Flyzone Calypso--Erratic Motor Operation
 

Flyzone Calypso RTF, everything stock (Tx, Rx, motor/ESC, battery, etc.). The motor seems to "surge" and power back on its own frequently during flight, despite having a fully-charged battery. I'm not sure what's causing this as all other controls seem to function normally (Rx bound successfully and ESC programmed successfully).

I'm thinking the cause could be narrowed down to two broad categories: internal (something amiss with the aircraft's components) or external (interference etc.--I use this as an instructional tool at a high school; we fly it in the soccer fields behind the school so maybe there is something the school contains that disrupts operation?).

Has anyone else experienced any difficulties with either the Calypso's motor specifically, or similar problems with a different aircraft/motor? I'm an old nitro guy so electrics are fairly new to me.