Sorry for the confusion. Direct drive in the brushless motor world means that you are bypassing the gears and have the prop attached to the motor shaft. I know the direct drive also means gears instead of a belt.

If the prop is mounted directly on the motor shaft without any gears, try using a 10X3 or 10X4 prop instead. This will not push as much air and probably say your esc's.

Or buy a gearbox and add it in. This will decrease the RPM at the prop. and increase torque. This method will also save your esc.

You still have not stated which prop you are using. How much the plane weighs, How long it take for the ESC to burn out, or if the airplanes fly at a good speed( enough power for 3d flight or just enough to keep the aircraft airbourne )

We need to know these details.