Today's Message Index:
----------------------
1. 05:33 AM - Backup Electrical Power (Eric M. Jones)
2. 06:16 AM - Re: Backup Electrical Power (Robert L. Nuckolls, III)
3. 07:17 AM - Do reporters ever get it right? (Robert L. Nuckolls, III)
4. 07:19 AM - Re:ARC RT-359A transponder manual? (MikeM)
5. 07:36 AM - Re: 10683 Mahan (Robert L. Nuckolls, III)
6. 09:10 AM - Re: Do reporters ever get it right? (Reed, Britt/FSC Salt Lake)
7. 10:12 AM - Red and Green LED Position lights (Eric M. Jones)
8. 10:51 AM - Crowbar O.V. & Internally Regulated Alternator (Z-24) (Steve Sampson)
9. 11:37 AM - Re: Crowbar O.V. & Internally Regulated Alternator (Z-24) (Phil Birkelbach)
10. 01:38 PM - Re: Crowbar O.V. & Internally Regulated Alternator (Z-24) (Robert L. Nuckolls, III)
11. 04:32 PM - Shielding the tach lead (Duncan McBride)
12. 11:25 PM - Crowbar O.V. & Internally Regulated Alternator (Z-24) (Steve Sampson)
Message 1
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| Subject: | Backup Electrical Power |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
Dan,
Looks good.
I am amazed that three lemons can make a jet exhaust so HOT!
By the way---Very tidy workshop you have there.
Eric M. Jones
Message 2
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| Subject: | Re: Backup Electrical Power |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:03 PM 7/30/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: "Dan Checkoway" <dan@rvproject.com>
>
>I have an idea for a backup electrical system for my RV-7...it involves
>having about 934 lemons onboard...
>
>http://www.checkoway.com/lemon_battery.html
>
>What do you think?
>
Neat posting! I've .pdf'ed a copy for sharing
with students. The experiment neatly demonstrates
reactions based on the electrochemical series tables
of common materials. It also demonstrates source
impedance (constant voltage, variable current
depending on depth of immersion).
Suggest you work toward the more elegant solution
of reducing number of lemons required . . . probability
of failure is 155x more likely than for say, 6 lemons.
Bob . . .
Message 3
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| Subject: | Do reporters ever get it right? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Interesting tid-bit from latest Avweb posing:
http://www.avweb.com/newswire/9_31b/complete/185409-1.html#5e
. . . I'm sitting here wondering how and "electrical failure"
can force a landing in a high-wing, gravity fed fuel system
aircraft.
Even more bizarre is the item just below the one cited.
Where can a pilot's head be at when an aircraft like this
runs out of fuel?
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 4
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| Subject: | RE:ARC RT-359A transponder manual? |
--> AeroElectric-List message posted by: MikeM <mladejov@ced.utah.edu>
> Does anyone have access to an ARC RT-359A transponder manual I could borrow?
>
> SigmaTek (who owns ARC) wants $125 for a copy. They generously knocked off 40%,
> but even $75 seems a bit much for a manual that hasn't changed in the last 20
> years.
>
> Regards,
> Kevin Kinney
Do you need the entire manual, or just an installation pin out?
MikeM
Message 5
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:25 PM 7/31/2003 +0000, you wrote:
>Below is the result of your inquiry. It was submitted by
>Fred Mahan (mahan@cfl.rr.com) on Thursday, July 31, 2003 at 06:25:20
>
>Thursday, July 31, 2003
>
>Fred Mahan
>
>,
>Email: mahan@cfl.rr.com
>Comments/Questions: Bob --
>Thanks again for the great book!
>Because of needing clearance in my particular installation (composite),
>I'd like to use a countersunk head 5/16" bolt for my ground (ring tab
>clamping between nuts, not between a nut and the countersink). I can't
>find 5/16" countersunk in brass, although 1/4" is available (and
>1/2"!). I can find bronze at the local marina. Is bronze an acceptable
>substitute for brass?
Sure . . . but I'm not sure I understand your problem. What surface
does the
flat-head screw clamp against? Do I presume there are NO electrical
connections between the head of the screw and the first nut?
>Fred I. Mahan
>mahan@cfl.rr.com
>PS I'm on the Aerolectric Connection list.
