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The longitudinal dynamic flight stability of abumblebee in forward flight is studied.The method of com-putational fluid dynamics is used to compute the aerodynamicderivatives and the techniques of eigenvalue and eigenvectoranalysis are employed for solving the equations of motion.The primary findings are as the following.The forward flightof the bumblebee is not dynamically stable due to the exis-tence of one (or two) unstable or approximately neutrallystable natural modes of motion.At hovering to medium flightspeed [flight speed u_e=(0-3.5)m s~(-1);advance ratioJ=0-0.44],the flight is weakly unstable or approximatelyneutrally stable;at high speed (u_e=4.5 m s~(-1);J=0.57),the flight becomes strongly unstable (initial disturbancedouble its value in only 3.5 wingbeats).
The longitudinal dynamic flight stability of abumblebee in forward flight is studied. The method of com-putational fluid dynamics is used to compute the aerodynamic derivatives and the techniques of eigenvalue and eigenvectoranalysis are employed for solving the equations of motion. The forward flight of the bumblebee is not dynamically stable due to the exis-tence of one (or two) unstable or approximately neutrally stable natural modes of motion. At hovering to flightpeed [flight speed u_e = (0-3.5) ms ~ (- 1); advance ratioJ = 0-0.44], the flight is weakly unstable or approximately transiently stable; at high speed (u_e = 4.5 ms -1; J = 0.57), the flight becomes strongly unstable (initial disturbance double its value in only 3.5 wingbeats).