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Summary

Symmetricalhoveringisfoundinhummingbirdsandinsects.Thiscanbesummarized

as follows:

1.

Body mass is usually small and the position of the orientation of the body may

be more or less vertical during hovering.

2.

Wings move forward and backward coupled with some kind of small rotation

at the base.

3.

Differential lift is produced during downstroke and upstroke; however, the lift

produced during downstroke is about an average value of 65%.

4.

Wings are rotated about the wing base during pronation and supination.

5.

Hovering is mainly sustained by the wingbeat frequency of the flier.

6.

The wing tip traces approximately a figure of ‘8’.

7.

The wing is relatively rigid and cambered and the wingspan does not change

during hovering.

8.

The hovering frequency is relatively high and the variation has a frequency

range depending on whether it is a neurogenic or myogenic flier.

9.

Hovering is a costly mode of flight in terms of energy consumption.

10.

All the seven theories of hovering flight relevant to the insects have been

discussed in detail.

11.

In hovering, most of the lift is produced during the downstroke and so also the

drag.

The wingbeat frequencies of different insects as calculated from above-mentioned

theories, particularly from mass flow theory, have been shown in Table 3.1. The

experimental and theoretical values as calculated are in good agreement.

In conclusion, for the wing design of an Insect Mimicking MAV, the structure of

a hovering insect flier appears to be a more ideal choice. Since it is made up of chitin

and has elastomere resilin at the main base. The chitinous thin wing membrane of

insects is traversed by a large number of longitudinal veins which contributes to the

elastic property of the wing. Aeroelasticity plays an important role in the design and

kinematic study of the wing motion since it involves axial stretching, buckling and

damped vibrations.

Non-uniform flexibility and structural deformation of the wing in hovering are an

important factor which need further study.

Addendum

Salient features of comparison of symmetrical and hovering insects and birds.

• Seen in hummingbirds and insects.

• Size/body mass (5–40 gr) is small and Hovering may be vertical.

• Wings move forward and backward and rotate at the base.

• Differential lift is produced during downstroke and upstroke.

• Wings are rotated at the fulcrum, during pronation and supination.

• Hovering is due to wingbeat frequency.