E
Elevator—A shorter name for the elevating planes or elevating rudder, used for directing the aeroplane upward or downward.
Ellipse—An oval figure outlined by cutting a cone through from side to side on a plane not parallel to its base. Some inventors use the curves of the ellipse in forming the wings of aeroplanes. See [Hyperbola] and [Parabola].
Entry—The penetration of the air by the forward edge of aircraft surfaces. See [Angle of Entry].
Equivalent Head Area—Such an area of flat surface as will encounter head resistance equal to the total of that of the construction members of the framework—struts, braces, spars, diagonals, etc., of the aerial craft.