Motor is an Enya 15 bb, prop 8x4, undies brown. It pulls well to within a bees whisker of the top of the loop at which point it seems to fall out of the sky (I'm sure its to chase me or why else would it do it?). During the fall the lines go slack however, therudder kicks in and the bugger then flies away from me - breaking at leasr one line - of course. A mystery to me!