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To restore the insect to its original vertical position, the average upward force during the downward stroke, F av, must be equal to twice the weight of the insect. Note that since the upward force on the insect body is applied only for half the time, the average upward force on the insect is simply its weight. [14]
Levitation is accomplished by providing an upward force that counteracts the pull of gravity (in relation to gravity on earth), plus a smaller stabilizing force that pushes the object toward a home position whenever it is a small distance away from that home position. The force can be a fundamental force such as magnetic or electrostatic, or it ...
Newton's third law requires that the air must exert an equal upward force on the wing. An airfoil generates lift by exerting a downward force on the air as it flows past. According to Newton's third law, the air must exert an equal and opposite (upward) force on the airfoil, which is lift. [15] [16] [17] [18]
Positive phototaxis can be found in many flying insects such as moths, grasshoppers, and flies. Drosophila melanogaster has been studied extensively for its innate positive phototactic response to light sources, using controlled experiments to help understand the connection between airborne locomotion toward a light source. [ 65 ]
Flying frogs use greatly enlarged webbed feet for a similar purpose, and there are flying lizards which fold out their mobile ribs into a pair of flat gliding surfaces. "Flying" snakes also use mobile ribs to flatten their body into an aerodynamic shape, with a back and forth motion much the same as they use on the ground.
Most ballooning journeys end after just a few meters of travel, although depending on the spider's mass and posture, [16] a spider might be taken up into a jet stream. The trajectory further depends on the convection air currents and the drag of the silk and parachute to float and travel high up into the upper atmosphere .
Some species, including the dragonhunter (Hagenius brevistylus), reduce exposure to the sun by perching with the abdomen pointed downward, rather than upward. The tropical skimmer dragonfly Diastatops intensa , whose wings are mostly black, points its wings rather than its abdomen at the sun, apparently to reduce the heat they absorb.
A pilot can create an indication of lift on uncompensated instruments by entering a climb by pulling back on the stick (hence "stick thermal"). This is not true lift because the increase in potential energy of the aircraft is achieved from decreasing airspeed rather than the result of flying in rising air. Gliders are equipped with instruments ...