corkscrew descent,” the better to avoid rockets and small-arms fire. It’s a standard military approach path. But for a civilian, it’s terrifying. “It’s pretty amazing what airplanes can do,” says Tom A. Peter, a freelance reporter who has flown into Baghdad several times. “I’ve never been in a plane crash, but I have to imagine that a corkscrew landing is about as close as you can come without actually wrecking a plane.”
NASA engineer Dustin Gohmert, who designed seat systems for the crew module of the Orion spacecraft, explains the military-civilian distinction in straightforward terms. “Comfort itself is difficult to quantify,” he says. “We look primarily at the safety of the crew.”
Designing for Safety"The human body is the only system in engineering that you can't take to failure."The standards are very high for NASA vehicles. Because a spacecraft can crash hours or days from help, “we have to make it such that the crew can self-rescue,” Gohmert says. And sometimes that means doing away with conventional amenities. In the Orion capsule plan, for instance, Gohmert’s team dispensed with seat cushions altogether. Cushions may separate the body from the hard seat underneath by just a few millimeters, but in a sudden deceleration, the body can close even that small distance with enough force to cause injury. The Orion seats fit each astronaut fairly closely, and the weight distribution makes for a more or less tolerable experience. But comfort isn’t the goal. The seats keeps the astronauts alive.
Of course, NASA also gets to be picky about who comes on board, a degree of selectivity that further limits what the agency can teach us about our own comfort. The Federal Aviation Administration requires commercial airlines to safely accommodate nearly the entire spectrum of humanity, from a 5th-percentile woman (about 5 feet tall) to a 95th-percentile man (over 6'3"). Not so at NASA. To make sure each astronaut fits the operating environment of the spacecraft, the agency assesses not just height and weight, but every measurement of every extremity. If you don’t fit, you can’t fly. “We do three-dimensional body scans of the astronauts as part of the screening,” Gohmert says. “If your femur is too long, it might disqualify you.” Air Force pilots must also properly fit their plane—legs longer than the engineered standard could break when the pilot ejects in an emergency.
Civilian passengers, no matter how tall or wide, expect gentle treatment. As a result, engineers must set extremely conservative tolerances. Rail system designers, for instance, consider the acceptable limit of linear and lateral acceleration (the force exerted on passengers by starting, stopping, and rocking from side to side) to be no more than 0.15 G—roughly what you’d feel on the moon. That limit allows passengers to dispense with seatbelts and walk around freely inside.
But design constraints also act as speed constraints. In 1990, engineers for a federal program called the National Maglev Initiative began to investigate the domestic potential for high-speed magnetic-levitation (maglev) trains—the fastest, a Shanghai airport shuttle, reaches 268 miles an hour. Daniel Patrick Moynihan, then the chair of the Senate subcommittee responsible for the U.S. highway system, had suggested that maglev trains be placed along the median of U.S. highways, so in July 1992, to better understand what it would be like to travel an interstate at maglev speeds, four engineers set out from National Airport in a private jet. “We did 180 mph and began banking as if we were obeying the turns you’d have to make on the New York State Thruway,” recalls Laurence Blow, now a maglev consultant. As the pilot cranked the plane back and forth, simulating the thruway, the engineers began to heave and retch. “It wasn’t the speed or acceleration that made us all sick,” Blow says. “It was the banking.”
Avoiding Nausea
Motion sickness is one of the few areas where civilian desires overlap with military requirements; no commander wants his soldiers or astronauts puking when they need to fight or fly. A lot of data has been generated. In 1995, for example, British naval doctors subjected participants to repeated vertical and horizontal motions while the participants were either seated upright or lying on their backs, and determined that the subjects found horizontal movement while prone to be the most tolerable, and seated horizontal movement to be least tolerable. And a 2006 study established that low-frequency movement (a camel’s gait) is more nauseating than high-frequency movement (a horse’s gait).
The accepted notion, proposed by the English physician J.A. Irwin in 1881 and largely confirmed by NASA in 1970, is that we get sick when our visual input contradicts our vestibular, inner-ear input—when what we see (an unmoving bulkhead) is in conflict with what we feel (sudden acceleration). This is why passengers get sick before drivers or pilots do. “It’s the lack of sightlines that are the problem in the backseat,” says Gary Strumolo, the manager of vehicle design and infotronics at Ford Motor Company. This helps to explain, he says, why even those people who are highly susceptible to motion sickness can often avoid it by driving.
