Paul,

Ok here we go:) Your approach to the calculation is interesting but makes
the idea perform better than they actually will. We have to calculate
the needed flow during the optimal injection window and then choose the
injector and duty cycle to achieve it.

Several points need to be expanded on. We won$B!G(Bt be able to, nor desire
to, inject during the full 360 degree rotation of the e-shaft even
though a P-port is at least partially opened most of this time.  I agree
we have to begin injection on the backside of the rotor after the intake
port is open. I don`t understand your comment that the port is open 270
degree of the time though. Not for a P-port. The earliest we can
practically start the injection cycle is a few degrees after the intake
port is fully open and the injector port holes (same degree location as
the oil injection holes) are uncovered.  The latest, "stop-injection,"
timing moment would be when the apex seal closes the intake P-port.
Testing may show that the sweet spot is only a few degrees but we really
don`t have much leeway to explore for it much in the higher rpms. Lets
just say for calculation purposes the acceptable injection zone is about
200 degrees of e-shaft rotation.  It could be more though we still need
to give these bad boys some  time off for good behaviour and allow for
their response time. The  Deka IV turns on in 1.14 ms and off in .85 ms
so we have plenty of time before and after the injection window to
handle this response.

Yes, we aren$B!G(Bt direct injecting on the pressurized side of the rotor. We
are, however injecting directly into the intake chamber part of the
stroke through the housing and that will eliminate the challenge of fuel
bouncing off the manifold walls, and side ports,  and condensing into
bigger droplets.  Of course the proof of the pudding is how good these
injectors really are at providing a fine mist and what happens when that
mist hits a hot rotor and incoming air.  I am boosting 2psi so  the VE
goes up to 150%. This means that my fuel pressure will need to be
higher. At least 4 bar. Otherwise near the end of the intake sweep the
fuel pressure  is fighting against the manifold pressure and flow
suffers.

I think most injectors are rated at 80% duty cycle and that generally is
the max. recommended as they start to get warm at higher duty cycles.
This is not to say they can$B!G(Bt or aren$B!G(Bt driven harder though for short
durations. Three minutes TO power  before reducing to climb power should
be OK at 90%. duty cycles.

Because the rotor will be so near to the fuel injectors inlet, as the
apex seal passes by, we will need to shorten the injection timing window
near the beginning as well.

Ethanol evaporates faster than gasoline and cools the interior 100
degrees so that will be an advantage but the disadvantage is we need
more volume (cc) of it in most parts of the power ranges.

  Yes, 6000 RPM is 100 revs a second. or once every .01 seconds or 100 ms.
  If we follow your example and agree that the injector accomplishes the
squirting event once per e-shaft revolution then at 6000rpm we have 100
msecs divided by 360  of e-shaft rotation to do it.. Degrees/time  is
then .27 msecs time per degree of e-shaft rotation.   To repeat myself
let us just say out of those 360 degrees of e-shaft rotation only about
200 of them are optimal for $B!F(Bintake chamber' fuel injection.

  So now our injection time window of opportunity is down to 55.5 ms.
( .277 ms times 200 degrees = 55.5 ms)  Again on each side of this window
we still have 160 degrees or 44.4 ms to turn the injectors on and off.
We only need about 2ms for this job. The remainder of the time is for
rest.

Lets approach the problem from a flow perspective and calculate in mass
flow. Using the DEKA IV injectors as an example, at the full rating of
60 pounds gasoline per hour each, that is the equivalent of 453 grams
per minute. (See spec. sheet) At 18 pounds per hour that injector is
flowing our 3 gallons a minute as  selected for cruise flow. This in
only is only 1/3 as rated,  or 151 grams per minute,  2.51grams per sec,
and divide by one thousand   .00252 gms per ms.

Now again it requires 100 ms for 360 degrees e-shaft rotation, and we
know we need .00252 gms per ms.   So each injection volume required
during this event is 100ms X .00252 or 0.252 grams.

However our chosen injection duration window is only 200 degrees or only
55.5% of the time.  We therefore need to increase the mass flow from the
injector.  We can increase the injection  time window, the fuel
pressure, or duty cycle.  We rather not (at this point in the
discussion) touch the first two variables so that leaves increasing the
duty cycle.

