Texas, weather, props, etc.
Has anyone consider a 4-stroke engine to swing the larger diameter / pitch props? Not as much RPM as a 2-stroke, but more torque. Overall horsepower approaches (and may even exceed ??) a 2-stroke of the same displacement at the target RPM where props are most efficient.
Both OS and YS make supercharged engines. The YS FZ91 swings a 14 x 14 to nearly 13,000 RPM. You would need a larger airframe because of weight (27 oz). A 14 pitch prop at 12,000 RPM geometrically is about 160 MPH (100% efficient). I wonder what one of these would do with an 16, 18 or 20 pitch prop of about 10"-12" diameter?
I also wonder if anyone has tried some of the small speed 400 airframes with glow engines that will will turn small props (7") up to very high RPMs. There has been discussion of .28 buggy engines, but I've read the old Conquest .15 (a 6 oz aircraft engine) turned 25,000+ on the ground with a 7" prop. Some posts I read said it would do 30,000 with a pipe. This would be suited for a speed 400 airframe, I would guess.