The same goes for air travel. “Pilots on the controls have a foreknowledge of the aircraft motion,” says Catherine Webb, a psychologist who studies motion sickness at the U.S. Army Aeromedical Research Laboratory at Fort Rucker, Alabama. For passengers, she explains, “expectations of aircraft motion often conflict with actual motion, and sickness often results.”
The drug dimenhydrinate, sold under the brand name Dramamine, can help, but it also causes drowsiness and can sometimes even act as a hallucinogen. NASA, eager for a substitute, is studying the use of LCD shutter glasses, like those worn at 3-D movies. The vestibular system, when disturbed, may prevent the retina from holding images steady, thereby inducing nausea. Shutter glasses create a strobe effect that breaks the view into discrete images, fixing each one in one place, which helps the brain coordinate the vestibular with the visual.
For now, a good view is the best way to ease motion sickness. But showing passengers the true movement of the plane can also create problems. In turbulence, a passenger seated at the rear of the plane is moving around in very different ways from the people seated up front. “If you have a clear view,” Planey says, “you can see the fuselage twisting, which is what it’s supposed to do.” But the sight tends to alarm passengers, so designers have learned to interrupt the view through the interiors of most modern jets with restrooms and curtains.
How Much Speed?
What are the real limits for commercial transit on Earth? Assume for a moment that vehicles can travel any route at any speed without tearing apart or running out of gas. Onboard, what can our bodies take?
The longest commercial nonstop flight in the world is Newark to Singapore—a 9,535-mile haul that takes just under 19 hours. Imagine the trip on a maglev train. On a smooth, straight, point-to-point track between the two cities, a commercial maglev operator wanting to avoid passenger complaints would still have to obey conservative, 0.15G limits on acceleration and deceleration. Within those confines, the train would accelerate continuously until, at a halfway point somewhere in the Arctic Circle, it very briefly reached a peak speed of 11,000 mph. Then it would immediately begin a comfortable 0.15G deceleration, for a total trip of just under two hours. If we allowed our theoretical supertrain to follow the more permissive standards of commercial flight, however—1.5 Gs of acceleration, 1 G of deceleration—the journey would be much faster. The train would use the first third of the trip to accelerate to 30,000 mph. Then it would use the remaining two thirds of the trip to (somewhat) gently decelerate. Total time: 46 minutes. All other considerations aside—such as the sonic booms that would deafen the towns along the way—these are the fastest trips any paying, conscious passenger will ever take on this planet.
How close are we to such a trip? In March 2001, Boeing announced its concept for a so-called Sonic Cruiser, capable of flights at just short of the speed of sound—as much as 20 percent faster than the Boeing 747-400, one of the fastest commercial jets in service. The new wide-body plane would, Boeing promised, shave nearly an hour off every 3,000 miles traveled.
Comfort Comes First
But airlines for the most part are finding that it’s easier and cheaper to distract passengers from the experience of travel than it is to make the trip faster and shorter. Passengers are happy to spend a bit of time on the plane, it turns out, if they have a sense of control over their surroundings. “Watching the moving-map display, inflight Internet, television—all of that helps,” Planey says.
Boeing, for its part, is betting that passengers will choose comfort over speed. The company shelved the Sonic Cruiser program in 2002 to focus on the 787 Dreamliner, due to make its first commercial flights next year. The new plane borrows much of the Sonic Cruiser’s structural design; composite materials make up 50 percent of the plane, as compared with 20 percent on the 777.
The flights will be no shorter. But a lighter plane requires less fuel, and, more important, Boeing claims that the composites will make for a more comfortable environment. In a conventional aluminum-fuselage plane, the metal can be corroded by humidity in the cabin, so engineers need to keep the environment extremely dry.
On a pressurized 747, passengers are sitting at the equivalent of 8,000 feet of altitude. In the 787, that perceived altitude can instead be 6,000 feet, and the air will be moister and more pleasant, because the composite materials don’t corrode as quickly. In a Boeing-sponsored Oklahoma State University study, 500 people took a simulated 20-hour flight in the cabin. Passengers reported feeling less achy and more relaxed in the new perceived altitude. Combined with in-flight entertainment and the right lighting, comfort seems to do away with the need for extra speed. If time seems to pass faster, why bother designing a faster plane?
