A chicken gun is a large-diameter, compressed-air cannon used 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, thin materials and are a vulnerable spot.
The chicken gun is designed to simulate high-speed bird impacts. It is named after its unusual ammunition: a whole, dead, standard-sized chicken, as would be used for cooking. This has been found to accurately simulate a large, live bird in flight. 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, Arizona, United States, 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.
The chicken gun was first used in the mid-1950s at de Havilland Aircraft, Hatfield, United Kingdom. It was fired with a correct countdown from a pillbox housed in the woods at de Havilland's. The chickens were killed shortly before firing and obtained from a local farm also at the edge of the woods. After firing, the jet engines were taken away and examined for damage. High-speed cameras recorded the complete action.
In popular culture
There is an urban legend that train companies borrowed the chicken gun for testing windshields for high-speed trains, and were shocked and confused at the amount of damage the gun did - the projectiles were not only breaking through the windshields but embedding themselves into seats farther down the train. When they asked the lenders what they were doing wrong, the reply came, "Gentlemen, thaw your chickens."
On MythBusters, Jamie Hyneman and Adam Savage designed and built a chicken gun to put that to the test. Jamie re-used and enlarged the design he used to create the "improved" 7Up vending machine for a commercial. In place of Goodyear's diaphragm, the air tank was connected to the barrel by a butterfly valve that could discharge the high-pressure air in an instant, and in place of the ice cream carton and the metal ring that stopped the carton, they constructed foam sabots that would fit the chicken inside the barrel and seal it but fall away into quarters before impact. After firing both frozen and thawed chickens at Piper Cherokee windshields and later at a metal plate with a high-speed camera (to measure time of impact), they declared the myth busted, but later overturned their verdict and confirmed the myth when they found that frozen chickens still penetrated further.
- "It's a Bird, It's a Plane... It's a Bird Striking a Plane". National Research Council of Canada. January 2007. Retrieved 2009-09-14.