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Tundra10
Joined: 14 Jun 2010
Posts: 102
Location: Scarborough, Ontario
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 Posted: Thu Apr 16, 2020 9:51 pm Post subject: New role for the E-Bus? |
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Hi Bob,
I just had a good look at Z101. I like it. Five comments, certainly
things you have thought of.
1) There is no overvoltage protection for the aux alternator. I
assume that is because having an overvoltage event immediately after
having a main alternator failure is too unlikely to justify it ?
2) Is the intention that the Engine Bus Alternate Feed be on during
normal flight ? If not, switching off the Master or a battery
contactor failure would remove power from the electronic ignition.
3) During normal flight, the brown out booster is unpowered, but the
power from the Clearance Delivery bus back feeds into its output. Are
these devices typically okay with this ?
4) Is there a risk that the brown out booster could generate a
significant overvoltage event ? Given their switching method to boost
voltage, I think not ?
5) The green color used for the engine bus circuitry is too light a
green, making it hard to read. I suggest a shade darker.
Thanks !
Jeff Page
Dream Aircraft Tundra #10
| Quote: | Time: 08:39:48 AM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
Subject: Re: Re: New role for the E-Bus?
I've been working on three new z-figures between
wrestling bouts with my dad's '87 GMC pickup
truck (fuel pump died . . . as long as I have
to pull the whole tank to replace the pump, I'm
replacing EVERYTHING . . . I'm down to the
last two fasteners holding the tank supports
on the frame . . . 30+ years of rust . . .
Impact wrench won't budge 'em. Been soaking
with penetrating oil but about resigned to
cutting the nuts off with an air-chisel!)
I've posted the latest iterations of the
drawings we've been combing out here over
the past couple of months.
Z100 at https://tinyurl.com/sfsbd2t
This is the generic architecture that's
been flown successfully in hundreds of thousands
of airplanes in the TC and OBAM aviation worlds.
This drawing could have been in Tony Bengelis
books . . . same as a C150 sans avionics bus
(which was never a good idea anyhow). Then:
Z101 at https://tinyurl.com/v9w7g4r
This is Z100 any combination of 4 options:
(1) Robust AUX Alternator
(2) Dual feed, triple source ENGINE bus
to support electrically dependent
engine and ancillary instrumentation.
(3) A CLEARANCE DELIVERY bus that offers
a means for powering up JUST the
COMM transceiver for preflight
planning
(4) A brownout boost feature on the
CD bus to support wobbly electro-whizzies
vulnerable to unacceptable reset
during starter inrush interval.
Then:
Z101/8 at https://tinyurl.com/vanp6yu
Essentially the same as Z101 except for a
smaller AUX alternator in lieu of the bigger
rascal depicted in Z101.
This configuration offers all the features
and reliability with reduced weight and
cost over Z101 where the builder's anticipated
loads under failure of main alternator are
modest. The way the AUX ALT is set up on
these drawings makes it easy to upgrade
from a /8 to the larger alternator as
later needs dictate.
These drawings depict variations suggested
in a constellation of Z-figures . . . a
kind of LEGO approach to acquiring capabilities
of any legacy z-figure at the simplest,
lightest, lowest cost yet failure tolerant
architecturs.
Bob . . .
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri Apr 17, 2020 3:36 pm Post subject: New role for the E-Bus? |
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|
At 12:46 AM 4/17/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: Jeff Page <jpx(at)qenesis.com>
Hi Bob,
I just had a good look at Z101. I like it. Five comments, certainly
things you have thought of.
1) There is no overvoltage protection for the aux alternator. I
assume that is because having an overvoltage event immediately after
having a main alternator failure is too unlikely to justify it ? |
EXACTLY. In an ideal world, the AUX alernator
will never be operated in 'distress'. In a practical
world, it would be unusual to have it see more than
a hand-full of hours operation over the lifetime
of the airplane.
It gets pre-flight tested. OV events are also rare.
Adding that protection just doesn't seem justified.
Hence simple, light, inexpensive. But easily 'adjusted'
with a crowbar ovm if the builder so desires.
| Quote: | 2) Is the intention that the Engine Bus Alternate Feed be on during
normal flight ? If not, switching off the Master or a battery
contactor failure would remove power from the electronic ignition. |
Yes. What is the probability of these events?
Battery contactors get fussy before they become
a failed-open device. If it DID fail open in
flight, you probably wouldn't know it . . . the
alternator would continue to run things nicely.
You might not know it was bad until you shut
down and happened to notice that everything
went dark on first motion of the master switch.
If not noticed, you'd sure pick it up during
next pre-flight.
