Carbon fiber has proved itself a valuable material for manufacturing aircraft. It is exponentially stronger and lighter than both steel and aluminum, making it a perfect replacement material in the quest to build ever larger planes with increased capacity. But wait, not all is sunshine and roses.
Using lighter materials comes at a trade-off. For example, carbon fiber wings are more prone to a phenomenon known as flutter thanks to their light weight. This phenomenon is nothing to scoff at and has been known to down a plane.
So how do you build carbon fiber wings that do not flutter? By embedding prototypes with sensors, putting those prototypes through extensive testing, and analyzing the signal data. Then you take all that knowledge and apply it to designing new wings and on-board monitoring and adjustment systems.
Building Wings in Europe
Building a better carbon fiber aircraft wing is the goal of a project known as Flutter free FLight Envelope eXpansion for ecOnomical Performance Improvement (FLEXOP). The European project is a partnership between multiple educational institutions and private sector aerospace organizations. They embarked on the project after realizing that European aviation was falling behind the U.S.
FLEXOP started out with the focus being primarily on active flutter control. It wasn’t long before directors expanded the mission to include passive load alleviation. In other words, they combined sensor-based mitigation technologies with a carbon fiber design to come up with a better wing that not only resists flutter but also better manages it when it occurs.
The Problem with Flutter
In aerospace, flutter is the undesirable oscillation of any part of an aircraft. It is especially problematic for wings. When a wing begins to oscillate, or vibrate if you will, it creates a couple of problems. First, a fluttering wing makes an aircraft harder to control. Significant flutter can cause pilots to lose control completely.
The other problem is that excessive flutter can actually cause an aircraft to break apart. If you have ever seen those old films of bridges swaying and breaking apart in the wind, you understand the problem. Flutter can distort aircraft wings to such a degree that they simply break up.
Figuring Out a Solution
Engineers working on the FLEXOP project have designed a carbon fiber wing with built-in passive load alleviation. They did so by aligning the fibers in their carbon fire material in different ways before testing each configuration for load alleviation. Meanwhile, another team was developing an array of sensors.
FLEXOP’s carbon fiber wing was eventually fitted with hundreds of electronic sensors along with traditional gyroscopes and accelerometers. The wing was then tested under a variety of different conditions so that data could be collected and analyzed. This allowed engineers to do two things.
First, the data helped them see what they were dealing with in terms of passive load evaluation. They have since used that data to design a wing that can actually twist and turn as needed to alleviate flutter. Second, they used the data to build new avionics that assist on-board computers in maintaining control when flutter does occur.
According to California’s Rock West Solutions, a big part of the project’s success lies in signal detection and analysis. Signal analysis is more or less the science of taking all of the data produced by an array of sensors, filtering out the noise, and providing actionable data that engineers can use to further their efforts.
So, how do you build a carbon fiber wing that does not flutter? By utilizing aerospace sensors and signal analysis to tell you exactly what is going on.