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After reading the literature from magnecor, I think I'll just go with their EMI suppressing leads, which I recieved in the mail yesterday. I just borrowed a smaller prop so I can achieve the higher RPMs on the ground, now to go ahead and start doing some testing on the ground. Everything else about the plane seems satisfactory- it flies and handles well on the ground and in the air, the engine cools well, I just need to figure out this misfiring thing before Igo up again.
Brian Trubee
-----Original Message-----
From: Tracy <rwstracy@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, Jul 9, 2011 12:03 pm
Subject: [FlyRotary] Re: sheilded plug wires
I tried shielding solid wire ignition leads on my first engine back in 1994. It caused the old 2nd gen coils to malfunction and miss badly for some reason. Didn't try it on other coils. The spiral wound wires are the way to go IMO. Never had a problem with ignition or radio noise since using them.
Tracy
On Sat, Jul 9, 2011 at 12:56 PM, Kelly Troyer <keltro@att.net> wrote:
Brian
Apparently the shield you are proposeing is not a good Idea..........The reason why is noted in the
"Magnacor" link in my previous post................
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: "bktrub@aol.com" <bktrub@aol.com>
Sent: Saturday, July 9, 2011 11:51 AM
Subject: [FlyRotary] Re: sheilded plug wires
Ok, theory is nice, I prefer to just think it is all magic. My apologies, but I am the product of our public school system : )
What I'd like to know is this- am I fabricating the wires correctly? I cut the insulation about 1/2 inch back from the inner conductor, and then crimp the terminal so that the conductor is folded back against the wire under the terminal crimp.
There is no outer braid or anything which actually grounds against the engine. I am thinking of putting an outer braid around the wires and then grounding that on one end.
Brian Trubee
-----Original Message-----
From: Charlie England < ceengland@bellsouth.net>
To: Rotary motors in aircraft < flyrotary@lancaironline.net>
Sent: Sat, Jul 9, 2011 9:11 am
Subject: [FlyRotary] Re: sheilded plug wires
To expand on that for the electron-challenged, an inductor is effectively a frequency dependent resistor. The higher the frequency, the higher the resistance. So, the fundamental pulse to the plug makes it through (though slowed slightly), while the harmonics (noise) that were generated can't get past the extra resistance presented to them.
The reverse is true for a capacitor. That's one of the reasons why you see capacitors with one leg tied to the power supply & the other to ground. The capacitor blocks DC but passes higher frequencies (the noise) to ground.
I have no doubt that the above will make physicists cringe, but it's close enough to working knowledge for us builders to use.
Charlie
On 07/09/2011 08:28 AM, Tracy wrote:
In this case "shielded" is the wrong term. The spiral wire does not actually shield the noise, it prevents the noise from being transmitted. It acts as an inductor to prevent the propagation of the noise generated at the spark gap from propagating up the wire.
Tracy
Sent from my iPad
It has to do with the resistance of the long thin Monel wire. An impedance mismatch and inductive reactance. What the mechanism is I do not know. That is why Tracy is here, to explain such matters.
Lynn E. Hanover
In a message dated 7/8/2011 11:08:09 P.M. Paraguay Standard Time, SBoese@uwyo.edu writes:
My last massage got a little garbled, the way I have my wires configured now, the conductor and spiral wrap are exposed and folded under the crimped teminal ends, so aren't both the conductor and the spiral wrap acting as a conductor? What is doing the shielding?
Brian Trubee
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