Fig. 1

Kinematic diagram of flapping-wing mechanism

Fig. 2

Elastic flat wing

Fig. 3

Kinematics of elastic flat wing （T = 1/f¯flap）

Fig. 4

Coordinate frames of flapping-wing vehicles

Fig. 5

Diagram for aerodynamics analysis in 3D

Fig. 6

Kinematics and aerodynamic forces of small bird-scale flapping-wing vehicles（T = 1/f¯flap）

Fig. 7

Experimental prototype of small bird-scale flapping-wing vehicles

Table 1

Structural parameters of small bird⁃scale flapping⁃wing vehicles

Table 2

Schematic diagram of wing structure

标号	机翼示意图	单侧机翼重量/g
1）无骨架机翼（低刚度）		0.4
2）少骨架机翼（中等刚度）		0.45
3）多骨架机翼（较大刚度）		0.5

Fig. 8

Test platform of static aerodynamic forces

Fig. 9

Test platform of dynamic aerodynamic forces

Table 3

Performance index of 3D force sensor

Fig. 10

Comparison of measured aerodynamic force and predicted aerodynamic force of frameless wings （T = 1/f¯flap）

Fig. 11

Comparison of measured aerodynamic force and predicted aerodynamic force of less-frame wings （T = 1/f¯flap）

Fig. 12

Comparison of measured aerodynamic force and predicted aerodynamic force of multi-frame wings （T=1/f¯flap）

Fig. 13

Comparison of measured and predicted data of average aerodynamic forces

Fig. 14

Deformation angles of three wings

Fig. 15

Comparison of measured aerodynamic force and predicted aerodynamic force of frameless wings （revised）

Fig. 16

Comparison of measured aerodynamic force and predicted aerodynamic force of less-frame wings （revised）

Fig. 17

Comparison of measured aerodynamic force and predicted aerodynamic force of multi-frame wings （revised）

Fig. 18

Comparison of measured and predicted data of average aerodynamic forces （revised）

Fig. 19

Relationship between predicted aerodynamic force and wingspan deformation and chord deformation

Fig. 20

Comparison of measured and predicted lift of multi-frame wings at pitch angle of 5°

Fig. 21

Comparison of measured and predicted lift of multi-frame wings at pitch angle of 10°

Fig. 22

Comparison of measured and predicted lift of multi-frame wings at pitch angle of 15°

Fig. 23

Average forward flight speed and average lift of small bird-scale flapping-wing vehicles