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Written by Stan Alexander
RC Scale
Digital bonus content for the February 2018 issue of
Model Aviation.

Approximately a third of my models are now electric powered. In some ways it’s a convenience, and in others it’s more complicated and dangerous. With electrics, you don’t have the cleanup you have with two-stroke engines. You also don’t have the sound, but I’ve heard some great sound systems that make electric-powered aircraft sound more scalelike.

When an electric system is armed and you or anyone else is near it, however, you are in danger if you aren’t careful. This is especially true with large electric-powered aircraft, such as the one I’ll discuss this month.

Last spring, I was at my local field preparing two electric Scale models for flight. I had assembled the first one and began putting together a Carbon-Z T-28. I had flown the model for almost a year at this point without any mishaps, but that day in April would be different and would affect me for the rest of the summer.

A Carbon-Z T-28 Trojan with the mode switch showing green, which means that the ESC is armed and the motor is ready to turn the propeller and fly. It’s simple to operate and install.

I had assembled the model in its cradle, which elevates it off the ground to a height of approximately 4 feet. To cycle the gear, the canopy needs to be removed and the battery connected to the ESC—no problems there. But on that day, I was holding the model’s fuselage in my right hand to cycle the gear and had the transmitter in my left hand. What happened next occurred so quickly that I had to play it back in my mind several times to allow it sink in.

I must have bumped the throttle with my leg. When I did, the motor started swinging the 14 x 7.5 carbon-fiber propeller. It had me before I knew what was happening. I protected my hands and was trying to get away from it, but it caught my left arm and chewed it up badly.

Later, the receptionist at the hospital asked, “Well, what have we done today?” Sort of tongue-in-cheek, I told her I’d cut my arm with a model airplane propeller. She said to have a seat in the waiting room, and added, “I guess I’d better have a look at it.” Her response was then, “Oh my, let’s get you into a room right now.”

My arm ended up with 40 stitches, both inside and outside. Some of me was missing too, but the doctor did the best he could. Shots and antibiotics followed, and I couldn’t use my arm for much of anything for approximately two weeks.

The handiwork that the author did to his arm—ouch! Using a SafeStart could eliminate the chance of other hobbyists doing what he did!

I recently ran across an item that might help those of us who fly electrics—whether it’s Scale or other types of models. It’s called SafeStart, and is available from Dave’s R/C Electronics.

The $35 SafeStart package, from Dave’s R/C Electronics, comes with instructions and color photos.

SafeStart is an easy-to-install and easy-to-use circuit that adds an extra layer of protection for modelers who use electric motors and ESCs. This little item will prevent unexpected motor starts that can be caused by a throttle bump, or if someone forgets to turn off the transmitter or unplug the electric circuit on a model.

Installing a SafeStart from Dave’s R/C Electronics is simple. Connect your ESC to one connector, which is labeled, and the other connector to the throttle slot in the receiver, which is also labeled. That’s it for the electronic part of it.

These are the only tools that the author used to install the SafeStart in his Horizon Carbon-Z T-28.

I used the recommended hot glue (which I’m not a fan of) to install the circuit boards in the model. Find a place on the fuselage through which you can drill a hole, with a flat surface behind it, or on the inside of the model for the board. Select where you want the switch/LED light to come through on the outside of the model and drill a hole in the foam, balsa, or whatever your model is built from. Make sure the hole is larger than the LED switch/light so that you can operate it without it dragging on the edges of the hole that you’ve drilled.

I positioned the circuit board on the spot where I planned to mount it and drew an outline with a marker to show where I needed to cut out some of the foam from the side of the fuselage. This must be done to allow the LED switch to be accessed from the outside of the fuselage.

The area carved out to place the Mode Switch in the airframe can be seen in this photo.

After making the outline, I took several knives and cut a pattern in the foam with them. Don’t cut all the way through the foam—just a little at first. Keep testing the circuit board to see how much more you need to take out.

When you are satisfied with the mount and the switch works properly, heat up your hot glue gun and apply glue to some of the edges of the board. Hold the board in place for a minute and that’s it. Add the main circuit board to another place near the LED switch using the same process.

The T-28 has the SafeStart installed. Note the added color on the propeller. Most propellers don’t have their tips painted anymore.

All of this and much more are described in the instructions and color photos that come with the unit. It works well and would have saved me a couple thousand dollars at the emergency room if I had been using it. This switch, or something like it, should be mandatory for large, electric-powered aircraft during the manufacturing process.

LED Indicators

• No LED on: The transmitter is not “on;” no signal is detected.
• LED blinking orange rapidly: The throttle stick position is not at “low” (startup only).
• LED solid red: Safe Mode—the throttle stick is not active.
• LED blinking red: Pre-Run Mode—if the throttle stick position is “low” and the switch is held for 3 seconds, the unit will enter Ready Mode.
• LED blinking green: Ready Mode—when the switch is released, the unit will enter Run Mode.
• LED solid green: Run Mode—the throttle stick is now active, as well as the propeller.

A close-up of the Mode Switch lighted green, which means the propeller and ESC are armed and ready to fly.

A close-up of the Mode Switch shows it glowing red. It is in Safe Mode and the throttle stick is not active.

This adds another layer of safety when flying electric-powered aircraft—especially large ones!

-Stan Alexander

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