Inadvertent opening of the master switch
in flight might be a concern . . .which
is why I recommend ergonomic grouping of
switches to separate DC power and engine
controls from things that get routinely
switched in flight.
https://tinyurl.com/ybaw83gd
But if one wished to fly with the alternate
power path to any bus closed, it's no big
deal.
| Quote: | 3) During normal flight, the brown out booster is unpowered, but the
power from the Clearance Delivery bus back feeds into its output. Are
these devices typically okay with this ? |
The ones I've fiddled with so far don't
mind. Backfeed currents observed are on
the order of 3 milliamps . . . typical
of resistance in the voltage setpoint
divider. But it's certainly something
to be verified. We could add a diode
to the output path. Since the device
is loaded for only seconds per flight
cycle, the diode could probably be an
axial lead, plastic device even if
'slightly' overloaded. I'll keep that
in the ponder-pot.
| Quote: | 4) Is there a risk that the brown out booster could generate a
significant overvoltage event ? Given their switching method to boost
voltage, I think not ? |
Yeah, an open resistor in the setpoint
divider could cause it to 'regulate' at
some higher voltage. These resistors
are surface mounted and lightly stressed.
Pretty bullet-proof I suspect.
| Quote: | 5) The green color used for the engine bus circuitry is too light a
green, making it hard to read. I suggest a shade darker. |
Check the 'fix' . . .
Thank's for the time/attention to this exercise!
Bob . . .
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Tundra10
Joined: 14 Jun 2010
Posts: 102
Location: Scarborough, Ontario
|
| Posted: Sat Apr 18, 2020 7:59 am Post subject: New role for the E-Bus? |
|
|
Hi Bob,
Regarding the Engine Bus Alternate feed, I was envisioning it being on
during normal flight operations, since pilots are trained to switch
off the Master if they suspect an electrical fire. This would shut
off the alternator too, resulting in the engine stopping unexpectedly.
It is unlikely that the pilot would remember to turn on that switch
before shutting off the Master, especially a second owner.
Jeff Page
Dream Aircraft Tundra #10
| Quote: | Time: 04:36:32 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
Subject: Re: Re: New role for the E-Bus?
At 12:46 AM 4/17/2020, you wrote:
>
> Hi Bob,
>
> I just had a good look at Z101. I like it. Five comments, certainly
> things you have thought of.
>
> 1) There is no overvoltage protection for the aux alternator. I
> assume that is because having an overvoltage event immediately after
> having a main alternator failure is too unlikely to justify it ?
EXACTLY. In an ideal world, the AUX alernator
will never be operated in 'distress'. In a practical
world, it would be unusual to have it see more than
a hand-full of hours operation over the lifetime
of the airplane.
It gets pre-flight tested. OV events are also rare.
Adding that protection just doesn't seem justified.
Hence simple, light, inexpensive. But easily 'adjusted'
with a crowbar ovm if the builder so desires.
> 2) Is the intention that the Engine Bus Alternate Feed be on during
> normal flight ? If not, switching off the Master or a battery
> contactor failure would remove power from the electronic ignition.
Yes. What is the probability of these events?
Battery contactors get fussy before they become
a failed-open device. If it DID fail open in
flight, you probably wouldn't know it . . . the
alternator would continue to run things nicely.
You might not know it was bad until you shut
down and happened to notice that everything
went dark on first motion of the master switch.
If not noticed, you'd sure pick it up during
next pre-flight.
Inadvertent opening of the master switch
in flight might be a concern . . .which
is why I recommend ergonomic grouping of
switches to separate DC power and engine
controls from things that get routinely
switched in flight.
https://tinyurl.com/ybaw83gd
But if one wished to fly with the alternate
power path to any bus closed, it's no big
deal.
> 3) During normal flight, the brown out booster is unpowered, but the
> power from the Clearance Delivery bus back feeds into its output. Are
> these devices typically okay with this ?
The ones I've fiddled with so far don't
mind. Backfeed currents observed are on
the order of 3 milliamps . . . typical
of resistance in the voltage setpoint
divider. But it's certainly something
to be verified. We could add a diode
to the output path. Since the device
is loaded for only seconds per flight
cycle, the diode could probably be an
axial lead, plastic device even if
'slightly' overloaded. I'll keep that
in the ponder-pot.
> 4) Is there a risk that the brown out booster could generate a
> significant overvoltage event ? Given their switching method to boost
> voltage, I think not ?
Yeah, an open resistor in the setpoint
divider could cause it to 'regulate' at
some higher voltage. These resistors
are surface mounted and lightly stressed.
Pretty bullet-proof I suspect.
> 5) The green color used for the engine bus circuitry is too light a
> green, making it hard to read. I suggest a shade darker.
Check the 'fix' . . .
Thank's for the time/attention to this exercise!
Bob . . .
|
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http://www.matronics.com/Navigator?AeroElectric-List |
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