[blakestyger]

The fly (a greenbottle) buzzing around my bedside light last night was going very quickly and cornering in very tight circles. It was annoying and yet admirable in turns.

So the question is - how do they steer without the tail or aerodynamic wing section that birds have?

[RD]

I think its wings are somewhat comparable to oars in a row boat.

[LeeE]

An aerodynamic tail isn't an absolute requirement for controlled flight, but it does make it easier, at the expense of adding drag.  Fly wings are aeroelastic, with the majority of their rigidity along the leading edge, where most of the force that is put in to flying is applied.  As the wing is raised and lowered the trailing edge lags behind the leading edge producing a bend across the chord, producing lift and control.  In addition to this, flies can vary the angle of attack of their wings by twisting the leading edge slightly, so they turn by flapping their wings differentially, both in sweep and in angle of attack.

[blakestyger]

Thank you LeeE - that is very well explained. I assume that the same goes for the twin-winged models, though they are bigger and therefore slower.

[LeeE]

Yup.

[paul.fr]

A short video here:

http://www.sciencefriday.com/program/archives/200808294

In this segment, Ira talks with bioengineering researcher Michael Dickinson of Caltech about new research into why flies are so good at evading an approaching fly swatter. Writing in the journal Current Biology, Dickinson and colleagues report that the fruit fly (Drosophila melanogaster) starts planning its escape as soon as it spots an approaching threat. After seeing the swatter, the fly calculates its location, creates an escape plan, positions its legs to hop away from the swatter, and corrects its posture to account for the activity it was engaged in--all in about 200ms, less than a blink of the eye. We'll talk about the finding, and what researchers hope to learn by studying the movement of fruit flies.

[LeeE]

I believe that regarding flies, it has also been established that they see 'more quickly' than we do.  For example, 25 frames per second is sufficient to give the impression of continuous motion to us - PAL TV frame rates are 25 fps, whereas a fly could see each individual frame as a still image (and see that the sequence of images was interleaved).

This may also apply to some of the 'higher' animals and small birds may be a good example - consider the planning and control aspects of flying into a tree and making a landing on one of it's many branches.  We, as humans, simply couldn't think quickly enough to do this and modern flight controls systems, as found in the latest combat aircraft, struggle to do basic aerobatics in free space, and that's without worrying about obstacles.