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wing beat frequencies in Neurogenic and Myogenic insect fliers having different

frequency range.

During the movement of a flier the aerodynamic forces such as lift, thrust and

drag (induced drag) involve their coefficients. L/D ratio indicates flight efficiency

and endurance in migratory flight. They in turn involve mass, wing dimensions,

displacement of air and density.

Reynolds number is variable in different groups of biological fliers as compared

to an aeroplane. Reynold number goes on increasing in insects, birds, bats and aero-

planes with increase in velocity. Reynolds number can also be interpreted as a ratio

of total momentum transfer to molecular momentum transfer which remains to be

elucidated fully. Various lift enhancing mechanisms in insects have been reviewed.

Formation of Leading Edge Vortex (LEV) is a general flow phenomenon in flapping

flexible wings of insects. In an aeroplane the Angle Of Attack (AOA) for stall is

about 16°, however, in insects the stall angle is above 60°. This helps in prolonged

manoeuverability and recovery during prestall period and prevents serious accident.

Leading edge vortices contribute to delayed stall which is highly significant in rela-

tion to CL and CD calculations. Formation of LEV is a general flow feature in flapping

wings having Reynolds number of 10⁴ or less and this knowledge helps in developing

flapping flexible wing for MAVs.

The Naiver Stoke’s equation in its non-dimensional form describes how the

velocity, pressure and density of moving fluid are related to each other. Hence it

comes out to be a useful phenomenon to understand insect flight under various

dimensions. The equation is non-dimensional one [1].

Moment of Inertia of the moving wing is calculated by strip analysis method.

However, strip number for the first time has been plotted against strip wing loading,

which gives the best possible information for a flapping flexible moving wing. A 3-D

study will help in the design of flexible membranous wings in MAVs. Moment of

inertia and effective radius of gyration have been calculated for soap-nut bug. The M.I

and mutilation study during hovering help in understanding aerodynamic forces in a

moving wing. Total energy of the insect and M.I of the wing are calculated. MI study

helps in determing torque needed for angular acceleration and for 3D movements

matrix and torque are essential.

The wing morphology suitable for insect flight is discussed by the authors in

greater detail. Wingbeat frequencies of insects, forward velocity and aerodynamic

flight parameters lift, thrust and drag along with certain additional derived flight

parameters such as wing span loading are elucidated. Insect wings are membranous

outgrowths of exoskeleton chitin originating from pleuron that allows the insects

to fly. The textural composition of wings and geometry are suitable for ecological

adaptability of the species.

Various theories of wingbeat frequency and their importance in hovering flight of

insects have been discussed in detail. Wingbeat frequency of some common insects

have been recorded and calculated. Fourier analysis of bioacoustic sound has been

carried out in our bio physics laboratory at Nizam college, O.U, Hyderabad. Aerody-

namically during hovering lift force must be sufficient to balance the total weight of

the flier, while forward velocity being zero. Wing beat frequency in hovering flight