ELEVATORS
An elevator works exactly the same way; however, elevators control the up-and-down movement of the plane (whereas the rudder controls lateral, or right and left movement). Controlling the movement of the rudder and elevator is the very basic way to control an airplane. It's all you'll need to get a paper airplane to do what you want. Full-sized planes need more. Take a look at Figure 12, below. If the pilot raises the elevator, then air will hit the elevator and get bounced up, pushing the tail down and the nose up.
AILERONS
Rudder turns tend to be slow. The plane slips to the side and kind of skids through the air in a wide circle. Full-sized aircraft and really good remote control aircraft use another trick. It's sort of like leaning a bicycle over to make a faster turn. Aircraft lean over too. That's called ROLLING. Rolling is controlled with ailerons, shown in Figure 13, below. Ailerons look a lot like elevators, only they're attached to the main wing. The control surface furthest from the body of the plane is usually the aileron on a full-sized plane. Imagine deflecting a little air downward off the right wing only. That wing gets pushed upward. The center of lift seesaw is still working. The left wing dips as the right wing lifts, and the plane leans left. If we add up elevator, the plane will now"climb" in a circle to the left. You can feel this method of banked turning when taking off or landing at most airports. A basic rudder adjustment doesn't offer the precision and control of an aileron turn. Watch soaring birds like hawks and seagulls execute turns. They use expert aileron-like adjustments of their feathers to make elegantly banked turns.
FLAPS
In addition to ailerons, full-sized aircraft also have FLAPS, shown in Figure 14. Flaps have a very basic function: they make the wing bigger during slower fight. Flaps are extended during takeoff and landing to make the wing bigger, adding LIFTING SURFACE. Aircraft designers make wings justbig enough to lift the plane and cargo at cruising speed. Pushing a bigger wing through the air would only create drag and cost more jet fuel to fly. The problem becomes how to take off and efficiently. A bigger wing allows the plane to get airborne at a slower speed. Imagine how big an airport would need to be if jumbo jets didn't use flaps. Runways would need to be much longer. The jet would need beefed-up landing gear to handle nearly 300 mph of ground speed before takeoff! Flaps neatly solve these problems by adding wing surface during slower flight. They get neatly tucked away once the airplane is up to cruising speed. Flaps are usually the control surfaces you see closest to the fuselage. I've yet to invent a paper airplane that has flaps. Perhaps you will, now that you know what they are. It's an intriguing possibility; to have the paper airplane somehow increase wing area during fight.
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