Ailerons twiching on idle
 

The Ailerons are moving eratically about 1/2 inch up and down when the engine is on idle only, it was doing the same thing with the previous owner, the ignition switch was in the cockpit togather with the batt switch, now those two switches are for batts and I installed a switch for the ignition by the cowl, the previous owner remembered the problem and we disconnected the ignition switch and did a direct batt to ignition module to test, it worked good, no more twiching of any kind.

My questions are, what's going on here? and will an optical kill switch fix that problem.

I'm new to gas but not new to the hobby, I'm trying to learnas much as I can ragarding the proper use and trobleshutting on gas engines and systems.

Thank you for your replies.


http://www.rcuniverse.com/forum/atta...mentid=1998577

Carlos, having the ignition switch next to the RC switch is not a good arrangement. You are probably getting radio frequency interference from the ignition module coupling right in to the receiver because those switches are close together. They should be separated as much as possible. An ignition kill switch will not cure your problem. Here is some advice from Futaba that you should always follow. Dan.


Guidelines for setting up gasoline engine models.
All ignition equipment, including an electronic kill switch, must be mounted at least 12", and preferably 14", away from all radio equipment, including throttle servos, etc. Ignition kill switch should always be on opposite side of fuselage from radio kill switch. All pushrods going to anything related to the engine must be non-conductive (just nonmetal clevises is not sufficient).

Hi Dan

Thank you for your reply, here are some pics of the set up on the Gee Bee, please feel free to make any comentes, that is what I'm looking to get from this thread to learn some more regarding gas installs,

As you can see the batt switches are about 15 inches or more away from the ignition ( they are in the cockpit ) the throttle pushroad is metal, the choke pushroad is metal .


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The olny time that we get the twiching is when idleling and when using the ingnition switch, bypassing the ignition switch cures the twiching.

Thanks

Carlos, a lot of guys are getting away with metal pushrods to the engine and having their throttle and choke servos very close by. It’s not the best way to do it but you can not argue with success. One of these days it may catch up with you. You said that relocating the ignition switch solved the problem. Be sure to do a very thorough ground check before you fly. Post some images of the receiver and servo area. I’ll try to upload some of mine. Dan.http://www.rcuniverse.com/forum/atta...mentid=1998627http://www.rcuniverse.com/forum/atta...mentid=1998628http://www.rcuniverse.com/forum/atta...mentid=1998629http://www.rcuniverse.com/forum/atta...mentid=1998630http://www.rcuniverse.com/forum/atta...mentid=1998631http://www.rcuniverse.com/forum/atta...mentid=1998632

The install that you see was done by the previous owner, by posting here i'm trying to learn from modelers like you what works and what should be avoided regarding installs.

I'm one of those that has flown many times and many diferent airplanes,so I'm in no hurry ( even if it is my first gasser ) to go flying, this airplane is not going to fly 'till I know more about installs and why some installs don't work, success the first time is my goal.

I sure apreciate your time and help, please keep it coming.

One of the first things I'm going to do is move the throttle servo back with the rudder servo that will increase the distance of the servo by two times the distance from the ignition, change the pushroad to nylon/plastic, second I'm thinking of eliminating the choke servo and go manua, that way I can use that channel for the optical kill switch,

What do you think?

Carlos, this is not an exact science. Any improvement will help. Moving the servo away from the engine and switching to a non-conductive pushrod is an improvement. Take some images of the rest of your installation similar to the ones I have posted. It would help to see how your receiver is mounted especially the antennas. Which radio are you using? Dan.

I understand, I will take some pictures and post them tonight, got to get ready to go to work tonight. At the moment it has a Spektrum AR7000 ( 7ch ) with the 6iX spektrum radio, I'm planing to switch it to my Futaba 10CAP 2.4 with a 7ch receiver this way I will have two channels for the Ail and Ele plus the Rudd, thro and kill switch ( kill switch is on the way, Rcexl v 2.0 )

I prefer the Futaba radio to fly this airplane

Carlos, I have used metal pushrods for throttle and choke with the servos mounted at the bottom of the motor box without issue. In your pictures, the one thing that I did not like is one of the plug wires directly on top of a battery. I also do not use ignition kill switches because of the multiple times I have read about them causing issues. For the most part, being able to shut the engine down via either throttle, choke or external power switch has been enough. I have progressed closer to the 21st century and on my latest airplane have a Tech Aero IBEC installed so I can shut the engine down electronically. IMO your original problem is that the ignition switch was emitting some noise that your aileron extensions were picking up on. RF is a very funny thing and not always something that we could have foreseen. This is why for most practical reasons it's best to follow the rule of keeping everything ignition related and RX related separated as far as you can.

