Abstract: A linearly adjustable fluid damper of the sliding plate adjustable orifice type damper system having a fixed flat plate with a plurality of specifically arranged trapezoidal shaped apertures therethrough, and a slideably adjustable flat plate also having a plurality of specifically arranged trapezoidal shaped apertures therethrough. The sliding plate is juxtaposed the fixed plate such that apertures of the sliding plate overlap apertures of the fixed plate, and aperture orientation of the sliding plate is reversed that of the orientation of the apertures on the fixed plate. The area of the resultant hexagonal composite orifice through both plates varies non-linearly from full open position to full closed position throughout movement of the sliding plate. The result is that fluid flow from zero fluid flow to maximum fluid flow through the resultant orifice is a straight line relationship with linear displacement of the sliding plate.