Today's Message Index:
----------------------
1. 04:51 AM - Re: Switchology Question (logansc)
2. 05:10 AM - Who Has Got The Time? ()
3. 07:14 AM - Re: Who Has Got The Time? ()
4. 07:39 AM - Re: Hobbs MeterHobbs Meter (Fran & Joe)
5. 09:02 AM - Re: Dual Battery Contactor (Robert L. Nuckolls, III)
6. 10:02 AM - Re: Dual Battery Contactor (P.S.) (Robert L. Nuckolls, III)
7. 10:11 AM - Re: Hobbs Meter (user9253)
8. 10:22 AM - Re: Dual Battery Contactor (Chris Stone)
9. 11:02 AM - Re: Switchology Question (Jeff Page)
10. 12:43 PM - Re: Dual Battery Contactor ()
11. 01:34 PM - Re: Who Has Got The Time? (BobsV35B@aol.com)
12. 02:35 PM - Re: Who Has Got The Time? (ray)
13. 03:25 PM - Re: Who Has Got The Time? (Robert L. Nuckolls, III)
14. 04:11 PM - Re: Dual Battery Contactor (Robert L. Nuckolls, III)
15. 06:46 PM - Power Mizer (Bill Bradburry)
16. 07:29 PM - Re: Power Mizer (Matt Prather)
17. 08:57 PM - Re: Power Mizer (Robert L. Nuckolls, III)
18. 10:25 PM - Re: Lopresti HID claims (XeVision)
Message 1
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Subject: | Re: Switchology Question |
Bob: Thanks for the response. I'll work out a "switchology" sequence today and
try it this afternoon.
Regards,
Lee...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=276676#276676
Message 2
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Subject: | Who Has Got The Time? |
12/6/2009 (and again on 11/8/2009)
Hello Fellow Pilots and Builders, The aeroelectric list has been filled
lately with discussions of hardware (meters) that keep track of time. Just
exactly what time is being kept, and for what purpose, is unclear. To shed
some light on the subject let's start by taking a look at what 14 CFR
(FAR's) say about time.
We'll take flight time first, then TIS (Time In Service):
1) Here is how pilot flight time is defined in section 1.1 of the FAR's :
"Flight time means: Pilot time that commences when an aircraft moves under
its own power for the purpose of flight and ends when the aircraft comes to
rest after landing;"
I am not aware of any meter that could keep accurate track of such time.
You'll find many pilots, and airlines, that do not keep track of flight /
pilot time in conformance with this definition. Standard compliance by all
pilots with this definition is unlikely because there is room for
interpretation.
Does "moves under its own power for the purpose of flight" mean the instant
the wheels start to roll as you leave the parking space in order to go
flying? Then that XXX minutes plus that you spend taxiing, doing engine run
up, and waiting for takeoff clearance at the end of the runway, would all be
flight time. Considering the delays involved in operating at some airports
one could become a multi thousand hour flight time pilot very quickly using
that interpretation.
On the other hand one is certainly exercising some very important PIC duties
from the time he leaves the parking space until starting takeoff roll.
Should all of that time be ignored and not recognized in some fashion?
2) Here is how section 1.1 of FAR's defines TIS (Time In Service):
"Time in service, with respect to maintenance time records, means the time
from the moment an aircraft leaves the surface of the earth until it touches
it at the next point of landing."
I suppose that there is hardware that could record this exact time, but it
certainly is not in common use in our category of airplanes.
So let's take a look at three common timing devices: the Hobbs meter, the
mechanical engine RPM based tachometer, and the software associated with
electronic flight instrumentation or engine instrumentation:
A) The Hobbs meter (you can look here for a quick review):
http://en.wikipedia.org/wiki/Hobbs_meter
It doesn't take very long to conclude that "Hobbs meter" has become a very
generic term (like Kleenex or Scotch tape) and that Hobbs meters come in
wide varieties and can be connected to record a wide variety of time. I
guess it is possible for a Hobbs meter to be connected up so that it records
one of the time definitions in the FAR's, but it doesn't seem easy.
B) FAR 91.205 (a) and (b) require an engine tachometer to be installed in
any powered standard category civil aircraft even for day VFR operations. By
far the most common type of tachometer found is the mechanical RPM based
tachometer. Presumably the purpose of the required tachometer is to inform
the pilot of his engine's RPM at any given instant, but somewhere along the
line these tachometers began including the total time of engine operation.
This required someone to decide how to convert instantaneous RPM into total
elapsed time of engine operation.
If, say 2,000 RPM were chosen as the standard mechanical ratio to convert
one minute at this RPM into one minute of elapsed engine operating time then
any engine operation at less than 2,000 RPM generates less than one minute
of elapsed engine operating time and any RPM greater than 2,000 generates
more than one minute of elapsed engine operating time. See some of the
tachometer conversion ratios between RPM and time available here:
http://tghaviation.rtrk.com/?scid=387399&kw=3649251
In any case it does not appear that any mechanical engine tachometer can
generate either of the elapsed times defined by the FAR's.
C) There is such a huge variety of electronic flight and engine
instrumentation systems and their associated software (and the ability of
the operator to modify the software in some cases) that any accurate
comparison of one airplane's / engine's / pilot's time to another airplane's
/ engine's / pilot's time would require some detailed examination of the
processes used to generate that time.
Again the probability that an electronic system would automatically generate
elapsed time in exact compliance with either of the FAR time definitions is
not likely.
So what is the builder / pilot to do? My suggestions:
a) Don't get all wrapped around the axle about generating time. Many people
are not recording flight time or time in service the same way that you are.
b) Pick some hardware and a system of documentation that seems to fit your
needs and go with it.
c) Be consistent in how you do things so that you can view and show the
results with some confidence.
d) Be wary of someone else's time claims, but don't make a big deal of time
unless you are billing by the hour.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
PS: My choice for my airplane was just to record "Tach time" from my engine
electronic data system for both flight time and TIS. My engine data system
generates zero
tach time anytime the engine RPM is less than 1,500 RPM and constant equal
running time in hours and tenths any time the engine RPM is above 1,500 RPM.
