M
Main Plane—The principal supporting surface of an aeroplane. In the biplane, or the multiplane type, it denotes the lowest surface, unless some other is decidedly larger.
Main Landing Wheels—Those wheels on the alighting gear which take the shock in landing.
Mast—A vertical post or strut giving angular altitude to guys or long stays. Also used (erroneously) to designate a spar reaching out laterally or longitudinally in a horizontal position.
Monoplane—An aeroplane with one main supporting surface. A Double Monoplane has two of such surfaces set one behind the other (tandem) but on the same level.
Multiplane—An aeroplane having several main planes, at least more than three (for which there is the special name of triplane).