MULler W, Patone G
FG Bionik and Evolutionstechnik, Technische Universitat Berlin, Ackerstrasse 71-76 (ACK 1), Germany.
J Exp Biol. 1998 Sep;201 (Pt 18):2591-9. doi: 10.1242/jeb.201.18.2591.
The flight feathers and their coverts of a European kestrel Falco tinnunculus have been tested for their air transmissivity. The transmissivity was measured in both directions, i.e. from ventral to dorsal and vice versa; the mean difference between the two directions was less than 10 %. However, the transmissivity of the inner versus outer vanes of the remiges and coverts differed significantly, with the outer vanes being more transmissive than the inner vanes. A functional interpretation of the different transmissivities of the inner and outer vanes is given, and we propose that its significance lies in the formation of a smooth, continuous wing surface. The individual feathers are pushed firmly towards one another as a result of the different transmissivities, which cause a pressure gradient to build up from the less-transmissive inner vane towards the overlying, more-transmissive outer vane of the adjacent feather. In another test series, the transmissivity of the flight and covert feathers of 27 species was measured; the differences found between species were small.
对一只欧洲红隼（Falco tinnunculus）的飞羽及其覆羽的空气透射率进行了测试。在两个方向上测量了透射率，即从腹侧到背侧以及相反方向；两个方向之间的平均差异小于10%。然而，飞羽和覆羽的内羽片与外羽片的透射率存在显著差异，外羽片比内羽片的透射率更高。给出了对内羽片和外羽片不同透射率的功能解释，我们认为其意义在于形成一个光滑、连续的翼面。由于不同的透射率，各个羽毛会被紧紧地相互挤压，这会导致从透射率较低的内羽片到相邻羽毛覆盖其上、透射率较高的外羽片形成一个压力梯度。在另一个测试系列中，测量了27个物种的飞羽和覆羽的透射率；发现物种之间的差异很小。
