[Diy_efi] fuel injection for an airplane engine

[William Shurvinton]

I have been resisting on this topic, mainly due to a lack of knowledge about
what is needed for a 'safe' aircraft, but here goes, feet first

The issue is being able to do a thorough FMEA on the system and to gather
requirements for what is needed.

The FMEA bit usually drive redundant systems (heading into an area where I
am getting dangerous, although my high availability analysis is limited to
telecomms which is not considered life critical). For example, if you have 4
cylinders then 2 ECUs can be used, each driving 2 cylinders, so if one fails
you are still in the air. Dual pumps, dual sensors etc, are all possible
depending on what is needed.

Where is gets interesting is the requirements. Aircraft, if i have it
correctly have about 3 operating modes

1. Idle on the ground
2. Take off and climb (max welly)
3. Cruise (max BSFC)

All of which in a fairly narrow operating RPM range. A stock ECU is well OTT
for this. The simpler the better. Where it gets hazy for me is the mixture
knob which most aviation FI systems still seem to have. Is this because
pilots don't trust ECUs or is it because more inputs are needed than the ECU
is aware of to make these decisions. Possibly a bit of both.

Anyway, if having a mixture control is considered a good thing it would
point to a very simple ECU design, not dissimilar to the old Bosch
LE-jetronic with minimum HW to handle the 3 operating modes. From what I
know of the GM ECMs you could strip that down to a minimum map, but without
exorcising all the redundant code it might be iffy. Ideally you want
something based on one of the newer MCU with a TPU chip (or an external chip
doing the same) such that once running steady state you could put a nail
through the CPU and it would keep going until told otherwise.

Interesting area.

Bill
----- Original Message -----
From: Bruce <nacelp at bright.net>
To: <Diy_efi at diy-efi.org>
Sent: Monday, May 27, 2002 7:37 PM
Subject: Re: [Diy_efi] fuel injection for an airplane engine


>
> ----- Original Message -----
> From: "Brian Michalk" <michalk at awpi.com>
> > The SDS has the simpler of the two with batch firing, plus they are not
> > afraid of aircraft.
>
> And, this is is from what?,
> The litagation from the families of those that depart this world.   While
> you might take responsibility, which is fine, too often the families take
> the lose as more then the risk taker figures, and then sue the
manufacturer.
>   Designing a Aero EFI sounds interesting, using a car based system
sounds,
> like a problem waiting to happen in my book.   Two totally different
design
> specs..  You need more then a limp home mode for aero use in an aircraft,
> IMO.
>   What might be slick in a car, maybe fatal in the air.
> Bruce



_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi