Kv doesn't have anything to do with physical size of the motor - that is why I also look at the weight of the motor. Kv has to do with the magnet strength and the actual windings.

The original motor you posted weighed about 50 g. and had a Kv of 2200 - that is the exact same motor that I use on my 1/2a size stunter, which is about 30" span and weighs about 13 oz. ready to fly. It turns a 6-4 prop at about 12000 RPM on TWO cells instead of the 3-cell batteries I mentioned above. It draws about 12 amps. The latest that you posted is the same diameter and a little longer - I am guessing that it would weigh about 65 grams but that very high (3650) Kv - means that it is likely wound to use in a helicopter, where they typically have a gear driven rotor. In our direct-drive c/l planes, even a little 5-2 or 5-3 prop would be drawing 40 or more amps and the ESC shown (a 30 Amp rated one) would burn up unless the motor burned up first!

The motor that I listed first - weighs about 80 g. and has a Kv of 1500 - turns an 8-4 at 11000 as stated, drawing about 20 amps. The planes weigh about 24 oz. RTF, and about 250 sq. (ie: about .15-19 size). I also mentioned a sister to that motor that has a Kv of 1200, but the motor still weighs about 80 g. It would fly the same plane but the 8-4 would turn less than 11000 (on the same battery) - you would need to move up to an 8-6 or 9-3 or 9-4 - It would turn any of those about 10000, probably but the power out would be about the same.

Then I mentioned a 2814-6 with a weight of 100 g. and a Kv of 1400 - turning 9-4's to 9-6's at about 30 amp.

Note - the weights are going up, the Kv's are different but not related to weight. The CURRENT draws are also going up because the power handling capabilities of the motor (due to it's increased weight) also goes up.

(All of the above setups mentioned 3 cell batteries - just like in a flashlight, the batteries add up in voltage so 1 cell is about 3.5 volts, 2 cells ~ 7.0 volts, 3 cells ~ 10.5 volts, etc.). Power is voltage multiplied by current. Voltage is about 10.5, current in my TnT is about 20 Amps so power is ~210 Watts. Current in the 2814-6 is about 30 Amp - so power is about 300-315 Watts.

The "Rule of Thumb" is for aerobatic performance, you want about 125-150 Watts per pound of Plane Weight. My 24 oz (1.5 lb.) models would be pretty aerobatic at 175-225 Watts. They will fly around in trainer mode at say 125 Watts but not be capable of much in the way of aerobatics. And your original motor question is flying on 2 cells (7 volts) at about 12 amps, so 85 watts. It is less than a pound - call it .75 lb. so we would (ideally) be at about 90 watts (125 W. per pound).

Oh, and one final question for you - You DID mean the Ringmaster JUNIOR, didn't you? The .15-19 size plane? If you meant the Baby or 1/2A size, then your original motor would work pretty well.