Recording this time for both flight time and TIS short changes me on pilot
flight time since a fair amount of time while practicing landings in the
landing pattern the engine is below 1,500 RPM. On
the other hand it will take much longer elapsed time for my engine to reach
its 2,000 hour TIS to be due for overhaul. This approach greatly simplifies
my bookkeeping.
Back when I was flying rental aircraft I just went with the flow and used
the FBO's Hobbs meter time for flight time -- I paid for it, I should be
able to log it.
Message 3
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Subject: | Who Has Got The Time? |
Couple of observations.
1. Regardless of all the wiz bang stuff out there, piloting is still
very much a human engineered activity. The rolling time is what the
pilot enters in his/her logbook and swears to it based on their
signature. If the FAA had the resources (and they don't) they could
easily match Hobbs with book entries to see how much you're cheating.
Until they begin using biometrics which are fed wirelessly to the FBI
database to log activity around and in aircraft, your word is good. I
hope I don't give anyone at the FAA any ideas?
2. Have you ever seen or flown antique aircraft? They don't have spit
for gauges. Ok, one airspeed dial and oil pressure. Again, pilot rules
the books and the sky.
3. Hobbs are useful in rental aircraft for obvious reasons and yes, it's
natural to log from them if you subtract the time the plane wasn't
actually moving under its own power, but idling there trying to warm up,
waiting for you etc. Someday we'll all have remote starters with
automatic shutdown if there is a problem so we can spend more time
drinking coffee by the window and BS'n in the pilot lounge while our
climate controlled cabins warm up.
4. Like many I am more interested in how long to my next service
interval than I am struggling to amass 10,000 hours in my log book.
Accuracy is good at all plateaus. I have two Dynons of which each has
more clocks and time settings than a Swiss train station.
Glenn E. Long
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
bakerocb@cox.net
Sent: Tuesday, December 08, 2009 8:07 AM
Subject: AeroElectric-List: Who Has Got The Time?
12/6/2009 (and again on 11/8/2009)
Hello Fellow Pilots and Builders, The aeroelectric list has been filled
lately with discussions of hardware (meters) that keep track of time.
Just
exactly what time is being kept, and for what purpose, is unclear. To
shed
some light on the subject let's start by taking a look at what 14 CFR
(FAR's) say about time.
We'll take flight time first, then TIS (Time In Service):
1) Here is how pilot flight time is defined in section 1.1 of the FAR's
:
"Flight time means: Pilot time that commences when an aircraft moves
under
its own power for the purpose of flight and ends when the aircraft comes
to
rest after landing;"
I am not aware of any meter that could keep accurate track of such time.
You'll find many pilots, and airlines, that do not keep track of flight
/
pilot time in conformance with this definition. Standard compliance by
all
pilots with this definition is unlikely because there is room for
interpretation.
Does "moves under its own power for the purpose of flight" mean the
instant
the wheels start to roll as you leave the parking space in order to go
flying? Then that XXX minutes plus that you spend taxiing, doing engine
run
up, and waiting for takeoff clearance at the end of the runway, would
all be
flight time. Considering the delays involved in operating at some
airports
one could become a multi thousand hour flight time pilot very quickly
using
that interpretation.
On the other hand one is certainly exercising some very important PIC
duties
from the time he leaves the parking space until starting takeoff roll.
Should all of that time be ignored and not recognized in some fashion?
2) Here is how section 1.1 of FAR's defines TIS (Time In Service):
"Time in service, with respect to maintenance time records, means the
time
from the moment an aircraft leaves the surface of the earth until it
touches
it at the next point of landing."
I suppose that there is hardware that could record this exact time, but
it
certainly is not in common use in our category of airplanes.
So let's take a look at three common timing devices: the Hobbs meter,
the
mechanical engine RPM based tachometer, and the software associated with
electronic flight instrumentation or engine instrumentation:
A) The Hobbs meter (you can look here for a quick review):
http://en.wikipedia.org/wiki/Hobbs_meter
It doesn't take very long to conclude that "Hobbs meter" has become a
very
generic term (like Kleenex or Scotch tape) and that Hobbs meters come in
wide varieties and can be connected to record a wide variety of time. I
guess it is possible for a Hobbs meter to be connected up so that it
records
one of the time definitions in the FAR's, but it doesn't seem easy.
B) FAR 91.205 (a) and (b) require an engine tachometer to be installed
in
any powered standard category civil aircraft even for day VFR
operations. By
far the most common type of tachometer found is the mechanical RPM based
tachometer. Presumably the purpose of the required tachometer is to
inform
the pilot of his engine's RPM at any given instant, but somewhere along
the
line these tachometers began including the total time of engine
operation.
This required someone to decide how to convert instantaneous RPM into
total
elapsed time of engine operation.
If, say 2,000 RPM were chosen as the standard mechanical ratio to
convert
one minute at this RPM into one minute of elapsed engine operating time
then
any engine operation at less than 2,000 RPM generates less than one
minute
of elapsed engine operating time and any RPM greater than 2,000
generates
more than one minute of elapsed engine operating time. See some of the
tachometer conversion ratios between RPM and time available here:
http://tghaviation.rtrk.com/?scid=387399&kw=3649251
In any case it does not appear that any mechanical engine tachometer can
generate either of the elapsed times defined by the FAR's.
C) There is such a huge variety of electronic flight and engine
instrumentation systems and their associated software (and the ability
of
the operator to modify the software in some cases) that any accurate
comparison of one airplane's / engine's / pilot's time to another
airplane's
/ engine's / pilot's time would require some detailed examination of the
processes used to generate that time.
