<snip
This works in theory but not in practice because of the latency (delay
between the leading edge of the pulse and the beginning of fuel
flow) of
the injectors. In order to get even distribution from one firing cycle
to the next, there would need to be at least 3 pulses per firing cycle
at the highest rpm. The injectors can't work that fast.  I am planning
to use the spark trigger as the start of the injection cycle, as
injector timing is not critical. At low rpm this is not optimum, but
is
works fine for higher rpm. Using one sensor for each injector/spark
plug
gives four independent ignition/injection systems for a two-rotor.
If a
sensor fails, it takes out only the related injector/plug. Turn the
mixture full rich and the rotor with the failed sensor runs lean but
still produces power, and the other rotor runs rich. Good for limp-
home.

To Craig Taylor - I'm not an engineer, just a guy who spent 45 years
working on airplanes and longer than that on electronics. I used to
tell
my technicians that a technician only need to know what direction a
change would go, but an engineer could tell you how far. In that
regard,
could you tell us the minimum time constant needed for a simple RC
filter to provide feedback to the inverting input of the op amp as
depicted in the schematic for the leaning system for operation from
1500
to 7500 rpm?

Victor Roberts

Victor -

1) I agree that you cannot achieve 3 pulses per firing cycle at our
RPMs.  Injectors require ~1ms to open, after which actual fuel starts
to flow.  Each pulse "wastes" ~1ms just to open and close.  Here's
some quick math:
2000RPM = 30ms/rev
4000RPM = 15ms/rev
6000RPM = 10ms/rev
7500RPM = 8ms/rev
You can see that at 6000-7500 RPM there's no time for more than one
pulse.

2) I agree that injector timing is not critical.  Hence my recent
proposal to keep the Simple 555 Timer ... simple.  Use a fixed pulse
FREQUENCY, and allow the MAF/555 to generate the required DUTY CYCLE.
I called this the IOT (Inject-Over-Time) scheme.

3) The problem with IPR (Inject-Per-Revolution) schemes is that they
de-simplify the "Simple 555 Timer Fuel Injection".  The MAF sensor and
555 Timer vary the pulse DUTY CYCLE to match fuel to air.  If you
start varying the pulse TIMING with RPM, then you have to start
compensating the pulse ON/OFF TIME with some RPM feedback mechanism,
just to keep the DUTY CYCLE accurate.  Otherwise you are messing up
the actual duty cycle.

4) To do this in the analog world would require a phase locked loop
and sawtooth waveform generator.  The easiest way I can think of to do
this is to go digital.
- Crank angle wheel sensor controls PWM counter
- Convert MAF sensor voltage to digital number
- Compare MAF number to PWM counter and inject accordingly
In PWM systems, pulse FREQUENCY doesn't matter (except at the
extremes) - it's the DUTY CYCLE that counts.  Remember this.

5) If a sensor fails and causes a lean condition, you just might spit
out an apex seal.  I am NOT an expert on the rotary's tolerance for
lean running, but the stories are out there about detonation
fracturing apex seals, caused by lean A/F ratios.  Then again, Tracy
told me that he can lean out his RV-Otter until the engine quits, and
it fires right back up when he reverses the mixture.  YMMV.

-Vince Orton

That is turbo charged engines. The NA just quits around 20:1.

Paul Lamar