If running your IPS over 11 watts, you should use a heat sink.

Propeller	Volts (V)	Amps (A)	Thrust (g / oz)	Power (W)	Efficiency (g/W)
HD-8060	7.2	1.2	75 / 2.65	8.64	8.68
HD-8060	8.4	1.5	101 / 3.56	12.6	8.02
HD-9075	7.2	1.9	116 / 4.09	13.68	8.48
HD-9075	8.4	2.3	137 / 4.83	19.32	7.09
EP-9070	7.2	1.65	110 / 3.88	11.88	9.26
EP-1047	6.0	1.28	101 / 3.56	7.68	13.15
EP-1047	7.2	1.67	129 / 4.55	12.02	10.73