We all like to hide items switches, fuel fittings, antennas, wing bolts, air valves and other items pertaining to the operation of radio control aircraft. We also camouflage these items to resemble something on the full scale counter part. The truth of the matter is our planes are in fact real airplanes. The most noticeable difference between the full size aircraft and our scale counterpart is the size. Some items are necessary to be readily available. A few examples are the receiver switch and the manual kill switch. These items necessitate easy access.

While the receiver switch speaks for itself, the manual kill switch is a required item as stated in the IMAA Safety Code. I have had several calls pertaining to the reason for the manual kill switch as well as how to install one.

The main reason for a manual kill switch is safety related. This switch, when turned off, will prevent the engine from running. While the Safety Code doesn't specify the location of this switch, it should be readily available if the need arises. Picture a pilot starting his engine, the transmitter battery is bad, and the throttle is about half way open. How would you stop the engine? Several years ago I seen this happen. The plane did not have a kill switch. He didn't want to break his $30.00 prop by throwing a towel into the prop like he did with his .25 size airplane, not to mention the risk involved in throwing an object onto a turning prop. So he had to let it turn while someone fetched his flight box to retrieve the tools to open the top hatch so he could pinch off the fuel line. This really doesn't sound like a safe way to remedy this situation. A kill switch could have been installed on the front side of the airplane and easily switched off by the spotter.

Another time I witnessed a run-away plane that had just landed and was heading for the pit area. The engine was running at about 3,000rpm and several people were chasing the plane. The plane was finally caught. No one could find the kill switch to stop the engine and the pilot was about 50 yards away just standing there watching. Finally the person holding the plane nosed it over to stop the engine, breaking the prop.

The point I am making is, the manual kill switch is strictly a safety feature. It is mandatory, not an option. Anyone who states that kill switches are not needed is in clear violation of the IMAA Safety Code. I have heard complaints as to why, when the engine stops with the throttle trim. Another safety feature of the kill switch is it prevents the accidental starting of the engine. Engines that have a spring starter or electronic spark do start very easily. We would all feel terrible if someone accidentally started an engine and got injured in the process, especially if it was a child. I hope that the above examples are reason enough.

Large glow engines that use glow plugs are the only engines that are exempt. There is no circuit in this type of engine. Engines that utilize throttle coupled advance and a battery pack for spark need this switch to turn off the battery supply. CD ignition engines have a solder tab or wire for the purpose of grounding the ignition to the engine to stop the engine.

I recommend a slide switch similar to the switch that comes with the radio system. These switches hold up to vibration well. The toggle switches don't hold up to vibration very well. I have seen some that were rated heavy duty that seemed to hold up fine.

Till next time, have fun and fly safe.