Steve, I would say your interpretation of my message was bang-on. However to further clarify what I was saying about fuel flow indicators ... once you have "tuned" the EC2 using whatever method you chose, the only thing that changes external to the EC2 is injector pulse width.  So in theory if your MCT is a flat line you could plot the injector pulse width Vs rpm and come up with a graph very similar to what Ed and I have submitted for our MCTs.  These MCTs were derived manually using Mode 1-only after first setting the post-staged injector flow rate with Mode 3.  I'm not saying this is the best way but to me at the time it removed the "mystery" of what the EC2 was doing with Modes 6 and 2 and thus the MCT is itself a truer representation of fuel delivery.
BTW, nice software package you have made available at rotarycopilot.com ... I will at some point download it.
Jeff

From: "Steven W. Boese" <SBoese@uwyo.edu>
Subject: RE: [FlyRotary] Re: Engine Tuning
Date: Thu, 19 May 2011 09:30:53 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Jeff,

One way of reading the controller parameters is described in the following website:

www.rotarycopilot.com/

The software to do this can be downloaded from this site.  If you already have a computer, the only cost to do this is the voltage converter for the serial connection, the wiring to the controller which may already be installed, and the time invested.

There is some indication that this data is available from the EM2/3 display.  It may be in hexadecimal format but converting that to decimal would be straightforward.  I don't have an EM2/3 so I am not positive that this is the case.

I have been flying with a default (flat line at midrange zero) mixture correction table for some time now with good results.  The tuning was performed as you describe.  A default mixture correction table has also been used on my engine test stand with various combinations of different sized primary and secondary injectors giving equally good results.

The values for mode 3, mode 6, the mixture control, and the mixture correction table all appear to be used to calculate an injector pulse width for a given manifold pressure and appear to be independent and additive.

The value at a particular address in the mixture correction table is not a pulse width, but a value used along with the others to calculate the pulse width to be used.  I am not aware of a readout of the pulse width in use that is directly available from the EC or EM equipment and have assembled my own equipment for this purpose.

The pulse width itself tells nothing about fuel delivery.  When combined with the injector characteristics, however, it very accurately defines the fuel delivery.

The controller has no initial knowledge of what the injector characteristics are or if an injector is even connected to it.  This information is supplied by feedback from the person doing the tuning through the adjustments of the parameters mentioned.

In Brian's case, I'm just suggesting that the feedback may have produced parameters that result in long enough pulse widths to cause static injector operation at the RPM's he is capable of attaining.  That particular combination of parameters (and many others) would produce static injector operation regardless of what injector would be connected to the controller.  The use of larger injectors may not have resulted in feedback leading to that combination of parameters, of course.  I am not contending that this is actually happening, but that it is possible and easy to verify.

I agree that the best way to monitor fuel flow would be through the use of a fuel flow meter.  Preferably one based on a sensor such as a Floscan type which is independent of the rest of the fuel system, but unfortunately expensive.  In the end, the engine will tell the operator if it is happy or not and the operator would already know this before looking at the fuel flow meter.  The O2 sensor seems to be more useful in keeping the engine happy.

I hope I have interpreted your message correctly and my response is just my way of looking at things with no claim of absolute certainty.

Steve



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