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 6
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| Subject: | Do reporters ever get it right? |
--> AeroElectric-List message posted by: "Reed, Britt/FSC Salt Lake" <BReed@slcrail.com>
Read further for the the Murphy related news -
...Bombardier Opens The Curtain...
program director Klemens Dolzer told us initial engineering flight tests in
a Murphy Moose experimental and a Piper Arrow are turning in even better
economy than originally planned.
-----Original Message-----
From: Robert L. Nuckolls, III [mailto:bob.nuckolls@cox.net]
Subject: AeroElectric-List: Do reporters ever get it right?
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
Interesting tid-bit from latest Avweb posing:
http://www.avweb.com/newswire/9_31b/complete/185409-1.html#5e
. . . I'm sitting here wondering how and "electrical failure"
can force a landing in a high-wing, gravity fed fuel system
aircraft.
Even more bizarre is the item just below the one cited.
Where can a pilot's head be at when an aircraft like this
runs out of fuel?
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 7
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| Subject: | Red and Green LED Position lights |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
I posted this on my website for anyone who want to see it.
http://www.periheliondesign.com/redandgreenledpositionlights.pdf
Regards,
Eric M. Jones
Message 8
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| Subject: | Crowbar O.V. & Internally Regulated Alternator (Z-24) |
--> AeroElectric-List message posted by: "Steve Sampson" <SSampson.SLN21@london.edu>
Bob - sorry if I am being a bit obtuse but there is something I cant figure
out in your book.
I am building and RV9a and already have a new internally regulated 60amp
alternator (Nippondenso) from VANS so I think I will use it. I have been
looking at Z-24 in order to minimise the fun of a runaway and am wondering
why the alternator disconnect contactor is needed?
In the event that the Crowbar OV trips the field current will go to zero and
the alternator will stop producing power.
If your answer is 'yes but an internal fault could put current back in the
excitation windings' then my question is so why don't you have the same
contactor in diags z-9 and z-23 for example? I guess the internals are less
complex but its still a problem. Is this the case of belt braces AND a bit
of string to hold your trousers up? I expect it is much more subtle than
that though!
Thanks, Steve
Message 9
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| Subject: | Re: Crowbar O.V. & Internally Regulated Alternator |
(Z-24)
--> AeroElectric-List message posted by: "Phil Birkelbach" <phil@petrasoft.net>
The problem is that the little wire on an internally regulated alternator is
not the field wire. The field current is supplied from the voltage
regulator which is inside the alternator. The little wire is the start-up
wire. It allows cars to keep the alternator from starting until after the
motor is running. Once the alternator starts you can disconnect power from
that wire all you want and the alternator will just keep on making juice.
(Lemon Juice ?? Sorry :-) The alternator doesn't even shut down when you
open the B-lead but at least it ain't connected to the airplane anymore.
Godspeed,
Phil Birkelbach - Houston Texas
RV-7 N727WB (Reserved) - Canopy
http://www.myrv7.com
----- Original Message -----
From: "Steve Sampson" <SSampson.SLN21@london.edu>
Subject: AeroElectric-List: Crowbar O.V. & Internally Regulated Alternator
(Z-24)
> --> AeroElectric-List message posted by: "Steve Sampson"
<SSampson.SLN21@london.edu>
>
> Bob - sorry if I am being a bit obtuse but there is something I cant
figure
> out in your book.
>
> I am building and RV9a and already have a new internally regulated 60amp
> alternator (Nippondenso) from VANS so I think I will use it. I have been
> looking at Z-24 in order to minimise the fun of a runaway and am wondering
> why the alternator disconnect contactor is needed?
>
> In the event that the Crowbar OV trips the field current will go to zero
and
> the alternator will stop producing power.
>
> If your answer is 'yes but an internal fault could put current back in the
> excitation windings' then my question is so why don't you have the same
> contactor in diags z-9 and z-23 for example? I guess the internals are
less
> complex but its still a problem. Is this the case of belt braces AND a bit
> of string to hold your trousers up? I expect it is much more subtle than
> that though!
>
> Thanks, Steve
>
>
Message 10
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| Subject: | Re: Crowbar O.V. & Internally Regulated Alternator |
(Z-24)
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 11:13 AM 7/31/2003 +0100, you wrote:
>--> AeroElectric-List message posted by: "Steve Sampson"
><SSampson.SLN21@london.edu>
>
>Bob - sorry if I am being a bit obtuse but there is something I cant figure
>out in your book.
