Fig.1

Rigid-elastic coupled flight dynamics model of heavy lift helicopter with external slung load

Fig.2

Flight dynamic couplings of HLH with slung load

Fig.3

Bousman’s rotor/fuselage coupling ground resonance test model［24］

Fig.4

System mode frequency variations to rotational speed of Bousman’s rotor/fuselage coupling ground resonance test results of configuration 1［19］

Fig.5

Trim characteristics validation of UH-60A helicopter carrying CONEX slung load

Fig.6

Frequency response characteristics validation of UH-60A helicopter carrying CONEX slung load （Roll attitude response to lateral control input in hover）

Table 1

Basic parameters of slung load system

Table 2

Mass and inertia parameters of sample heavy lift helicopter carrying slung load

Fig.7

Eigenvalues of heavy lift helicopter carrying slung load with various slung load mass ratios and velocities

Fig.8

Close-up of main rotor lag progressive mode and fuselage vertical bending mode

Fig.9

Variations of lag progressive eigenvalue and fuselage vertical bending eigenvalue to fuselage vertical bending frequency at maximum slung load mass ratio in hover

Fig.10

Eigenvectors of lag progressive mode and fuselage vertical bending mode at maximum slung load mass ratio in hover

Fig.11

Air resonance mechanisms of lag progressive mode and fuselage vertical bending mode couplings

Fig.12

Variations of fuselage bending eigenvalue and sling stretching eigenvalue to sling stiffness at minimum slung load mass ratio in hover

Fig.13

Sling stretching eigenvector at minimum slung load mass ratio in hover with various sling stiffness

Fig.14

Fuselage vertical bending eigenvector at minimum slung load mass ratio in hover with various sling stiffness

Fig.15

Air resonance mechanisms of fuselage vertical bending mode and sling stretching mode couplings

Fig.16

Lag regressive eigenvectors of hovering with light/heavy slung loads