That pilotless Learjet crossed most of the country on its own, and except for the one system needed to keep everyone breathing, the rest of the plane appeared to be functioning flawlessly. The flight couldn’t have been more comfortable, perhaps even for the passengers and crew. The progression of hypoxia—disorientation, sedation, unconsciousness—is often imperceptible to the victim. With a drink or a half-finished latte in their hands, the passengers probably remained in their seats throughout the flight.
The experience of travel gives us the illusion that motion comes at no cost. But vehicles are essentially cocoons, and the systems that cradle us inside them have one fundamental purpose: to keep us from feeling how fast and how far we’ve come.
How It Works: A Smarter Crash-Test Dummy
How the next generation of sensor-packed devices gather 70,000 data points per second to make cars safer for flesh-and-blood humans
To that end, the newest generation of dummies is getting an upgrade. Improvements include faster data collection and RibEye, a chest cavity loaded with sensors that helps engineers better understand how the rib cage compresses during a crash. “Now,” says Michael Jarouche, a vice president at Humanetics Innovative Solutions, which supplies dummies to all the major automakers, “we just have to figure out how to give the dummy internal organs.”
Click the image above to see how the GM Anthropomorphic Test Device gathers data during a crash. If you are unable to view Flash files, .
More How It Works:
This month's is brought to you by Digikey. All posts are purely editorial content, which we are pleased to present with the help of a sponsor; the sponsor has no input in the content itself.
The Good Kind of Mass Destruction
Sometimes the safest way out of a dangerous situation is to burn everything to the ground. From a house full of explosives to 134 tons of Mexican marijuana, here are nine instances when the best solution is controlled calamity
A federal grand jury indicted the home’s tenant, 54-year-old George Djura Jakubec, on charges related to making destructive devices and robbing three banks. Meanwhile, a bomb squad detonated the explosives in his backyard but concluded that it was too risky to send technicians into the cluttered house, where clothing and dishes were stacked next to volatile chemicals. They also ruled out a robot, which could knock into a mess and trigger an explosion. The chemicals were so unstable that the safest solution—the bomb squad, hazmat team and FBI all agreed—was to burn the place to the ground.
Detonating or burning explosives produces the same gaseous admixture of carbon dioxide, water vapor and various nitrogen oxides. But burning releases the gases slowly, without dangerous force, and is thus a tried-and-true disposal technique for weaponry. After World War II, obsolete or unserviceable munitions were often set aflame in giant trenches. Following the 2003 U.S. invasion of Iraq, soldiers captured tons of bulk munitions dumped throughout the country, which Army Corps of Engineers contractors dispatched in open burns. At least 10 Army sites in the U.S. still burn old ammo in open pits.
In Escondido, firefighters built a 16-foot containment wall coated with fire-retardant gel, removed surrounding vegetation, and bored holes into the roof to allow more oxygen to reach the fire. More than 200 properties within a roughly 300-yard perimeter were readied for evacuation, and nearby Interstate 15 was scheduled for temporary closure. They waited until the weather was just right (clear skies, mild winds coming from the west toward the freeway) and, on the morning of December 9, a bomb unit placed black powder and wooden pallets inside the house. Then, ignition. The fire went according to plan—1,800°F and a plume of dark smoke that shot up about 2,000 feet. There were no major explosions, although onlookers heard some loud bangs from the grenades and ammo. The property owner’s attorney later demanded the county pay $500,000 for the damage.
More often than you might think, occasions arise where nothing solves an issue better than a hefty dose of good old-fashioned fire.
A Sensor That Tracks Cosmic Particles Could Spot Hidden Nuclear Threats Before They Cross Our Borders
Only a few percent of the 15 million or so cargo containers that enter the country every year are screened for nukes, a number that Congress mandates must be 100 percent by 2012. That benchmark is impractical using today’s tech, however. Standard detectors can miss nuclear material hidden behind lead or steel, and naturally radioactive cargo such as kitty litter gives false positives, requiring a labor-intensive hand-search.
