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Old 06-22-2019, 09:05 PM
Philkoury is offline
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I agree there should be multiple methods to kill a gas engine from the TX and don't want to get involved in the "best" method. I am interested in the AMA dim view comment. Can you provide a link to the AMA document that supports this statement? It was an IMAA rule I am not aware of the AMA requirement for TX kill switches.








FYI: all my gas engines have at least two TX engine kill methods.
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Old 06-22-2019, 09:24 PM
RCAddiction is offline
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I did a search for this earlier today on the AMA site. There was a requirement from AMA that I found, circa 2006 or so, that required a manual ignition cut off switch on the outside of aircraft used for giant scale racing events. It does not otherwise seem to be a requirement, just what I personally believe to be a smart and simple safety practice, like not sticking one's hands in a prop, properly restraining an aircraft before starting the engine, using strong enough servos for an application, making sure batteries are in good condition so they don't fail, etc, etc. None of those are AMA requirements AFAIK.


I did find quite a number of club websites that do require a radio-actuated ignition kills switch to fly there.
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Old 06-23-2019, 06:51 AM
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A few years ago my first 50cc plane was a used older Kangke Laser. I put a new DLE 55 and Futaba 9156 servos in it to update it. For the first flight I had a friend maiden it for me since I never flew something like this before. He took off and flew a couple of laps with it and said it flew fine. I took off and after a couple of minutes we heard what we thought was flutter. I immediately went to land and that's where the fun started. All of the sudden the muffler dropped off and then I had no throttle. It just chugged along for a little then shut off and I was able to land it. Walking over to the plane I couldn't get over the muffler just coming loose, I Loctite everything. Then we saw what happened. The Zinger wooden prop split and the motor vibrated so much that the stand offs pulled through the firewall. The throttle cable and cowl kept the motor from leaving the plane. That's why the throttle cut didn't work! Now optical kill on everything!
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Old 06-23-2019, 09:11 AM
Bunky F. Knuckle is online now
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And crickets from the OP........
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Old 06-23-2019, 09:12 AM
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Quote:
Originally Posted by 3DJP View Post
So before the days of an ignition kill.. what was acceptable??
Lots of guys used micro switches with a servo operation.
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Old 06-23-2019, 11:15 AM
Languid Virago is offline
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Chix fly too.
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Before ignition kills , and computer radios, we use throttle max down on the trim tab, and on a fail safe, rarely cut the engine reliably. We would take off with the trim tab on max for the idle we wanted, slide the trim tab down to kill the engine.

As a side note, when we first started GS, fail safe boxes was set to full up and full rudder, low idle to spin the model in, I am so glad things have moved on.
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Old 06-23-2019, 11:38 AM
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I remember carefully gluing micro switches (from Radio Shack) to the top of the throttle servo. At full down trim the servo arm would close the switch and kill the ignition!

Getting decent range in the old AM 72mhz radios, when flying a magneto engine was quite a challenge!
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