Constant Kc electric motor AR DRONE 2.0 power edition (Need help)


Hello !
I’m a french student, for my exam at the end of the year i must realize a Scientific project. I chose to work about
transport of packets by drones and my college lend me an AR DRONE 2.0 power Edition for my experiences and i work on the battery duration but i had to create a model so, i had to link torque and motor current but i need the constant C in the formula C= Kc*I ! i didn’t find something about it on the web.
Can someone help me ?
Thank you.