RCGF Engines
07-23-2017, 06:33 PM
#6801
Glitchy ailerons and flaps in a hanger 9 super cub with RCGF 21cc twin. Near constant erratic movement of all 4 wing control surfaces. Oddly enough the Rudder and elevator servos are not affected. All servos are the same HS645MG's. Servo movement occurs even before engine starts, with ignition switch on, and motor turning over just using an electric starter causes the same erratic movement. Golden rod between throttle servo and carb. Ignition module and ignition battery are in the fuselage on each side of the fuel tank just behind the firewall. The receiver and receiver battery are located in the rear seat position, about 10-12 inches from the ignition module and ignition battery. I was using a physical switch between the ignition battery and ignition module but the issue persists even with the battery connected directly to the module.
Any ideas? Since servos are analog would digital servos be less susceptible to ignition noise? Are the long leads up and to the aileron and Flap servos a problem? 106" wing span.
Don
Any ideas? Since servos are analog would digital servos be less susceptible to ignition noise? Are the long leads up and to the aileron and Flap servos a problem? 106" wing span.
Don
Ailerons only.
07-23-2017, 06:37 PM
#6802
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I am certainly no gas expert but it seems that issues like yours can be a loose sparkplug cap . Dodgy extension leads ? Look on Fl-ing giants forums . Theres been lots of posts and answer to this very problem . Cheers
07-24-2017, 05:45 AM
#6808
I suggest that the ignition be disconnected from the power source, and the Rx be powered up. If the problem persists, it's not the ignition.
If the problem goes away, there is now a basis to work from.
07-24-2017, 10:04 AM
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Thank you all for the comments and suggestions. I will touch on each comment.
I'll post my findings after testing.
Don
- Plug Caps appear (and feel) to be seated, no hex nut plug base showing, and they appear to hit the top of the head.
- The servos all worked fine while flying the super cub with electric power (Rimfire 160) before changing over to the Gas Engine.
- The erratic movement of all 4 servos only occurs when the engine is rotating and the ignition on (either running on its own power, or when just turning over with an electric starter, but not running.
I'll post my findings after testing.
Don
07-24-2017, 12:02 PM
#6810
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Interesting discussion, I have a rcgf 15cc on a BTE Flying King 80" . About two weeks ago I had an issue at the field, out cruising around I was at full throttle the Flying King rolls over on it's back heads for ground. Pulled back on the throttle regained control came around and landed. Tied it down, ran it up to full throttle and wow, full deflection on the ailerons. I did a re-bind and checked all of the aileron connections and fired it back up. Everything worked, no issues, let it cool down, and ran it a least two more times on the ground. Went for spin around the patch everything went fine. Before this incident I had run about two gallons through this engine with no issues like this, I guess it was a bad aileron connection. Just kind of spooky after reading some of the previous posts.
07-24-2017, 12:34 PM
#6812
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Don
07-25-2017, 04:41 AM
#6814
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Just curious what size and brand servos are these??
I had a similar issue with Graupner mini servos on a 10 cc. Metal gear,digital and torque ratings was plenty for the application. The aileron servos started twitching on this plane after a few flights, with no issues at first when the engine was started. If I held the aileron the twitching would stop. Then they started twitching when the starter was used for the first start of the day engine not running yet. I didn't feel comfortable flying with them even though the elevator,rudder and throttle servo didn't do it. These were all the same servos including the ones in the ailerons.
I changed them all out to a different brand and larger size servos with no issues now.
If all else fails swap out the servos and see what happens.
I had a similar issue with Graupner mini servos on a 10 cc. Metal gear,digital and torque ratings was plenty for the application. The aileron servos started twitching on this plane after a few flights, with no issues at first when the engine was started. If I held the aileron the twitching would stop. Then they started twitching when the starter was used for the first start of the day engine not running yet. I didn't feel comfortable flying with them even though the elevator,rudder and throttle servo didn't do it. These were all the same servos including the ones in the ailerons.
I changed them all out to a different brand and larger size servos with no issues now.
If all else fails swap out the servos and see what happens.
07-25-2017, 06:08 PM
#6815
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Aileron and flap servo Glitching problem solved!
Aileron and flap servo Glitching problem solved!
Evidently The spark plug caps were not making good contact. At the suggestion of comments on this thread and the RCGF Rep I used small hose clamps to secure the base of the caps, and also inserted a section of a ball point pen spring (about five turns of the spring) on the head of the spark plug before pressing on the plug cap. I don't think the existing spring in the top of the cap was making contact with the spark plug, causing arcing and subsequent interference. The spark plugs and caps are of the 1/4-32 variety. Before this modification the flaps and ailerons were extremely glitchy, and after the mod they were rock solid. Thanks to the guys on this thread and to Joe at RCGF USA for the suggested fix. I would never have believed it would have been something that simple.
Don
Evidently The spark plug caps were not making good contact. At the suggestion of comments on this thread and the RCGF Rep I used small hose clamps to secure the base of the caps, and also inserted a section of a ball point pen spring (about five turns of the spring) on the head of the spark plug before pressing on the plug cap. I don't think the existing spring in the top of the cap was making contact with the spark plug, causing arcing and subsequent interference. The spark plugs and caps are of the 1/4-32 variety. Before this modification the flaps and ailerons were extremely glitchy, and after the mod they were rock solid. Thanks to the guys on this thread and to Joe at RCGF USA for the suggested fix. I would never have believed it would have been something that simple.
Don
08-10-2017, 02:20 AM
#6820
Based on a recommendation of one of our local gasoline engine experts, i have mixed a gallon of fuel with conventional oil at 32/1. My RCGF 20RE seems to really like that mixture. I will run a gallon or two of this mixture and then back to 40/1 Redline. Others starting out with synthetic oil in these engines may want to try this as well to get some break in time.
08-10-2017, 04:41 AM
#6823
The reason i have been running 40/1 Redline is that a retired racing go cart engine builder/friend of mine told me years ago when i first started flying gasoline that if i used that combination i would never have an oil related failure. I am always open to change for the better.
I can tell you that i saw the inside of an engine this year that the fellow had been running 32/1 conventional oil and it had a lot of carbon build up. I suspect that it is from running conventional oil too long after break in versus the ratio.
I can tell you that i saw the inside of an engine this year that the fellow had been running 32/1 conventional oil and it had a lot of carbon build up. I suspect that it is from running conventional oil too long after break in versus the ratio.
