REFLECTOR: It's been really quiet this week

Tue Feb 18 14:42:35 CST 2014

Brian,

For some unknown reason, when the plugs are changed from massive to Iridium
fine wire,
the CHT seams to increase quite a bit. Running my Franklin engine over the
last six years in Florida ,
I never had high CHT problems until I changed to the fine wire plugs. At
John's suggestion, I reduced
my advance from 28 degrees to 25 degrees and the temps returned to what I
saw before the change.
Ironically, the engine seems to develop slightly more power and run much
smoother.

Mike W.

On Tue, Feb 18, 2014 at 1:59 PM, Laurence Coen <lwcoen at hotmail.com> wrote:

>  Brian,
>
> 7 GPH sounds like you are running at best power which can be spelled
> "detonation".  The factory CHT spec is for bayonet temp not gasket temp.
> If your bayonet temp is good you're trying to solve a non existent problem.
>
> Larry Coen
> N136LC
>
>  *From:* Brian Michalk <michalk at awpi.com>
> *Sent:* Tuesday, February 18, 2014 9:43 AM
> *To:* Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> *Subject:* Re: REFLECTOR: It's been really quiet this week
>
> Hmm, I am a proponent of reducing timing to lower CHT's, and have my mag
> and EI set to 28BTDC, advancing to 32BTDC above 2600 RPM.  The book value
> is 28-32 degrees.
>
> I will retard it some more and we'll see what happens.
>
> On the EI, I am running NGK Iridium IX plugs, with a fairly shallow
> reach.  I don't have the exact rating available at the moment.
>
> I am seeing conflicting data.  My gasket thermocouples are reading redline
> temps on takeoff, but the bayonet thermocouples are reading cool.  Do you
> know what could be causing this?
>
> On 2/18/2014 8:51 AM, John Dibble wrote:
>
> On 2/17/2014 11:44 AM, Brian Michalk wrote:
>
> I've been flight testing.  It's a slow process for me, since my engine
> design while Franklin based, has EFI and EI.
> I have been battling high CHT's even in the cooler weather, and am seeing
> positive results as the engine breaks in.
>
> Sorry for repeating myself, but I really think you need to reduce the
> timing advance to 24-25 degrees.  My anecdotal experience has been that any
> departure from the mag/massive electrode combination increases the
> detonation tendency for the Franklin engine.  Further, multiple changes
> compound the problem.  When I bought my plane it had one mag and one EI,
> both using massive electrode plugs.  I experienced minor detonation
> symptoms such as an occasional plug fouled with metal and an occasional
> high CHT.  When I switched to auto plugs for the EI, the symptoms worsened
> with more frequent plug fouling, erosion of the electrode and an occasional
> engine stumble right after takeoff, a real attention getter.  When I
> switched the mag plugs to fine wire, the engine stumbling became more
> frequent and I had to replace a cylinder and piston due to severe pitting.
> I have eliminated the symptoms by reducing the timing advance.  I manually
> increase the EI advance once I'm above 9k for max power.  Maybe Mike W will
> comment also.
>
> John
>
>
> Specifically, I've been testing the forward CG limits, and have decided
> that my decision to move equipment as far forward as possible was a bad
> one.  I was intending to have Juanita be able to fly the airplane without
> ballast, but with my weight, I can't really carry much in the copilot
> seat.  I mounted a big Optima Red Top at a 15 inch arm location.  This
> weekend I relocated it temporarily to just forward of the whales tail, but
> for a permanent solution, I am looking at some of the really lightweight
> batteries that are out there, and am having a hard time making up my mind.
>
> Option 1: some lightweight lead/acid battery
> Option 2: an alternative chemistry
>
> For option 1, John mentioned the Braille batteries.  I looked online, and
> people seem to think that Braille is stretching their performance numbers,
> but if Velocity is using them, then that's a pretty good endorsement.
> There are also Odyssey batteries that look pretty good as well.
>
> Option 2 for me would be the new LiFe (Lithium Iron) batteries that are
> used in some motorcycles, snowmobiles and jet skis.  Those are all pretty
> high vibration environments, which was my first concern.  Next, they are
> really incredibly lightweight.
> Now, when these batteries reach 13 volts, they are basically dead, with
> 30% capacity remaining.  They are fully charged at 14.3 volts, and appear
> to take a charging voltage up to 15 volts.  For me, I'd need to convert my
> internal regulated alternator to external, and bump up the voltage to
> accommodate these new batteries.
> Another down side is, like the LiPo batteries, these need to have the
> cells balanced.  There is a special connector that ensures all of the cells
> are charged to their proper voltage, but balancing a battery doesn't have
> to be performed for every charge.  I also think that rather than charging
> through the balancing port, a person could use a hobby grade balancer that
> places a load on cells to draw down their voltage, achieving the same
> goal.  Bulk charge through the terminals, then balance by discharging
> excess capacity.
> And another downside is that they like to be stored at something like 80%
> capacity.  This may be fine for our needs.  As long as they can start the
> plane, they can be charged at high currents, so within a few minutes after
> starting they would be at 100%.
> Okay.  For one final upside:  The higher operating voltage will spin a
> prop faster, and will have smaller voltage drop in your cables.  I'm solid
> state switching, losing a couple of tenths of volts across each solid state
> relay.  This bump up in voltage would really be nice for my electric gyros,
> which are always complaining about low voltage until I bring up the engine
> RPM's.
>
> LFX19A4-BS12MSRP: $199.95 SHORAI LFX Lithium-ion Powersports battery,19AH
> 12V, "A" polarity, Case Type 4
> Length 5.83"
> Width 3.39"
> Height 3.46"
> Weight 2.32lbs
> CCA 285amps
>
> I would need two of those, which would put me at the lower end of my CCA
> requirements.
> www.shoraipower.com
>
>
>
>
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