Ignition Module Placement
03-23-2011, 05:45 PM
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Ignition Module Placement
I've got the bug to start working on my Bud Nosen 1/4 scale Citabria again and so today I mounted a CRRC 40 on it, inverted. I'm new to gas and was looking for advice on the ignition placement. Originally I was thinking of the back of the firewall but I found that it fits on the front of the firewall directly behind the crankshaft with about a millimeter to spare on each side between it and the aluminum stand offs and about 3/4 of a inch from the back of the crankcase. Would this be a good place to mount it? Would engine heat be a problem? My understanding was the farther from the radio the better. Any input would be appreciated. Thanks
03-23-2011, 07:20 PM
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RE: Ignition Module Placement
You will never have interference WITH the ignition. You can have interference BECAUSE of the ignition. Some ignitions are better than others in that respect. I don't know what the CRRC has.
Heat is a very great enemy of ignition systems, regardless of maker, but again some ignitions are much more tolerant of heat than others. Consider how much heat will be radiated by the muffler that will impact the ignition. the back of an engine normally, and I repeat normally, does not generate a tremendous amount of heat. The jighest generators of heat are the cylinder head and the muffler.
Will the heat radiated by the head and muffler become trapped inside a cowl? If so, reconsider the location of the ignition. Inside the firewall would probably be better since that area generally does not receive or trap much heat from the engine compartment.
Heat is a very great enemy of ignition systems, regardless of maker, but again some ignitions are much more tolerant of heat than others. Consider how much heat will be radiated by the muffler that will impact the ignition. the back of an engine normally, and I repeat normally, does not generate a tremendous amount of heat. The jighest generators of heat are the cylinder head and the muffler.
Will the heat radiated by the head and muffler become trapped inside a cowl? If so, reconsider the location of the ignition. Inside the firewall would probably be better since that area generally does not receive or trap much heat from the engine compartment.
03-24-2011, 06:30 AM
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RE: Ignition Module Placement
Thanks for the input. I think I will put it on the inside of the firewall. I'm worried about it being nose heavy anyway and that would move a bit of weight back. Another question while we are at it. I was planning on operating the choke with a servo. Do I need the electronic cut off for the engine in this case? I already purchased one but it seems to me I could save the weight and wires by just killing the engine with the choke. Is it normal to have both a radio operated electronic kill and a radio operated choke on gas engines? Thanks for your reply.
03-24-2011, 09:02 PM
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RE: Ignition Module Placement
I will not be the one to say you do or do not need an electronic engine kill. Personally, I believe a correctly set up engine does not, and is no more or less gangerous than a glow engine that has never had similar means of cut off.
A choke servo is a very effective means of cutting off an engine. So is correctly setting up carb linkage and servo throws where the iodle trim lever has the ability to fully close the throttle plate. So ask yourself, do you need three different ways of cutting off the engine and or ignition on top of the externally mounted ignition swith? That makes four. How fast are you with your radio? By the time you ran through the first three any impending doom would have already occurred.
As an aside, I have yet to hear of a brand of electronic kill switch that hasn't failed, or generated considerable grief with electronic feedback or interfering with ignitions. My feelings are if someone is so terrified of flying gas they should remain flying glow. They don't use electronic kill switches there, and the stats are pretty clear. Glow fliers experience far more accidents per capita than gas flyers, usually caused by putting hands in propellers or driving planes into the pitts. The hand thing is dumb. The pitts situation simply means they should not have been off a buddy cord yet.
Utimateley it's your call.
A choke servo is a very effective means of cutting off an engine. So is correctly setting up carb linkage and servo throws where the iodle trim lever has the ability to fully close the throttle plate. So ask yourself, do you need three different ways of cutting off the engine and or ignition on top of the externally mounted ignition swith? That makes four. How fast are you with your radio? By the time you ran through the first three any impending doom would have already occurred.
As an aside, I have yet to hear of a brand of electronic kill switch that hasn't failed, or generated considerable grief with electronic feedback or interfering with ignitions. My feelings are if someone is so terrified of flying gas they should remain flying glow. They don't use electronic kill switches there, and the stats are pretty clear. Glow fliers experience far more accidents per capita than gas flyers, usually caused by putting hands in propellers or driving planes into the pitts. The hand thing is dumb. The pitts situation simply means they should not have been off a buddy cord yet.
Utimateley it's your call.
03-26-2011, 08:10 AM
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RE: Ignition Module Placement
Thanks T.O.M. I'm not terrified of gas. It's just that it's my first and I want to do it right. I was inclined to think the electronic cut off was over kill but I thought it might be a requirement for gas. I think I'll go without it then, at least initially. Thanks for your help...... Peter
03-26-2011, 08:54 AM
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RE: Ignition Module Placement
Some will attest this is an area that is a pet peeve of mine.
