Broken seats in commercial aircraft are more than just inconveniences, and while a defective seat by itself cannot cause a major safety issue inside a plane, it is often an indication of a bigger, ongoing problem.

The seats used by every passenger on commercial aircraft are quite sturdy things: They are designed to resist fairly high G-forces and the weight of an adult for hours at a time. They are easy to clean and modular, so that if something fails it can be repaired or replaced between flights. However, seats are today being, literally, overwhelmed by big fannies.

Indeed, lack of maintenance can cause problems in seats too, and it is easy to associate that with the quality of service in an airline, but overweight passengers make repairing and maintaining things more difficult and costly. If you consider that just a brand-new, aircraft-grade seat belt could cost about seventy dollars, imagine what costs to actually repair a whole seat.

The average weight of an adult human in an aircraft has been calculated years ago at 77 kg - this is an ICAO standard. Aircraft are normally designed with tolerances of 30% or so, meaning that you can have people of up to 100 kg or so sit safely for a variety of reasons that go from the resistance of the seat materials to weight and balance distribution in the aircraft.

But here is where problems begin: Aircraft have not been designed in this fashion so that obese people would fit better inside, but due to safety concerns as well as flight mechanics: Indeed, when a plane flies it is subjected to increased "Gs" at times. This means that during those phases of flight, the plane "weights" more or less than it really weights. For example, if something that flies suffers 2G, even for an instant, its weight doubles and the structure suffers two times the stresses than normal. Thus, if you consider that today, people in some countries like the US are averaging about 92kg, it is easy to see that things are reaching the limit in terms of safety.

New aircraft are indeed being designed taking into account the new parameters but there are many vehicles - not just old aircraft - that still offer only the older standards. It would be nonsensical from a financial point of view to force every manufacturer and operator to change things just because people don't eat well. Moreover: Since the average weight of adults actually tends to increase and is expected that in a few years it will go beyond 92 kg. Such changes would not result in any long-term positive solution. Making sturdier seats usually means leaving less space inside the fuselage of ain aircraft or the body of a car, bus, etc. which means higher transportation costs per passenger because the vehicle will be forced to carry less people or cargo.

In the case of small aircraft it usually means replacing the whole fuselage, something prohibitively expensive unless the plane is yours and you are desperate to fly without paying much attention to weight loss. Indeed: you can get wider fuselages for little planes like a Piper Cub, but that means losing a lot in the power-to-weight ratio as well as aerodynamics, so the trade-off may not be acceptable for everyone.

Anything that goes beyond the tolerances must be deemed as unsafe locally - i.e. the seat will likely break - and globally -i.e. such overweight will alter the weight and balance of the plane and put it outside the safety envelope. Since you cannot modify aircraft easily or quickly, the only sensible solution to the problem is unfortunately to leave overweight people in the ground.

This is why sometimes pilots choose to leave obese passengers behind; it is not a matter of discrimination, but physics.

Source: Pablo Edronkin, Andinia.com

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WASHINGTON - More than 100 student teams from around the globe will drive their specially crafted lunar rovers through a challenging course of rugged, moon-like terrain at NASA's 17th annual Great Moonbuggy Race in Huntsville, Ala., April 9-10.

Some 1,088 high school, college and university students from 20 states and Puerto Rico, Canada, Germany, Bangladesh, Serbia, India and Romania are expected to participate in the race at the U.S. Space and Rocket Center.

Students begin to prepare for the event each year during the fall semester. They must design, build and test a sturdy, collapsible, lightweight vehicle that addresses engineering problems similar to those overcome by the original Apollo-era lunar rover development team at NASA's Marshall Space Flight Center in Huntsville in the late 1960s.

The buggies are based on the design of those classic rovers, which American astronauts drove across the moon's surface during the Apollo 15, 16 and 17 missions in the early 1970s. Teams of students build their vehicles using trail bike tires, aluminum or composite-metal struts and parts. The best teams drive trains, gears, suspension, steering and braking systems they find or construct.

Top prizes are awarded to the three teams in both the high school and college/university divisions that post the fastest race times, which include assembly and penalty times. A variety of other prizes are given by race corporate sponsors. These include "rookie of the year" and the "featherweight" award, presented to the team with the lightest, fastest buggy.

NASA's Great Moonbuggy Race is one of many educational projects and initiatives the agency conducts each year to attract and engage America's next generation of scientists, engineers and explorers. They will carry on the nation's mission of exploration to unchartered destinations in our solar system.

"NASA is committed to inspiring young people in science, technology, engineering and math, and the Great Moonbuggy Race is an excellent way for us to reach out to young people and get them excited and involved in technical opportunities available to them," said Mike Selby, an avionics technical assistant in the Marshall Center's Engineering Directorate. While completing his engineering degree at the University of Alabama in Huntsville, Selby was a member of the school's moonbuggy teams, helping them to a second-place finish in 1995 and to first place in 1996. Since 2001, he has served each year as a volunteer scorekeeper.

The race is hosted by the U.S. Space and Rocket Center, and is sponsored by Lockheed Martin Corporation, The Boeing Company, Northrop Grumman Corporation, and Jacobs Engineering ESTS Group, all of Huntsville.

For a list of this year's competitors, visit: http://moonbuggy.msfc.nasa.gov/email.html

For more information about the competition, visit: http://moonbuggy.msfc.nasa.gov

For information about other NASA education programs, visit: http://www.nasa.gov/education

Source: NASA

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WASHINGTON - U.S. university faculty and students are invited to a weeklong workshop to learn how to build and launch a scientific experiment into space. NASA's Wallops Flight Facility in Virginia is hosting the RockOn! 2010 workshop June 19-24 in partnership with the Colorado and Virginia Space Grant Consortia. Registrations for the 2010 workshop are being accepted through March 22.

The hands-on workshop teaches participants to build experiments that fly on sounding rockets. During the week, participants will work together in teams of three to construct and integrate a sounding rocket payload from a kit in four days. On the fifth day of the workshop, June 24, their experiments will fly on a NASA Terrier-Orion sounding rocket expected to reach an altitude of 73 miles.

Each experiment will provide valuable scientific data, analyzed as part of the student led science and engineering research. The program engages faculty and students in science, technology, engineering and mathematics skills critical to NASA's future engineering, scientific, and technical missions.

Approximately 100 faculty and students participated each year in the 2008 and 2009 workshops. All experiments have been successful, completed on time, launched and recovered.

NASA initiated the National Space Grant College and Fellowship Program in 1989. The Space Grant national network includes more than 850 affiliates from universities, colleges, industry, museums, science centers, and state and local agencies. The goal is to support and enhance science and engineering education, and research and public outreach efforts for NASA's aeronautics and space projects. These affiliates belong to one of 52 consortia in all 50 states, the District of Columbia and the Commonwealth of Puerto Rico.

For more information about RockOn! and to register online, visit: http://spacegrant.colorado.edu/rockon

For more information about NASA education programs, visit: http://www.nasa.gov/education

The Sounding Rockets Program Office at NASA's Wallops Flight Facility will be providing the rocket and launch operations during the workshop. For more information about NASA's sounding rocket program, visit: http://sites.wff.nasa.gov/code810

Source: NASA

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