 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
nuckolls.bob(at)aeroelect
Guest
|
 Posted: Sat Oct 26, 2013 9:33 pm Post subject: Battery contactor failure |
 |
|
At 12:00 AM 10/27/2013, you wrote:
| Quote: | I believe that some of the installations of the Rotax 912 (and
probably other power systems) do not windmill (but the 912 may not
be electrically-dependent ).
|
Only if the fuel is delivered by engine driven pump
or gravity. The ignition is electronic driven directly
from magnets on the starter ring gear.
| Quote: | However, I don't think you can categorically say that ALL engines
will windmill. In addition some flight conditions may cause a
windmilling prop to stop. A possible scenario: The pilot becomes
task saturated on the electrical failure and lets the airspeed bleed
down and the prop stops.
|
That's s double failure again. Failure tolerant systems
with a plan-b do not saturate pilots.
| Quote: | Dooh! I forgot about the alternator - BUT - I've never trusted an
alternator that was not connected to a battery, therefore I would be
reluctant to have that as a fall back.
|
Because you know them to be unreliable or simply
don't know. Actually, Cessna and others who opted
for the split rocker switch were probably in violation
of legacy design goals.
Until that time, airplanes flew nicely on either
battery, generator or both. When the alternator
came along, the airframe guys elected to put
alternators on even tho they were not plug-n-play
for the failure tolerance offered by generators.
The Bonanza and Barons continued to offer alternator-
only operations but if I recall correctly, the Liberal
airplanes had split rockers.
PM alternators are easy to get on-line without a
battery and it may well be that belt-driven alternators
on a Lycoming are too. They run very fast. I need to
get some time on B&C's test bench and run some experiments.
| Quote: | What about moving the starter feed to the battery side of the master?
|
If you're willing to have an always hot feeder to a
starter contactor . . .
Bob . . .
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
 |
jluckey(at)pacbell.net
Guest
|
| Posted: Sun Oct 27, 2013 6:30 am Post subject: Battery contactor failure |
|
|
My comment is italics
-Jeff
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
To: aeroelectric-list(at)matronics.com
Sent: Saturday, October 26, 2013 9:32 PM
Subject: Battery contactor failure
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
At 12:00 AM 10/27/2013, you wrote:
| Quote: | I believe that some of the installations of the Rotax 912 (and probably other power systems) do not windmill (but the 912 may not be electrically-dependent ).
|
Only if the fuel is delivered by engine driven pump
or gravity. The ignition is electronic driven directly
from magnets on the starter ring gear.
| Quote: | However, I don't think you can categorically say that ALL engines will windmill. In addition some flight conditions may cause a windmilling prop to stop. A possible scenario: The pilot becomes task saturated on the electrical failure and lets the airspeed bleed down and the prop stops.
|
That's s double failure again. Failure tolerant systems
with a plan-b do not saturate pilots.
Disagree - There is way too much case history of pilots becoming distracted, over seemingly trivial issues, to suggest that you can write-off this scenario.
| Quote: | Dooh! I forgot about the alternator - BUT - I've never trusted an alternator that was not connected to a battery, therefore I would be reluctant to have that as a fall back.
|
Because you know them to be unreliable or simply
don't know. Actually, Cessna and others who opted
for the split rocker switch were probably in violation
of legacy design goals.
Once upon a time waaay back in the late 70s I had seen a few alternators lose voltage regulation when battery became disconnected. This was in the marine environment. Regulators are most certainly better now but those experiences have stuck with me.
Until that time, airplanes flew nicely on either
battery, generator or both. When the alternator
came along, the airframe guys elected to put
alternators on even tho they were not plug-n-play
for the failure tolerance offered by generators.
The Bonanza and Barons continued to offer alternator-
only operations but if I recall correctly, the Liberal
airplanes had split rockers.
PM alternators are easy to get on-line without a
battery and it may well be that belt-driven alternators
on a Lycoming are too. They run very fast. I need to
get some time on B&C's test bench and run some experiments.
| Quote: | What about moving the starter feed to the battery side of the master?
|
If you're willing to have an always hot feeder to a
starter contactor . . .
Are there reasons to not do this? Is that any worse than having an always hot feed to the "main" bus?
-Jeff
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
anthonyharding
Joined: 15 Nov 2013
Posts: 1
|
| Posted: Fri Nov 15, 2013 11:01 pm Post subject: Re: Battery contactor failure |
|
|
Often this is a great time to install Battery Master Switch...Well then the main battery starter cable through the car is “Dead” after start up....So i gives a better suggestion you can used the well batteries and you can found the well shop at : http://www.johnslittlegadgetstore.com.au/.. Thanks..
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
_________________
anthony harding |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
