simple analog fuel injection comments from CSH, HQ

garfield at pilgrimhouse.com garfield at pilgrimhouse.com
Wed Jun 24 23:22:31 GMT 1998


On Wed, 24 Jun 1998 04:17:34 +0000, xxalexx at ix.netcom.com wrote:

>> Besides, in airplanes, we tend to wanna stay away from computers. Too
>> many cases of the dog biting it's master, ifyaknowadamean.

>I have a bro at M-D- Boeing in F15 flight simulation, I will see
>what they use for airline computers, I sure hope I feel better about 
>flying.   I got my A&P in 75, from Parks, in Cahokia,ILL  we had a 
>lot of surplus WWII radial fuel injection type carbs.

Well, the art by now is well-perfected in the big birds, but for the
eXperimentals that try to use normal auto ECMs with NO backup or
redundancy, you're just twirlin the cylinder and snappin the trigger,
Russian-like. There are static phenom that occur in the air, not to
mention lightnin EMPs causing all the cpus to freak. When you're in the
air, things are DIFFERENT than when you're on the ground, as far as what
kinda glitch exposure you're able to tolerate. And since an airplane
cain't "limp home" on 35-50HP like a car can, "limp home mode" takes on
an altogether new meaning when contemplating using a stock programmed
ECM in an airplane. It's more like, if you end up in "limp home mode",
that's the state your body's gonna be in when you finally get home. Heh.
Hence XA's accent on fully dual-redundant, dirt simple controllers for
BOTH IGN & EFI. Another example of how just a slightly different mission
statement can alter your implementation enormously.

There IS a newer form of CIS FI that's sold by Air Flow Performance, but
it's essentially a mechanically coupled MAF to metering device. Hence
it's "new" to aviation, but passe' to automotive. B)  So it's more like
a giant leap into the "near past", instead of landing in Flintstone land
with the rest of the stuff. But not exactly current technology, by any
means. A TREMENDOUS technology gap exists between certificated General
Aviation engine technology, both in the engine proper, as well as the
induction & ignition systems. And it's in this fertile delta wide open
spaces gap that we XA engine experimenters play, where we can apply the
latest in EFI injectors & drivers, and yet pass on the baroque computers
and opt for the raw simplicity of a straightforward fuel delivery
equation, and spend our energy and time perfecting something that you
can't kill even if you take a pair of wire cutters to it and "cut once
anywhere" (the concept that no "single point of failure" can defeat the
system).

>Is there a newer system than old Continental? Most likely general
>aviation has not changed in 23 yrs?

Oddly enough, both the Bendix and Continental are still in use, and NO,
to my knowledge nuthin newer has been introduced in GA. [I mentioned
above the one single "innovation" in the XA arena]. Remember 23yrs is
nothing in General Aviation; we're talkin "glacial time constants"
there.

Anyway, as in ANY interdisciplinary domain, lots to learn from either
side of the fence.

Gar




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