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Date: Wed, 18 May 2011 18:02:57 -0400
From: Ernest Christley <echristley@nc.rr.com>
Reply-To: echristley@att.net
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Reliably starting
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On 05/18/2011 05:21 PM, josrph berki wrote:
> Ernest,
> Will you be running Megasquirt for flight or is it a gound development 
> tool?  Do you have any words of wisdom for someone contemplating 
> Megasquirt?  I would really like to see an electronic analog injection 
> / ignition system developed.  Software that controls the engine scares 
> me.  Thanks for any help.
>

Analog injection/ignition systems scare me.  Well...not really.  All 
software systems are analog underneath.

I will be flying with the MegaSquirt, but I can throw it a lot further 
than I trust it.  But, that is ok.  The goal is do design the system so 
that it fails gracefully.  The MS gives an incredible amount of 
flexibility and configuration control.  It is REALLY nice to have.  So I 
take the benefits, but have backup(s).

If the MS quits on me for some reason one day, I have a 3/16" line 
plumbed to the throttle body with a needle valve sitting next to me in 
the cockpit.  I've already verified that on the ground, with gas barely 
covering the bottom of the tank, I get flow to the throttle body.  I'd 
probably never be able to get the engine started with this setup using 
the starter, but with the wind still spinning the prop I will be able to 
slowly open the valve till I can maintain altitude.  Then I can make for 
the longest runway I can find.

That's good for fuel, but what about spark?  I'm having the MegaSquirt 
control EDIS ignition control modules.  The EDIS handles  all the VR 
pickup, dwell and other such details.  These things have proven to be 
very solid performers during a decade of use.  All MS is doing is 
getting a tach signal from the EDIS, and sending back a signal to 
control advance.  Two wire interface.  If the EDIS looses communication 
with the MS, it falls back to its limp-home mode which is 10*BTDC.  I 
shifted the VR so that I actually get 25*.  But, that just shifts the 
critical failure from the MS to the EDIS.  I don't have it wired up yet, 
but eventually I will have two EDIS modules running, one on Leading and 
one on Trailing.  The second will have its own power source, driven by 
the distributor shaft.

Sure, power will degraded if all I have is the trailing plugs and I'm 
dumping fuel into the throttle body instead of a proper spray, but it 
isn't meant to be a normal mode of operation.  It is meant to get me 
past the crash site.  I don't have to be scared of the software, because 
I'm not hanging my life on it.

The only other advice I have is buy one of the MS3s.  They have a USB 
interface, and can datalog directly to a flash card.  I'm stuck with an 
MS2 for now.  Because of that, I have to use a 15yr old laptop, because 
it is the only one I have that has a serial port.

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    On 05/18/2011 05:21 PM, josrph berki wrote:
    <blockquote cite="mid:list-4987895@logan.com" type="cite">
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      <div><font face="Arial" size="2">Ernest,</font></div>
      <div>&nbsp;</div>
      <div><font face="Arial" size="2">Will you be running Megasquirt
          for flight or is it a gound development tool?&nbsp; Do you have any
          words of wisdom for someone contemplating Megasquirt?&nbsp; I would
          really like to see an electronic analog injection / ignition
          system developed.&nbsp; Software that controls the engine scares
          me.&nbsp; Thanks for any help.</font></div>
      <br>
    </blockquote>
    <br>
    Analog injection/ignition systems scare me.&nbsp; Well...not really.&nbsp; All
    software systems are analog underneath.<br>
    <br>
    I will be flying with the MegaSquirt, but I can throw it a lot
    further than I trust it.&nbsp; But, that is ok.&nbsp; The goal is do design
    the system so that it fails gracefully.&nbsp; The MS gives an incredible
    amount of flexibility and configuration control.&nbsp; It is REALLY nice
    to have.&nbsp; So I take the benefits, but have backup(s).&nbsp; <br>
    <br>
    If the MS quits on me for some reason one day, I have a 3/16" line
    plumbed to the throttle body with a needle valve sitting next to me
    in the cockpit.&nbsp; I've already verified that on the ground, with gas
    barely covering the bottom of the tank, I get flow to the throttle
    body.&nbsp; I'd probably never be able to get the engine started with
    this setup using the starter, but with the wind still spinning the
    prop I will be able to slowly open the valve till I can maintain
    altitude.&nbsp; Then I can make for the longest runway I can find.<br>
    <br>
    That's good for fuel, but what about spark?&nbsp; I'm having the
    MegaSquirt control EDIS ignition control modules.&nbsp; The EDIS handles&nbsp;
    all the VR pickup, dwell and other such details.&nbsp; These things have
    proven to be very solid performers during a decade of use.&nbsp; All MS
    is doing is getting a tach signal from the EDIS, and sending back a
    signal to control advance.&nbsp; Two wire interface.&nbsp; If the EDIS looses
    communication with the MS, it falls back to its limp-home mode which
    is 10*BTDC.&nbsp; I shifted the VR so that I actually get 25*.&nbsp; But, that
    just shifts the critical failure from the MS to the EDIS.&nbsp; I don't
    have it wired up yet, but eventually I will have two EDIS modules
    running, one on Leading and one on Trailing.&nbsp; The second will have
    its own power source, driven by the distributor shaft.&nbsp; <br>
    <br>
    Sure, power will degraded if all I have is the trailing plugs and
    I'm dumping fuel into the throttle body instead of a proper spray,
    but it isn't meant to be a normal mode of operation.&nbsp; It is meant to
    get me past the crash site.&nbsp; I don't have to be scared of the
    software, because I'm not hanging my life on it.<br>
    <br>
    The only other advice I have is buy one of the MS3s.&nbsp; They have a
    USB interface, and can datalog directly to a flash card.&nbsp; I'm stuck
    with an MS2 for now.&nbsp; Because of that, I have to use a 15yr old
    laptop, because it is the only one I have that has a serial port.<br>
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