Wings
Wings produce the aerodynamic forces that enable an insect to fly. A developed wing consists of a thin membrane with two layers separated by veins and covered in a thick cuticle (Champman 1998).
Wings alternate their angle or pitch in a flight cycle to produce thrust and drive the insect forward while avoiding stalling (stopping the insect in midflight) (Dickinson 1985). Similar to a propeller of helicopters, in each stroke the wings will move around the base of the body and flip making an ellipse (Dickinson 1985).
Vortexes are formed as air is drawn faster over the wing providing lift through a suction like force that pushes against the under surface of the wing and elevates the insect.
Forces that Act on Wings
As insect wings are constantly changing position the force of lift is always changing and will be either positive or negative (Champman 1998). During the entire wing beat cycle the lift is positive and pushes the insect body upwards (Champman 1998).
Wings alternate their angle or pitch in a flight cycle to produce thrust and drive the insect forward while avoiding stalling (stopping the insect in midflight) (Dickinson 1985). Similar to a propeller of helicopters, in each stroke the wings will move around the base of the body and flip making an ellipse (Dickinson 1985).
Vortexes are formed as air is drawn faster over the wing providing lift through a suction like force that pushes against the under surface of the wing and elevates the insect.
Forces that Act on Wings
As insect wings are constantly changing position the force of lift is always changing and will be either positive or negative (Champman 1998). During the entire wing beat cycle the lift is positive and pushes the insect body upwards (Champman 1998).
The vortexs formed during insect flight that drive the insects forward by pushing against the wings.Image provided by Willmer et al.(2000).
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Schematic of insect flight paths. Image provided by Willmer et al.(2000).
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Hovering
In order for bumblebees to hover the body must be almost vertical and have a horizontal stroke plane. In this position the wings rotate at least 100˚ at the end of the stroke to allow the angle of the wings to be similar to normal flying (Champman 1998). This produces even more vortexes that bring air downwards and supports the insect and makes them hover; this is called downwash (Champman 1998).Interestingly the flying mechanism of bumblebees and honeybees influenced the development of helicopter flight (Heinrich 1979).
In order for bumblebees to hover the body must be almost vertical and have a horizontal stroke plane. In this position the wings rotate at least 100˚ at the end of the stroke to allow the angle of the wings to be similar to normal flying (Champman 1998). This produces even more vortexes that bring air downwards and supports the insect and makes them hover; this is called downwash (Champman 1998).Interestingly the flying mechanism of bumblebees and honeybees influenced the development of helicopter flight (Heinrich 1979).
Bumblebee using hovering flight technique. Image provided by Flath(2007).
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The force of downwash is seen as the air hits against the water. Image provided by U.S. Coast Guard (2006).
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Independent Control of Wings
Depending on wing position or the types of flight, vortexes are created differently. Bomphrey et al (2009) used smoke visualisation to study the vortexes made by bumblebees. Bumblebees were found to make separate vortices on the left and right wings (Bomphrey & Taylor 2009). This is different to insects such as the locusts that only produce a single vortex, a much more efficient method of hovering (Bomphrey & Taylor 2009). This may lead you to ask why the bumblebee evolved this energy expensive mechanism. It may be simply the biological constraint of the bumblebee’s large thorax that doesn’t permit a single vortex to be made (Bomphrey & Taylor 2009). However, it may have evolved to allow the bumblebee to have more independent control of the left and right wings and therefore high manoeuvrability when searching for delicious pollen (Bomphrey & Taylor 2009).
Depending on wing position or the types of flight, vortexes are created differently. Bomphrey et al (2009) used smoke visualisation to study the vortexes made by bumblebees. Bumblebees were found to make separate vortices on the left and right wings (Bomphrey & Taylor 2009). This is different to insects such as the locusts that only produce a single vortex, a much more efficient method of hovering (Bomphrey & Taylor 2009). This may lead you to ask why the bumblebee evolved this energy expensive mechanism. It may be simply the biological constraint of the bumblebee’s large thorax that doesn’t permit a single vortex to be made (Bomphrey & Taylor 2009). However, it may have evolved to allow the bumblebee to have more independent control of the left and right wings and therefore high manoeuvrability when searching for delicious pollen (Bomphrey & Taylor 2009).
A comparison of bumblebee(left) and locust (right) vortex formation (A) and forces of downwash (B). Image provide by Bomphrey & Taylor (2009).
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