Aeroplane using the Queens.
Airplane is easier, but 'aircraft' resolves all ambiguity, however it's better said within the industry, i.e. imagine pointing up in the sky telling your children " look at that aircraft, i wish I could have a go flying that beauty " or "look at that aeroplane..." The former sounds better in general I thinks.
I'm no linguist however the word air as blended to airplane is a noun. Aero, as blended into aeroplane, is an adjective and so describes the plane component of the word aeroplane. Plane me thinks is an adjective that contributes to the dimension of the aero. So alls in alls me thinks aero fits wit plane better and more proper... given the choice between aero and air that is.