The IMAA was the organization that came up with the dual ignition kill requirement for gas engines. The IMAA is an AMA SIG so those rules were accepted by the AMA a long time ago. Bear in mind that when the requirement was developed the vast majority of gas engines were using magnetos, which remain hot all the time unless an electrical interrupt is incorporated. Improperly adjusted carb linkages did not always cut the engine, and a hot magneto kept it running. So the regulation simply added the inclusion of a user operated ignition interrupt switch in addition to idle cut off. That switch was intended to be a manually operated switch on the exterior of the aircraft that was manually/physically activated after landing. IMAC may now have some rule forcing use of an electronic kill but if you like being able to always have fun you might not like IMAC.
There is no formal AMA rule that insists a remote operated choke or remotely operated electronic kill be incorporated on the plane. A lot of people that have never read any regulations at all have listened to people that know only marginally more than themselves and come up with the concept that kill devices are mandatory or make flying gas engines safer. Essentially "tribal knowledge" has been used to develop products to generate greater profits. Then fear of the unknown was promoted to embed the concept even further. Clubs that incorporated an electronic ignition kill rule did so out of ignorance.
An electronic kill is not a bad thing but not a requirement. They should not be "forced" on people because of someone elses fear, unsupported allegations of enhanced safety, or unfounded claims of an equipment requirement. Any enhanced level of safety is 100% dependant on the person using the radio, especially where a plane might become uncontrolled on the ground. If the user isn't extremely fast it won't do a bit of good. How many times have you seen someone on the flight line freeze at the controls because they didn't know what to do? How many times were gound incidents the fault of a glow flyer versus a gas flyer? For the most part there is only the idle cut off available for use with glow engines and those are generally considered safe and acceptable for propellers spinning at higher RPM than a gasser. There are some fuel cut off devices for glow engines used in specific competition fields but they are not generally found on sport planes.
If enhanced safety is truly the goal, people would be setting up their failsafes at the radio to send the plane into a terminal flight path in the event of radio failure. That same failsafe could set the throttle to idle or idle cut off, killing the engine, thus reducing the amount of energy during impact. A great many people only use the factory default for their failsafe, which typically holds servos at their last commanded position. Not very smart or safe at all. As far as linkage failures are concerned, if people quit removing the idle return springs on carbs the carb would automatically go to the cut off position and kill the engine if the linkage fell off. This is guaranteed if the idle stop screw was removed from the carb. Been there, done that. We're not flying a weedeater so that screw is uneccessary. Mathmatically, the odds of needing an electronic cut off in an emergency are astronomically high if everything else was done close to correctly. I know that some people are still using less advanced radios that do not have a failsafe function but those people have become few and far between with the advent of 2.4 technology.
If people are truly concerned about safety they would take the time to learn the various functions and how to use their radios, learn how to inspect, install components correctly, and apply that knowledge. They would range test their equipment at minimum before the first flight of every flying day. They would not fly alone at any time, and they would not fly solo unless they were truly qualified. They would also not be flying aircraft or equipment they were not qualified to use. They would not reach around propellers from the front of the aircraft to adjust needles or remove glow drivers. They would ALWAYS have a second person restraining a plane when starting it. They would read and at least acknowlege the AMA safety rules and not fly over or behind the pits. I used to be a club safety officer and have seen all the above and more every flying day. It was a full time endeavor to "enlighten" modelers about protecting themselves from themselves. An endeavor that was often not received favorably by the guilty parties.
On any given day at the field, how many times have you seen one or more of the above violated? How many times was it done by a glow flyer? How many times was it done by a gas flyer? How many times was it done by those with a lot of knowledge and experience? I think you"ll recognize where I'm coming from after those considerations and make the same determinations. Gas flyers are not more dangerous than anyone else. Since they are a smaller percentage of the enthuasists present, by numbers alone they are a lessor risk. The glow flyers are the majority of the people involved in modeling accidents so if there is a need for specific engine safety equipment that's where the focus should be directed.
So that's my story and I'm stickin' to it. It's a hot button topic for a lot of people (especially me) and disagreement is assured. That's OK because it promotes deeper thought and contemplation where model operation safety is concerned.
The IMAA was the organization that came up with the dual ignition kill requirement for gas engines. The IMAA is an AMA SIG so those rules were accepted by the AMA a long time ago. Bear in mind that when the requirement was developed the vast majority of gas engines were using magnetos, which remain hot all the time unless an electrical interrupt is incorporated. Improperly adjusted carb linkages did not always cut the engine, and a hot magneto kept it running. So the regulation simply added the inclusion of a user operated ignition interrupt switch in addition to idle cut off. That switch was intended to be a manually operated switch on the exterior of the aircraft that was manually/physically activated after landing. IMAC may now have some rule forcing use of an electronic kill but if you like being able to always have fun you might not like IMAC.
There is no formal AMA rule that insists a remote operated choke or remotely operated electronic kill be incorporated on the plane. A lot of people that have never read any regulations at all have listened to people that know only marginally more than themselves and come up with the concept that kill devices are mandatory or make flying gas engines safer. Essentially "tribal knowledge" has been used to develop products to generate greater profits. Then fear of the unknown was promoted to embed the concept even further. Clubs that incorporated an electronic ignition kill rule did so out of ignorance.
