For that aircraft, the Cobra 4120/12 motor could be used, but only if you were planning on using a 4-cell Li-Po battery. The Kv value of this motor is a bit too high to use with a 5-cell or 6-cell battery pack.
100 watts per pound is a good power level for a plane like the Kadet Senior Sport, so with an estimated flying weight of 8 to 8.5 pounds, a motor that produces 800 to 850 watts of power is ideal. If you run the Cobra 4120/12 motor on a 4-cell Li-Po pack with an APC 12x6E prop, you will get the following full throttle performance numbers.
Volts – 14.8
Amps – 55.5
Watts – 822
RPM – 10,250
Thrust – 118 ounces
Pitch Speed – 58 MPH
This would give you the same flight performance as a strong .45 size glow engine, and provide very good performance. To get decent flight times, a 4-cell 5000 to 5500mah battery pack would be ideal. This will provide 7-10 minutes of typical flying time per charge, depending on the throttle level used.
To complete this power package, I would suggest the Cobra 80 amp ESC, since the motor has a maximum current rating of 75 amps, and you always want to make sure that the current rating of the ESC is equal to, or higher than, the max current rating of the motor.
Here are the links to these items on our website.
Cobra 4120/12 motor - http://innov8tivedesigns.com/cobra-c-4120-12-brushless-motor-kv-850
Cobra 80 amp ESC - http://innov8tivedesigns.com/cobra-80a-esc-with-6a-switching-bec
APC 12x6E prop - http://innov8tivedesigns.com/parts/propellers/apc-12x6e-propeller
If you wanted to have the option of using a 5 or 6-cell Li-Po pack, then the Cobra 4120/16 motor, which has a Kv value of 610, would be a better choice. With this motor you would use an APC 13x6.5E prop if using a 5-cell battery, and use an APC 12x6E prop if running on a 6-cell battery. Hopefully that answers your question. If you have any more questions, please feel free to email our technician at email@example.com with this as the Subject in your email. Thank you!