English: Steady-flight equilibrium of a conventional (top) and a three surface aircraft (bottom). Because the three surface aircraft can generate foreplane lift instead of merely tailplane downforce, the wing is less loaded and the gross aerodynamic lift force is smaller. Note: for clarity of drawing, horizontal distances are not to scale, the scale of stabilizer forces are exaggerated and the required change in equivalent air speed (so that both aircraft may have the same angle of attack) are not represented.