An electronic kill is not a bad thing but not a requirement. They should not be "forced" on people because of someone elses fear, unsupported allegations of enhanced safety, or unfounded claims of an equipment requirement. Any enhanced level of safety is 100% dependant on the person using the radio, especially where a plane might become uncontrolled on the ground. If the user isn't extremely fast it won't do a bit of good. How many times have you seen someone on the flight line freeze at the controls because they didn't know what to do? How many times were gound incidents the fault of a glow flyer versus a gas flyer? For the most part there is only the idle cut off available for use with glow engines and those are generally considered safe and acceptable for propellers spinning at higher RPM than a gasser. There are some fuel cut off devices for glow engines used in specific competition fields but they are not generally found on sport planes.
If enhanced safety is truly the goal, people would be setting up their failsafes at the radio to send the plane into a terminal flight path in the event of radio failure. That same failsafe could set the throttle to idle or idle cut off, killing the engine, thus reducing the amount of energy during impact. A great many people only use the factory default for their failsafe, which typically holds servos at their last commanded position. Not very smart or safe at all. As far as linkage failures are concerned, if people quit removing the idle return springs on carbs the carb would automatically go to the cut off position and kill the engine if the linkage fell off. This is guaranteed if the idle stop screw was removed from the carb. Been there, done that. We're not flying a weedeater so that screw is uneccessary. Mathmatically, the odds of needing an electronic cut off in an emergency are astronomically high if everything else was done close to correctly. I know that some people are still using less advanced radios that do not have a failsafe function but those people have become few and far between with the advent of 2.4 technology.
If people are truly concerned about safety they would take the time to learn the various functions and how to use their radios, learn how to inspect, install components correctly, and apply that knowledge. They would range test their equipment at minimum before the first flight of every flying day. They would not fly alone at any time, and they would not fly solo unless they were truly qualified. They would also not be flying aircraft or equipment they were not qualified to use. They would not reach around propellers from the front of the aircraft to adjust needles or remove glow drivers. They would ALWAYS have a second person restraining a plane when starting it. They would read and at least acknowlege the AMA safety rules and not fly over or behind the pits. I used to be a club safety officer and have seen all the above and more every flying day. It was a full time endeavor to "enlighten" modelers about protecting themselves from themselves. An endeavor that was often not received favorably by the guilty parties.
On any given day at the field, how many times have you seen one or more of the above violated? How many times was it done by a glow flyer? How many times was it done by a gas flyer? How many times was it done by those with a lot of knowledge and experience? I think you"ll recognize where I'm coming from after those considerations and make the same determinations. Gas flyers are not more dangerous than anyone else. Since they are a smaller percentage of the enthuasists present, by numbers alone they are a lessor risk. The glow flyers are the majority of the people involved in modeling accidents so if there is a need for specific engine safety equipment that's where the focus should be directed.
So that's my story and I'm stickin' to it. It's a hot button topic for a lot of people (especially me) and disagreement is assured. That's OK because it promotes deeper thought and contemplation where model operation safety is concerned.
03-27-2011, 10:21 AM
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RE: Ignition Module Placement
That was an interesting and informative post. I did a little more research on it and realized there are strong opinions on both sides. I found a 22 page string on another forum arguing over it. Anyway, I now know what is required. Thanks again.
03-27-2011, 11:39 AM
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RE: Ignition Module Placement
T.O.M.<div>
</div><div>Well thought out, well reasoned, and well presented, as usual from you.</div><div>
</div><div>Thank you for a level-headed take on the issue.</div>
</div><div>Well thought out, well reasoned, and well presented, as usual from you.</div><div>
</div><div>Thank you for a level-headed take on the issue.</div>
03-27-2011, 03:45 PM
#10
RE: Ignition Module Placement
Just a couple of comments from someone that owns a CRRC 40. If you use the choke for a routine shut down device, it will flood the engine and make it hard to restart. Replace the Chinese plug with an NGK BPMR6F plug. My original ignition was very weak and it did not run well. I replaced it with a RCexel conversion and it runs much better and idles better. My engine needed quite a bit of break in time before it starting performing satisfactorily. Don't give up on it, I put quite a few boring break in flights on mine, and now it idles and revs up pretty well and the top end is getting fairly decent spinning a 19X8 Xoar. Good luck.
http://www.agaperacingandhobby.com/v...?productid=223
This is the conversion module for the CRRC 40 if you are interested.
http://www.agaperacingandhobby.com/v...?productid=223
This is the conversion module for the CRRC 40 if you are interested.
03-28-2011, 06:00 AM
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RE: Ignition Module Placement
Texasbird, I've heard the ignition doesn't like low voltage. I'm going to try it stock first but I've bookmarked that ignition and might go that route eventually. There's a huge string on the CRRC 26 I'm going to have to re-read. Thanks for the advice.
