I had one of these for a while, before passing it on to a collector. Opposed-twin geared-down 2-stroke, powered a much smaller drone than the Mac. Two of these on a CriCri would be interesting. I have been told that new surplus Righters in cosmoline can still be had, pretty inexpensively.
One of the factory workers at Righter was a little gal named Norma Jean Dougherty, who later moved on to better things (maybe) under another name. Walter Righter, Reginald Denny, and Norma Jean make for an interesting story. Check it out. Google "Righter drone engine," or try http://www.ctie.monash.edu.au/hargra...dioplane4.html