Now I don`t have information on the duty cycle verses flow curve of these
injectors.  We  assume flow vis-a-vis duty cycle is linear.  It may not
be.

For calculation purposes we are at 1/3 flow or 18 lbs per hour, per
injector so that means (if a linear curve) 33.33% of the 80% rated duty
cycle. This gives us a duty cycle of 26.7% if my math is correct.
Increase this 55.5% to get the flow we need into our 200 degree window
of opportunity and duty cycle becomes  1.555 X 26.7% = 41.5% . No sweat.
  This gives us some manuevering room if we want to increase the flow
more and shorten the time duration. The challenge of course is as we go
up in rpms we have less and less time to inject more and more fuel.
Fuel injection effieciency perhaps drops off near the end of the window.

At idle speeds it is easy to imagine the consequences of injecting too
near to the over lap period.  Result.  Some raw fuel going into the
exhaust.

At 8,000 engine rpm on E-85 ethanol and making 300hp,  with 2psi boost
and  .7 BSFC it gets rather marginal but I$B!G(Bll leave that calculation
for your homework.  The advantage may be easier tuning as the injection
happens closer to where you want it.
.....
George and others. These are extremely rough calculations and my engine
as now planned will not have a tuned intake as it is slightly boosted.
How an injector or two in the housing plays out with tuned intakes
manifolds is beyond my understanding.  Either way it requires a boat
load of dyno time to make, understand and tweak a good map.  I am
assuming it won`t be easy and the sweet (best bsfc) injection timing
windows will move around depending on MAP, and rpm. Wouldn't it be nice
if the best burn efficiency could be dialed in to corresponded to the
least engine friction rpm?


Doug in Japan

It truly is open 270 degrees of E-shaft rotation. The rotor is
moving backwards at one third e-shaft speed :)
One of the reasons the clever Wankel engine breaths so well.
The piston engine intake is only open 90 degrees roughly.

I maintain you don't need a good map in a rotary.
It will run over a wide mixture range. 10:1 to 20:1
At constant RPM, constant prop load cruise you adjust it for the mixture you want.

It is also possible to run a piston engine with a sunk float in the carb.
In effect.... way over rich. You use the mixture control to keep the engine running
smoothly. I have done it. Sunk floats were common in 172's carbs  until the AD.

Klaus has run his engine with nothing more than a small pipe, gravity feeding
fuel from an aux tank, directly into the engine intake manifold. The same
as the Wright Brothers.

Of course we don't have a map in a 555 system. The fuel going into the engine
is directly proportional to the air and the RPM. The mass airflow sensor
adjusts the basic pulse width up and down. The main parameter or primary control is RPM.
No computer to program or map. Not required. Far easier to trouble shoot and
maintain. What you see is what you get. No mysterious computer program to deal
with.

-------------------------------------------------------

I think I made a serious mistake here.
6000 RPM is 100 revolutions per second.
There fore the time it takes to make one rev
is .01 seconds. That is only 10 msecs.
So the max width of the pulse is less than 10 msec.
The 13 msec it takes the fuel to get to the end of the 2' runner
is 13 msec at 150 FPS. There is indeed potential overlap. Best to inject
the fuel closer to the P-port. Say half way down the runner.

I had to make a change to my schematic for the crank angle
simulator to widen the trigger pulse. The original would not
trigger the 555 reliably. Here is the new schematic. The input
cap was changed from .005 uf to .05 uf
-- 
Paul Lamar ...No rotor no motor.

Paul,
My preliminary calculations suggest 30 millisec for each rotor face at 360
degrees of crank rotation and for 200 degrees it's 16.6 milliseconds.
However the speed of the inlet air to carry the fuel is also a factor.

Proof:
6,000 rpm / 60 sec =100 revs per sec (we all agree).
There are 3 rotor faces for each rev ( 100 / 3 = 33.33 rotor faces per sec).
1,000 ms/33.33 = 30 millisec ( per rotor face).
30 ms/ 360 deg = .083 ms per degree
.083 x 200 = 16.6 millisec.
If I am wrong can you suggest where I went wrong.

BTW for 180 degrees it's 15 millisec. Would you both settle for 180 degrees
as the most suitable allowing for 10 degrees each side of the event for
variances.
George (down under)

The rotor is backing up at one third the speed of the e-shaft so there are not
3 rotor faces per e-shaft revolution.