The Dragonfly is a marvel of nature, rated to be one of the all time most effective predators. Similarly, the Spitfire was a breakthrough, fighter-interceptor in the skies over Britain, just under eighty-three years ago. And, oddly, both share a common design feature, elliptical wings:
This is of course an interesting convergence of natural and human technologies. Though, the advantages are with the Dragonfly, a natural helicopter.
(More details, here.)
U/D, Mar 23: Note the clipped wings and radial engine of the Hawker Sea Fury (many later Spitfires also had clipped wings):
Notice, the P-47:
also, the MiG 15, showing where onward technological evolution would go:
It’s worth noting on the Pterostigma, a counterweight often seen as a dark block towards the tip of the leading edge:
The action has been summarised by Norberg:
The pterostigma of insect wings usually is a pigmented spot close to the leading edge far out on the wing, having a greater mass than an equally large wing piece in adjacent wing regions . . . A wing having its mass axis behind its torsion axis is very susceptible to self-excited coupled flapping and feathering vibrations, making gliding flight above a critical speed impossible. Due to unfavourable, inertial, wing pitching tendencies, a still lower speed limit is set to active flight. Due to its mass contribution and favourable location, the pterostigma tends to raise these speed limits by causing favourable, inertial, pitching moments during the acceleration phases of wing flapping . . . The function of the pterostigma of raising the critical gliding speed, at which self-excited vibrations set in, was demonstrated in dragonflies. Although contributing only 0.1 % (one pterostigma) of the total dragonfly weight, it raised the critical speed by 10–25% in one species.
The beauty and subtlety of design! END