Again the probability that an electronic system would automatically
generate
elapsed time in exact compliance with either of the FAR time definitions
is
not likely.
So what is the builder / pilot to do? My suggestions:
a) Don't get all wrapped around the axle about generating time. Many
people
are not recording flight time or time in service the same way that you
are.
b) Pick some hardware and a system of documentation that seems to fit
your
needs and go with it.
c) Be consistent in how you do things so that you can view and show the
results with some confidence.
d) Be wary of someone else's time claims, but don't make a big deal of
time
unless you are billing by the hour.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
PS: My choice for my airplane was just to record "Tach time" from my
engine
electronic data system for both flight time and TIS. My engine data
system
generates zero
tach time anytime the engine RPM is less than 1,500 RPM and constant
equal
running time in hours and tenths any time the engine RPM is above 1,500
RPM.
Recording this time for both flight time and TIS short changes me on
pilot
flight time since a fair amount of time while practicing landings in the
landing pattern the engine is below 1,500 RPM. On
the other hand it will take much longer elapsed time for my engine to
reach
its 2,000 hour TIS to be due for overhaul. This approach greatly
simplifies
my bookkeeping.
Back when I was flying rental aircraft I just went with the flow and
used
the FBO's Hobbs meter time for flight time -- I paid for it, I should be
able to log it.
Message 4
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Subject: | Re: Hobbs MeterHobbs Meter |
This link works:
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU 7-0077&gclid=
CISGmb-Lx54CFQ_xDAodcwNRrA
Message 5
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Subject: | Re: Dual Battery Contactor |
At 05:34 PM 12/7/2009, you wrote:
Chris,
Thanks for the tip and lead on a great solution for preserving
alternators from high stress loads...
Not sure there is "benefit" to be realized for shielding
an alternator from "high stress" loads.
As converters of mechanical to electrical energy, these
devices have specifications. They also tend to be designed
for a particular marketplace task. The prudent designers,
manufacturers and installers of such devices understand the
capabilities and limits. That understanding is factored
into satisfaction of design goals and establishment
of maintenance programs.
Subscribing to the notion of "stress mitigation" on
an alternator by programming the manner in which loads
are applied to the machine suggests that design goals,
capabilities and limits are suspect or perhaps known
to be poorly married.
The aux battery management module for OBAM aircraft was
first proposed in an article I wrote for Sport Aviation
many moons ago. The intent of this device was to provide
automatic management of an auxiliary battery included
to power flight critical electro-whizzies. The ABMM
prevented connection of the aux battery to the system
unless bus voltage was high enough to avoid discharging
the battery (i.e. alternator on line). Hence the 13.0
volt switchpoint calibration for closing the contactor.
The corollary idea was that the ABMM opens the contactor
automatically during alternator shut down or failure
thus isolating the aux battery and preserving contained
energy for a specific task.
The product being discussed appears to perform in
precisely the same manner where it's desirable
to isolate a RV vehicle battery from recreational
electro-whizzies battery unless the alternator
is available to service BOTH batteries.
This is a PARTICULAR case where the recreational
battery is EXPECTED to be deeply discharged. Now,
if the vehicle battery has not been abused while
parked, then the bus is expected to rise above
13.0 (or 13.2) volts seconds after the engine
starts. This device would spare the alternator
from "high stress" loads only if BOTH batteries are
deeply discharged. But even then, I can't imagine
that the bus will stay below 13.2 volts for very
long even if the vehicle battery was drawn down
completely and the engine was started with jumper cables.
Finally, irrespective of number of batteries and
no matter how you've abused the batteries, your
alternator should be EXPECTED to happily deliver
full rated output for an indefinite period of time.
If not, there's something wrong with the selection
of alternator or the manner in which it has been
installed.
Bob . . .
Message 6
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Subject: | Re: Dual Battery Contactor (P.S.) |
At 05:34 PM 12/7/2009, you wrote:
Chris,
Thanks for the tip and lead on a great solution for preserving
alternators from high stress loads...
<snip>
. . . . irrespective of number of batteries and
no matter how you've abused the batteries, your
alternator should be EXPECTED to happily deliver
full rated output for an indefinite period of time.
If not, there's something wrong with the selection
of alternator or the manner in which it has been
installed.
P.S. There's another article I wrote in 1998 that
speaks to the physics and operational considerations
of diodes vs. contactors for battery management. See:
http://www.aeroelectric.com/articles/bat_iso2.pdf
Bob . . .
Message 7
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The link in the previous post did not work, but this one should:
Joe
http://www.alliedelec.com/Search/ProductDetail.aspx?SKU 7-0077&gclid=CISGmb-Lx54CFQ_xDAodcwNRrA
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=276718#276718
Message 8
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Subject: | Re: Dual Battery Contactor |
This brings to mind a question as to what happens to the alternator when the load
placed on it exceeds it's output capacity? Will the output voltage start to
drop as capacity is exceeded? If overload is continued are the diodes the weak
link in the chain? Will the diodes fail before overheating of the stator
windings? What is the common failure mode?
Chris Stone
RV-8
-----Original Message-----
>From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
>Sent: Dec 8, 2009 11:55 AM
>To: aeroelectric-list@matronics.com
>Subject: Re: AeroElectric-List: Dual Battery Contactor
>
>
>At 05:34 PM 12/7/2009, you wrote:
>
>Chris,
>Thanks for the tip and lead on a great solution for preserving
>alternators from high stress loads...
>
> Not sure there is "benefit" to be realized for shielding
> an alternator from "high stress" loads.
>
> As converters of mechanical to electrical energy, these
> devices have specifications. They also tend to be designed
> for a particular marketplace task. The prudent designers,
> manufacturers and installers of such devices understand the
> capabilities and limits. That understanding is factored
> into satisfaction of design goals and establishment
> of maintenance programs.
