Can anyone clairify the rules/regulations on kill switches on gas engines?Does a throttle fuel cut-off satisfy AMA/IMAA or is it mandatory to have an ignition cut-off via the receiver? I use a DX8 and set up the trainer button to close the throttle thus cutting off fuel into the carb. Thanks in advance!

Being able to shut the ignition down with the radio would be nice but is not required.

I don't have anything but the idle cut off on my glow engines.

AFAIK some sort of ignition cut-off is required by the AMA on gas engines?.

Not sure, but I dont think its an AMA requirement. But I think it is for IMAA. I'm sure someone that knows will chime in soon enough. I use an ignition cutoff and throttle. Just cause I can, not for any particular reason.
Edwin

I remember reading about a year ago (when jody and TOM were still posting here) that a throttle cut and ignition power switch on the side of the plane was sufficient for IMAA, some will insist otherwise though...

The AMA rules for Giant Scale size planes requires a engine cutoff switch controllable from the transmitter. Now that could the the choke servo or a separate servo controlled switch or an electronic switch. It just needs a way to kill the engine should the throttle servo fail or something else happens.

ref http://www.modelaircraft.org/files/520-a.pdf

I noticed that covers the Large Model Aircraft (LMA), 55lbs to 77lbs. There is also a giant scale size of greater than 80" mono, 60" bipe up to 55lbs. Granted, smaller than the LMA, but many of us still consider those as giant scale. As far as I know, the up to 55lb range doesnt have the same requirement. But still, that LMA size would be pretty impressive to see. Seems like monster scale would be appropriate for those.
Edwin

If you fly at an IMAA sanctioned event you are REQUIRED to have both a manual cutoff switch on the outside of the aircraft PLUS
a transmitter controlled method to kill the enging. It is covered in the IMAA Safety Code Rule 5 - to wit:

SECTION 5.0: EMERGENCY ENGINE SHUT OFF (Kill Switch)
5. Magneto spark ignition engines must have a coil-grounding switch on the aircraft to stop the engine. This will also prevent accidental starting of the engine.
This switch shall be readily available to both pilot and spotter/helper. This switch is to be operated manually and without the use of the Radio System.
5.2 Engines with battery powered ignition systems must have a switch to turn off the power from the battery pack to disable the engine from firing.
This will also prevent accidental starting of the engine. This switch shall be readily available to both pilot and spotter/helper.
This switch shall be operated manually and without the use of the Radio System.
5.3 There must also be a means to stop the engine from the transmitter. The most common method is to close the carburetor throat completely using
throttle trim, however other methods are acceptable. This requirement applies to all glow/gas ignition engines regardless of size

Some inspectors will want to see that your manual switch works and some will also want to see the transmitter kill function also. I have found the inspections
vary from event to event.

I use either an opti_kill, an IBEC or a magneto kill from the transmitter on all my gas engines.

Dan

Very interesting...In an IBEC set-up of the ignition, the radio switch is the activator for both radio and ignition. The IBEC also allows control of the CDI from the radio remotely when the readio is on.The single radio switch should cover both types of switches required in the rules in an IBEC set-up. It may not have been the intent when the rule was written probably aimed at redundancy, but nevertheless, a singular switch is simpler and safer in the long run

And at some events, there is no inspection!

An optical kill switch is cheap insurance against reciever power failures, fail safe events, throttle servo failures, and throttle linkage failures. Regardless of requirements

+1!
In the case of an IBEC, if power is lost to the receiver, there's no question as to whether the engine will quit as well. I guess that's what we would call "crash safe-er"!
Pete

Since an optical kill switch caused interference, I do not use them anymore.
In all the regulations I do not see a requirement for an optical kill switch unless you plane weighs more then 55 lbs.

All you need is a battery cut off switch you can reach from the outside and some cut - off , which can be the throttle.
If anything else is needed, I'd rather use a choke servo which come in handy in setups where the choke is hard to reach.

I may try whatI have on hand for a kill switch. Plan...take a real free running servo that will work a good ignition switch in fuse. A spring (attached too servo arm) would open the switch as soon as Radio signal was lost...killing the engine. Now if the interference was from you engine set-up you may regain control of the airplane to make the best landing you can. May work ok on 30cc & up....do not know. Just a thought ! Capt,n

Pretty "creative"Capt,n, but I'll be staying with my interference causing opti switches for the time being. They seem to be working out pretty well for me so far....

I have 5 gassers with optic kill switches with futaba 2.4 receivers NO issues! There was a problem with Aurora receivers and the kill switches.

Chris923

Well, great they work for you. I am not saying they are all bad. Mine was - I took it out and the interference was gone, no doubt the
opti switch has caused the problem.
And this was on a Futaba FASST receiver. Some say that interference can not happen on a 2.4 Ghz radio. They are wrong.

<span style="font-family: Verdana, Arial; font-size: 13px; background-color: rgb(251, 252, 255); ">There was a problem with Aurora receivers and the kill switches.</span><br style="font-family: Verdana, Arial; font-size: 13px; " /><br style="font-family: Verdana, Arial; font-size: 13px; " /><span style="font-family: Verdana, Arial; font-size: 13px; background-color: rgb(251, 252, 255); ">Chris923....</span>

Actually not the switches, but ignition modules from what I see here....

http://hitecrcd.com/blog/?cat=7




<br type="_moz" />

There was a problem announced early on that I heard about, but as I was not having any trouble. I just proceeded as I had been. I never did hear if there was a resolution to the issue - or if it was just left in a "proceed with caution" status?

