Cushioning the impact of flight vibrations
Military and civilian aircrew alike routinely fly long hours, often in an environment of relentless jolting and shaking that can cause fatigue and discomfort. The effects of this persistent vibration can not only jeopardize flight comfort and safety but can also cause long-term health issues such as chronic back and neck pain. Nowhere is this more apparent than for helicopter crew who are often weighed down by heavy gear and equipment.
In response, the Department of National Defence (DND) tasked its Directorate of Technical Airworthiness and Engineering Support (DTAES) with finding a solution that could be used across the aerospace industry to dissipate the negative effects of this vibrational energy, which is typically transmitted through aircraft seats.
To meet their goal of ensuring the health and safety of aircrew while also improving comfort levels, DTAES enlisted the assistance of NRC’s Flight Research Laboratory, which has been studying the cause and effects of noise and vibration for more than fifteen years. Together, they would pursue a solution to increase energy absorption while still maintaining the airworthiness and stringent safety requirements of aircraft seating.
Taking a front seat to innovation
With an advanced knowledge of energy-absorbing materials, NRC experts began by measuring fabric performance and properties such as stiffness and flammability. Once complete, they tested and validated new configuration options using the human-rated shaker device, a mechanical chair that mimics the effects of in-flight movement on human test subjects. The result was an innovative seat cushion design that integrates traditional foam with a novel energy-absorbing material that will reduce the health and safety risks associated with whole-body vibration issues.
“We needed a cost-effective yet high-quality solution to mitigate helicopter vibrations,” says Major Matthew Maxwell, Team leader of Human Factors Engineering/Human System Integration at DND-DTAES. The new design features a unique hexagonal cell pattern that interconnects with a system of air vents to dissipate vibrational energy. “We have been working with NRC in this area for over a decade and we knew they would be the right partner for this project.”
However, before the new cushion technology could be cleared for authorized use, its performance first needed to be tested, in this case using NRC’s Bell-412 helicopter which provided a real-world flight testing environment under controlled circumstances. “At NRC, we leverage our expertise and unique research infrastructure to provide the aerospace industry with innovative solutions that can effectively be transferred to the marketplace,” says NRC's Ian Potter, Vice-President of Engineering and Business Management.
The results of the test flights ultimately verified the ability of the new cushion to dissipate vibrational energy. It has since been selected for integration into the new armoured seat for the Canadian Armed Forces CH-146 Griffon fleet to help improve the comfort and health of its aircrew.
And while this new technology was originally developed for military use, its application in the civilian market is also promising. DND and NRC have in fact already entered into a licensing agreement to transfer the technology to Dart Aerospace of Hawkesbury, Ontario for immediate use in the commercial helicopter market. “NRC’s expertise has been crucial for us to move this valuable technology from the conception stage to market,” says Peggy McDonald, Sales Executive at Dart Aerospace.
Looking ahead, future research will delve more deeply into the biomedical effects of flight vibration, using techniques such as applying electrodes to gauge muscular response to various intensities during flight manoeuvres. Efforts to develop a 'smart cushion' are also underway as part of the ongoing search for new and innovative solutions that will help to steady the course forward.