>
> Subscribing to the notion of "stress mitigation" on
> an alternator by programming the manner in which loads
> are applied to the machine suggests that design goals,
> capabilities and limits are suspect or perhaps known
> to be poorly married.
>
> The aux battery management module for OBAM aircraft was
> first proposed in an article I wrote for Sport Aviation
> many moons ago. The intent of this device was to provide
> automatic management of an auxiliary battery included
> to power flight critical electro-whizzies. The ABMM
> prevented connection of the aux battery to the system
> unless bus voltage was high enough to avoid discharging
> the battery (i.e. alternator on line). Hence the 13.0
> volt switchpoint calibration for closing the contactor.
> The corollary idea was that the ABMM opens the contactor
> automatically during alternator shut down or failure
> thus isolating the aux battery and preserving contained
> energy for a specific task.
>
> The product being discussed appears to perform in
> precisely the same manner where it's desirable
> to isolate a RV vehicle battery from recreational
> electro-whizzies battery unless the alternator
> is available to service BOTH batteries.
>
> This is a PARTICULAR case where the recreational
> battery is EXPECTED to be deeply discharged. Now,
> if the vehicle battery has not been abused while
> parked, then the bus is expected to rise above
> 13.0 (or 13.2) volts seconds after the engine
> starts. This device would spare the alternator
> from "high stress" loads only if BOTH batteries are
> deeply discharged. But even then, I can't imagine
> that the bus will stay below 13.2 volts for very
> long even if the vehicle battery was drawn down
> completely and the engine was started with jumper cables.
>
> Finally, irrespective of number of batteries and
> no matter how you've abused the batteries, your
> alternator should be EXPECTED to happily deliver
> full rated output for an indefinite period of time.
> If not, there's something wrong with the selection
> of alternator or the manner in which it has been
> installed.
>
> Bob . . .
>
>
Message 9
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Subject: | Re: Switchology Question |
> You won't see any output from the SD-8 without being
> well above 2000 rpm.
This caught me off guard and triggered me to look at the specs on the
B&C website.
I often cruise at 2200rpm.
Their web site says that for a Lycoming engine, the vacuum pad runs
1.3:1 compared to the crankshaft.
So at 2200 rpm, the SD-8 is turning 2860 rpm.
Interpolating their chart idicates about 6A at that speed.
While idling, I will get a low voltage indication on my aux bus that I
hadn't anticipated. Perhaps I should be considering an SD-20.
Jeff Page
Dream Aircraft Tundra #10
Message 10
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Subject: | Dual Battery Contactor |
Chris,
As Bob noted, the alternator will continue to output at its rated capacity as long
as the regulator is demanding it. Each alternator should be able to run at
its rated capacity for N hours before failing (some calculus test performed at
the factory).
The bigger question is what are you doing in your cockpit while you are waiting
for the alternator to explode and your bus architecture to melt down? Answer,
you should be activating your fire gear. No, a diode won't immediately melt if
you drop to 8 volts, but by then you should have your contingency plan in action.
Should you experience 1 or more failures in any situation, you should start
shedding load and if the alternator seems to be a problem, shut it down.
Two heads are better than one and one good battery and two alternators are better
than 2-3 batteries any day.
Glenn
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Chris Stone
Sent: Tuesday, December 08, 2009 1:20 PM
Subject: Re: AeroElectric-List: Dual Battery Contactor
This brings to mind a question as to what happens to the alternator when the load
placed on it exceeds it's output capacity? Will the output voltage start to
drop as capacity is exceeded? If overload is continued are the diodes the weak
link in the chain? Will the diodes fail before overheating of the stator
windings? What is the common failure mode?
Chris Stone
RV-8
-----Original Message-----
>From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
>Sent: Dec 8, 2009 11:55 AM
>To: aeroelectric-list@matronics.com
>Subject: Re: AeroElectric-List: Dual Battery Contactor
>
>
>At 05:34 PM 12/7/2009, you wrote:
>
>Chris,
>Thanks for the tip and lead on a great solution for preserving
>alternators from high stress loads...
>
> Not sure there is "benefit" to be realized for shielding
> an alternator from "high stress" loads.
>
> As converters of mechanical to electrical energy, these
> devices have specifications. They also tend to be designed
> for a particular marketplace task. The prudent designers,
> manufacturers and installers of such devices understand the
> capabilities and limits. That understanding is factored
> into satisfaction of design goals and establishment
> of maintenance programs.
>
> Subscribing to the notion of "stress mitigation" on
> an alternator by programming the manner in which loads
> are applied to the machine suggests that design goals,
> capabilities and limits are suspect or perhaps known
> to be poorly married.
>
> The aux battery management module for OBAM aircraft was
> first proposed in an article I wrote for Sport Aviation
> many moons ago. The intent of this device was to provide
> automatic management of an auxiliary battery included
> to power flight critical electro-whizzies. The ABMM
> prevented connection of the aux battery to the system
> unless bus voltage was high enough to avoid discharging
> the battery (i.e. alternator on line). Hence the 13.0
> volt switchpoint calibration for closing the contactor.
> The corollary idea was that the ABMM opens the contactor
> automatically during alternator shut down or failure
> thus isolating the aux battery and preserving contained
> energy for a specific task.
>
> The product being discussed appears to perform in
> precisely the same manner where it's desirable
> to isolate a RV vehicle battery from recreational
> electro-whizzies battery unless the alternator
> is available to service BOTH batteries.
>
> This is a PARTICULAR case where the recreational
> battery is EXPECTED to be deeply discharged. Now,
> if the vehicle battery has not been abused while
> parked, then the bus is expected to rise above
> 13.0 (or 13.2) volts seconds after the engine
> starts. This device would spare the alternator
> from "high stress" loads only if BOTH batteries are
> deeply discharged. But even then, I can't imagine
> that the bus will stay below 13.2 volts for very
> long even if the vehicle battery was drawn down
> completely and the engine was started with jumper cables.
