Anti Depression Guide

If you want a bird's eye view of what is over the next hill, your best bet is a micro air vehicle – an autonomous aircraft with a wing span of less than 15 centimetres. Making a fixed wing aircraft of this size is straightforward enough but there are a number of drawbacks, such as being easily buffeted in by light gusts of wind.

Nature's answer to this problem is to give small birds wings that can be flapped in bursts to avoid sudden gusts. But human engineers have found it hard to build a flapping mechanism that is both light and efficient enough to get a small vehicle off the ground while also carrying a suite of useful instruments, such as a camera and a radio transmitter.

That has not stopped Sunil Agrawal, director of the Mechanical Systems Laboratory at the University of Delaware, and colleagues from trying.

One problem is that flapping is not a simple up and down movement, but a complex series of motions that include rotating the wing to "feather" it in the upward part of a stroke.

With funding from the US Army Research Office, Agrawal, says he has solved this problem using a novel mechanism powered by a single actuator. As well as powering an ornithopter, the group says the mechanism could be used to create a flapping air current, or to propel an underwater vehicle.

Read the full ornithopter UAV patent application.

Justin Mullins, New Scientist consultant