Henry Nee came up with a great idea. If we standardize on a spreed sheet
format for
the mixture map we can share (even across programs). Yours and mine.
This is the megasquirt format.
It is broken down into 8 RPM's and 8 manifold pressures.
Usually EFI programmers interpolate between these values.
Keven, Please do this. It will help other people greatly.
The idea is to be able to dump the table to a PC through the USB and edit
it in the
PC as necessary. Then reload it back into the chip.
This is how it is done in Megasquirt.
These are median values so they can go down to zero and up to 255 as
necessary.
They are also a function of the injector used. If you find that the values
are all on
the high side you could go up on the injection pressure or use larger
injectors.
Same vice versa.
Tracy uses two staged injectors per rotor so there could be one table for
each
injector. The tables only require 65 bytes of flash memory each.
I am using one computer per rotor.
Paul Lamar
Paul,
You said earlier that the rotary typically uses a fixed 22 deg BTC firing
arrangement with both plugs firing simultaneously- are the turbo guys using
this setting as well?
Normally when using higher boost levels, the timing is retarded several
degrees as boost pressure increases. I was thinking that my timing table
would have a few more lines than standard to allow for this. As pressures
go above standard i.e. 31 inches, the timing would progressively be
retarded. I have read in more than one place that using as little as 8 psi
of boost in racing engines requires the timing to be retarded to as little
as 5 degrees BTC. At 8000 RPM this doesn't give much time to burn the
fuel/air charge, but this setting is selected to prevent pre-ignition.
Any thoughts?
Kevin Alderman
As far as I know they do. They may retard. Are you doing a turbo? It has
it's
advantages if one plug goes out.
Well what ever you do keep the ign and inj tables the same so others can
use them.
I am going to keep it simple and let the CAS fire the 2nd gen ignition
directly.
If the computer fails the engine will still run using a small tube into
the intake
with a needle valve from a header tank. Worked for the wright brothers :)
"The Wright Brothers 1903 aircraft piston engine fuel flowed through a
small metal
fuel line from the high mounted tank to the engine. The fuel dripped into
a flat,
enclosed pan that sits on the top of the engine. The floor of the pan was
hot because
it sat over the hot engine cylinders. Air was drawn into the pan through
the air
intake, because of the action of the pistons. The combination of air being
drawn over
the fuel and the heat of the floor of the pan caused the gasoline to
evaporate."
"The fuel flow to the engine was adjusted while the aircraft was waiting
on the
launch rail. When the engine was running as fast and smooth as possible
the aircraft
was ready for launch. The pilot had a control lever which was connected to
a cut-off
valve to stop the engine at the end of the flight. The brothers had no
throttle or
engine control during the 1903 flights. The Wright "carburetor" and intake
system had
no moving parts. Without the moving parts, the brothers engine ran at just
one speed
throughout the flights of 1903."
http://www.rotaryeng.net/simple-cheap-555.html
Klaus set that up recently and he found it works much to his surprise. No
carb no
nothing, nada :)
Paul Lamar
I was planning to add another sensor to the factory CAS, 90 degrees from
the first. Separate boards will read each signal and fire each rotor-
similar to what you are doing. I have 3 boards- identical except the third
is equipped specifically to output to Android software. The third board is
even bluetooth capable, so I dont even have to use usb if I dont want to.
The OEM CAS turns half engine speed. It has 2 tits on top, and 24 teeth on
bottom. The sync signal will be firing signal for rotor 1, and RPM will be
read from the 12 tooth count off of the bottom wheel. Count to 12, start
over. See how long it took. Do it again.
The third board is capable of running both rotors if need be, and can be
programmed to read all of the same inputs and give the same outputs as
board 1 and 2, again redundancy. The switching might be interesting to
design, but one step at a time.
The programming for each board will essentially be the same, it is just a
matter of switching over the units in the air when everything else is going
wrong.
Paul, after you get your boards going, you could port them to the board
that I have and read them on any android tablet. I am going to work on the
EFI part first, and then port the output to the Android board so that I can
read it on my tablet. After I get it working, I can send the code and info
to the group so that any of us can do it. If I can get it to work, this
board could be wired to read the output of Tracys computer and log
everything to a tablet that we can use while we fly to see what is going
on. Everything that Tracys computer is reading, as well as everything it is
saying to the engine too. If my system works as planned, I will be able to
use the touch screen (in calm air!) to alter the engine while I am flying.
Kevin Alderman
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