Precision-Fin Indexing Device for Wind Tunnel Models.

An indexing device includes an adapter conforming to the contours of the test model body with a cavity for housing a ring gear which has internal teeth segments in two diametrically opposed quadrants and is rigidly attached to the adapter. A movable fin with an aerodynamic surface includes a cylindrical hub welded to the base portion thereof. The hub is provided with a central shaft extension which engages a close fitting opening in the adapter and with two curved slots to accept clamping fasteners that thread into tapped holes in the adapter. A spur gear, modified to mesh with the modified ring gear on the adapter, is bolted on the under surface of the hub concentric with the shaft extension. (Author)
Supersedes PAT-APPL-017 626-79, AD-D006 045.