Gas engine electronis Questions

[Azhar]

Folks,

I am almost finish with my CA extra with a Taurus 52 engine. DUe to cg issues, I would like to move my servoes and batteries forward. I have notice in a lot of setups that the receiver electronics and engine electronics are almost side. I understand that this interference issues are not so much of a problem anymore. Is this true for all engines? Or is it only true for some?

My new setup will probably place the receiver batteries almost beside the ignition battery. ALso will be moving the receiver and throttle servo closer forwrd to (about 6-8 in from ignition electronics). Is this advisable?

Thanks

Azhar

[3DBatixkid]

Is it an electronic ignition? Putting the battery near the module is not always a bad thing, but the servo and receiver could be an issue. You might want to braid or twist the wires that are close to eachother just to try and keep the electronic noise down.

[aerografixs]

	Quote: Originally Posted by Azhar
	Folks, I am almost finish with my CA extra with a Taurus 52 engine. DUe to cg issues, I would like to move my servoes and batteries forward. I have notice in a lot of setups that the receiver electronics and engine electronics are almost side. I understand that this interference issues are not so much of a problem anymore. Is this true for all engines? Or is it only true for some? My new setup will probably place the receiver batteries almost beside the ignition battery. ALso will be moving the receiver and throttle servo closer forwrd to (about 6-8 in from ignition electronics). Is this advisable? Thanks Azhar

Try putting your ignition battery, along with ignition module as close to the engine as you can to keep the distance from your regular radio equipment.
Also, the ignition battery switch also should be away from the receiver, and don't rely on a PCM receiver, it will only mask the problem and not remove it.
Roger

[KrisW]

Oh HORSE POCKY!!!!!!!

If you are going to get interference from an ignition, your radio components can be in the TAIL and you will still get hits!!

Ideas: Move all your engine components as far forward as possible .. . having the receiver battery up by the ignition is NOT a problem (I've had my receiver packs withing 2-3" of the ignition for YEARS. . never a hit or problem). Shift your rudder servo forward as far as possible and use pull-pull.

comments: Keep your receivers near CG. You do not need them near the ends of the plane where they are inaccessible and can come loose in a violent maneuver, and they only weigh about an ounce anyway, so the weight shift is minimal. Spiral winding the servo wires helps stop RF degradation and feedback, but is not really necessary with FM or PCM systems. Do it if it makes you feel better. . it also looks very cool. Route your antenna toward the tail of the plane, and do a good range check with the engine both running and off. If there is any degradtion in radio performance with the engine running, fix the problem before ever flying the plane. If there is no degradation of range, then everything is fine, and the ignition is adequately shielded.

Hope this helps.

[Azhar]

Thanks guys,

i will move things forward and do the necessary radio check.

Azhar

[Kiwi]

Oh HORSE POCKY!!!!!!! Kris,

Its always a good bet to seperate your ignition system as far away as possible from your reciever or any item physically attached to it by wire.

The Taurus engine has excellent write ups and is very well built but it appears to have a CH ignition system on it. They too are great, in fact almost bullet proof. But they have a seperate earth wire to ground the ignition to the engine crankcase. That stops most, if not all stray ignition RF. But if it ever comes off or breaks or chaffs through your going to get all sorts of RF issues.

By having your system seperated as much as possible you will reduce the chance of shooting yourself down. Its just good practice, its a smart way to build your planes. And if you dont, one day it will bite you and you will likely never know why.

There are lots of ways to get your weight forward. Heavier spinners, move the engine forward a 1/4 inch. Spinner back plates dont need to rub on cowlings. Put your ignition pack up under the engine firewall, as far forward as possible.

The last possible resort is moving your rx forward. Battery packs an inch or two and its likely OK. Bunch your flight packs and ignition pack together and you signed the death warrant. It will get you.

Kiwi

[KrisW]

	Quote: Originally Posted by Kiwi
	Oh HORSE POCKY!!!!!!! Kris, Its always a good bet to seperate your ignition system as far away as possible from your reciever or any item physically attached to it by wire. The Taurus engine has excellent write ups and is very well built but it appears to have a CH ignition system on it. They too are great, in fact almost bullet proof. But they have a seperate earth wire to ground the ignition to the engine crankcase. That stops most, if not all stray ignition RF. But if it ever comes off or breaks or chaffs through your going to get all sorts of RF issues. By having your system seperated as much as possible you will reduce the chance of shooting yourself down. Its just good practice, its a smart way to build your planes. And if you dont, one day it will bite you and you will likely never know why. There are lots of ways to get your weight forward. Heavier spinners, move the engine forward a 1/4 inch. Spinner back plates dont need to rub on cowlings. Put your ignition pack up under the engine firewall, as far forward as possible. The last possible resort is moving your rx forward. Battery packs an inch or two and its likely OK. Bunch your flight packs and ignition pack together and you signed the death warrant. It will get you. Kiwi

Uh. . with all due respect, Kiwi. . you are wrong.

First off, I advised AGAINST moving the Receivers forward at all.

Secondly, the item in your radio setup LEAST likely to be affected by, and to transmit, RF interference is the BATTERY. Batteries act like big electrical shock absorbers, and effectively "absorb" spurious electrical pulses. It's like hitting a waterbed with a hammer. It just kind of sloughs off the pulse, wiggles a bit, and goes back to just sitting there.

Third. . its never the primary ignition pulse that causes interference, since the internal electronics of the ignition are all inside a shielded box, that has a grounded casing that carries a common ground with the engine itself, so any primary side pulsing problems are all shielded, as well as absorbed by the ignition battery itself.

Fourth. . . 99% of ignition interference comes from one source. . breaking down of the shielding and insulation inside the plug cap. The other 1% comes from a break-down of the conducting wire inside the plug wire itself, and is then allowed to escape by a bare spot in the shielded outer ground wrap. When you get interference from an ignition, you can pick it up on an AM radio as far as 100 yards away, and it's a HUGE blast of RF interference. You can have your receivers mounted in the tail, use twisted wires, optical isolators, in-line ceramic ferrite discs, and every other RF filter out there, but a leaking sparkplug cap will still give your receivers hell. It does not matter if the components are 2" or 20' away from the bad ignition component, they will be saturated with RF pulses.

Now, all that being said. . about 2 years ago I designed, and used, a battery system that totally removed a discrete ignition battery from the system. Instead, it took voltage from BOTH receiver packs, before it got to the regulators, and then fed a 5.1 volt regulator to the ignition itself. that's right. . no extra ignition battery. . all the electrons running from the receiver battery. I sent a schematic of the system to Fromeco and talked over the idea with Kurt. We actually discussed production of a stand alone system based on the design, but shelved the idea due to the rabid distrust many modellers would have for it . .simply because it provided power to the ignition as well as the receivers.

I flew that system for about 80 flights. . never a problem. . never a glitch. . never a hit or PCM lockout. Then my Extra landed in the Tree at Joe Nall, and when I repaired it 9 months later I put a "Standard" system in it, with a NiMH pack for the ignition.

So. . please .. Horse Pocky??

[RTK]

As long as your engine on/off radio check is with in 10% of each other and at proper distances I see no reason in not trying it. I have "broken" some of the cardinal rules and have not yet had any problems. (knock on wood) RX pack next to ign module, ign pack next to RX, servos next to all, etc.
I usually do not do this purposely, but sometimes..............

[Azhar]

I am actually going to try it and do the proper range check with and FM receiver. Will also go through the airplane to make sure there are no metal-to metal contact that could cause issues. thanks for all the advice guys.

Azhar