AEDC at 75: Distinct purpose earns Arnold AFB Chicken Gun lasting fame

ARNOLD AIR FORCE BASE, Tenn. – The occasional article about it still crops up from time to time. Its story remains a highlight of public tours of Arnold Air Force Base, headquarters of Arnold Engineering Development Complex. Those who worked at the installation when it was active often remark on its notoriety when discussing their time at Arnold. Although it has been more than two decades since the last shot was fired at the S-3 Bird Impact Range, the test area, more commonly referred to as the “Chicken Gun,” continues to be one of Arnold AFB’s most well-known facilities and a topic of interest. S-3 was initially used to test windshield materials and full-scale canopies for various military and commercial aircraft. It was later utilized to support NASA in the agency’s effort to return to manned spaceflight. While the concept was unique, the Chicken Gun’s mission was not. Like other efforts across AEDC, testing at the range was conducted in the interest of pilot and passenger safety. During windshield and canopy tests at the range, chicken carcasses were fired to simulate in-flight bird strikes to the test articles. This was done to research the damage caused by such strikes and to prevent harm to members of the aircrew. The Chicken Gun was capable of propelling poultry at speeds of more than 700 mph. Since the advent of the plane allowed humans to share the skies with them, the potential for bird strikes has existed. According to the U.S. Fish & Wildlife Service, bird and other wildlife strikes cause more than $900 million in damage to U.S. civil and military aircraft each year. They also put members of the aircrew and passengers at risk. The FWS website states that since 1988, more than 250 people have been killed worldwide as a result of wildlife strikes. To track wildlife strikes across the U.S., the Federal Aviation Administration previously developed a Wildlife Strike Report Database. According to that report, more than 350,000 wildlife strikes have been reported since 1990. The overwhelming majority of these strikes involve birds. The development of a bird-impact test facility was prompted by the loss of F-111 Aardvark aircraft during the Vietnam War. While many planes, according to the FWS, fly at higher altitudes than birds, especially commercial jets, the F-111 was equipped with terrain-following radar that allowed pilots to fly at high speeds only a few hundred feet from the ground. The combination of high-speed flight and low altitudes resulted in multiple mid-air collisions between the bombers and birds inhabiting the skies of Southeast Asia. Air Force officials charged the Aeronautical Systems Division at Wright-Patterson Air Force Base, Ohio, with exploring ways to reduce the dangers of direct bird impacts. The ASD reached out to ballistic range experts at Arnold AFB and asked if they could develop a bird strike test. The Bird Impact Range was built by Arnold engineers using scrap hardware, including an 8-inch Naval gun. The barrel of the single-stage air gun they fabricated was 60 feet long and contained a 10-cubic foot chamber that could be filled with pressurized air. Test articles were installed in an open shed downrange of the gun. A chicken carcass was placed into a balsa wood sabot which was then loaded into the barrel. Between the barrel and air chamber was a thin plastic diaphragm. To fire the Chicken Gun, this diaphragm was ruptured, allowing high-pressure air from the chamber to enter the barrel, pushing the sabot down the tube in the direction of the test target. A tapered and threaded section of the barrel stripped away and stopped the sabot, launching the carcass contained within toward the test article. High-speed cameras were used to capture the impacts of strikes. This allowed engineers to better assess how well a test article withstood a strike, as both the integrity of the article and its ability to deflect the flung fowl needed to be determined. “Even if the windshield or canopy survives, if it hits the pilot in the head, he’s dead,” Randall Watt, then-project manager for the Arnold Bird Impact Test Facility, said in 1996. “And, sometimes, the pilot’s head is within an inch or two of that bubble canopy.” Early on, methods to substitute chicken carcasses were explored. Although the Air Force preferred actual carcasses to be used, the American Society for Testing and Materials permitted the use of imitation bird for impact testing. However, experiments with water bags and other materials used to simulate birds did not deliver reliable data. Engineers quickly learned there’s nothing like the real thing. “Again, the best thing to use to simulate a bird strike is a bird,” Watt said in 1996. “And chickens are the easiest to come by. The preference of most of the Special Program Offices is to simulate the event as close to reality as possible, using whole chicken carcasses.” Arnold AFB purchased its Chicken Gun ammunition – 4-pound carcasses – from a local farmer. The impact of climate on canopies and windshields was taken into account during S-3 testing. The test area was heated to 200 degrees Fahrenheit to simulate a scenario in which a plane sitting in the desert must quickly take off and happens to strike a bird as it is doing so. To simulate a situation in which sudden takeoff would be required in a frigid area, a thermal enclosure was placed around the test area and cooled gaseous nitrogen was supplied. The “Rooster Booster,” as it was known to some, was first fired in the fall of 1972 at an F-111 crew escape module. It was fired more than 1,000 times during its useful life. Data from Chicken Gun testing was used to redesign and strengthen components to better withstand bird strikes. Aside from the F-111, canopies and other materials were tested on aircraft including the A-7 Corsair II, A-10 Thunderbolt II, F-15 Eagle, F-16 Fighting Falcon, F/A-18 Hornet, B-1 Lancer and C-130 Hercules. Commercial aircraft tested included the Northrop Grumman Gulfstream V. Along with canopies and windshield samples, the range was used to test materials such as steel plates to measure impact forces at various velocities and angles of attack. An instrumented manikin was used in at least one test to analyze the dangers to the crew of a high-performance aircraft fitted with a particular windscreen. In 1996, S-3 was used to fire plastic spheres to simulate rocket tube cover debris that could possibly impact the crew of an Army vehicle following rocket launches. This marked the first time since its infancy the Chicken Gun was used to fire anything other than chicken carcasses. The final tests involving the original Chicken Gun were conducted in the early 2000s. The facility was revamped to conduct testing for the NASA Space Shuttle Return to Flight program, initiated in the wake of the Space Shuttle Columbia disaster in 2003. The gun was used to launch hundreds of block-shaped projectiles made of the insulating foam material used on the space shuttle external tank. This simulated pieces of the external tank foam breaking away from the tank during flight, which occurred with Columbia, and striking various parts of the shuttle. These firings occurred at various angles and velocities to determine the effects of foam impacts, provide information on the ability of the shuttle to withstand impacts and build a database for the future. This is the 27th in a series of articles highlighting the history of Arnold Engineering Development Complex during its first 75 years. Additional articles will be published throughout 2026 to commemorate the anniversary of AEDC.

Legal Disclaimer:

EIN Presswire provides this news content "as is" without warranty of any kind. We do not accept any responsibility or liability for the accuracy, content, images, videos, licenses, completeness, legality, or reliability of the information contained in this article. If you have any complaints or copyright issues related to this article, kindly contact the author above.