Avoiding RC Transmitter Switch Mistakes

At the most recent meeting of my RC club, several pilots got into a discussion about the embarrassment of accidentally flipping the wrong switch on their radio transmitter. The consequences of this mistake ranged anywhere from scuffed paint to a full-bore crash into the turf. Given the complexity of modern radios and the forest of protruding switches, it’s easy to understand how even a seasoned pilot could mistake one switch for another. It is even more understandable when you realize that many pilots are reluctant to take their eyes off of their aircraft. The myriad switches are often navigated purely by muscle memory and feel.

Nearly everyone had a story to share about causing damage to a favorite model from an absent-minded switch throw. Most stories were followed by a description of what was done afterward to mitigate the risk of future mistakes. The majority of pilots chose to modify a critical switch in order to differentiate it from its neighbors.

Modern RC transmitters are often complex. Hitting the wrong switch can cause an embarrassing and costly mishap.

For many pilots, their target switch to modify is the one which activates retractable landing gear. Obviously, you want to be able to easily locate that switch so that you can safely lower the gear when it’s time to come in for a landing. This is especially true if you’re already dealing with an in-flight emergency such as a dead engine.

Correct operation of the landing gear is also vital when the model is on the ground. One pilot relayed an incident where he intended to retract the wing flaps while taxiing his expensive jet model. He inadvertently hit the landing gear switch instead. As the landing gear tucked itself away, his jet belly-flopped onto the hard runway, causing considerable mechanical and cosmetic damage. Another flyer talked about the time he accidentally retracted a model’s landing gear while the engine was warming up. His transgression ruined a very costly propeller.

You want to be able to quickly identify switches by feel.

Many multi-rotor models have switches that control flight modes and/or the ‘return home’ function. Changing either of those could fundamentally alter how the model responds to your control inputs. Correct positioning of the switch is vital.

Whatever your hot-button (or two) may be, the intent of modifying the corresponding switch is the same. You want to be able to quickly identify that switch by feel so that you can move it when you need to and leave it alone when you don’t. What follows are three proven methods to modify a critical switch.

The Simple Method

Most transmitter switches are the toggle variety. Perhaps the easiest method to alter the look and feel of a toggle switch is to cover the arm with a soft material. You can buy rubbery covers made just for switches, but I’ve found that silicone fuel tubing works quite well. This is a standard hobby shop item that is often available in a variety of colors. All you have to do is cut the tubing to the length you need and slip it over the switch arm.

Hobby shop fuel tubing is a cheap and easy way to change the look and feel of a critical switch on your transmitter.

I adopted the fuel tubing modification when I began pulling up gliders with a rope attached to a tow plane. I configure my gliders with a servo-actuated release mechanism so that they can detach from the tow rope when they reach soaring altitude. I also install a release on the tow plane for emergencies. If there is ever a problem with the glider, I don’t want it dragging down the tow plane too (or vice versa). That contingency plan has saved a few models over the years. Whether the tow is nominal or there is an emergency, I want both pilots to be able to release quickly and without having to look away from the airborne models. So, I fitted the tow release switch for both transmitters with a sleeve of fuel tubing.

When towing gliders it’s important for both pilots to be able to release the tow rope at the first sign of trouble. Photo by Lee Ray.

An alternative to commercial switch covers or fuel tubing is heat shrink tubing. This provides a more subtle difference in texture than the other, thicker options, but it looks a bit cleaner. It may be helpful to leave some tubing overhanging the switch arm in order to get a more pronounced difference in the feel of the switch.

Heat shrink tubing provides a more subtle switch marking alternative to fuel tubing.

The Permanent Method

Another common switch modification is to make the switch arm considerably shorter. This method has two benefits. First of all, the shortened switch is easily identifiable by feel. Secondly, the short arm makes the switch much less prone to accidental movement during routine handling of the transmitter.

There are also drawbacks to this modification method. Cutting the switch can be messy. Many modelers use a Dremel tool with a cut-off wheel to saw through the switch arm. This method will spread fine, metallic dust, so be sure to protect the rest of the transmitter from this. You’ll also want to make sure that the modified switch arm does not have any sharp edges.

Physically cutting the switch arm is a common way to identify a critical switch while also ensuring that it doesn’t get easily bumped.

This is obviously a permanent change to the transmitter. Stay away if you’re squeamish about making such changes or doubt your ability to do so effectively. You may also want to check with the manufacturer to see if such a change will void your warranty.

The Alternate Method

Not all critical transmitter switches are toggles. One of my friends recently crashed his multi-rotor by accidentally engaging a push-button switch. His quad uses a Yuneec ST-10+ transmitter, just like the one used for the Blade Chroma 4K that I previously reviewed. On that transmitter, the button used to take still photographs is located near, and is very similar to the button used to start and stop the motors. I don’t suppose I have to tell you what happened to cause the crash.

My buddy was open to ideas to help prevent another incident. And frankly, his crash opened my eyes to how easily I could do the same thing…and I don’t want that! After a little brainstorming, I came up with a simple solution—thread protectors.

Thread protectors are common hardware store items. They are rubbery caps meant to be placed over exposed machine screws. They’re available in different sizes to fit different screws. The idea is to protect the exposed screw threads from wear and tear. Thread protectors are also useful to guard fleshy parts from the dangers of protruding screws. There are several of them on my kids’ playset.

With a rubber thread protector in place, I can still push the motor start/stop button, but it is easily distinguished from the nearby photo button.

I found that a 3/8″-diameter thread protector fits snugly over the base of the motor start/stop button of the ST-10+. My original plan was to use the thread protector as a switch guard. It would keep me from pressing the motor button while flying, but I could remove the guard when I needed to start or stop the motors.

After installing the thread protector, I discovered that I wouldn’t have to remove it. It definitely makes the motor button feel different from the photo button and prevents any incidental switch movement. At the same time, it is possible for me to engage the motor button while the guard is in place. It just takes a deliberate and forceful motion to do so. To me, that is the best of both worlds. I get clear distinction between the switches, but I don’t have to manage a separate piece for the transmitter.

What’s Your Method?

There are just a few simple ways that I identify the critical switches on my radios. There are definitely more ways to tackle this problem. What do you do to prevent switch-related mishaps? Feel free to share your switch management techniques in the comments section below.

Terry spent 15 years as an engineer at the Johnson Space Center. He is now a freelance writer living in Lubbock, Texas. Visit his website at TerryDunn.org. You can also follow Terry on Twitter and Facebook.


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