Just my opinion from previous experience and the solution found on the gas engine forum. You can either have a defective IG module or the spark plug cap is not seated properly. In my situation I replaced the IG module and that cured the problem.

Carlos, those images I sent you are for the installation of a Futaba 8 channel receiver that I use with a 10CAG transmitter. Notice that I have the two antennas enclosed in some inner Sullivan rod pushrods well away from anything metallic and anything large like the tank. Dan.

Try this before you go moving a lot of stuff around using out dated information.

Thank you all for the advice, I got home very late last night so no pictures 'till today around 7pm, I will be reporting on the changes and if that fixed the problem.

Question, do I keep the ignition switch after I install the opt kill switch?

Thank you

Yes.

The sequence is battery, ignition switch, kill switch and then the ignition module. Dan.

Got it Dan.
Here are few pictures, not much in there.


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Carlos, that installation looks nice and basic. Make sure the receiver antennas are well away from any wires, especially the ones carrying any current. The foam wrapped objects are batteries, I assume. If one of them is the ignition battery, move it as far forward as possible. Don’t leave it there. Post another image when you get the Futaba receiver in. Where are the aileron servo wires? Dan.

I'm assuming that the Y connector is for the ailerons? Using separate leads into CH 1 and Ch 6 then using the dual aileron function in your TX may just end up fixing the twitch. I have found that some setups with long leads do not like Y connectors.

Thats a much better idea than moving stuff around because 99.9 percent, thats not what is causing your issue

Thank you all

The previous owner experience the twitching with the Aileron on separate channels, the ignition batt was on top of the ignition box and he had the radio and ignition switches in the cockpit the way you see them right now.

I moved the ignition batt to the side of the engine box, added another switch for the ignition right by the ignition batt just behind the cowl and use both switches that are in the cockpit as radio batts switches.

When we run it a few days ago he disconnected the ignition switch because the Ailerons were twitching just the way they were when he had it running about two years ago with the switches set up as stated above.

In conclusion we are having the same problem with different installs, I supposed I will have to make more changes to the install to see what fixes it.

Carlos, it looks like you have an older BME twin there with a CH ignition that has braided ground straps that attach to the cylinders. Those grounds have to be good. Try hitting the connection with an OHM meter and see what resistance you have. Do you have resistor plugs in the engine? Maybe a newer ignition with shielded wires and caps would be a consideration? I agree with Andy that I can't ever say I have seen an ignition interfere with a 2.4 GHZ system but if the RF noise has enough power behind it the servo leads can pick up on it. If you think about it, any wire with some length can act as an antenna. One easy thing you can try is to twist the aileron extensions and see if that has any effect. This will somewhat shield the signal lead although I would not consider that an actual fix.

I just remember that my friend said that the engine was flying a Spitfire before, he has not mention having any kind of wlitches with the Spitfire, so if the Spitfire run good with this engine and now the Gee Bee has wlitches with the same engine I'm leaning towards the install of the components in the Gee Bee.

As we can see in the pictures there isn't much to move in there, I'm thinking I will move the ignition batt next to the ignition box to move it away from the spark plug cable, the throttle servo will move back 5 inches for a total of 13 inches away from the firewall and will change the metal push rod to plastic, will check the spark plug booths and ground cables, will remove the choke servo and change the push rod to plastic plus add the throttle kill that I order and is home by now and change the AR7000 Spektrum for my 7ch Futaba.

Ok, time to get busy.

Speed

I totaly agree the Ailerons extentions could be picking up a signal from the ignition, so I'm going to try to eliminate that bridge with the changes.

Thank you all for your suggestions and will keep you posted.

Carlos-
Make sure your spark plugs are in tight. Have seen a loose plug cause this problem.