Fig.1

Schematic mission profile of climb phase of TBCC aircraft

Table 1

Basic data sets for combined-cycle system

Fig.2

Schematic diagram of a hypersonic vehicle inlet at a certain angle of attack

Fig.3

Plot of thrust and fuel consumption rate coefficient versus angle of attack［29-30］

Fig.4

Schematic diagram of chicken foraging behaviour

Fig.5

Schematic diagram for initial values selection of chicken’s control volumes

Fig.6

Schematic diagram of updating based on current optimal position and based on previous generation position

Fig.7

Schematic diagram of effect of updating position of hens after improvement

Fig.8

Algorithm process of improved CSO-Gauss pseudospectral method

Table 2

Information of simulation groups

Fig.9

Comparison of simulation results of eight groups

Fig.10

Comparison of results before and after improving updating rules of chicks and hens

Fig.11

H-Ma plot of optimization results of three algorithms

Fig.12

m-t and γ-t plots of optimization results of three algorithms

Fig.13

H-t and H-x plots of optimization results of three algorithms

Fig.14

α-t and φ-t plots of optimization results of three algorithms

Fig.15

H-Ma plot of optimization results for decreasing lift-to-drag ratio

Fig.16

m-t and γ-t plots of optimization results for decreasing lift-to-drag ratio

Table 3

Fuel consumption and time consumption for climb trajectories with different values of lift-to-drag ratio

Fig.17

Selection of points in switching window between turbojet engine and sub-burning ramjet engine

Fig.18

H-Ma plots of optimization results at different switching points

Fig.19

Plots of overall fuel consumption and time consumption for each climb trajectory at different switching points

Fig.20

m-t plots of optimization results at different switching points