Primitive plane

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(Spherical Projection) the plane upon which the projections are made, generally coinciding with some principal circle of the sphere, as the equator or a meridian.

See also: Primitive

References in periodicals archive ?
DEADLY Dogfights in primitive planes were just one of the perils facing WWI fliers
THINK of war in the air a century ago and there they are, Biggles in his Sopwith Camel, the Red Baron leading his famed Flying Circus, primitive planes piloted by chivalrous young paladins duelling above the clouds, knights of the sky idealised in films like Dawn Patrol and Hell's Angels.