This paper presents a classic missile-type parallel-approach guidance law for fixed-wing UAVs in coordinated formation flight. The key idea of the proposed guidance law is to drive each follower to follow the virtual target point. Considering the turning ability of each follower, the formation form adopts the semi-perfect rigid form, which does not require the vehicle positions form a rigid formation, and the orientations keep consensus. According to the mission characteristics of the follower following a leader and the leader following a route, three guidance laws for straight, turning, and circling flight are designed. A series of experiments demonstrate the proposed guidance law’s improved response and maneuvering stability. The results of hardware-in-the-loop simulations and real flight tests prove that the proposed guidance law satisfies the practical UAV formation flight control demands.

This paper experimentally studied the influence of the notch shape and size on the damage evolution and failure strength (tension and torsion) of carbon fiber-reinforced epoxy matrix (CFRP) laminates. Hashin’s damage criteria were utilized to monitor the evolution of multi-damage modes, and FEM simulations were also performed by using the ABAQUS code to clarify the specific damage modes in detail as an instructive complement. The failure characteristics of all the notched samples were analyzed and compared with those without notches. The measured results presented that the existence of a variety of notches significantly impaired the load carrying capacity of CFRP laminates. The tensile strengths of C-notch and U-notch increase with an increasing notch radius, while the ultimate torques of C-notch and V-notch decrease with an increasing notch size and angle. The variation in notched properties was explained by different notch shapes and sizes, and the failure characteristics were also presented and compared among notched CFRP laminates with varied notches.