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The purpose of this paper is to describe the longitudinal dynamics of a hover‐capable rigid‐winged unmanned aerial vehicles (UAV) under various equilibrium flight conditions. The effects of the variable‐incidence wing in comparison with the fixed in‐incidence wing on the dynamics of UAV are also discussed.

The aerodynamic modeling of the vehicle covers both pre‐stall and post‐stall regimes using a three‐dimensional vortex lattice method incorporating viscous corrections. The trim states across a velocity spectrum are evaluated using a nonlinear constrained optimization scheme based on sequential quadratic programming. Then linearized dynamic analysis around trim states is carried out in order to compare the characteristics of the conventional platform with the modified platform incorporating variable‐incidence wing.

It is found that with the variable‐incidence wing, the longitudinal equilibrium flights can be achieved with reduced thrust‐to‐weight ratio demands and lower elevator deflection. However, the use of the variable‐incidence wing changes the dynamic characteristics of the vehicle considerably as indicated through the linear dynamic analysis.

The results presented in this paper are based on linear dynamic analysis about static trim point data. Further analysis taking into account nonlinearity, the unsteady aerodynamic effects and associated cross‐coupling because of asymmetric forces may be needed to reveal the true dynamics of the vehicle under unsteady maneuvers.

The variable‐incidence wing is a useful design feature to reduce the thrust‐to‐weight ratio requirements and to increase elevator control authority, however its effect on the dynamics warrants further investigation.

This is the first paper highlighting the effects of variable‐incidence wing on an agile hover‐capable UAV.

The purpose of this paper is to describe the research performed on flexible-wing micro air vehicle (MAV). Typical attributes associated with the aerodynamics of MAVs are low Reynolds number, low altitude flying environments and low aspect ratio platforms. These attributes give birth to several challenges such as poor aerodynamic performance, nonlinear lift patterns and reduced gust tolerance. Flexible-wing MAV is renowned for improved aerodynamic characteristics such as smooth flight in gusty conditions than its rigid-wing counterpart.

The wind-tunnel experiments are carried out for various configurations to determine the ways of further enhancing lift. The baseline geometric description for all MAVs includes 15-cm box dimension and an aspect ratio of 1. The experimental results of the baseline configuration are compared with other experimental results available in literature. After due validation, the effects of following parameters are quantized and compared with the rigid-wing counterpart: underlying skeleton; wing membrane extension; wing membrane relaxation; and wing membrane material (latex, silk, poly-vinyl chloride plastic sheet and nylon).

It is found that the skeleton layout significantly governs the lift characteristics. The effect of membrane extension and relaxation proved to be of little advantage. Latex sheets are found to be the best choice for membrane material. The aerodynamic assessment at low Reynolds number has demonstrated significant improvement of lift characteristics for flexible wings over rigid-wing counterparts.

The results presented in this paper are based on wind-tunnel experimentation. Further experimentation through flight test may be needed to reveal the true aerodynamic performance under unsteady maneuvers.

The material properties vary significantly during fabrication. A technique to standardize the properties of flexible membranes is a missing link in literature and warrants further investigation.

This concept of flexible wing has shown high potential. The primary objective of this paper is to experimentally investigate ways of further enhancing the lift of flexible-wing MAVs by controlling flexibility passively. While various researchers have spent many years on developing the optimum wing frame for the flexible wing, research on different wing materials has been limited. This is the first paper of its kind covering all aspects of wing-frame design, material, effects of extension and relaxation on wing membrane.

With possible practical application in a micro aerial vehicle (MAV), propulsion characteristics of a flapping wing with modified pitch motion are investigated both theoretically and experimentally in this paper.

Modified pitch motion is defined as a sinusoidal pitch motion with the pitch axis outside the wing chord line. Based on the momentum theory, an analytical model is developed to analyze the propulsion characteristics of the defined flapping wing. Following that, a water tunnel study of the effects of pitch axis distance, pitch frequency, and stream velocity on thrust generation is carried out. Thrust is directly measured using a 1‐D load cell and the flow visualization is captured using a high speed video camera.

It is found that shifting pitch axis outside wing chord line benefits the thrust generation significantly. Positive average thrust is produced at a relatively low frequency and increases almost quadratically with the motion frequency. The effect of stream velocity on the thrust time history is signified but has little effect on the average thrust magnitude.

Compared to other types of flapping wing motions, the proposed flapping can be achieved with simple mechanism and thus has the edge in practicality for propelling MAV or other submarine systems.

The paper provides useful aerodynamic characteristics of a type of flapping wing motion which possesses mechanical simplicity and relatively large thrust generation at low‐flapping frequency. This flapping wing has the potential to provide propulsion for a MAV or other submarine systems.