rideon67

My Feedback: (1)

Finally got the nerve to fly the Byron Christen Eagle w/ 3.7 Sachs electronic conversion. Range check without engine is OK but with engine running I got a couple of small glitches on the ground going away from and coming toward me. Distance didn't seem to make much difference. Being born stupid and without patience I reasoned that they were so insignificant that flying would be ok. Did I say stupid? There is no insignificant glitch when landing. Prop and some other fixable Small damage but that old plane flew GREAT, so all in all a good day.

These glitches have got to go before the plane flys again and I'm not sure where to start looking. Rear Stabilizer Flying wires are metal clevis on metal tab with fuel tubing over clevis at the connection point to keep from rattling. They are tight enough to always have tension and the tubing seems to keep them in place. Should the metal clevis be replaced with nylon or is this setup common on giants? No other metal to metal contact and the pull pull cables are routed inside plastic tubes to keep them separated.

The receiver is 23" from the firewall and the antenna is routed back thru the fuselage rear inside a plastic tube. The antenna does go thru the elev & rudder pull/pull cables which also are inside the fuse. The antenna does not run thru servo leads. The circuit board for the ignition is mounted inside the firewall, and the spark box part of the ignition is mounted outside the firewall. The sparkplug wire is as it came with the ignition with rubber outside. Should I put some additional shielding on the ignition wires and sparkplug wire? If so, what would that be? Where else should I look for possible sources?
Thanks for the help.

GreaTOne_65

Howdy, rideon, having just read your post, I am some what familiar with your airplane, as I have had 2 of the Byron Pitts Specials. From what you discribe, the one thing you could try easily is route the antenna outside the fuse. I've had that work a number of times. You are absolutely right about the glitches, no glitch is a good glitch, no matter how small.

That thing must be a beast with a 3.7 on it!! I used a Quadra 42 on both of the ones I had.


Good Luck

Dale

sillyness

My Feedback: (25)

The metal on metal vibration may not be the problem... but then again it may.


If you have metal rods connected to metal straps that are bolted through the stabs with metal screws, then you formed a continuous loop of metal... sort of like an antennae or a gaussian cage... not sure which way it acts, but it's not good.

Don't use a plastic clevis... it will break.

Go to your LHS and look for some plastic landing gear straps... just like the metal ones but obviously made of a different material. You only need to use them on one set of connections to break the contiuous metal loop. Simply bolt a plastic strap to one of the metal ons already installed on the stab. Then connect the metal clevis to the other side of the plastic strap... you will need to shorted your flying wire by the length of the metal strap.

Hope this helps.

Also... make sure that your ignition components are well shielded.

CK1

My Feedback: (60)

I have been flying Byron CEII's for years with the same tailwire setup you have on all of mine with no interference concerns . The foam doesnt transfer the
frequencies like it does in built up planes . I would look elsewhere for your glitch source .
Check all servo leads for wear , pin fit , be sure the leads are heavy enough .
Definitely route the antenna outside of the fuse .
be sure to seperate Ign and rec. batts and switches as far away from each other as possible
Use nyrod for throttle cable , do not use a metal clevis on the throttle ,engine vibration and a metal throttle clevis can cause interference regardless of the foam
fuse.

bodywerks

My Feedback: (4)

What receiver are you using and is it PCM and is it new or previusly flown in a different plane? I recommend PCM and I recommend having it checked out if it has been previously used. Gas engines bring out the gremlins in your radio system, so it better be perfect.

mglavin

My Feedback: (31)

Check the sparkplug for an "R" in the part number, R denoting a resistor type plug.

As long as the ignition wire is shielded additional shielding is not required. Verify that the shield is grounded, once at the plug end (either to the plug or the engine) and once again to the spark-box housing. NO additional grounds are required and in fact create a resonate loop.

What brand ignition? Separate components as noted are uncommon.

Do not use a PCM RX to fly the model until you have eliminated the source of interference. A PCM RX may ignore the problem and allow you to fly, but on the hand the interference is still present and may bite you later.

rideon67

My Feedback: (1)

To all responders......thanks for the help. Altho it may not be the culprit, at this point nothing is being ruled out. I modified a piece of plastic to use as the connecting strap on the fuse bottom for the rear stap flying wires. Don't want any passengers named Gauss on this flight (a well know terrorist). Antenna now comes out fuse bottom right next to the Rx (standard Futaba R127 FM type which has been used in another plane without problem --glow not gas.

Ignition batt & switch are near firewall & Rx batt & switch are at least 20" away. The glitches have included motor, elev, and I think aileron from the way the plane reacts. All the servos are new (Hitec & Futaba) and extensions were soldered. The Y-connectors and connectors have been double and triple checked & feel solidly connected. There's a bunch of wires with all the servos needed (12), but from the way the glitches always seem to happen at about the same place on the field it seems more like RF interference rather than leads or metal to metal vibrating.

Spark plug is Champion RCJ8 and the ignition was installed by Charlie Minton at Air Hobbies. I don't know what shielding is needed on this ignition system -- I'm using is as it came. The sparkplug cable is all outside the firewall and does not appear to have a grounding shield. The spark box is a sealed unit with two wires coming from the printed circuit board inside the firewall and the sparkplug wire. No place to ground anything -- it's held on to the outside of the firewall by zip ties.

As soon as the new prop gets to the LHS we'll make a trip to the field to see if the external antenna and/or plastic flying wire strap have run off the glitch gremlins.

Anybody else got other ideas?

bodywerks

My Feedback: (4)

The shielding he speaks of is that braided wire-looking wrap around the ignition lead. I have yet to see an ignition that didn't have that - yours should, too. Also, it cannot be damaged in any way and should be isolated such that it doesn't rub against anything.
Mglavin is right, you can use FM and it will reveal any interference to your system in a hurry, but I strongly recommend flying with PCM. Why, you ask? If you get all your problems fixed and everything is all hunkydory for a few months, you may forget to check the integrity of certain things, like the ignition wire shielding. On one flight, it could start or could have started rubbing against something to the point that it damages its shielding ability. If your flying FM, the plane goes down and all is lost. If it were PCM, you would be able to continue flying and would notice it in your post-flight checks - you do those, right?