HIT-Hawk and HIT-Phoenix: Two kinds of flapping-wing flying robotic birds with wingspans beyond 2 meters

Abstract

Inspired by large and medium-sized birds, two kinds of flapping-wing flying robots with wingspans beyond 2 meters were developed. They have the appearance of a hawk and a phoenix respectively, so they are called HIT-Hawk and HIT-Phoenix. In this paper, the bionic concept, theoretical analysis, design and manufacturing are introduced in detail. Firstly, the flight principle and characteristics of large and medium-sized birds were summarized. Then, the aerodynamics was modeled based on the thin airfoil theory, and the main design basis was established. Secondly, the mechanical structures of HIT-Hawk and HIT-Phoenix were designed to ensure the lateral and longitudinal stability and have optimized flight performance. Moreover, an autonomous flight control method was proposed and realized in highly integrated on-onboard controller; it satisfies the strict restrictions on mass, size, power and shape. Finally, the prototypes were fabricated and verified through practical flight experiments. The wingspans of these two flapping wing aircrafts are 2.0 m and 2.3 m respectively, the take-off weights are 1.15 kg and 0.86 kg, and the maximum stable endurance is 65 min (with battery of 3S LiPo, 4300 mAh) and 8 min (with battery of 3S LiPo, 800 mAh). Their wind resistance can both reach level 4. Compared with the small and micro flapping-wing aerial vehicles that mimic insects or small birds, they both have strong load capacity, strong wind resistance and long endurance.