Forward flight stability in a drone-fly

Abstract

Previous studies on forward flight stability in insects are for low to medium flight-speeds. In the present work, we investigated the stability problem for the full range of flight speeds (0-8.6 m/s) of a drone-fly. Our results show the following: The longitudinal derivatives due to the lateral motion are approximately 3 orders of magnitude smaller than the other longitudinal derivatives. Thus, we can decouple these two motions of the insect, as commonly done for a conventional airplane. At hovering flight, the motion of the dronefly is weakly unstable owing to two unstable natural modes of motion, a longitudinal one and a lateral one. At low (1.6 m/s) and medium (3.1 m/s) flight-speeds, the unstable modes become even weaker and the flight is approximately neutral. At high flight-speeds (4.6 m/s, 6.9 m/s and 8.6 m/s), the flight becomes more and more unstable due to an unstable longitudinal mode. At the highest flight speed, 8.6 m/s, the instability is so strong that the time constant representing the growth rate of the instability (disturbance-doubling time) is only 10.1 ms, which is close to the sensory reaction time of a fly (approximately 11 ms). This indicates that strong instability may play a role in limiting the flight speed of the insect.

Joint improvements of radar/infrared stealth for exhaust system of unmanned aircraft based on sorting factor Pareto solution

“…PO and physical theory of diffraction (PTD) are used to solve the electromagnetic scattering characteristics of each individual in each offspring 3 . According to the magnetic vector position caused by the induced current on the surface of the target model, the electric field and magnetic field can be obtained as follows: where r is the coordinate vector of the field point, ω is the electromagnetic wave angular frequency, k is the wave number in free space, R is the distance vector between the field point and the source point, r ′ refers to the coordinate vector of the source point, ε is the dielectric permittivity 28 – 30 , J s represents the induced current on the target surface. When calculating RCS, the integral surface of the model is treated as an ideal conductor.…”

Quasi-steady aerodynamic modeling and dynamic stability of mosquito-inspired flapping wing pico aerial vehicle

“…Dimensions of thorax for active actuation are 2.14 2.40 3.95 (mm). As in previous studies ( Zhu et al, 2020 ), it is also assumed that the center of pressure (CP) is located near the rotational axis in the chord-wise direction. The product of the wing length and the radius of the second moment of inertia determines the span-wise CP location.…”

Joint Improvements of Radar/infrared Stealth for Exhaust System of Unmanned Aircraft Based on Sorting Factor Pareto Solution

“…PO and physical theory of diffraction (PTD) are used to solve the electromagnetic scattering characteristics of each individual in each offspring [3]. According to the magnetic vector position caused by the induced current on the surface of the target model, the electric field and magnetic field can be obtained as follows: (2) where r is the coordinate vector of the field point,  refers to the electromagnetic wave angular frequency, k represents the wave number in free space, R is the distance vector between the field point and the source point, r′ refers to the coordinate vector of the source point,  is the dielectric permittivity [28][29][30], Js represents the induced current on the target surface.…”