Technical/Competitions
FAILSAFE
By JC Zankl, AMA Competition and Technical Director | johnz@modelaircraft.org
This month’s column will lean toward the technical aspects of modeling. Are you using failsafe? Every transmitter manufacturer—Futaba, JR PROPO, Spektrum OpenTx/EdgeTx—has failsafe functions built in. You should always use a failsafe function for safety.
There are a couple of reasons to use failsafe, with safety being number one. If your receiver loses signal with the transmitter, it should go into failsafe mode. I set mine (helicopters) for the engine to turn off or go to idle. This does two things: It lets me know that there is a problem, and, if set properly, it will hopefully minimize damage to the model, property, or worse.
A couple of times, I have witnessed where failsafe should have been used and it wasn’t. There were a couple of instances this past summer at AMA where we had some fly-aways. One was a borrowed airplane that was being tested. The pilot forgot to set failsafe and had a fly-away.
At the speed that the airplane was being flown, it would have traveled some distance anyway. Had failsafe been used and the throttle returned to idle, it might have been easier to locate the model. That was in late August, and we have not yet found it.
Another instance was at an event. I heard a man yell, “I don’t have it!”—words you always hate to hear. This was odd because the airplane was not flying in a path that would suggest a “brownout.” It was all over the place. It was as though the pilot had control of the model the entire time and it just got too far out.
I say that because it is all too common for pilots to lose their model and blame manufacturers. If it was a failure with signal, failsafe would have brought the throttle back to alert the pilot to the issue. It is hard to confirm whether it was a signal issue or a pilot error of flying too far away and losing orientation.
You can test your failsafe features on your workbench. I take all of the blades and propellers off of the models. It is easy to do on a nitro/gas model because the engine doesn’t have to be running to test it. Simply watch the throttle servo. Go to your transmitter’s failsafe screen and set it so that the throttle channel goes to zero or idle. When you think you have it set correctly, simply go to roughly half-throttle, and then shut the transmitter off. If it’s correctly set, the throttle servo or ESC should go to idle or off. If not, adjust it until it does.
This is just a safety measure so that if there is something wrong with the transmitter and your receiver is in good working condition, it should help minimize damage and give you something to help diagnose what might have happened.
If your receiver is bad, failsafe will not always work. It is good practice after a mild or severe crash to always send in your receiver to be checked for shock damage or cut antennas.
Safety should always be your first rule. I hope this article was helpful.
