How do you make a helicopter safer to fly? You crash one. NASA aeronautics researchers at Langley Research Center in Hampton, VA, recently dropped a small helicopter from a height of 35 feet to see whether an expandable honeycomb cushion called a deployable energy absorber could lessen the destructive force of a crash. On impact, the helicopter’s skid landing gear bent outward, but the cushion attached to its belly kept the rotorcraft’s bottom from touching the ground. Researchers must analyze the test results before they can say for sure whether the deployable energy absorber worked as designed.
According to the National Transportation Safety Board, more than 200 people are injured in helicopter accidents in the United States each year, in part because helicopters fly in riskier conditions than most other aircraft. They fly close to the ground, not far from power lines and other obstacles, and often are used for emergencies, including search and rescue and medical evacuations.
For the test, researchers used an MD-500 helicopter donated by the U.S. Army. The rotorcraft was equipped with instruments that collected 160 channels of data. One of four crash test dummies was a special torso model from Johns Hopkins University equipped with simulated internal organs.
Technicians outfitted the underside of the helicopter’s crew and passenger compartment with the deployable energy absorber. The device is made of Kevlar and has a unique flexible hinge design that allows the honeycomb to be packaged and remain flat until needed.
Researchers tested the deployable energy absorber under realistic conditions. It was suspended 35 feet in the air using cables. Then, as it swung to the ground, pyrotechnics were used to remove the cables just before the helicopter hit, so that it reacted like it would in a real accident. The test conditions imitated what would be a relatively severe helicopter crash. Engineers say the MD-500 survived relatively intact as a result of the honeycomb cushion.
For more information, visit www.nasa.gov/topics/aeronautics/features/helo-droptest.html.