MapProjection on 2d map

Well in my currebt project i use WebMecatorProjection , now when i draw circle with big radius like 2000km the circle behavior is influenced by the ellipsoid of earth. My need is that the map will be presented as a flat x y without any influence of the ellipseoid of earth ? Its also happens when i draw polyline they curves.. there is anyway to earth beavior not effect it ?

Sorry, these are inherent side effects of projecting an ellipsoid to a 2D map.