Before you select a new mission (whether it's a quick misson, single mission, or campaign), hold the right Alt + Ctrl + Shift buttons and select the mission. DON'T RELEASE ANY KEYS. The Atomic Moth will be added to your available aircraft. Select this plane, start flying and release everything.

At the title screen, hold Alt + Ctrl and select Quick Mission or Single Mission. Pick any plane you want. Keep holding those buttons until the Load Ordinance screen appears.