Lifting-wing multicopter

Lore & Background

In 2015, the University of Leuven, Belgium, proposed a hybrid configuration aircraft with a lifting-wing structure, named VertiKUL2, whose wing and rotor are installed at 45 degrees to improve wind resistance. The reliable flight control group of Beihang University formally proposed the lifting-wing multicopter configuration in 2018 and began prototype design and basic performance verification. Experiments concluded that power consumption could be reduced by about 50% within a certain cruise speed range compared to traditional multicopters.

In 2019, the Beihang group began design of the lifting-wing multicopter, proposed evaluation methods for range and transition time performance, and established a comprehensive model. Flight experiments achieved expected results. Also in 2019, VOLITATION designed a multicopter with lifting wing named VesperTilio, and Amazon designed Prime Air for delivery. Starting in 2022, the Beihang group conducted control experiments including unified controller validation, precise trajectory tracking, bio-inspired high-agility flip maneuvers, disturbance and wind rejection, propeller failure tolerant control, and tethered lifting-wing multicopter research.

The lifting-wing multicopter differs from common hybrid UAVs in control, smoothly transitioning from hovering to forward flight. During forward flight, rotors provide forward force and part of lift, while the lifting wing provides the other part. The optimized wing design lowers the center of gravity, enhances stability, and avoids toppling due to large windward surface when landing. Its airframe and flight control design are more complex than convertiplanes and tail-sitters, but its use efficiency is significantly better. Compared with traditional multicopters, convertiplanes, and tail-sitters, the lifting-wing multicopter has relatively compromised performance, serving as a supplement to current hybrid UAVs.

Reader's Guide

The lifting-wing multicopter represents a distinct approach to hybrid UAV design, notable for its continuous operation in a mixed flight mode rather than switching between discrete multicopter and fixed-wing states. This characteristic necessitates a unified controller for the full flight phase, as developed by the reliable flight control group of Beihang University. Because the aircraft only needs to tilt at an angle often smaller than 45 degrees—rather than 90 degrees like tail-sitter UAVs—the risk of stall is reduced. Cooperative control between rotors and ailerons on the lifting wing enables energy savings, as aileron control is more energy-efficient than rotor-based roll control.

Its significance lies in addressing the efficiency limitations of traditional multicopters while retaining their structural simplicity and wind resistance. The fixed-angle wing-rotor installation (e.g., 30–45 degrees) improves forward flight efficiency, with experiments showing up to about 50% power reduction within a certain cruise speed range. The design also enhances stability and avoids toppling during landing. However, the complexity of its airframe and flight control is greater than that of convertiplanes and tail-sitters, and its overall performance is described as compromised relative to those types. The lifting-wing multicopter thus fills a niche as a supplement to existing hybrid UAV configurations, offering a unique balance of efficiency, stability, and wind resistance.

Did You Know?

• The lifting-wing multicopter's rotor disc and wing are installed at a fixed angle, typically 30–45 degrees.
• In 2015, the University of Leuven proposed the VertiKUL2 with a 45-degree wing-rotor angle to improve wind resistance.