Last year a finshed up an old G Shark MKII that had been sitting around for quite a while.

The motor is a Quadra 42 CD. Two batteries and switches each battery sits alongside the fuel tank just ahead of the landing gear. THe switches are the MPI heavy duty and mounted just ahead of the canopy one on each side of the plane. The throttle servo sits just behind the carb mounted such that a short rod runs from the servo output wheel to a nylon arm on the throttle butterfly.

I got a few flights in on the plane now and I'm gettting some sort of glitching. In an effort to isolate the cause I've done the following.

Moved the receiver 10" further back in the plane...

Re routed the antenna twice.. first mounting out the bottom, second out the side to an H. Stab tip and finally out the top just behind the canopy to the tail

Switched receivers and crystals

removed the wing removing 2 long servo leads to ailerons

individually disconnected each servo from the receivers not including throttle

Removed the dubro pull pull rudder cable (plastic coated metal).

Verified that all the linkages and tail wires (kevlar) are tight and lock tighted along with all the servo arms etc..

I'm left with about 3 things I can think of to sort this out:

Disconnect the throttle servo... Coming up with another linkage to make geometery work given the arm orientation is gonna be tough.

Move the batteries further back...

Replace the ignition module etc..

Anyone else have suggestions?

Thanks

CHris

hello
i knew someone that had a simular problem turned out to be the shield on the sparkplug wire ,he bought a new moduel and the same thing happened it turned out that was bad also ,it abouy drove him nuts ! make sure its a resister type plug if it is try changing it also you never know ? anyway thats my two cents worth good luck!
stan

Sounds as though it was fine for a few flights and then started to act up? Is it only glitching with the engine running and at what speed? Are all the servos glitching? A little more info might be helpful.

I'll try a different plug.

Its glitchy when you get about 35 yards from the plane with the antenna down.

Rudder and throttle seem to be the most impacted although I've seen glitches on all the controls. It seems to be most prevalent at lower RPMs.

I'm really thrown for a loop on this one. I've never had a problem with gas engines and this sort of thing before.

Thanks

Chris

could it be the connetor inside the cap on the plug wire? It it were not snug metal to metal?

Well, that's 105 feet which is about normal. Does the glitching stop if you extent the antenna?
It doesn't really sound ignition related if it's mostly at lower rpm's. The plane is gonna shake the most at lower rpm's, maybe some component is being affected by it. I'm assuming the range check is OK with engine off?

It definitely happens with the aerial all the way out.... Last time I flew it it went into a 90 degree bank on final... Made for a little bit more challenging landing but no damage.

I'll check the plug again.

Today I'm going to switch plugs and see what happens when I unplug the remaining variables... throttle, elevator servos, batteries..

Chris

switched plugs

disconnected batteries and used a battery further back in the plane

disconnected the throttle servo

Still no luck. My earlier estimate of the distance was incorrect its 22 yards. This is nose on with the antenna down.

So is it time for a new ignition?

THanks

Chris

I made a call to B&B and got lucky.... They were answering the phone.

They recommended I try two things, first make sure the pick up and magnets weren't rubbing. That wasn't the issue.

THe second thing they had me do was wrap a couple layers of tin foil around the plug wire and cap and then run a tab off that tin foil to the head.

I got 70 paces before I quit walking with no appreciable interference so it looks like my CDI and wire and plug boot have issues.

THanks for all the help folks

Chris

Chris,
I have been going through the same thing so I know your pain. I got an ignition tester from C+H and I am going to do some range checks with it to determine if it is ignition or vibration related. Since yours started after several flights it may be something as simple as a metal clevis vibrating on the threaded rod, I had the jam nut back off one of these and it reduced my range dramatically. I also have a small glitch that occasionally makes the plane drop a wing hard to one side. If it happens again I will try and remember which way it goes and then switch the aileron servos and see if it goes the other way. I know that is a risky way of determining the problem but it is very intermitant.

I also may send in my ignition and let them look it over but I think it's a servo, lead problem. One other question, are you using a reversing "Y" on your elevator?

No I'm running seperate elevator servos on each half.

I've also checked and rechecked all the jam nuts. All still in place and the lock tite is holding as well.

Chris

take a look at the cristal inside your reciver, a few years ago I had the same problem and the change of the crystal solve the problem

i was having the radio prob with a ryobi 31cc couldnt get 15 ft away the put the foil on it and it worked great so i went abd pur armour sheiled wires on it you can get the braided wire at most parts houses that carry hi performance parts

I solved this by taking the shielding out of a coax cable encasing the high tension lead then grounded the coax to the case.

Thanks

Chris

How did you get it over the plug wire with coil on one end and plug boot on the other? Last plug wire I tried to replace ended in failure as it was not screwed into the coil. Sodered then the epoxy case was poured. Hindsight[]

I had the same worries. The guy from B&B gave me a bunch of advice on how to do it. Basically you push the coil that encases the plug head out the plug boot and then remove that coil. Then I could pull the plug boot and slide the shielding over the high tension lead. When I had it done I put heat shrink over the now shielded plug line and then reassembled it.... Reversed what was done above and then shrunk the heat shrink.

It turned out to be a lot easier than I expected.

Chris

the sheilding will expand to a point if you push it together i did not worry about the coil the wire was my leak and the only thing i found was critical was be sure to ground the sheild