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Bob,
If you don't remember, I will remind you to tell us
when the time of engine testing comes about. I've got a feeling that a 2" into
4" and then into 12 outlets will make the sound quite deep and the extra length
will scrub down the exhaust sound -I'd be surprised it didn't work well for your
application.
George ( down under)
George,
Havent
started it yet. Hope to by the end of the year. Each fo the 2" outlets actuall
have a 1" exhaust port in each of them. I'm hoping for some muffler action by
doing that. I cant wait to hear it, but I wont fire it untill I think
everything is ready.
Bob Mears
Supermarine
Spitfire
-----Original Message-----
From: George Lendich
<lendich@optusnet.com.au>
To: Rotary motors in aircraft
<flyrotary@lancaironline.net>
Sent: Wed, 17 Oct 2007 5:29
pm
Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits
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?
Email and AIM finally together. You've gotta check out free AOL Mail!
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