The wing motion in free flight has been described for insects ranging from
1 to 100 mm in wingspan, To support the body weight, the wings typically pr
oduce 2-3 times more lift than can be accounted for by conventional aerodyn
amics, Some insects use the fling mechanism: the wings are clapped together
and then flung open before the start of the downstroke, creating a lift-en
hancing vortex around each wing. Most insects, however, rely on a leading-e
dge vortex (LEV) created by dynamic stall during flapping; a strong spanwis
e flow is also generated by the pressure gradients on the flapping wing, ca
using the LEV to spiral out to the wingtip. Technical applications of the f
ling are limited by the mechanical damage that accompanies repeated clappin
g of the wings, but the spiral LEV can be used to augment the lift producti
on of propellers, rotors and micro-air vehicles (MAVs). Design characterist
ics of insect-based dying machines are presented, along with estimates of t
he mass supported, the mechanical power requirement and maximum flight spee
ds over a wide range of sizes and frequencies. To support a given mass, lar
ger machines need less power, but smaller ones operating at higher frequenc
ies mill reach faster speeds.