Flight of Insects


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A mecânica do voo dos insetos.
Documento produzido pela University of Virginia, nos Estados Unidos.

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Flight of Insects

  1. 1. Insect Flight Mechanisms:Anatomy and Kinematics Carl R. Knospe Associate ProfessorMechanical and Aerospace Engineering University of Virginia Fall 1998
  2. 2. Overview- highly evolved and complex biomechanical system- all locomotion originates from the insect’s thorax, specifically the pterothorax.- power produced by muscles is transmitted to the wing via the complex interactions of hardened parts of the skeleton
  3. 3. PterothoraxThe pterothorax can be divided into the- tergum (back)- pleura (sides)- sternum (belly)The wing is elevated ordepressed by deformation of thetergum
  4. 4. Anatomy of the TergumTergum parts are separated by internalskeletal folding, ridges, and sutures.Tergum composed of notum, andpostnotum.The notum can be further subdividedinto the prescutum, scutum, andscutellum (PSC, SC, SCT)During flight each part of tergum reactsto the contraction of muscles bymoving in a specific direction ordistorting in a particular way.These complex elastic deformationscause wing movement
  5. 5. Wing, Tergum, and PleuraThe anterior and posterior phragma (front and rear ofthe tergum) are attachment points for thedorsolongitudinal musclesThe wing joins the tergum at anterior and posteriorattachment points - anterior (ANP) and posteriornodal processes (PNP)Dorsal surface of the wing connects to the tergumVentral surface attaches to the pleural wall Lateral View of the Pterothorax
  6. 6. Flight Muscles 10% to 30% of the total body mass Two types: indirect and direct. The indirect muscles - do not directly effect wing - attach to the tergum - distort the thoracic box when contracted - distortion transmits forces to the wing. - two bundles of indirect muscles: dorsolongitudinal (DLM) dorsoventral (DVM) - dorsolongitudinal span the length of the tergum - dorsoventral extend from the tergum to the sternumThe Indirect Flight Muscles in Pterothorax
  7. 7. Direct Muscles and LigamentsThe direct muscles connect directly fromthe pleuron (thoracic wall) to individualsclerites located at the base of the wing.The subalar and basalar muscles haveligament attachments to the subalar andbasalar sclerites,Resilin - a highly elastic material- forms the ligaments connecting flight muscles to wing apparatus- 100 times greater energy storage capabilities than muscleThere are other muscles that are directlyinserted into the first and third axillary sclerite. The Direct Flight Mucles Within the Wing- Bearing Segment: (a) lateral view; (b) cross- sectional view.
  8. 8. More Evolved InsectsDiptera (flies) and Hymenoptera (wasps)• the indirect muscles occupy the greatest volume of the pterothorax and function as the primary source of power for the wingstroke.• contraction of the dorsolongitudinal muscles causes severe arching of the notum which depresses the wing• contraction of the dorsoventral muscles causes opposite motion of notum.• direct muscles are important in controlling the wingbeatPrimitive InsectsOrthoptera (locusts), Coleoptera (beetles), and Odonata (dragonflies)• direct muscles are responsible for developing the needed power for the up and down strokes
  9. 9. Axillary ApparatusRegion at the base of the wing containing all the intricate mechanical components Most Important Parts: First axillary sclerite (1AX) - articulates with the anterior notal process - forms the horizontal hinge Second axillary sclerite (2AX) - articulates with an extension of the thoracic wall, the pleural wing process (PWP), - support the radial vein, (main mechanical axis for the wing) Third axillary sclerite (3AX) - important in wing flexing - vertical hinge.
  10. 10. The Wing- Membranous cuticle stretched between veins in the wing- Unlike an aircraft wing, it is neither streamlined nor smooth.- Folds facilitate deformation during flight- Veins increase the mechanical rigidity of the wing (alternate in concave and convex patterns).- Radial vein is the longitudinal rotational axis of the wing, about which occur pronation and supination. General Wing Layout
  11. 11. Wing MotionNot simply up and down - much more complex! Wingtip Trajectories
  12. 12. Wing MotionCan consider as motion as beingcomposed of three different rotations: flapping, lagging, and feathering Lagging HingeThree Hinges of the Wing Apparatus ForwardHorizontal (flapping) VelocityVertical (lagging) Feathering Hinge Flapping HingeTorsional (feathering)Each hinge occurs at the intersection of a vein and a fold
  13. 13. Hinges The horizontal hinge • - occurs near the base of the wing next to the first axillary sclerite - this hinge allow the wing to flap up and down. The vertical hinge ‚ - located at the base of the radial vein near the second axillary sclerite (2AX) - responsible for the lagging motions of wing, The torsional hinge ƒ - more complicated interaction of sclerite and deformable folds
  14. 14. Four Phases of Wing Motion1. depression and turning forward2. turning backward and beginning supination3. elevation and end of supination4. pronation
  15. 15. Flight Variables- wingbeat frequency: the frequency of oscillation of the wing during a stroke- stroke angle: the full angular displacement of the wing during a complete stroke- stroke plane angle: the angle between the stroke plane and the vertical axis- body angle: the angle the between the longitudinal body axis and the flight path
  16. 16. Bi-Motor Type FlightDragonflies (Odonata)- extreme functionality of the two wing pairs (two motors)- complete independence of each of the four wings- high maneuverability- gliding and high-speed flight- low wingbeat frequency (25-30 Hz)- low stroke amplitude (~ 30°)
  17. 17. High-Frequency Type FlightHymenoptera (bees and wasps) and Diptera (flies and mosquitoes)- high wingbeat frequency (>100 Hz),- low -medium stroke amplitude- high speed flight- enhanced maneuverability- variable stroke plane angle - hover
  18. 18. Wingstroke Amplitude vs. Wingbeat Frequency Wingstroke Amplitude vs. Wingbeat Frequency 80 70 Wi ng str ok 60 e Am plit ud e (de 50 gre es) Diptera 40 Hymenoptera Lepidoptera Coleoptera 30 Neuroptera Odonata 20 0 50 100 150 200 250 300 350 Wingbeat Frequency (Hz)
  19. 19. Maximum Flight Speed vs. Wingbeat Frequency Maximum Flight Speed vs. Wingbeat Frequency 8 Diptera 7 Hymenoptera Lepidoptera 6 Coleoptera Neuroptera Maximum Flight Speed (m/s) Orthoptera 5 Odonata 4 3 2 1 0 0 50 100 150 200 250 300 350 Wingbeat Frequency (Hz)
  20. 20. Wingbeat Frequency vs. Body Mass Wingbeat Frequency vs. Body Mass 350 mosquito Diptera 300 Hymenoptera Lepidoptera Coleoptera 250 Neuroptera OdonataWingbeat Frequency (Hz) 200 150 100 Lucanus corvus (beetle) dragonfly 50 0 1 10 100 1000 10000 Insect Body Mass (mg)
  21. 21. Wing Loading vs. Wingbeat Frequency Wing Loading vs. Wingbeat Frequency 40 Diptera 35 Hymenoptera Lepidoptera 30 Coleoptera NeuropteraWing Loading (N/m ) 252 Orthoptera Odonata 20 15 10 5 0 1 10 100 1000 Wingbeat Frequency (Hz)