>
> Finally, irrespective of number of batteries and
> no matter how you've abused the batteries, your
> alternator should be EXPECTED to happily deliver
> full rated output for an indefinite period of time.
> If not, there's something wrong with the selection
> of alternator or the manner in which it has been
> installed.
>
> Bob . . .
>
>
Message 11
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Subject: | Re: Who Has Got The Time? |
Good Afternoon OC,
I tried to make the same point when this message first surfaced, but no one
seems to care! <G>
Such is life.
Happy Skies,
Old Bob
In a message dated 12/8/2009 7:11:53 A.M. Central Standard Time,
bakerocb@cox.net writes:
--> AeroElectric-List message posted by: <bakerocb@cox.net>
12/6/2009 (and again on 11/8/2009)
Hello Fellow Pilots and Builders, The aeroelectric list has been filled
lately with discussions of hardware (meters) that keep track of time. Just
exactly what time is being kept, and for what purpose, is unclear. To shed
some light on the subject let's start by taking a look at what 14 CFR
(FAR's) say about time.
We'll take flight time first, then TIS (Time In Service):
1) Here is how pilot flight time is defined in section 1.1 of the FAR's :
"Flight time means: Pilot time that commences when an aircraft moves under
its own power for the purpose of flight and ends when the aircraft comes to
rest after landing;"
I am not aware of any meter that could keep accurate track of such time.
You'll find many pilots, and airlines, that do not keep track of flight /
pilot time in conformance with this definition. Standard compliance by all
pilots with this definition is unlikely because there is room for
interpretation.
Does "moves under its own power for the purpose of flight" mean the instant
the wheels start to roll as you leave the parking space in order to go
flying? Then that XXX minutes plus that you spend taxiing, doing engine run
up, and waiting for takeoff clearance at the end of the runway, would all
be
flight time. Considering the delays involved in operating at some airports
one could become a multi thousand hour flight time pilot very quickly using
that interpretation.
On the other hand one is certainly exercising some very important PIC
duties
from the time he leaves the parking space until starting takeoff roll.
Should all of that time be ignored and not recognized in some fashion?
2) Here is how section 1.1 of FAR's defines TIS (Time In Service):
"Time in service, with respect to maintenance time records, means the time
from the moment an aircraft leaves the surface of the earth until it
touches
it at the next point of landing."
I suppose that there is hardware that could record this exact time, but it
certainly is not in common use in our category of airplanes.
So let's take a look at three common timing devices: the Hobbs meter, the
mechanical engine RPM based tachometer, and the software associated with
electronic flight instrumentation or engine instrumentation:
A) The Hobbs meter (you can look here for a quick review):
http://en.wikipedia.org/wiki/Hobbs_meter
It doesn't take very long to conclude that "Hobbs meter" has become a very
generic term (like Kleenex or Scotch tape) and that Hobbs meters come in
wide varieties and can be connected to record a wide variety of time. I
guess it is possible for a Hobbs meter to be connected up so that it
records
one of the time definitions in the FAR's, but it doesn't seem easy.
B) FAR 91.205 (a) and (b) require an engine tachometer to be installed in
any powered standard category civil aircraft even for day VFR operations.
By
far the most common type of tachometer found is the mechanical RPM based
tachometer. Presumably the purpose of the required tachometer is to inform
the pilot of his engine's RPM at any given instant, but somewhere along the
line these tachometers began including the total time of engine operation.
This required someone to decide how to convert instantaneous RPM into total
elapsed time of engine operation.
If, say 2,000 RPM were chosen as the standard mechanical ratio to convert
one minute at this RPM into one minute of elapsed engine operating time
then
any engine operation at less than 2,000 RPM generates less than one minute
of elapsed engine operating time and any RPM greater than 2,000 generates
more than one minute of elapsed engine operating time. See some of the
tachometer conversion ratios between RPM and time available here:
http://tghaviation.rtrk.com/?scid=387399&kw=3649251
In any case it does not appear that any mechanical engine tachometer can
generate either of the elapsed times defined by the FAR's.
C) There is such a huge variety of electronic flight and engine
instrumentation systems and their associated software (and the ability of
the operator to modify the software in some cases) that any accurate
comparison of one airplane's / engine's / pilot's time to another
airplane's
/ engine's / pilot's time would require some detailed examination of the
processes used to generate that time.
Again the probability that an electronic system would automatically
generate
elapsed time in exact compliance with either of the FAR time definitions is
not likely.
So what is the builder / pilot to do? My suggestions:
a) Don't get all wrapped around the axle about generating time. Many
people
are not recording flight time or time in service the same way that you are.
b) Pick some hardware and a system of documentation that seems to fit your
needs and go with it.
c) Be consistent in how you do things so that you can view and show the
results with some confidence.
d) Be wary of someone else's time claims, but don't make a big deal of time
unless you are billing by the hour.
'OC' Says: "The best investment we can make is the effort to gather and
understand knowledge."
PS: My choice for my airplane was just to record "Tach time" from my engine
electronic data system for both flight time and TIS. My engine data system
generates zero
tach time anytime the engine RPM is less than 1,500 RPM and constant equal
running time in hours and tenths any time the engine RPM is above 1,500
RPM.
Recording this time for both flight time and TIS short changes me on pilot
flight time since a fair amount of time while practicing landings in the
landing pattern the engine is below 1,500 RPM. On
the other hand it will take much longer elapsed time for my engine to reach
its 2,000 hour TIS to be due for overhaul. This approach greatly simplifies
my bookkeeping.
Back when I was flying rental aircraft I just went with the flow and used
the FBO's Hobbs meter time for flight time -- I paid for it, I should be
able to log it.
