REFLECTOR: Re: REFLECTOR Competition

[Greg Poole]

Boy what a competitive lot of builders we have ...IVO vs MT vs Catto, Mags
vs electronic ignition, Lyco power vs Sub vs GM vs rotary.... seems
everybody needs to back their own MO!  Sure makes it interesting for us
fence sitters!

I am also on the BearHawk list (nice place but an entirely different mission
capability/role and a '60's look) and one of the plan builders there was
really letting loose on glass planes by saying how glad he was to be flying
low and slow and using this as the basis for reasoning that this was the
reason he would live a much longer and safer life based on the accident
records of fast glass such as Lancairs etc.  I pointed out the lack of
objectivity in his analysis and reasoning but he could not be swayed. Seems
we glass plane builders are far more ready to fly through cloud and storms
trying to outrun the weather to get home first than they that fly STOL
types. Didn't occur to him that with a bit more speed, we probably can give
storm cells a wider berth and get landed and in the hangar than those
bumping along at 120kts.

To each his own I say....trouble is I love so many mission capabilities that
I want one of every type!

....I'll finish my Velocity first though!

Best,

Greg.



----- Original Message ----- 
From: "Alex Balic" <alex157 at direcway.com>
To: <Jim_Agnew_2 at yahoo.com>; "Velocity Aircraft Owners and Builders list"
<reflector at tvbf.org>
Sent: Sunday, July 18, 2004 2:37 PM
Subject: RE: REFLECTOR: new electronic ign.


> Jim-
> That is exactly why mags are used on racing engines, because at high RPM
> they generate a ton of power, more than an electronic unit can... problem
is
> at 2500 rpm, they are pretty weak. I am interested that yours can throw a
1"
> spark - I don't have my formula handy, but at sea level, dry air, I would
> think that it would require several thousand volts- do they use a
capacitor
> in the high altitude units? I though that they were just better insulated
to
> prevent internal arcing at altitude..... I suppose that if there is enough
> spring tension on that impulse coupler that it could simulate momentarily,
> several thousand RPM though........ I have been a grounding source for a
> magneto in the past, it wasn't a fun experience that I want to repeat, but
> once again, it happened when the coupler tripped, and the speed could have
> been pretty high....
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Jim Agnew
> Sent: Saturday, July 17, 2004 9:11 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: RE: REFLECTOR: new electronic ign.
>
>
> Scott,
>
> I have Bendix high altitude mags on my IO-360 and if you
> turn the prop by hand the impulse coupled mag will throw a
> 3/4-1" spark so I doubt if .035" would bother them.
>
> On AA Fuel dragsters the cylinders are filled with an
> almost liquid mixture and they use mags to fire it!! and at
> 10K+ RPM.  The problem with mags is their lack of automatic
> spark advance that gives the electronic ignitions an
> advantage.  They solved this in cars in the 40s so this
> isn't exactly a new development.
>
> BTW it is said that the mags on those dragsters at top RPMs
> produce a spark of 42 AMPS so if you think that mags have a
> weak spark at high rpms you are wrong.  The mag output is
> weak at low rpms and increases as rpms increase.
>
> Jim
>
> --- Scott Derrick <scott at tnstaafl.net> wrote:
> > WHile there may be mags with a good spark, you won't find
> > one on an
> > airplane.   THe spark is absolutly lousy.
> >
> > I gap the plugs on my one slick mag at 18, I gap my plugs
> > on my lightspeed
> > at 35.  Hmmm.. WHy?  Reason is the mags are so weak any
> > larger gap will
> > just arc across the points in the mag instead of the
> > plug.  The lightspeed
> > on the other hand has a very hot spark that can jum the
> > 35 gap with ease.
> >
> > I can run my engine on one mag and loose, minimum 25%
> > power, closer to
> > 35%, I can run on the lightspeed and loose at the most
> > 10%, probably
> > closer to 5%.
> >
> > WHen I do a mag check I drop 75 rpm when running on the
> > mag, I drop less
> > than 10 rpm when shutting the mag off.
> >
> > Mags suck in all respects except one, they don't need any
> > external power.
> >
> > Mags fail all the time and have very short lives. The TBF
> > for a well
> > designd EI is longer than the life of the plane.
> >
> > Scott
> >
> > > Mags do not have a lousy spark. They need two spark
> > plugs per cylinder
> > > because it is too big to combust properly with only one
> > ignition point,
> > > especially a 540. And you need two ignition units
> > because anything can
> > > and will eventually fail. Electronic units fail
> > instantly instead of
> > > running rough like an old style mag.  bg
> > >
> > > -----Original Message-----
> > > From: reflector-bounces at tvbf.org
> > [mailto:reflector-bounces at tvbf.org] On
> > > Behalf Of Scott Derrick
> > > Sent: Saturday, July 17, 2004 10:15 AM
> > > To: Velocity Aircraft Owners and Builders list
> > > Subject: Re: REFLECTOR: new electronic ign.
> > >
> > >> Try and remember: you do not have two mags because
> > they give better
> > >> ignition that way - they give lousy ignition the day
> > you install them,
> > >> and go downhill from there. You have two mags because
> > one of them is
> > >> *certain* to fail. One electronic unit provides better
> > ignition (saves
> > > a
> > >
> > > While I agree that mags are much more failure prone
> > than an EI and that
> > > one of the reasons for two is redundency in case of
> > failure.
> > >
> > > Mags have a lousy spark and you will not get full power
> > with just one.
> > > two are required.  Even with EI's two plugs will
> > provide a more complete
> > > burn and more power than one.
> > >
> > > Scott
> > >
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>
> =====
> James F. Agnew
> Jim_Agnew_2 at Yahoo.Com
> Tampa, FL
> Velocity 173 Elite Aircraft Completed & Flying
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