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Non-Flammable Fuel?
When we're flying high above the Earth, few of us give much thought to aircraft safety. We're usually too busy wondering when lunch is going to be served.

But flying safely is a goal of NASA's Glenn Research Center (GRC) in Cleveland, Ohio. They're working on the problems that could arise if fuel in the tanks were to accidentally ignite in flight or during an emergency landing.

A team of Glenn's scientists, headed by Dr. Clarence Chang, is trying to find better ways to make the stored fuel less flammable.

Air separation module Image Left: The Air Separation Module (ASM). The "safety kit" is composed of air separation modules about 4 feet long and 8 inches in diameter. The arrows show the direction of air flow through the ASM. Nitrogen-enriched air flows out the other end while the oxygen-enriched waste air stream comes out the side. Credit: NASA

"We know that in order to initiate combustion, three ingredients are needed: oxygen, fuel vapor and an ignition source," Chang said. "We can't remove the fuel from the tank, and we've already removed just about all of the known ignition sources. Since we can't remove the ignition sources we don't know about, decreasing the oxygen level is currently the easiest way to avoid fuel tank explosion."

According to Chang, the U.S. military already uses inerting systems (a method of reducing the fire potential of fuel) to protect aircraft. But these systems are heavy, take up a lot of space and are very expensive to buy and operate.

The science team has been working on technologies for air separation modules that are smaller, more affordable and more efficient then the type currently being proposed for use in commercial aircraft fuel tanks today. No current commercial aircraft as yet uses inerting technology.

Ignition experiments are being performed to look at the amount of oxygen removal that would be needed to protect a fuel tank from accidents. In addition, changes in the fuel itself can work in concert with inerting to make the fuel harder to ignite and decrease the need for inerting devices. The trick is to have a fuel that is safe in storage, but burns great in the engine.

Boeing 747 ferrying Space Shuttle Image Right: NASA Space Shuttle Columbia hitched a ride on a Boeing 747 carrier aircraft for the flight from Palmdale, Calif., to Kennedy Space Center, Fla. The 747 is typical of the type of plane being used for the ASM test. Credit: NASA

Also, scientists are developing sensors that monitor the gasses inside the tank. But at this time the hostile environment inside the tank is a formidable challenge to overcome. These advanced technologies in inerting, gas detection and fuel reformulation will make future aircraft safer from fuel-fed fire.

In the meantime, NASA has arranged to test-fly a current-generation inerting device developed by the Federal Aviation Administration on the same Boeing 747 that has been used for transporting the Space Shuttles. The new ASM safety kit demonstrations are planned for mid-May of this year.

In February, the Federal Aviation Administration announced its intent to require tank inerting on all commercial aircraft.

Whew! One less thing for white-knuckled flyers to worry about..........When does the movie start?

For information about NASA's Glenn Research Center, visit:
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Elaine M. Marconi, KSC Staff Writer
NASA's John F. Kennedy Space Center and Glenn Research Center