Message 12
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Subject: | Re: Who Has Got The Time? |
Old Bob and OC,
I read both your posts and appreciate the time spent to write them.
Guess I should have said something. Problem is, then I'd have to write
every day! This list is a great resource and I for one appreciate being
able to lurk while others solve problems and present a variety of
opinions and solutions. I'm sure I'm not the only one. Both of you and
everyone else, PLEASE continue posting, there's a lot of us out here
reading them.
Raymond Julian
Kettle River, MN.
do not archive
BobsV35B@aol.com wrote:
> Good Afternoon OC,
>
> I tried to make the same point when this message first surfaced, but no
> one seems to care! <G>
>
> Such is life.
>
> Happy Skies,
>
> Old Bob
>
> In a message dated 12/8/2009 7:11:53 A.M. Central Standard Time,
> bakerocb@cox.net writes:
>
>
> 12/6/2009 (and again on 11/8/2009)
>
> Hello Fellow Pilots and Builders, The aeroelectric list has been filled
> lately with discussions of hardware (meters) that keep track of
> time. Just
> exactly what time is being kept, and for what purpose, is unclear.
> To shed
> some light on the subject let's start by taking a look at what 14 CFR
> (FAR's) say about time.
>
> We'll take flight time first, then TIS (Time In Service):
>
> 1) Here is how pilot flight time is defined in section 1.1 of the
> FAR's :
>
> "Flight time means: Pilot time that commences when an aircraft moves
> under
> its own power for the purpose of flight and ends when the aircraft
> comes to
> rest after landing;"
>
> I am not aware of any meter that could keep accurate track of such time.
> You'll find many pilots, and airlines, that do not keep track of
> flight /
> pilot time in conformance with this definition. Standard compliance
> by all
> pilots with this definition is unlikely because there is room for
> interpretation.
>
> Does "moves under its own power for the purpose of flight" mean the
> instant
> the wheels start to roll as you leave the parking space in order to go
> flying? Then that XXX minutes plus that you spend taxiing, doing
> engine run
> up, and waiting for takeoff clearance at the end of the runway,
> would all be
> flight time. Considering the delays involved in operating at some
> airports
> one could become a multi thousand hour flight time pilot very
> quickly using
> that interpretation.
>
> On the other hand one is certainly exercising some very important
> PIC duties
> from the time he leaves the parking space until starting takeoff roll.
> Should all of that time be ignored and not recognized in some fashion?
>
> 2) Here is how section 1.1 of FAR's defines TIS (Time In Service):
>
> "Time in service, with respect to maintenance time records, means
> the time
> from the moment an aircraft leaves the surface of the earth until it
> touches
> it at the next point of landing."
>
> I suppose that there is hardware that could record this exact time,
> but it
> certainly is not in common use in our category of airplanes.
>
> So let's take a look at three common timing devices: the Hobbs
> meter, the
> mechanical engine RPM based tachometer, and the software associated with
> electronic flight instrumentation or engine instrumentation:
>
> A) The Hobbs meter (you can look here for a quick review):
>
> http://en.wikipedia.org/wiki/Hobbs_meter
>
> It doesn't take very long to conclude that "Hobbs meter" has become
> a very
> generic term (like Kleenex or Scotch tape) and that Hobbs meters come in
> wide varieties and can be connected to record a wide variety of time. I
> guess it is possible for a Hobbs meter to be connected up so that it
> records
> one of the time definitions in the FAR's, but it doesn't seem easy.
>
> B) FAR 91.205 (a) and (b) require an engine tachometer to be
> installed in
> any powered standard category civil aircraft even for day VFR
> operations. By
> far the most common type of tachometer found is the mechanical RPM based
> tachometer. Presumably the purpose of the required tachometer is to
> inform
> the pilot of his engine's RPM at any given instant, but somewhere
> along the
> line these tachometers began including the total time of engine
> operation.
> This required someone to decide how to convert instantaneous RPM
> into total
> elapsed time of engine operation.
>
> If, say 2,000 RPM were chosen as the standard mechanical ratio to
> convert
> one minute at this RPM into one minute of elapsed engine operating
> time then
> any engine operation at less than 2,000 RPM generates less than one
> minute
> of elapsed engine operating time and any RPM greater than 2,000
> generates
> more than one minute of elapsed engine operating time. See some of the
> tachometer conversion ratios between RPM and time available here:
>
> http://tghaviation.rtrk.com/?scid=387399&kw=3649251
>
> In any case it does not appear that any mechanical engine tachometer can
> generate either of the elapsed times defined by the FAR's.
>
> C) There is such a huge variety of electronic flight and engine
> instrumentation systems and their associated software (and the
> ability of
> the operator to modify the software in some cases) that any accurate
> comparison of one airplane's / engine's / pilot's time to another
> airplane's
> / engine's / pilot's time would require some detailed examination of the
> processes used to generate that time.
>
> Again the probability that an electronic system would automatically
> generate
> elapsed time in exact compliance with either of the FAR time
> definitions is
> not likely.
>
> So what is the builder / pilot to do? My suggestions:
>
> a) Don't get all wrapped around the axle about generating time. Many
> people
> are not recording flight time or time in service the same way that
> you are.
>
> b) Pick some hardware and a system of documentation that seems to
> fit your
> needs and go with it.
>
> c) Be consistent in how you do things so that you can view and show the
> results with some confidence.
>
> d) Be wary of someone else's time claims, but don't make a big deal
> of time
> unless you are billing by the hour.
>
> 'OC' Says: "The best investment we can make is the effort to gather and
> understand knowledge."
>
> PS: My choice for my airplane was just to record "Tach time" from my
> engine
> electronic data system for both flight time and TIS. My engine data
> system
> generates zero
> tach time anytime the engine RPM is less than 1,500 RPM and constant
> equal
> running time in hours and tenths any time the engine RPM is above
> 1,500 RPM.
