Flaps on gas RC chipmunk constantly shaking
01-04-2022, 06:58 PM
#1
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Flaps on gas RC chipmunk constantly shaking
Hi guys, this is my first post on here and would like some thoughts on a problem I have with my 25cc petrol Seagull Chipmunk.
I did some run ins this morning and found that the flaps were vibrating very badly and moving a lot when the plane was sitting and running at idle. With power applied they still randomly moved.
Has this happened to anyone else? I have been told to move the receiver away from the batteries and also remove the remote reciever as well as it could cause interference etc
any help will be much appreciated
I did some run ins this morning and found that the flaps were vibrating very badly and moving a lot when the plane was sitting and running at idle. With power applied they still randomly moved.
Has this happened to anyone else? I have been told to move the receiver away from the batteries and also remove the remote reciever as well as it could cause interference etc
any help will be much appreciated
01-04-2022, 09:02 PM
#2
Sounds like the radio system is picking up ignition noise from the engine.
The first thing to check is the cap on connecting the ignition to the spark plug. Make sure it is tight, and fully seated. Some even put a small hose clamp around it to make sure it is tight. Also verify the exact brand of spark plug the ignition maker (not engine maker) designed the cap for. While the type of plug may be the same for different plug companies, according to the type code, the overall shape can vary, leading to a cap that doesn't fit quite right. Rcexl, for example, designs around a NGK plug. Their cap on a Champion plug of the same kind just doesn't fit right, and noise leaks out.
In the olden days, the watchword was complete separation between all engine components and all electronics. Usually a minimum of 12". No wires, or any metals (like a steel pushrod) going from near the engine to near the other wiring/batteries/receiver/servos/antennas/etc. The ignition would have its own battery and switch way up front, and everything else way far back, This includes the throttle servo, that would use a long nylon pushrod.
Modern system are much better at noise reduction, and so one rarely needs to be that extreme. If your cap and plug are right, and there are still issues, work on separating things as much as you can, and see if you can find a configuration that eliminates it.
An IBEC (made by Tech-Aero) optically isolates a power line from the battery to the ignition, allowing one to have a kill switch and use the normal flight pack, eliminating the separate ignition battery. There are other similar products, but results are mixed - for many they work fine, but some find they still conduct noise to the radio system. Tech-Aero is the gold standard.
Don't discount vibration/loose connections as the cause. Try swapping servo leads around and see if the jitter/problems change to different control surfaces.
I chased one problem for a year, and it turned out to be a bad power switch being intermittent due to vibration. But that affected all controls, not just one.
Still have issues? Start googling your radio system and see if there have been similar reports for the receiver(s) you are using. Or at least what receivers for your brand are most recommended for gas planes. Some from some companies may be great for electrics, but don't have the higher level of filtering needed to deal with all the RF noise put out by a gasser.
The first thing to check is the cap on connecting the ignition to the spark plug. Make sure it is tight, and fully seated. Some even put a small hose clamp around it to make sure it is tight. Also verify the exact brand of spark plug the ignition maker (not engine maker) designed the cap for. While the type of plug may be the same for different plug companies, according to the type code, the overall shape can vary, leading to a cap that doesn't fit quite right. Rcexl, for example, designs around a NGK plug. Their cap on a Champion plug of the same kind just doesn't fit right, and noise leaks out.
In the olden days, the watchword was complete separation between all engine components and all electronics. Usually a minimum of 12". No wires, or any metals (like a steel pushrod) going from near the engine to near the other wiring/batteries/receiver/servos/antennas/etc. The ignition would have its own battery and switch way up front, and everything else way far back, This includes the throttle servo, that would use a long nylon pushrod.
Modern system are much better at noise reduction, and so one rarely needs to be that extreme. If your cap and plug are right, and there are still issues, work on separating things as much as you can, and see if you can find a configuration that eliminates it.
An IBEC (made by Tech-Aero) optically isolates a power line from the battery to the ignition, allowing one to have a kill switch and use the normal flight pack, eliminating the separate ignition battery. There are other similar products, but results are mixed - for many they work fine, but some find they still conduct noise to the radio system. Tech-Aero is the gold standard.
Don't discount vibration/loose connections as the cause. Try swapping servo leads around and see if the jitter/problems change to different control surfaces.
I chased one problem for a year, and it turned out to be a bad power switch being intermittent due to vibration. But that affected all controls, not just one.
Still have issues? Start googling your radio system and see if there have been similar reports for the receiver(s) you are using. Or at least what receivers for your brand are most recommended for gas planes. Some from some companies may be great for electrics, but don't have the higher level of filtering needed to deal with all the RF noise put out by a gasser.
01-05-2022, 05:10 PM
#3
Yep, good answers; For the OP; the number one cause of electrical glitching on our models is loose sparks that should have gone to the sparkplug. If the cap is on the sparkplug tight, make sure that lead from the control module to the sparkplug is in good shape, no nicks, abrasions or cuts from things like holes it goes through the cowling, If that is good, this is a very good time to try bypassing the on/off switch as mention, by hooking it up to a battery directly. I got a bad shaking/rough engine and a friend told me to bypass that switch and that was the issue as mentioned. I also found a fiber optic kill switch which had gone bad.
Checking the servo lead connections is up next if the vibrations are still there. I'd disconnect all the servos from the rx and start by plugging them back in one at a time starting with the throttle of course.This will allow you to check each servo and by removing the lead from the rx and then replacing it, that movement will help to clean the contact surfaces of any minor corrosion that occasionally develops.
Most of the time, it'll be that sparkplug connection. Good luck.
Checking the servo lead connections is up next if the vibrations are still there. I'd disconnect all the servos from the rx and start by plugging them back in one at a time starting with the throttle of course.This will allow you to check each servo and by removing the lead from the rx and then replacing it, that movement will help to clean the contact surfaces of any minor corrosion that occasionally develops.
Most of the time, it'll be that sparkplug connection. Good luck.
