Nine for mechanical and fourteen for PICAXE.
Several are building PICAXE systems and only Hurant Karribian is building
a
mechanical system as far as I know. Since I have considerable experience
building real time computer systems both hardware and software it is no
real
challenge for me. Been there done that for 25 years. Instead I opt for the
mechanical system. More interesting from my point of view.
I have some advice for those developing PICAXE systems. KEEP IT SIMPLE.
Trade cheap computer hardware for software whenever possible. Hardware is
getting cheaper and cheaper while software is getting more and more
expensive in terms of labor cost. This cuts the cost of low volume
computer systems in terms of time to develop. This does not apply
to mass produced in huge quantity cell phones of course.
Use one PICAXE per function whenever possible. For example; use one
PICAXE to control the mixture and another to send data to a small
paper back book sized computer for the cockpit display.
The mixture control code is greatly simplified. Load the
mass air flow sensor A to D. Goto the table address indicated.
Read the table value and store it in the PWM fuel pump location.
Go back and do it again.
****** Errors and bugs in software are proportional to the number of lines
****** of code CUBED.
This also leads to hardware redundancy. If one computer fails
your entire system is not down. Another example. Use a separate $10 PICAXE
for each rotor mixture control. You only need one or two analog to digital
converters for controlling the mixture. That translates to a cheaper
PICAXE with
fewer input output pins.
Don't bother measuring the intake manifold pressure. It is less sensitive
at WOT than a mass air flow sensor. That is one reason mass air flow
sensors
are universally used on car EFI systems these days. Manifold pressure can
be all
over the lot at wide open throttle and is a function of WHEN you measure
it.
Particularly when a slide throttle is used mounted close to the rotor
housings.
If an upstream plenum located pressure sensor is used to measure intake
manifold
pressure with one throttle upstream of the sensor manifold pressure
sensors work
better but still not good at WOT. This is what Tracy is doing on his side
intake
port manifold systems.
The mass airflow sensor automatically measures intake air temperature so
a separate intake air temp sensor is not needed saving one analog to
digital
converter in the computer. AND the time and code to read and process
the information for that matter.
****** REMEMBER Errors and bugs in software are proportional to the number
of
****** lines of code CUBED.
I highly recommend trying pules width modulation of the fuel pump instead
of using traditional timed fuel injection. Timed fuel injection does not
work at 7000 RPM anyway so it is over kill for a rotary aircraft engine.
You must have a fuel pump in any system but you don't need expensive
individual
solenoid operated fuel injectors. Control the pump to send only the amount
of fuel needed. This greatly simplifies the plumbing and eliminates the
fuel pressure regulator and return flow lines and valves.
I'll be here to answer any questions and help in any way I can.
Paul Lamar ...No rotor no motor.
When I first saw this poll for Picaxe controlled injection I thought about
how we had went from machining passages in the Teflon slide, to needle
valves, to Mikuni carbs then back to fuel injection. I thought we were
looking for a simpler solution trying to eliminate dependency on
electronics. But then it occurred to me that every thing that was tried in
the past was not the ideal or suitable for application to the P port. So I
guess the goal is finding the simplest system for the P port for fuel
delivery. If electronic control is necessary I think the Picaxe is
something that a majority of builders can master. I have been playing with
a Picaxe reading a temp probe that I pulled off of a 13B and have had
encouraging results. Do I want to stake my life on it? Not quite yet but I
need to learn more. The code is really easy to download so we could
standardize the software.
Joe Berki
Limo EZ
Please upload your code Joe so people can see what it looks like
and get a feel for it.
I am still working on the mechanical slide idea with a ramp instead of holes.
Paul Lamar
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