The key thing here is that the engine is peaked at 10k, then backed off.

My experience with 4 strokes shows that many of them "flatten out" at around 10k on the ground. For example, my OS .61FS will turn a 12x6 APC at about 10k. But it will also turn a 13x6 APC at the exact same RPM.

Clearly the 14x6 is too small a prop for the engine in question. Try a bigger prop. No question about it.

Get back to us with some RPM readings and flight tests on larger 2-bladed props if you want to sound less like a goofball.

A couple of other notes:

I suspect CL acrobatic guys use multi bladed props for reasons that have nothing to do with pulling ability. Looking closly at some CL acro planes, some have rather short gear legs. The CL guys also do a lot of engine tuning to get the engine to pull hard on the up lines but slow down in level flight. Some guys do this by setting the mixture, pipe length and other engine parameters (like prop, glow plug, etc) so that the engine is off the pipe in level flight, but in a vertical upline, the engine leans out, goes on the pipe, and pulls harder. It's possible a multi-bladed prop makes this easier to set up right. CL guys are also appearanced judged, so a cool looking prop might be just the thing to help get in to the first row. The point being that pointing at CL acro guys as evidence that a multi-bladed prop pulls better is bogus. Too many other factors there.

In a simular way, a lot of IMAC pilots are now going to 3 bladed props. But they are doing it for one simple reason. The are now judged on noise, so having a "quieter than average" plane makes for points, enough points to decide the contest. 3 blade props are quieter due to lower prop tip speed.

It just happened that I was looking over a full scale SU-26M last weekend. I noted the BIG 3 bladed prop. I also noted how close to the ground the tips were. When that thing is up on two wheels, as during take off, the tips must be awfully close to the ground. Clearly, the 3 bladed prop is there because a 2 bladed prop of approprate size would dig a trench on take off. No question about it.

Britbrat and company are right.

Jeep, you need to get more experience with engine-prop-airframe combinations.