NASA Chicken Gun

__NOTOC__The (misnamed) NASA Chicken Gun is one of several large diameter compressed air cannon used by the Federal Aviation Administration and US Air Force to test the strength of aircraft windshields and the safety of jet engines. A common danger to aircraft is that they collide with birds in flight. Most parts of an aircraft are strong enough to resist such a bird strike. Jet engines may sustain serious damage, however, and cockpit windows are necessarily made of transparent materials and are a vulnerable spot. The "Range S-3" gun was designed to conduct tests to determine the risk.

The Chicken Gun is designed to simulate high speed bird impacts. It is named after its unusual projectile: a whole dead standard-sized chicken, as would be used for cooking. This has been found to accurately "simulate" a fairly large bird, (as it actually is one). The test target is fixed in place on a test stand, and the cannon is used to fire the chicken into the engine, windshield, or other test structure.

The gun is driven from a compressed air tank. In the 1970s Goodyear Aerospace in Litchfield Park, AZ, used a gun with a ceramic diaphragm to seal the compressed air in the tank from the gun's barrel. To fire the gun, a solenoid-driven needle struck and ruptured the diaphragm, allowing the compressed air to drive the chicken (in its container - a cylindrical cardboard ice cream carton) down the barrel. At the muzzle, a metal ring stopped the carton, but allowed the chicken to pass through. Slow-motion cameras photographed the chicken impacting a fighter windshield in the test bed. These cameras were started in time with the breaking of the diaphragm.

There is a longstanding urban legend about the gun being loaned to some other agency, who fired frozen chickens instead of thawed chickens. Research indicates that this is apparently a myth. [cite web|url=http://www.snopes.com/science/cannon.htm|title=Chicken Cannon|publisher=Snopes|accessdate=2008-06-16]

Guns are operated by the FAA and the US Air Force rather than NASA, as is commonly believed.

The British connection

The first recorded use of a chicken gun was by the Royal Aeronautical (Aircraft) Establishment (RAE) in Farnborough, UK in 1961. [cite web|url=http://www.nrc-cnrc.gc.ca/highlights/2007/0701chicken_e.html|publisher=National Research Council of Canada|title=It's a Bird, It's a Plane... It's a Bird Striking a Plane|date=2007-01|accessdate=2008-06-16]

Pop culture

The chicken gun was first used in the mid 1950's at Dehavilland Aircraft Hatfield UK. It was fired with a correct count down from a 'pill box' housed in the woods at DeHavilland's. The chickens were killed shortly before firing and obtained from a local farm also at the edge of the woods. Two DeHavilland employees (Vic and Robbie from DeHavilland Propellers Ltd.)witnessed this regularly as they were each building a boat in the old hangers there. After firing the jet engines were taken away and examined for damage. High speed cameras recorded the complete action. Robbie was actually a film camera employee so knew the hi-tech emphasis on the project.

On "MythBusters", a chicken gun was used in various experiments. The experiments conducted used both frozen and thawed chickens to test the cockpit window of a private aircraft.

The 1970s test of the British High Speed Train windscreens used the Farnborough chicken gun and expertise, not NASA based expertise, busting the Mythbusters myth relating to NASA telling the British "defrost the chickens first".

References

External references:

* [http://www.arnold.af.mil/aedc/test.htm Arnold Air Force Base Test Department] Dead link|url=http://www.arnold.af.mil/aedc/test.htm|date=May 2008
* [http://www.arnold.af.mil/aedc/testhighlights/stats.pdf (PDF) Arnold AFB test facilities capabilities, including range S3, Bird Impact Range]
* [http://www.fodnews.com/duck_site.html Article on the US Air Force gun at FODNews.com]
* [http://www.snopes.com/science/cannon.htm Snopes entry on frozen chicken myth]