Researchers at UP’s Department of Mechanical and Aeronautical Engineering are investigating the use of bird-inspired designs on the performance of unmanned aerial vehicles (UAVs) with the hope of finding efficiency improvements. This is part of the large drive underway in the aviation industry to find new aircraft configurations that are superior to the traditional configurations in terms of performance and fuel efficiency due to the growing environmental concerns around airflight.
“The question arose during a flight test of the Project AREND, a UAV we have developed at UP to monitor and fight rhino poaching, about whether we could remove the vertical tail and instead copy a bird, which practically has no vertical tail.” says Ankit Sharma, a Masters student in Mechanical and Aeronautical Engineering investigating these tailless bird-inspired UAVs. “A tailless aircraft offers far less air resistance, but is harder to control. But loading the wing planform with non-elliptic lift distribution as compared to elliptical lift distribution combined with modern electronics and software means we can still control the tailless aircraft”
A computational fluid dynamics (CFD) simulation of the original AREND UAV with a vertical tail
A tailless aircraft also has the potential to offer multiple avenues of improved aerodynamic performance, especially if the wing planform takes responsibility for all stability requirements, as the tailless aircraft has no vertical stabilizer seen in conventional configurations.
The existing AREND UAV with a vertical tail and an elliptically loaded wing was compared to an improved tailless aircraft with a non-elliptic lift distribution (NELD). Both the original AREND and the newly proposed NELD AREND wings were numerically analysed using computational fluid dynamics to investigate the aerodynamic and flight mechanic trade-offs and benefits.
A CFD simulation of the newly proposed NELD AREND UAV with a bird-inspired design without a vertical tail
The comparison showed that the bird-inspired NELD configuration increased the aerodynamic efficiency by approximately 10%, with additional benefits of weight reduction and a wider centre of gravity range. The bird-inspired NELD glided 10% longer than the original AREND design, consumed 10% less energy, and turned 32% faster.
The reduction in weight from having no tail, the smaller wake zone of the blended wing-fuselage and an unconventional wing design using non-elliptic lift distribution were considered to be the reasons for the improvement.
The proposed configuration has the potential not only to allow for a reduction in structural weight but also a reduction in drag that leads to an increase in fuel efficiency. This serves as another step toward addressing the growing environmental concerns in the aviation industry.