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kill switch on gas engine IMAC rules?

Old 10-16-2003, 11:07 AM
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LeeL
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Default kill switch on gas engine IMAC rules?

can some one flying IMAC competitions please answer this question or maybe tell me where I can find the answer? Does an on/off switch for the battery qualifiy as a kill switch on a gas engine with an electronic ignition? The reason I am asking is one of the guys at the field I fly at told me that it was a requirement for IMAC competition and my thoughts are the on/off switch kills the power to the ignition and not having a magneto making power this would kill the engine making the switch a kill switch also. Any body know if this is ok or not thanks in advance for your help
Old 10-16-2003, 12:37 PM
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Flyfalcons
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Default RE: kill switch on gas engine IMAC rules?

Sounds good to me. I don't think IMAC has rules about this, but if I remember right, IMAA has a rule that states you must be able to kill the engine with the transmitter and at the plane itself (such as a kill switch). Throttle trim does count as a way to kill the engine from the transmitter.
Old 10-16-2003, 12:59 PM
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Bill Kersey
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Default RE: kill switch on gas engine IMAC rules?

No , to the best of my knowledge there is no requirement for a "radio operated" kill switch. I've been competing for 2 1/2 years now and I've never heard of such a requirement and it has never been checked or questioned at all the different fields I've flown at. Now noise is a different issue....

Bill Kersey
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Old 10-16-2003, 01:52 PM
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Default RE: kill switch on gas engine IMAC rules?

Bill, who are you responding to? If it is to my post, check my last sentence. If you have no way to kill your gas engine with your radio, then that is a dangerous setup. I also said it may be an IMAA rule, not IMAC. With a typical setup, you can kill the engine using one of two methods - the switch on the side of the plane or your radio.
Old 10-17-2003, 02:01 AM
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Default RE: kill switch on gas engine IMAC rules?

If you have a choke servo in the plane that is activated via a switch at the TX-- then you can simply flip the choke switch to kill the engine. Works almost instantaniously.
Old 10-17-2003, 06:35 PM
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Default RE: kill switch on gas engine IMAC rules?

Thanks for the answers guys, I am going to use a servo to work the choke so I guess that the plane will be "legal" for IMAA, IMAC, and AMA at least I hope it will be. This is my first 33% sized plane and only my 2nd. gas engine. I am planning to start flying IMAC competitions in 2004 and didn't want any suprises when I show up to my first comp.
Old 11-01-2003, 06:19 AM
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Default RE: kill switch on gas engine IMAC rules?

LeeL. . whether the "Rules" require it, or not, having a transmitter controlled way to "kill" the engine, in addition to throttle trim shutoff, is just a really good idea. I have only one plane that can't be shut off that way, but the throttle trim on the plane also has to be 4 trim clicks above center in order to run at 1200 rpm, so if I slide the trim all the way back you better believe it's gonna shut down.

That being said, a choke servo is a handy item to have, as it keeps you from reaching near the engine during the startup procedure, and doubles as a "kill" mechanism. Best way to set it up is so that if the engine moves forward it closes the choke. That way, in case of the engine coming loose it will tend to shut down, which is a big help in case of a broken prop blade or motorbox failure. A choke servo only takes a mini-sized servo with a long arm movement, so you can use a 30-35 ounce mini sized servo for choke. Total weight added is about 2 ounces tops, including the linkages, and tied into the LG channel lets you operate it on-off.

One caution. . if you are able to, assign the gear to a switch that is well away from your Rate switches, so that you do not accidentally trip it while switching rates. It's a bad idea to go into 3D maneuvering and try to hit the Rate switch, and then shut the motor off instead. . . Had it happen a couple of times. . I finally assigned it to a push-button instead of a switch, and have never had a problem since.

some things are just a good idea to have on the airplane.. this is one of them.
Old 11-04-2003, 04:35 PM
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Bill Kersey
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Default RE: kill switch on gas engine IMAC rules?

Sorry I was away for so long, I was getting ready for the SE Regional Championships. I didn't clarify my first response in a timely manner and noticed that I apparently ruffled RYAN's feathers, but since you didn't post the original question Ryan, you can assume I wasn't responding to anything you had to say. LeeL asked if there was an IMAC rule, not IMAA, and I answered his question. As a matter of fact "LEEL", there isn't even an AMA rule posted in the "2004 AMA Safety Codes" that discuss such a requirement. NOW, in response to Ryan's post, I do happen to agree with what he said about it being a good idea to have your trim set to shut the engine down, as almost all competitors do, however under certain weather conditions this isn't a guaranteed method of "killing" the engine. The ignition switch, is the guarantee. The extra servo for the choke is another method, but adds a few extra ounces of weight. The best method for safety is to have your "required" caller/safety observer with you. Their primary function is the launch and recovery of your aircraft, oh, and calling the sequences can be important also. Anyway LEEL, I looked forward to meeting you in the future and good luck next year.

Bill Kersey

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