The newer RCexcl ignitions are excellent value, well shielded, and make good replacements. That would solve your problems right away.

jetfixr,
My first gasoline engine-powered model (It was also a WH Edge) caused much grief at first also. On it the rudder servo was glitching a lot. And, at times, some or all of the others would glitch also. This was only with the engine running.
This airplane has a ZDZ 50 in it. The choke and throttle servos are both linked to the engine with metal pushrods using plastic clevises at the carburetor. The choke and throttle servos are inside the engine box, a few inches (two or three) behind the engine. The ignition box is mounted to the outside of the engine box, as is the ignition battery.
The radio in it is an FMA FS-8 receiver (with the lighted, external annunciator that indicates losses of the rf link from the transmitter to the receiver) with seven Hitec servos. The receiver is mounted to the aft side of the wing tube that runs through the fuselage.
I found three problems that were causing all of the glitching:
1. The engine had a non-resistor plug in it. When I found that I thought my problems were over. Not so. Changing to a resistor plug made no difference. Although, the resistor plug is still in the engine.
2. The switch in the ignition circuit was intermittently emitting rf noise. I found this by eliminating the switch from the circuit and running the engine. That switch was the source of most of the trouble.
3. Gasoline engines seem to vibrate a lot. ANY vibrating metal-to-metal contact will cause interference. You must be certain that every metal-to-metal contact point in the airframe is tight and not free to vibrate. As an aside to this, I have found that if the annunciator on the FS-8 ever indicates any loss of signal it means that something is vibrating in the airframe.. Also, as an aside, in this particular plane the bolts inserted from the inside of the fuselage to hold the wings on have a tendency to vibrate loose. They will do this regardless of the used of lock washers or how much force is used to tighten them.

Before the switch was determined to be the cause of the rf noise I looked at everything else. I had replaced servos, sequentially disconnected servos and linkages, tried different receivers...you name it! I had done everything but bypass the ignition switch! It was a tedious and discouraging process. However, now the airplane is fine to fly, nothing glitches in flight, and on the rare occasion that the receiver tells me there was an interruption to the signal I know to look for something loose. This is with a non-PCM 72 mHz receiver.

For me, the learning curve for gasoline-engined airplanes was very steep.

I certainly can not speak for other engines and ignition systems but, for this airplane, neither the proximity of the servos to the engine or ignition system nor the use of metal pushrods made one bit of difference to the behavior of the radio system.

Good luck with your airplane...the large ones really do fly better.

PS: This was being written while the previous two or three posts went up. If you have a leaky ignition system that would sure do it. That was my first thought when the problems surfaced in my Edge.

I agree with using a different pushrod material. Altavillan has you covered. Check out the Sullivan graphite pushrods from Tower.

These are 2-56 size. They work great. Nothing more is needed for a simple throttle pushrod. No load here. Very flexible, but stiff enough to do the job. Run your pushrod as straight as possible and make gentle curves. Use a piece of balsa or lite-ply as a brace every 6" or so.
http://www3.towerhobbies.com/cgi-bin...&I=LXFV43&P=SM

Here is the 4-40 size in case you want a little heavier. Keep in mind, it's not necessary unless you simply cannot get a 2-56 link on the carb throttle arm. The 4-40 isn't as flexible. Still recommend making gentle curves and a couple braces along the way. Keeps it from flexing.
http://www3.towerhobbies.com/cgi-bin...&I=LXFV45&P=SM

I think you accidentally installed an antenna by using the metal cable. It's a direct antenna to carry RF back to the throttle servo. Once you get feedback or interference in the throttle servo--it can travel back through the servo lead and interfere with the rest of the RX system.

10" may be just fine. I usually try and get 12", but I understand that it's just not possible all the time.

I think the graphite pushrod will solve your issues.

Read your thread twice just to see if I missed any thing, I agree with most every thing that has been said, but having a vary similar problem a coupla of years back, and when all was said and done it turned out to be the reciver (long story) sent it to radio south with a request for bad parts to be sent back and what it. got the reciver back with a note and a part called a front end cristal.

Just a thought Bob

Thanks for all the advice. I am definitely going to change out the throttle pushrod. Do you guys think that the lack of a ground wire on the sparkplug cap could cause anything? I will probably try and rig one up and run ti to see if anything changes. The sparkplug wire is metal shielded with a shielded cap, but there is no ground wire from the shielding to the engine case.

