Anybody who says NASA researchers don’t know how to have a smashing good time has not met a team at NASA’s Langley Research Center in Hampton, Va. They are test engineers whose job it is to make aircraft safer by crashing them.
In late August those engineers plan to drop a 45-foot long helicopter fuselage from about 30 feet to test improved seat belts and seats and to collect crashworthiness data. NASA is collaborating with the Navy, Army and Federal Aviation Administration on the Transport Rotorcraft Airframe Crash Testbed full-scale crash tests at NASA Langley’s Landing and Impact Research (LandIR) Facility.
LandIR, a 240-foot high, 400-foot long gantry, has an almost 50-year history. It started out as the Lunar Landing Research Facility, where Neil Armstrong and other astronauts learned to land on the moon. Then it became a crash test facility where engineers could simulate aircraft accidents. And recently it added a big pool where NASA is testing Orion space capsule mock-ups in anticipation of water landings.
The August drop test is one of the most complicated and ambitious aircraft crash experiments at NASA Langley in recent memory. “We have instrumented a former Marine helicopter airframe with cameras and accelerometers,” said lead test engineer Martin Annett. “Almost 40 cameras inside and outside of the helicopter will record how 13 crash test dummies react before, during and after impact. Onboard computers will also record more than 350 channels of data.”
External cameras will capture images of an unusual looking helicopter. Instead of the usual Marine gray, technicians painted one entire side in black polka dots over a white background. It is not a fashion statement, but a photographic technique called full field photogrammetry. Each dot represents a data point. High speed cameras filming at 500 images per second track each dot, so after everything is over, researchers can plot and “see” exactly how the fuselage buckled, bent, cracked or collapsed under crash loads.
Something else that is being used for the first time during this test is a well-known video game motion sensor. “We installed an Xbox Kinect inside the helicopter,” said Justin Littell, test engineer. “We want to see if it can be used as an additional instrument to track dummies’ movements.
All the dummies, cameras, sensors, instruments, and experiments will come together, some even perhaps literally, when the helicopter is lifted into the air about 30 feet – then pendulum swung by cables into a bed of soil. Just before impact pyro-technic devices release the suspension cables from the helicopter fuselage to allow free flight. The helicopter will hit the ground at about 30 miles an hour. The impact condition represents a severe but survivable condition under both civilian and military requirements.
Another crash test of a similar helicopter equipped with additional technology, including composite airframe retrofits, is planned for next year. Both tests are part of the NASA Aeronautics Research Mission Directorate’s Fundamental Aeronautics Program Rotary Wing Project.
The Navy provided the CH-46 Sea Knight helicopter fuselages, seats, a number of crash test dummies and other experiments for the test. The Army contributed a crash test dummy that is lying down similar to a patient on a medical evacuation litter. The FAA provided a side facing specialized crash test dummy and part of the data acquisition system. A private company, CONAX Florida Corporation DBA Cobham Life Support in St. Petersburg, Fla., also contributed an active restraint system for the cockpit.
NASA will use the results of both tests to try to improve rotorcraft performance and efficiency, in part by assessing the reliability of high performance, lightweight composite materials. Researchers also want to increase industry knowledge and create more complete computer models that can be used to design better helicopters.
The ultimate goal of NASA rotary wing research is to help make helicopters and other vertical take off and landing vehicles more serviceable – able to carry more passengers and cargo – quicker, quieter, safer and greener. Improved designs might allow helicopters to be used more extensively in the airspace system.