Bats are fantastic creatures, being the only naturally flying mammal and the inspiration for so many horror stories. It is the former we are interested in because of how complicated bat wings are compared to other flying animals. Researchers at Brown University have made several strides toward understanding bat wings by recreating one and putting it in a wind tunnel.
The artificial wing is not nearly as complex as the real thing, which has over 25 joints and 34 degrees of freedom, but while building the wing, the researchers found themselves recreating certain aspects of bat wings. For example, the elbow of a bat has some musculature that defies explanation as in humans it is used to rotate our hands, but bats do not have an analogous motion. While building the fake elbow joint, the researchers found it was constantly breaking under stress and had to reinforce it, which appears to also be the purpose of the musculature.
Of course the researchers have learned more than just the construction of bat wings as they used servo motors to flap them. The hope is that the information gathered from the artificial wing, which was able to generate enough lift to pick up the species of bat it was modeled after, can be used to develop advanced flapping aircraft.
Source: Brown University