The Future of Aviation: Fold-able Airplane Wings
Aerodynamics is an integral part of flying—the better they are, the better the flight. Likewise, with superior aerodynamics aircraft consume lesser fuel and fly faster. Recently, NASA conducted a series of flight tests at the Armstrong Flight Research Center in California. These tests were a part of the ambitious Spanwise Adaptive Wing or SAW project, which aims to validate the usage of a lightweight material that will be able to fold the outer segments of the aircraft wings and therefore, control their outer surfaces to optimal angles while in-flight. Although the technology of foldable wings has been there for quite some time, the actual system was actually cumbersome and required heavy hydraulics to operate. This newer technology, currently in development-phase, makes use of a shape memory alloy. Let’s find out more in this post.
What is Spanwise Adaptive Wing Testing?
The SAW or Spanwise Adaptive Wing project is a joint effort between Langley Research Center in Virginia, Armstrong ( NASA’s Glenn Research Center in Cleveland), Area-I Inc. in Kennesaw, Georgia, and Boeing Research & Technology in St. Louis and Seattle. Together, these agencies aim to introduce a number of futuristic, in-flight developments for both supersonic and subsonic aircraft. Coming to the folding wings functionality while in-flight, studies have been ongoing since the days of the North American XB-70 Valkyrie during the 1960s. Earlier, the aircrafts had to use bulky hydraulic systems and conventional motors to obtain the ability to fold their wings during flight. According to the latest tests conducted by the NASA, the newer version of this technology uses a shape memory alloy, is more efficient and doesn’t require heavy machinery. Rather, it relies on the temperature-activated properties of the alloy. When provided with adequate thermal energy, the shape memory alloy activates a twisting motion in the tubes, which in turn, serve as the actuators in the wings. Subsequently, the wings' outer portion can be moved up to 70 degrees in either upwards or downwards direction.
Why Shape Memory Alloy?
This cutting-edge, lightweight alloy is temperature-triggered and works by using thermal memory in a tube to function and move as an actuator. Upon heating, the alloy activates a twisting motion in the tubes. This, eventually, moves the outer portion of the aircraft’s wings up or down, up to 70 degrees—whichever allows for better flight control in that instance. The special alloy was developed jointly by NASA and Boeing and has shown consistent results, starting from initial testing up to actual flight tests. To test this new technology, NASA chose to operate an autonomous flight testbed, Prototype Technology-Evaluation Research Aircraft (or PTERA) inside Area-I. Indigenously designed and developed by Area-I, PTERA integrates a shape memory alloy-actuated, wing-folding mechanism. In additionally, this UAV also features extensive flight instrumentation gather data on the SAW.
The potential benefits of having foldable wings on subsonic aircrafts such as commercial airliners include improved controllability and maneuverability. This will help reduce the dependency on heavier parts of the airliner such as the tail rudder. Overall, the aircraft’s fuel efficiency will improve significantly and in future, long-winged aircraft will be able to easily taxi in airports. In case of supersonic flights, however, the benefits of folding wings while in-flight are tremendous. Tests have found that while flying supersonic, the ability to fold the wing tips downward, helps reduce the drag. With reduced drag, aircraft can not only have superior performance but also be able to seamlessly transition between subsonic and supersonic speeds.