>
> Recording this time for both flight time and TIS short changes me on
> pilot
> flight time since a fair amount of time while practicing landings in the
> landing pattern the engine is below 1,500 RPM. On
> the other hand it will take much longer elapsed time for my engine
> to reach
> its 2,000 hour TIS to be due for overhaul. This approach greatly
> simplifies
> my bookkeeping.
>
> Back when I was flying rental aircraft I just went with the flow and
> used
> the FBO's Hobbs meter time for flight time -- I paid for it, I should be
> able to log ========================= nbsp; (And Get Some
> AWESOME FREE to find Gifts tric re b k you for p;
> -Matt Dralle, List ======================== = Use utilities Day
> ================================================ -
> MATRONICS WEB FORUMS =================================================
>
>
>
> *
>
>
> *
Message 13
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Subject: | Re: Who Has Got The Time? |
At 04:32 PM 12/8/2009, you wrote:
>
>Old Bob and OC,
>
>I read both your posts and appreciate the time spent to write them.
>Guess I should have said something. Problem is, then I'd have to
>write every day! This list is a great resource and I for one
>appreciate being able to lurk while others solve problems and
>present a variety of opinions and solutions. I'm sure I'm not the
>only one. Both of you and everyone else, PLEASE continue posting,
>there's a lot of us out here reading them.
In our own self-interested way, we're participants and
exploiters of what Thomas Friedman has identified as a
constellation of forces that are "flattening the world". See:
http://future.iftf.org/2006/05/thomas_friedman.html
for a brief peek at his thinking.
When EAA was but a gleam in Father Paul's eye,
what we knew and could learn about this hobby we
cherish came through narrow pipes of communication
with barely enough content and clarity to get a
VW powered Headwind flying.
35 years later we find ourselves members of a
world wide community that successfully builds and flies
aircraft that rival (if not surpasses) the cost-
performance figures for the highly touted
production machines. Mr. Friedman has astutely
identified a combination of milestones in our
planet's culture that made this all possible.
Here on the Matronics lists and elsewhere, folks
have an opportunity to tap the time, talents and
resources of thousands of fellow travelers in the
world of OBAM aviation. It grew up not by any
particular grand plan but spontaneously as the
Ten Great Flattenters evolved.
We live in fascinating times of unprecedented
opportunity. We would do well by ourselves and
our children not to screw it up . . . or let anyone
else screw it up either.
Bob . . .
Message 14
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Subject: | Dual Battery Contactor |
At 02:40 PM 12/8/2009, you wrote:
>
>Chris,
>
>As Bob noted, the alternator will continue to output at its rated
>capacity as long as the regulator is demanding it. Each alternator
>should be able to run at its rated capacity for N hours before
>failing (some calculus test performed at the factory).
In the aviation world we test alternators/generators/motors to rated
loads and worst case temperatures to meet specifications. If the customer
observes published limits, they have a high probability of seeing
the laboratory experience repeated in the field.
>The bigger question is what are you doing in your cockpit while you
>are waiting for the alternator to explode and your bus architecture
>to melt down? Answer, you should be activating your fire gear. No, a
>diode won't immediately melt if you drop to 8 volts, but by then you
>should have your contingency plan in action. Should you experience 1
>or more failures in any situation, you should start shedding load
>and if the alternator seems to be a problem, shut it down.
>
>Two heads are better than one and one good battery and two
>alternators are better than 2-3 batteries any day.
Exactly. I'll re-enforce that idea with the notion that
except for unanticipated failure, NOTHING that goes on
in your electrical system should be a surprise. I've written
often about failure mode effects analysis wherein all
normal and abnormal operating conditions are deduced,
studied for deleterious effect to be mitigated by design.
The ONLY way you're going to beat the @#$@# out of your
alternator is to jump-start with a DEAD battery and
then launch into the blue with all your electro-whizzies
turned on. Until the battery's recharge demands begin to
taper, the alternator will be running flat-out. The duration
of this event is generally a few tens of minutes at the
most. All other times, I would hope that the builder has
PREDICTED what loads can be serviced under any/all
conditions and is operating the airplane accordingly.
Chapter 17 in the 'Connection speaks to this process
in detail. I've also suggested that the hierarchy of
importance for surviving the flight experience stacks
up like this:(a) airframe, (b) owner/builder/pilot
(c) powerplant (d) all other things.
The significance of the second item goes far beyond
the knowledge and skills needed AFTER the wheels are
up. There is a great deal that can be done in the
craftsmanship, understanding and decisions made long
before the airplane leaves the shop . . . like due
diligence to the study of category (d).
Bob . . .
>Glenn
>
>
>-----Original Message-----
>From: owner-aeroelectric-list-server@matronics.com
>[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Chris Stone
>Sent: Tuesday, December 08, 2009 1:20 PM
>To: aeroelectric-list@matronics.com
>Subject: Re: AeroElectric-List: Dual Battery Contactor
>
>
>
>This brings to mind a question as to what happens to the alternator
>when the load placed on it exceeds it's output capacity? Will the
>output voltage start to drop as capacity is exceeded? If overload
>is continued are the diodes the weak link in the chain? Will the
>diodes fail before overheating of the stator windings? What is the
>common failure mode?
>
>Chris Stone
>RV-8
>
>-----Original Message-----
> >From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
> >Sent: Dec 8, 2009 11:55 AM
> >To: aeroelectric-list@matronics.com
> >Subject: Re: AeroElectric-List: Dual Battery Contactor
> >
> <nuckolls.bob@aeroelectric.com>
> >
> >At 05:34 PM 12/7/2009, you wrote:
> <skywagon@charter.net>
> >
> >Chris,
> >Thanks for the tip and lead on a great solution for preserving
> >alternators from high stress loads...
> >
> > Not sure there is "benefit" to be realized for shielding
> > an alternator from "high stress" loads.
