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Bob,
Have you had the engine running with those exhausts
- do they cut the noise down any. I certainly like the look of the exhausts
especially for that type of plane, but wonder if you discovered any
advantage in multiple outlets.
George (down under)
I'm
thinking I purchased after the snubber update. Is there a certain date of
manufacturer that insures me of this? I dont remember the date on the box, its
at home and I'm screwing around on the computer at work instead of working
;)...I do know that my unit already has the right choke installed.
Bob
Mears
Supermarine Spitfire
-----Original Message-----
From:
Tracy Crook <tracy@rotaryaviation.com>
To: Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent: Wed, 17 Oct 2007 9:33
am
Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits
Bob, I don't know when you last updated your EC2 but if you have
the snubber update already, there is no need to update again due to the diode
and staging relay changes being discussed here. These changes are to
parts external to the EC2. If it is not clear to you where to add the
diodes and relay by looking at the schematic I posted, feel free to ask for
specifics. I want your project to succeed almost as much as you
do.
If you don't have the snubber update, I would highly recommend that you
get it prior to any engine testing or tuning.
Tracy Crook
On 10/17/07, bmears9413@aol.com <bmears9413@aol.com> wrote:
So
does this mean I shouldnt finish installing my EC2 cause I may have to send
it back to Tracy? Nows the time for me. I'm installing now.
Bob
Mears
Supermarine Spitfire
-----Original Message-----
From:
Joe Ewen <Jewen@comporium.net
>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent:
Sun, 14 Oct 2007 10:28 pm
Subject: [FlyRotary] Re: EC2 20B Injector
Power Circuits
Hi Bob,
Don't know if you don't ask. A diode is a
device that allows current to flow only in one direction (DC circuit.)
Schottky is a particular diode construction. One desirable feature of
a Schottky is that it has a low forward voltage drop. All diodes have
a drop in voltage (like a small resistor.) In this case, the lower
voltage drop allows the injectors to continue firing slightly longer than
other diode types in the event of an alternator failure and lowering battery
voltage.
On the 20B, the injector control lines are
wired together, installing the diodes prevents the current / voltage from
back feeding between the primary and secondary circuits and the possible
failure modes I noted earlier. Application of diode(s) in this manner
is typically referred to as isolation diodes.
Since the EC2 controller internal jumps the 2
controller power feeds, I installed isolation diodes (Schottky) to prevent
similar problems between the 2 supply circuits.
You may also find diodes useful in
making annunciator press to test circuits. If you have 2
devices such as a transponder and a GPS that both need to share
altitude encoder inputs, isolation diodes would be used. Of course
with any avionics installations, follow the manufactures guidelines.
Joe
----- Original Message -----
Sent: Sunday, October 14, 2007 10:16
PM
Subject: [FlyRotary] Re: EC2 20B
Injector Power Circuits
Al
Hate to continue to
display my ignorance but what is a Schottky diodes. When it comes to
electronics I'm as dumb as a stump.
Bob K
From: Rotary motors in aircraft [
mailto:flyrotary@lancaironline.net] On Behalf Of Al
Gietzen
Sent: Sunday, October 14, 2007 5:42 PM
To:
Rotary motors in aircraft
Subject: [FlyRotary] Re: EC2 20B
Injector Power Circuits
Joe;
You are right. We
discovered this crossfeed issue some time back. Is applies only to
the 20B version as the 13B has separate drivers for each set.
Install Schottky diodes in the circuits for each injector.
Tracy is aware of this, and has installed the diodes in his as well.
Al
-----Original Message-----
From: Rotary
motors in aircraft [
mailto:flyrotary@lancaironline.net] On Behalf Of Joe
Ewen
Sent: Sunday, October 14, 2007 3:20 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] EC2 20B Injector Power
Circuits
I have been
testing my wiring harness from the EC2. I found a behavior that I
did not expect. The manual drawing (EC2 manual) show a single
injector supply that splits at the Injector primary and secondary disable
switches. On my installation, I have 2 separate feeder circuits,
supply Primary comes from battery 1, and supply Secondary comes from
battery 2. I did this for redundancy. If I had a failure such
as a short to ground in either circuit, its related overload should trip,
but the other circuit should remain active.
While
testing the injector circuits, I noticed what I would term an
abnormality. With both injector disable switches in the enable
position, I turned on the power for the primary circuit (I have LED
indicators on all circuits that annunciate power present) and the
secondary circuit also showed power present even though the power switch
for the secondary circuit was off. The same is true when the
secondary circuit is engaged and the primary is off.
Initially
this led me to think I had miss wired something in the circuit.
After checking out the wiring, I found no issues. So I took a closer
look at the wiring diagram in the manual. It turns out the power was
being back feed through the injectors to the opposite circuit. On
the 20B version of the EC2, the injector control lines for each rotors
injectors are junctioned going into the EC2. For example the Rotor 1
Primary and Secondary control lines are junctioned into a single input
point at the EC2.
I can see
several situations where this may lead to undesirable operation. For
example, if the Primary circuit had a hard short to ground, it would take
out the primary circuit's overload (CB or Fuse.) Since the primary
and secondary circuits are electrically connected on the control line, the
other circuit would also trip. Another situation that could occur is
a medium to high resistance short. Current would then flow
uncontrolled through the unaffected circuit's injector to the affected
circuit's injector then to the resistance short. This could keep
both injectors on 100%. While this situation is unlikely,
it seems possible.
I
believe the 13B version uses separate control lines for each
injector, so this in not likely to be an issue on the 13B
version.
It appears
that isolation diodes are needed to prevent these possible problems.
Before making any changes I have to look the circuit over more closely, as
well as a call to Tracy on the next service day. My question to the
group, especially anyone with a 20B, is am I looking at this wrong?
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