The shielding carries the ground.

Don't try to improve on the existing cap and shielded wire. It's great just the way it is.

Now that you hav 900 answers, go out and try one, and only one, thing at a time until you isolate the issue.

Got it. First step will be the push-rod. Thanks

Well, I started making a new push-rod for the throttle today. I started out by checking its resistance with a multi-meter, and found out that the carbon-fiber tubing that I have has the same resistance value as a steel rod. Zero resistance to electrical current. So, I am off to the LHS to get a plastic one.

Should asked. Most of us already knew that. It's also why you never stick a carbon lead pencil into a working Jacobs ladder. Did that as a kid once. Instant education about conductivity and what a high voltage electric shock can do. Superman wasn't the only human that could fly........

Could this be why carbon is used as the conductor in noise-suppressing spark plug wires?

Jetfixr,

Please keep us posted on your progress. Thanks.

I will definitely keep you posted. I am currently at work, but I may get to change it out when I get home tonight. I did however get the pushrod. While I was at the hobby shop, the owner was telling me about noise supressors. He said that with regular FM radio systems, they are a must. Has anyone had any experience with these. Do I need them?

You don't know if it's RF interference yet. It could be many things but try to do one at a time. And I see no reason to mask a bad situation.

Follow what has already been suggested in the thread. There is something wrong with the system and do them one at a time so you can see what went wrong. You shouldn't need any type of noise suppression. You just might be masking the problem temporarily. For example if it is RF noise, who is to say it couldn't get worse and overwhelm the suppressor while your flying....... Bill

I was thinking the exact same thing about the supressors. I didn't really want to use them. I was afraid that one could fail in flight. I will definitely try all the suggestions this weekend and see what I come up with.

Ok, I got the throttle linkage swapped out to a plastic one. It was a really easy switch. All I had to do was enlarge the holes I already had by one drill bit size and then just run the new one. I like it even better than the push-pull cable already anyway. It is more rigid. I will try it out tomorrow. I don't think the neighbors would appreciate me testing it now!

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You make an excellent point, altavillan.


Ed Cregger

It's fixed!! I ran it this morning after I had changed the throttle cable, and it ran perfectly. I then did some range checks, and they were perfect also. I then went out to the flying field and put a maiden flight on it. It was completely successful, except for the spark plug wire coming off of the spark plug in flight. I made an uneventful dead stick landing, and checked everything over. All good to go!! Thanks for all the great advice in this thread. I couldn't believe that cable made that much difference.

If your sparkplug wire was loose enough to fall off that was the source of RF. The ground is dependent on the plug cap and with no where to go it was looking for the next available path to release energy. That was the metal cable. Running without a ground can make the spark come out the Hall sensor which tends to shorten its life to near 0. You got lucky and I'm happy for your good fortune. We all need some good luck now and then.

What engine is that? Normally the cap fits very tightly to the plug body and will not vibrate loose. You may need to push the cap hard until it touchs the engine body.

Glad the glitch is gone.

HUUM, I usually have to put both feet on the cowl and pull with both hands to get my plug wires off. Me thinks yours was a little loose. The plug is the biggest RF noise maker you have.

The engine is a Peak 65cc. It runs great, but it may have the wrong spark plug. It fits somewhat tight, but not nearly as tight as what you guys have. I will have to figure out why it came off.

Post a pic. Maybe we can suggest a simple way to secure it.

Jetfixr,

Hey I got one of the Peak 65cc engines I haven't ran it yet still waiting for the good weather god to bless us here in St. Louis. The spark plug that comes with this engine has a head thats a little small, mine came with the rcxel ignition and it doesn't fit at all, I dont' even thing the plug is a resistor type either, I changed min out with one from the LHS that they had in stock its a torch plug. I'll let you know how it goes once I get it running...

Ok. I might have to look into that. I have replaced it already, but maybe it still isn't right. I tried really putting some pressure on it, and I think I got it on tighter. Then I put a really tight zip tie around the base of it where it flexes to go over the plug. It feels really tight now. I will have to run it to tell though. Did your engine come with the new style muffler, or the old style. How many outlet pipes does it have?