Installing the Electronics

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This is the sixth lesson in the Learn to Build RC series of lessons. In this lesson, we will learn how to install the radio electronics onto a profile airplane. We do this by continuing our construction of the Eagle-RC.com Boeing PT-17 Stearman airplane that we have been working on in the previous lessons. So...let's get started!

The Control Horns

In order to mount each of the control surfaces to their servos, we must first install control horns onto each of the control surfaces. These control horns can be made from a variety of materials. For this airplane, I am using the plastic control horns that are included in a GWS airplane kit. These can also be cutout from any stiff material.

To begin, cut slots for the horns on the side of the surface where you intend to mount the servo. These slots should be located a short distance from the hinge of the surface. The longer the distance the slot is from the hinge, the less the control surface will be able deflect.

As a result, it is important to select a location for the slots that will best suit the needs of your airplane. I like to mount it as close to the hinge as possible. A cut slot and its location is shown in Figure 1.

Once a slot is cut for the control horn, install the control horn by gluing it with hot-glue. A finished control horn is shown in Figure 2 below:

Figure 1 - Cut slot for control horn	Figure 2 - An installed control horn

The Connecting Rods

Once the control horns have been installed, the metal connecting rods which connect the control horns to the servos must be formed. They are made by bending a thin metal rod into shape.

I like to use needle-nose pliers to bend the rods into shape (Figure 3). The v-bend included in the shape of the rod allows the length of the rod to be later adjusted by changing the shape of the bend. The completed shape of the rod is shown below in Figure 4.

Figure 3 - Bending the connecting rod into shape	Figure 4 - The finished connecting rod

The Servos

After the control horns are installed and their control rods are connected, the servos must be installed on the airplane and attached to the control rod. I am using GWS Pico servos.

To attach the servos, I like to use a strip of double-sided equal to the size of the servo. The tape is placed on the servo and the servo is placed on the airplane by pressing it onto the airplane firmly.

When attaching the control rod to the servo, I like to use the outermost hole of the servo arm (Figure 4). This gives the greatest amount of control deflection. If I would later like to reduce the amount of deflection, it will be done digitally with the transmitter.

The installed aileron servos are shown in Figure 5, and the installed elevator and rudder servos are shown in Figure 6 below:

Figure 5 - The aileron servos	Figure 6 - The elevator and rudder servos

The Receiver and ESC

After all of the servos are installed, it becomes time to install the receiver and the electronic speed control. I am using a GWS 6 channel receiver and an E-flite 20 amp brushless ESC.

Before mounting the receiver, make sure that you plug all of the servos into their correct slots. These are the channel configurations for a JR radio: channel 1 - throttle, channel 2 - aileron, channel 3 - elevator, channel 4 - rudder, channel 5 - flap, channel 6 - gear.

For this airplane, I am controlling one aileron servo with channel 2 (aileron) and am mixing it with channel 6 (gear). The other aileron is connected to the mixed channel 6. The mixing channels will allow both ailerons to operate from the aileron channel. Two servos can also be used with only one channel using a Y servo cable.

Once the wires are installed, the receiver is mounted as the servos were with a piece of double-sided tape (Figure 7).

To install the ESC, begin by connecting the motor wires to the ESC. When connecting them, make sure that the blue wire is connected to the center slot. The red and black wires are connected to the outer slots. The particular slot for each wire depends on the desired direction of the motion of the motor.

The installed ESC and other electronics are shown in Figure 8 below:

Figure 7 - The receiver	Figure 8 - The ESC and other electronics

The Battery

Finally, after everything else is finished on the airplane, the battery is installed. The battery is located so that the balance of the airplane is at its intended CG. The intended CG is shown on the PDF plans of the airplane. To mount the battery, I cut two thin slots for a strip of velco to be run through. The verco is then wrapped tightly around the battery. The mounted battery is shown in Figure 9.

When mounting the battery and the other electronics, it is sometimes beneficial to mount them underneath the fuselauge if possible. This makes them hidden when the plane is viewed from above (Figure 10).

Figure 9 - The battery	Figure 10 - The hidden electronics

The Finished Airplane

After the battery is installed, the airplane is finished and ready for its First Flight! Pictures of the finished airplane are shown below in Figures 11 and 12:

Figure 11 - The finished airplane	Figure 12 - The finished airplane

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