Hummingbird Flight
There's a fascinating article over at the National Science Foundation about how hummingbirds fly. Here's an excerpt on their methodology:In this study, the researchers applied "digital particle imaging velocimetry" (DPIV) to follow the flapping wings. DPIV is used in various applications to study flow characteristics of liquids and gases. By taking pictures with a special computer-coupled camera lighted with a laser, the distance traveled by individual particles seeded in a liquid or gas can be tracked through successive images. Hence, DPIV allows the researchers to follow the particles' movement image by image, like looking through the pages of a high-tech flipbook.
To observe the hummingbird in flight, the air in a wind tunnel was seeded with microscopic particles of olive oil, and digital images were captured every 300 microseconds as the bird hovered at a feeder. The wing beats caused the air to circulate, which in turn caused the floating oil particles to move. Computer-aided image analysis of each oil particle's position in consecutive frames allowed the scientists to reconstruct the lift and characteristics associated with each up and down wing movement.
So I feel really stupid now, which is fortunately kind of a hobby of mine.
Here's the link:
http://www.nsf.gov/news/news_summ.jsp?cntn_id=104263&org=NSF.
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