http://www.osengines.com/parts/xr15470.html
Part list (illustrated) for the 46 FXH ringed engine. This would be a Heli engine if I'm correct but could be modified with a smaller head. I found no record of a production airplane version on the OS site.
There was a 46 SF ringed though
http://www.osengines.com/parts/xr15420.html