Engineer Yu-Chong Tai with a more traditional flapping flyer.

Imagine a 747 with flapping wings. It might not be the most comfortable flight, but that doesn't mean it's not an efficient way to go.

In "Flapping Flyers," Paul MacCready demonstrates some of his more unusual designs, based on the Flapping Flyers of insects. For MacCready, these little flappers are fun experiments that might help him solve other design problems.

The defense department, however, sees more potential in the tiny Flapping Flyers. They could zoom around indoors, carrying cameras and sensors into enemy buildings, or into disaster areas considered too dangerous to send human search crews. However, loading all this equipment- not to mention motors and power supplies- onto the miniature planes has so far proven to be an insurmountable obstacle.

This device relies on synthetic "muscles" to flap its wings.

Engineers at SRI International are trying a more natural wing pattern called "clap-fling," and have constructed artificial muscles that contract or expand in response to electricity. Though neither of these ideas has gotten off the ground yet, it's only a matter of time before MacCready-style inspiration and experimentation yields the perfect tiny flapper.