Message-ID: <3AF4E21E.B45A6202@progress.com>
Date: Sun, 06 May 2001 01:33:18 -0400
From: Marcelo Pacheco <pacheco@progress.com>
Organization: PROGRESS Software Professional Services
MIME-Version: 1.0
To: lancair.list@olsusa.com
Subject: Re: transition: ROP to LOP
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Reply-To: lancair.list@olsusa.com

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Hope I won't offend anybody by taking a stab at questions directed at George...

>1.  Do you think that the FADEC that will be forthcoming shortly for the IO-550
>will be programmed to be as aggressive and allow running LOP for this normally
>aspirated engine?
By adjusting each combustion event to the perfect spark timing point, a few
improvements are acomplished:

1 - When you're taking of with full power, the right amount of fuel can be used
to deliver the maximum amount of power while avoiding any detonation. Less fuel
is more power on the rich side of peak, so FADEC can lean the mixture just
enough to prevent detonation. As you lift off and speed up, the engine gets more
cooling, which could allow for leaner mixtures right there. Adjustments to the
spark point will also prevent excessive heat while maintaing maximum power
possible.

2 - When flying at reduced power and higher airspeed (more engine cooling)
cruise settings, FADEC should run the engine lean of peak, adjusting the spark
timing for best fuel consumption. Now this will heavily depend on what kind of
baseline engine this will be used upon. If TCM's FADEC is tuned for poor fuel
distribution injectors they ship right out of the factory, it might be limited
to running the engine rich of peak. Are you aware that GAMI is developing their
own FADEC ? I don't have details (I have heard about it from John Deakin's
articles), but a FADEC system that expects well tuned GAMIjectors will be able
to deliver better engine performance than a FADEC system that can't rely on
almost perfect fuel distribution.

3 - An advanced FADEC system would be able to perform full time lean of peak
operations, where it could run the engine at full power lean of peak (but very
close to peak), until temps get high enough to warrant switching (on the very
next combustion cycle) to rich of peak. This could allow a well baffled engine
to run lean of peak almost all the time, while allowing FADEC to compensate for
cooling deficiencies with a power loss.

>2. So far the discussion seems to be centered on engines that appear to be
>mostly sparked by mags. How would an electronic ignition, such as Klaus
>Savier's, improve the operation and affect horsepower & efficiency? This
>question is directed at a normally aspirated IO-550 to be installed on the ES.

Electronic ignition improves the power of the spark, causing a more immediate
combustion, which enables a little further delay in the spark, helping both
reduce temps and increase power output.


Those are just thoughts based on what I leaned from engines on the web, so
definitely George's more knowledgeable reply would be much better.

Marcelo Pacheco
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