RE: O.S. BGX-1 3500 Anyone?
I have done a lot of testing, tuning, and modifying to my BGX over the years. All of my reference props are old and most of my data has been lost. The BGX likes some nitro 10-15% and will pull big props but needs close to 8000rpm to draw fuel well. They would spin an old Zinger 18-8 @ 8200, 18-10 @ 7300, 20-8 @ 7300, 20-10@ 6600. These old props have heavier loading than most newer style props. I got best flight performance with 18-10s that were cut down for more rpm. Modern 18-10 or 20-8 should be ideal.