>
>I am building and RV9a and already have a new internally regulated 60amp
>alternator (Nippondenso) from VANS so I think I will use it. I have been
>looking at Z-24 in order to minimise the fun of a runaway and am wondering
>why the alternator disconnect contactor is needed?
>
>In the event that the Crowbar OV trips the field current will go to zero and
>the alternator will stop producing power.
>
>If your answer is 'yes but an internal fault could put current back in the
>excitation windings' then my question is so why don't you have the same
>contactor in diags z-9 and z-23 for example? I guess the internals are less
>complex but its still a problem. Is this the case of belt braces AND a bit
>of string to hold your trousers up? I expect it is much more subtle than
>that though!
Field excitation for an internally regulated alternator comes
directly from the b-lead through solid state devices. The itty-bitty
wire that goes into the back of an internally regulated alternator
is a CONTROL wire to an integrated circuit. During an OV condition,
you cannot guarantee that removal of signal from this wire will
shut down the runaway alternator. In fact, on some cars, this wire
is used only to DELAY onset of alternator operation until after
the ECFI system says "okay to load engine" . . . once turned on
by way of the control wire, it cannot be turned off even when
the alternator is working perfectly.
http://216.55.140.222/temp/Internal.jpg
Consider what happens when transistor Q1 shorts . . .
hence the need for b-lead disconnect contactor IN ADDITION to
removal of control voltage.
On the other hand, alternators with external regulators get
100% of field current through the itty-bitty wire. Disconnecting
this wire from the bus via (1) OV relay, (2) crowbar tripping of field
breaker or (3) simply shutting the alternator down via panel switch
will bring a recalcitrant system to heel.
See http://216.55.140.222/temp/External.jpg
If one were really paranoid about all possibilities, I have
seen ONE INSTANCE of alternator runaway on a Mooney about
30 years ago wherein the OV relay could not control the event.
This was a case of a failure internal to the alternator
that took the field excitation directly to the b-lead terminal.
This was a mechanical failure due to poor design which Mooney
took steps to correct immediately.
One can build a firewall against this event by adding a b-lead
contactor in series with all alternators . . . excite the
contactor from bus voltage taken DOWNSTREAM of ov protection
but BEFORE regulator. I've never warmed up much to this
notion, I believe probability of re-occurrence is extremely
low.
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 11
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| Subject: | Shielding the tach lead |
--> AeroElectric-List message posted by: "Duncan McBride" <duncanmcbride@comcast.net>
I called Lockwood aviation for any ideas they may have about reducing noise. You
may recall I'm getting a lot of raspy white noise in a Microair 760 when the
PTT is pushed. I get the same noise when the radio is completely isolated from
the aircraft's (Kolb Twinstar Mk III, Rotax 912UL) and powered by a battery,
so I'm working under the theory that I need to reduce radiated noise. The
guys at Lockwood immediately asked if I had shielded the tach lead. They said
this is a problem they see a lot. There are two leads from the Rotax that in
the installation manual are shown going to a "rev-counter". I have the Grand
Rapids EIS, which calls for one of the leads to be grounded, and the other to
go to pin #6 of the unit. So here is my question - if I use shielded wire for
the lead going to pin 6, do I ground the shielding at both ends? Or could I
connect the shielding to the second Rotax lead and ground it at the panel near
the EIS? The simplest thing would be to ground the shielding and the second
lead on the grounding block near the engine. I don't know, it's just hard for
me to believe that the tach lead could really be the problem, but I'm trying
anything I hear, and I'd like to give this a shot. Any thoughts?
Thanks,
Duncan
Message 12
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| Subject: | Crowbar O.V. & Internally Regulated Alternator (Z-24) |
--> AeroElectric-List message posted by: "Steve Sampson" <SSampson.SLN21@london.edu>
Bob - sorry if I am being a bit obtuse but there is something I cant figure
out in your book.
I am building and RV9a and already have a new internally regulated 60amp
alternator (Nippondenso) from VANS so I think I will use it. I have been
looking at Z-24 in order to minimise the fun of a runaway and am wondering
why the alternator disconnect contactor is needed?
In the event that the Crowbar OV trips the field current will go to zero and
the alternator will stop producing power.
If your answer is 'yes but an internal fault could put current back in the
excitation windings' then my question is so why don't you have the same
contactor in diags z-9 and z-23 for example? I guess the internals are less
complex but its still a problem. Is this the case of belt braces AND a bit
of string to hold your trousers up? I expect it is much more subtle than
that though!
Thanks, Steve
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