an meters is used to wings unwind sail
airplanes has wings fore_and_aft_sail is sail. fore_and_aft_sail is not sail. head_sail is not sail. lugsail is not fore_and_aft_sail. sea_eagle_cruise_missile is powered_device. head_sail is sail. lugsail is fore_and_aft_sail. balloon_sail is not sail. foresail is not sail.