Having read about (but never experienced) heat failure-related issues with Futaba receivers I place all of my receivers standing upright in the box using velcro and do not wrap them. The box pad + velcro provides enough of a cushion for hard impacts & vibration and the velcro ensures that the receiver isn't going to move. I prefer velcro over sticky tape as it makes it very easy to pull the receiver to swap/move/adjust wires when cleaning or fixing things.