My receivers (4 on gas now) are all Hitec Optima 7's, using an A9 transmitter....

Others using Hitec w/opti's at our field not having issues either.

Not saying there isn't an issue, only that myself and the guys I know first hand are not having any issues....

I'm hesitant to use a killing device with signal loss as the signal loss may be only temporary.

I was flying my Yak on 72mhz with fail safe set to return the throttle to idle. At 150 ft and fortunately level, the throttle went to idle and I checked for elevator and had no control. I sang out, "I've lost it, did someone just turn on?". The person who had, realized it and shut off. By the time signal was regained, the plane was much too far away to have made it back to the field if the engine had quit. In fact recovery was dicey with the plane out far enough where orientation was difficult.

Facts: Had the engine quit from some sort of engine shut down device, the plane would not have been returned safely to the field.

Had I not been using a PCM receiver with fail safe, the controls would likely have gone far over and the plane crashed quickly and I'd not sensed the warning that I'd lost signal control when the engine went to idle. A second or two delay in sensing I'd lost signal would not have allowed time to sing out the problem and get the offender to cut off so as to regain control and have the plane close enough to recover.

Had our field had a proper pin requirement, the offender would likely not have turned on without a pin. I'd lobbied for a pin requirement on 2.4 for those who continued to fly some 72mhz stuff. Instead, it was adopted that all 2.4 users were required to get a pin... and they ignored the requirement and the intent of the pin requirement was lost. That I know of, mine was the only example of a near shoot down because of 2.4/72 mix but our field has seen several 72mhz crashes from failure to extend antenna by those flying both.

Had my fail safe been set up to kill the engine.... the plane would not have been recovered.

Had fail safe not been set to take the throttle to idle, I'd not gotten the early warning of the problem that turned out to be critical in allowing time and space to recover.

No doubt that this is just one scenario and that there are other examples where killing the engine completely was better but until regulations are changed, I'll opt for using a fail safe to go to idle rather than killing the engine.

I would rather dead stick a plane any day than to take a chance of it still running when it hit or flying off into never never land at a high idle.

Please dont take this the wrong way, this is a general feeling on the issue and not directed at you. If you're not capable of dead sticking a plane, or willing to sacrafice one in the name of spectator/bystander ect safety, then you don't belong flying a giant scale plane.

Strangely you say, "not directed at you" but then use the pronoun you... twice. C'mon man, it was directed at me, eh.

Your opinion is duly noted. And... I noted forty years ago that any one who had soloed, is capable of landing dead stick.

Have you made your feelings known to the AMA and IMAA that their rules are inadequate for safe flight of giant scale? I note you are sometimes a CD... do you require your feelings/rules applied to fliers at events you direct or are the AMA and IMAA rules used?

I was at an IMAA event at Topeka a few years ago where one flyer let another fly his rather large Yak. He accidently flipped the optical kill switch perhaps thinking it was the smoke switch. The engine killed. No way of restarting it and it crashed into a shed. I'm hesitant of optical kill switches relying on my idle cut off instead.

"You" was meant to anyone reading it. Truly.

As a writer, instructor, and club officer, I make my recommendations and feelings known, especially to those who seek my advice for setup.

As a CD I enforce the rules as they are written.

<p class="MsoNormal"><span style="font-size: larger;"><span style="line-height: 115%; font-family: Arial, sans-serif;">Good discussion guys. Back to the topic: I have my gas planes' throttle set up such that with the throttle trim switch, I can lower the throttle to where the engine will die (i.e. slightly above the trim position where the throttle trim is fully lowered.) This also allows me to lower the RPM for landings, raise it for a high speed idle when flying, and kill the engine, using the trim switch.</span>I thought we all setup our Giants' throttles this way. ?? It made sense to me when I read this site's post on how to set up throttles. Guess not. Eh? I did have to remove the throttle stop on the DLE 111s to get the throttle travel to go to the point the engine shut off.<span style="line-height: 115%; font-family: Arial, sans-serif;">

I also have the SmartFly Optical Kill Switch as a means to preclude a high speed flyaway and do normal engine kills. When the transmitter signal is lost, the ignition is cut off. This cutoff is in the Rxer's Preset Failsafe settings. While this type of cutoff does cause a deadstick condition, it seems to me to be much safer, for everyone potentially involved, than having a spinning 28" prop going on its own path, especially around crowds. All other flight controls return, once the transmitter reestablishes the link with the receiver.

I have thought much about having the ignition cut off on me if there was a "Hold" on my transmitter. However, I have seen one "Hold" and the engine kept running. I have not seen any brownouts, that I know of, with dozens of hours on the plane. And, &hellip; I fly those planes way out there, sometimes a mile or more. I usually see 0 Frame Losses", 0 "Holds" and 40-50 "fades" on each of the 3 remote Rxers per 15 minute flight. (DLE 111, AR9210, DX8 + TM1000)

Also, being a retired N-Plant guy, I would never feel safe with a single method to accomplish a Giant plane's engine kill. Too many things can go wrong. Where safety can be compromised, always have a plan B.</span></span></p>

Plan B - "Run like hell".
The other way preferably.