On Sat, 10 Jul 2010 20:13:07 +0200, DAN wrote:

The airfoil is a "Wobble Plate Stabilizer" which consisted of a small
wing mounted on and behind the non-rotating portion of the wobble
plate and served primarily as a means of trimming the inherent control
forces and damping any displacements occurring during flight.

quoted from http://www.uscg.mil/history/webaircr...orsky_HO3S.pdf

Ken



As for the airfoil, it does not appear in other HO3S photos.
Maybe this is the specially-modified HO3S-3 ?