On Mon, 4 Jun 2007 20:12:47 -0500
"Bill Schertz" <wschertz@comcast.net> wrote:

>
> ----- Original Message -----
> From: "Bob White" <rlwhite@comcast.net>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Monday, June 04, 2007 5:50 PM
> Subject: [FlyRotary] EC2 operations, was Re: Houston, we have a problem...
>
>
> > On Mon, 4 Jun 2007 15:11:53 -0800
> > "Al Gietzen" <ALVentures@cox.net> wrote:
> >
> >> Tracy does some magic stuff with that EC2.  With a V8 there are always
> >> two injector firing at once.  As best I can understand it, the fuel is
> >> squirted in sort of whenever and the engine sucks it in when it needs
> >> it.  So for a 20B, he uses 3 signals for the injectors and one for the
> >> staging relay which applies power to the secondaries.
> >>
> >> Bob W.
> >>
> >> Unfortunately, taking that approach on the 20B version lead to a
> >> back-door
> >> circuit to the secondary through the primary, allowing about 1/2 voltage
> >> pulses to the injectors that are turned off.  It's going to take some
> >> diodes
> >> in the injector circuit to cut that off.  Haven't installed those yet.
> >>
> >> Al
> >>
> >
> > Hmmm, I wonder if that has anything to do with the fact that when I
> > disable the primary injectors the EM2 RPM reading doubles.  I expected
> > it to go to zero.  It reads fine with the secondaries disabled.  This
> > is on a 13B of course.  Eventually I would have put a scope on it but
> > now I'll let the next guy do it. :)
> >
> > Bob W.
> >---------------------------------
> This has high relevance/interest for me! I have been test running the
> engine, and to get it to run smoothly, I need to remove power (disable) the
> primary injectors. When primary's are on, the engine runs much too rich. I
> noticed the RPM seemed awfully high, so we got a prop tach, and discovered,
> as Bob mentions above, that the EM-2 Tachometer is reading 2x the actual
> RPM!!  I switch to primaries and it reads correctly.
>
> I ran for ~40 minutes at ~ 3500 RPM, and the OIL PAN temperature reached 200
> F, the OIL Temp at the filter reached~170 and pretty much stabilized, and
> coolant temp was between 170 and 190F.  This was all on running on the
> secondaries only, with periodic attempts to run on the primary's, terminated
> as the engine bogged down rich.
>
> During this run, on the seconaries, the EGT's were 1500 and 1400
> respectively. Whenever I would turn onthe primaries in addition to the
> secondaries, the EGT's would drop, indicating too rich (down to 900 F).
>
> A second run was made, where I tried to force it to run on the primaries,
> using mode 3 to reduce injector flow rate. Multiple pushes on the store
> button brought the mixture down somewhat, but the EGT spread was 1300 on one
> rotor, and 1000 or below on the other.
>
> The third experiment was to run on secondaries, and switch to controller B.
> It had no noticable effect. However I did notice the effect of reducing
> injector flow rate from the second run mentioned above because I had to do
> considerable enrichment to get it to run smoothly.
>
> My conclusion is that
>
> 1. I have a faulty primary injector on one rotor, causing it to run rich.
>
> 2. I was totally puzzeled by the doubling of Tach RPM when running on
> secondaries only. Has anyone else noticed that?
>
> 3. My cooling seems to be doing okay so far. Temps stabilized with extended
> running at above idle speed.
>
> 4. I have to move my fuel pressure regulator, as it sets up motion that will
> lead to fatigue eventually.
>
> 5. I have a small oil leak around the oil pressure sensor threads.
>
> 6. It must sound 'different' because various builders/pilots came by to see
> what was making the racket while I was running it.
>
> Bill Schertz
> KIS Cruiser #4045
>

Hi Bill,

One other possibility for item 1, the signal lead to one of the primary
injectors could be shorted to ground, or the EC2 driver is bad.  I
think you would flood the rotor with the shorted lead pretty quickly as
soon as you applied power to the injectors so it's probably a long shot.

That sounds like the way my engine was running on my last flight.  With
the primaries on, the engine bogged down but not rough.  With the
primaries off it ran fine.  I did a continuity check on my system and
didn't find any obvious shorts.  I still haven't tested the injectors.

Bob W.


--
N93BD - Rotary Powered BD-4 - http://www.bob-white.com
3.8 Hours Total Time and holding
Cables for your rotary installation - http://www.roblinphoto.com/shop/