Control Surfaces
Last updated
Last updated
Control surfaces are moveable parts of the plane that allow your plane to maneuver through the air.
Refer to the aerodynamics section for an explanation of why control surfaces allow the plane to maneuver.
So that the control surface can move, you will first need to make a score cut, making sure to cut through one layer of paper but leaving the opposite layer intact. This will allow your control surface to move... but only in one direction. So that the control surface can move in both directions, you will need to make a bevel cut in the foam. A bevel cut is an angled cut in the foam that allows it to bend.
Tips: Bevel cuts take practice. For a smoother cut, cut with your blade at an angle to the foam rather than perpendicular. If you cut too shallow, you can go back and make it deeper, if you cut too deep, you will make a hole in the paper, so it's better to take your time and make shallower cuts. If you do cut too deep, you can simply reinforce the paper with scotch tape.
Servos: Angular servo motors are used along with pushrods and control horns to move control surfaces. Angular servos can be programmed to turn between 1 and 180 degrees. They have three wires coming out of them which are connected at the end. GND/negative is the black or brown wire, plus/power is the red or orange wire, and the signal/data wire is white or yellow. Most servos will have either black, red, and white wires or brown, orange, and yellow. Your transmitter will take care of converting your joystick movements into degrees for each servo to turn. While flite test may recommend 4-5 gram servos for smaller planes, 9g servos are recommended because they are more readily available. Before gluing servos into your plane, make sure they are centered so that they will have ample room to move in both directions. You can center them using an Arduino or by hooking them up to your receiver.
Push Rods: Control surfaces are rarely attached directly to your servo because it's difficult to attach the servo horn to the foam and it is inconvenient to have to place your servos right next to your ailerons/rudder/elevator. Pushrods are used to transfer the force of the servo over longer distances. For example, you can have your servos positioned inside the fuselage while controlling a control surface on the other side of the plane. Pushrods have a Z-Bend at each end which allows them to attach to the servo horn and control horn (making a z bend). Pushrods will come with flite test prefabricated kits.
Control Horns: Control horns are small components that attach directly to your control surfaces and have a hole through which the pushrods go. When the servo horn moves, it pushes the push rod, which pushes the control horn, which pushes the control surface. Control horns come with flite test prefabricated kits.
Y Harnesses: Most receivers+transmitters only have one channel for the ailerons, what you can use (if you don't want to set up a transmitter mix) is a y harness. This splits one servo output into two identical ones.
Linkage stoppers: if you are using a Y-harness for your ailerons, you may find it difficult to adjust trim and endpoint values, what you can use are linkage stoppers. Linkage stoppers are screwed onto your servo and hold the pushrods on one end. They may also be used instead of z-bends.
