I have been flying my Great Planes Combat RC ARF Spitfire lately with some electric power to compare several electric motors. The Spitfire has a 38" span and comes in at 3.5 lbs
I built the model with a OS-35FP originally and it has lots of power, maybe not enough for carrier but way more than I need for CL scale
Then I installed an E-Flite E10, with a 3S battery and an 11" APC electric prop...the performance let's say was lackluster at best, even from a CL scale point of view it was underpowered...but still wanted to know what the E10 could do. The max number of cells on the E10 per specification is an 3S.
Then I installed the E25 with the same electric APC prop and 3S battery, slight improvement but not much improvement. Remember the E25 is rated for a 3S or a 4S. This combination was still underpowered from a CL scale point of view, and way underpowered from a CL carrier point of view. This combination flew at cruise at about 2/3 power. So that combination was ruled out.
Then I installed a 4S battery on the E25, with the same prop and it had alot more power, way more than I would need for CL scale project I am building so that is what will be installed on that project. This combination flew at cruise at 1/3 to 1/2 power, at full power it had some speed, not enough for CL carrier but enough for CL scale.
What I have learned is that the power that you get out any given electric motor varies depending upon what battery and some degree what diameter of prop you use. My watt meter has been very handy to help determine what prop diameter is best suited for power or to lower the amp draw.
I think the battery we choose to use has a bigger affect on the power output than the prop that is selected.
Trying to nail down a electric motor that is equal to a .40 or .60 is diffiicult to do, there to too many variables that can change the power output such as battery voltage and prop diameter.
Fred Cronenwett