RE: RPM range for O.S. 46fx
CG's got the way, for sure...
A way I've told my students, and it's worked so far, is don't try to flare, as such. Instead, on late final, continue your glideslope until the plane is about a foot off the runway. The engine is at idle, the plane gliding. Try to fly the plane in this condition as long as possible without adding elevator. You'll find that you need to feed more and more elevator, as teh plane sinks. This is flaring. Finally, your plane is in a plowing glide, an inch off the runway, nose up and the wing finally makes less lift than the plane weighs. You land, and as slow as possible for that plane.
Now, this technique works great for more docile planes, but there are those that cannot be flared in, due to a tendancy to tip stall. Warbirds, in general, are a prime example. They must be flown to the ground, and indeed "flown" until they stop rolling, in many cases.
With that prop, slowing enough to flare will be easy. Harder will be remembering to keep some power on so it doesn't sink too fast!
J