A new detector from Decision Sciences, a security company in California, sees through anything and can scan a semi in less than a minute. It tracks muons, cosmic particles constantly bombarding Earth. Muons penetrate everything but are deflected more by heavy atoms such as uranium and plutonium. The detector tracks these deflections.
The company finished lab tests this spring and is now building detectors to deploy at several ports in the next year. “As long as it works quickly enough, it should fit the bill,” says Robert Dynes, a physicist at the University of California at San Diego who reviewed radiation detectors for Homeland Security. Tests indicate that the device should be speedy on real cargo, says Decision Sciences’s chief technology officer, Allan Wegner. And it’s nearly foolproof. Wegner can’t go into detail about its weaknesses (for obvious reasons), but he assures us that kitty litter and watermelons will no longer threaten national security.
How It Works
As muons come from the sky, they pass through the top detector, the truck and the bottom detector. The muons create ionization trails in the scanner's gas-filled detector tubes, which sensors record.
Heavy atoms, such as uranium and plutonium, deflect muons more than lighter ones do. If the angles of muons' entrance and exit paths vary by a wide magin, nuclear material could be present.
The detector also senses gamma radiation, which the computer combines with muon data to build a 3D view of suspicious muon-scattering objects, alerting customs agents exactly where to search.
The Latest Toxic Chinese Export? Drywall that Could Fill Your Home With Sulfuric Acid
Investigators say hot and humid conditions can cause the tainted building product to release gas sulfur compounds that smell of rotten eggs and react with moisture in the air to create sulfuric acid, a key ingredient in acid rain and car batteries. Unleashed in a home, sulfuric acid can corrode and blacken metal, attacking electrical wiring, air conditioning coils, fire alarms, TVs and stereos. It can also exacerbate asthma and cause bloody noses, headaches and wheezing.
In many cases the damage has been so intense that victims have abandoned their homes or have been forced to finance gut renovations that often cost more than their original property is worth. CPSC scientists were careful to rule out common sources of sulfur contamination in homes, including well water, sewer gas, even jarred pickles, says CPSP spokesperson Alexander Filip.
U.S officials at the U.S.-China Strategic and Economic Dialogue meetings in Beijing this week are pressing the Chinese government to urge Chinese drywall companies implicated in the crisis to cooperate with the CPSC’s investigation. Port checks have confirmed that no new drywall has been imported from China since 2009.
So who’s to blame? Here, the CPSC names names, with a list of the top 10 manufacturers of drywall whose product had the highest emissions of hydrogen sulfide:
Knauf Plasterboard (Tianjin) Co. Ltd.: (year of manufacture 2005) China
Taian Taishan Plasterboard Co. Ltd.: (2006) China
Shandong Taihe Dongxin Co.: (2005) China
Knauf Plasterboard (Tianjin) Co. Ltd.: (2006) China
Taian Taishan Plasterboard Co. Ltd.: (2006) China
Shandong Chenxiang GBM Co. Ltd. (C&K Gypsum Board): (2006) China
Beijing New Building Materials (BNBM): (2009) China
Taian Taishan Plasterboard Co. Ltd.: (2009) China
Shandong Taihe Dongxin Co.: (2009) China
Suspect tainted drywall in your home? Call the CPSC 800-638-2772 or visit their web site .
Video: In Pioneering Study, German Robots Given the Chance to Stab Humans
First ever study of how robots attack tests their murderous ways
Human volunteers also subjected their arms to the tender mercies of the slasher bots, but only when a prototype safety system was engaged. The collision detection system used torque sensors to spot when it hits a different substance and freeze in mid-motion, so that damage to the human subjects was limited.
We're still a bit puzzled as to why human volunteers were in this experiment at all, when there's perfectly good ballistic dummies being eviscerated every week on Spike TV's Deadliest Warrior. But perhaps the Institute of Robotics and Mechatronics at the German aerospace agency felt human arms would represent a less expensive option.
The study was presented at the 2010 IEEE International Conference on Robotics and Automation, held in Alaska earlier this month. We're all for developing safety systems that engage for robots too dumb to recognize Asimov's Laws of Robotics, but we'd still recommend carving your own steak in the future.
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