REFLECTOR: It's been really quiet this week

[John Dibble]

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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