Since I'm now obligated to use a conventional aircraft engine, I'm already
working on an electonic fuel injection/ignition system (aka FADEC) to get
the  huge advantages of these systems.I think this discussion should be
taken up by the group to see if there's enough experience and knowledge out
there to give us an redundancy alternative. If you had these 3 items, it
could truly be equivalent to an a/c engine, and it just might increase the
safety/reliability of our engines.

Chuck Harbert

Bill Freeman wrote:

  Chuck,

   I disagree about the "huge advantages" of these systems.  For an engine that
runs at an essentially constant load for long periods (hours) a manually
adjusted
mixture used by a reasonably intelligent person can essentially equal what a
FADEC
can do as far as fuel consumption.  Witness the market failure of the Porsche
aircraft motor.  It weighed a bit more, used the same fuel and had more
installed drag
due to poor layout of the cooling air system.  The FADEC was very, very simple
to operate and very reliable but it burned the same fuel, went about 5-10
kts slower in
cruise and nobody wanted one.  I predict that FADECs will follow the
LAZAR ignition into the dustbin of history, primarily due to high cost with
little
advantage over the cheaper (YIKES - calling an aircraft part "cheaper"!!).
Aircraft
are VERY different from cars.   Cars have continuously varying load and speed
most of the time (not so much on the interstate in Kansas . . . .) and can
get big benefits
from computers adjusting the fuel and spark all the time.  A constant load
system has MUCH less benefit and the costs of redundant and certified
systems will be very high.  I'll predict you'll pay $4000-6000 *additional*
for a
FAA certified FADEC and get a 5% improvement in furl burn.

Homebuilt systems like Tracy's are great and work just fine.  The biggest
advantage that I see is the tunablility of the system and the availablilty at
a reasonable price due to using auto parts.

Of course, fuel injection is safe from carb icing, too.  I big advantage, but
"dumb" mechanical fuel injection systems like Continental's work
extremely well and are very reliable and can be hand leaned in cruise
to a gnat's whisker of optimum.  I have absolutely nothing against
electronic fuel injection systems, it is just that they aren't really a heck
of a lot better than a good carb or really stupid mechanical fuel
injection system with a slightly skilled user *when the load is constant*.

Bill

I am with you Bill. If you are going to do all that to an aircraft engine
you might as well stick with a rotary.

Paul Lamar
 
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