REFLECTOR: dual Plasma IIIs

Fri Aug 5 09:38:57 CDT 2011

I just went though the mags on our Cherokee, we put them on new but I couldn't remember how many hours they had. It was getting hard to start but the mag drop was well within spec. The points were pitted badly and the capacitors were very weak and the internal timing was way off. I checked the logs and it was 525 hours since they were installed. I think the manufacturer has a log more engineering expertise than I do so I tend to adhere to their recommendations.

Best regards,
Nick

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Scott Derrick
Sent: Friday, August 05, 2011 9:45 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: dual Plasma IIIs

I don't know about 500 hours..

Mags are known to work very reliably for a couple thousand hours between overhauls.  Most folks replace during engine overhauls.

Scott

-------- Original Message --------
Subject: Re: REFLECTOR: dual Plasma IIIs
From: Jones Nick <nick.jones at volvo.com><mailto:nick.jones at volvo.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org><mailto:reflector at tvbf.org>
Date: 08/05/2011 06:56 AM

Let's not forget the mags need maintenance too. Slick recommends 500 hour overhaul or replacement. You don't want your mag's performance to be marginal when you need it.

Best regards,

Nick and Connie Jones
Velocity XL-RG
N10CN
99% done 90% to go

From: reflector-bounces at tvbf.org<mailto:reflector-bounces at tvbf.org> [mailto:reflector-bounces at tvbf.org] On Behalf Of Scott Derrick
Sent: Thursday, August 04, 2011 5:20 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: dual Plasma IIIs

I've been running single Plasm and a Mag for 650 hours total on an IO360 and IO520.  I haven't had a Plasma failure but I still like two independent systems and one that will still run even if the battery falls out of the airplane.

I also didn't want the added complexity of dealing with electrical failure.  Klaus says you can get 5% better performance with duals vs single, but I question that number..

My Slick mag may have been initially designed when  dinosaur's were still roaming the earth,  but there is something to say about their proven dependability.

Scott

-------- Original Message --------
Subject: REFLECTOR: dual Plasma IIIs
From: Douglas Holub <douglas.holub at gmail.com><mailto:douglas.holub at gmail.com>
To: reflector at tvbf.org<mailto:reflector at tvbf.org>
Date: 08/04/2011 03:00 PM

One of my Plasma III boxes failed while flying to Tennessee from Texas last summer. After a post-mortem, Klaus couldn't explain why it failed. The box was the same one that was DOA when it was new, and was then subsequently repaired by Klaus. At that time he said he found a loose wire in the box, so I suspect that the flopping wire did some undetectable damage which eventually caused the box to fail while we were flying.

So today I'm replacing that electronic ignition with a Slick magneto, and I am amazed how much complexity it removes from my wiring. With only one electronic ignition I don't need: 1. The auxilliary back-up battery, 2. The auxilliary back-up battery charging circuit, 3. The circuit that detects and indicates the fault condition that causes the auxilliary battery to provide power (so I know when the back-up battery is being used), 4. The circuit that lets you know when one Plasma III is working while the other one isn't.

The reason you need #4 is because the ignitions are so good, there is often no perceptible RPM drop when one of them fails. And that's why I wish I had used one Plasma III and one magneto from the beginning. I thought I would get better performance with two Plasma IIIs, but if there is no RPM drop, I don't think the second one is helping much.

I my engine has 14mm spark plug holes on top and bottom, so that's a little problem switching to a magneto wiring harness. But I found some shielded automotive spark plug adapters from Great Plains, the VW conversion people.

Doug Holub

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