> >
> > As converters of mechanical to electrical energy, these
> > devices have specifications. They also tend to be designed
> > for a particular marketplace task. The prudent designers,
> > manufacturers and installers of such devices understand the
> > capabilities and limits. That understanding is factored
> > into satisfaction of design goals and establishment
> > of maintenance programs.
> >
> > Subscribing to the notion of "stress mitigation" on
> > an alternator by programming the manner in which loads
> > are applied to the machine suggests that design goals,
> > capabilities and limits are suspect or perhaps known
> > to be poorly married.
> >
> > The aux battery management module for OBAM aircraft was
> > first proposed in an article I wrote for Sport Aviation
> > many moons ago. The intent of this device was to provide
> > automatic management of an auxiliary battery included
> > to power flight critical electro-whizzies. The ABMM
> > prevented connection of the aux battery to the system
> > unless bus voltage was high enough to avoid discharging
> > the battery (i.e. alternator on line). Hence the 13.0
> > volt switchpoint calibration for closing the contactor.
> > The corollary idea was that the ABMM opens the contactor
> > automatically during alternator shut down or failure
> > thus isolating the aux battery and preserving contained
> > energy for a specific task.
> >
> > The product being discussed appears to perform in
> > precisely the same manner where it's desirable
> > to isolate a RV vehicle battery from recreational
> > electro-whizzies battery unless the alternator
> > is available to service BOTH batteries.
> >
> > This is a PARTICULAR case where the recreational
> > battery is EXPECTED to be deeply discharged. Now,
> > if the vehicle battery has not been abused while
> > parked, then the bus is expected to rise above
> > 13.0 (or 13.2) volts seconds after the engine
> > starts. This device would spare the alternator
> > from "high stress" loads only if BOTH batteries are
> > deeply discharged. But even then, I can't imagine
> > that the bus will stay below 13.2 volts for very
> > long even if the vehicle battery was drawn down
> > completely and the engine was started with jumper cables.
> >
> > Finally, irrespective of number of batteries and
> > no matter how you've abused the batteries, your
> > alternator should be EXPECTED to happily deliver
> > full rated output for an indefinite period of time.
> > If not, there's something wrong with the selection
> > of alternator or the manner in which it has been
> > installed.
> >
> > Bob . . .
> >
> >
> >
> >
> >
>
>
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 15
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This is off the airplane subject, but concerns electricity and I don't know
where to find a more knowledgeable group.
I was shown a device today called the Power Mizer which is supposed to be a
capacitor that will reduce the current draw of inductive devices. An
electric motor pulled about 10A on startup and then settled down to about 6A
without the device turned on. With it on, the start up draw dropped to
about 5A and the steady state draw to about 2.4A.
This makes no sense to me. I smell a rat. Check out this video and let me
know if this is hogwash.
You can contact me off line to keep the traffic down on the list.
http://www.youtube.com/watch?v=YMZjWkbF9bQ&feature=related
Thanks for the assistance.
Bill B
Message 16
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I don't think this is a new idea.. Power factor correction is probably
nearly as old as AC power distribution.
There's a fairly good description of power factor correction on the
Wikipedia page:
http://en.wikipedia.org/wiki/Power_factor
Regards,
Matt-
> <bbradburry@bellsouth.net>
>
> This is off the airplane subject, but concerns electricity and I don't
> know
> where to find a more knowledgeable group.
> I was shown a device today called the Power Mizer which is supposed to be
> a
> capacitor that will reduce the current draw of inductive devices. An
> electric motor pulled about 10A on startup and then settled down to about
> 6A
> without the device turned on. With it on, the start up draw dropped to
> about 5A and the steady state draw to about 2.4A.
> This makes no sense to me. I smell a rat. Check out this video and let
> me
> know if this is hogwash.
>
> You can contact me off line to keep the traffic down on the list.
>
> http://www.youtube.com/watch?v=YMZjWkbF9bQ&feature=related
>
> Thanks for the assistance.
>
> Bill B
>
>
Message 17
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>I smell a rat. Check out this video and let me
>know if this is hogwash.
It depends . . . but your skepticism is not unwarranted.
In the DC power world of our airplanes, the power system
is very UNdynamic. I.e. relatively steady state levels
of voltage and current. For our purposes, Watts of beneficial
power is simply a matter of multiplying volts x amps. In
the AC world, it doesn't HAVE to be more difficult. The
lowly incandescent lamp and heaters in your water heater
do not present a highly reactive load on the power source.
As soon as you wrap wires around cores of magnetic materials,
'stuff' happens. The counter EMF of magnetic fields building
in cores will lag behind the applied voltage thus causing
current to no longer be in phase with the applied voltage.
Apparent power is still volts x amps. But true power
consumed is multiplied by the cosine of the difference
in phase angles between current and voltage to produce
a correction value or "power factor".
The BIG downside of powering large loads of poor
power factor is that the WIRE size in the motor, sizes
of breakers, feeder wires, and wires in transformers
must be rated for apparent current. The industry uses
capacitors at judicious places throughout their distribution
systems and large users will use capacitors in their
installations to counteract the inductive components of
low power factor loads.
Watt-hour meters on the back of your house measure
true power consumed. I.e. they're corrected for any
differences between true and apparent power. Now, if your
house is plagued with lots of continuous duty, low power
factor loads, the overall system efficiency can be degraded
due to increased heating in the wiring needed to supply
the SAME amount of energy to the working task.
The demonstration in the video was with an unloaded
motor which has decidedly different characteristics
compared with a motor that is loaded to name-plate
rated horsepower. Hence the demonstration was bogus.
Further, measurement of current alone is NOT a true
indication of system efficiency.
I've written to the company to see if they'll share
a engineering report on the testing claimed in their
promotional videos and literature. I'm betting that they
won't.
Bottom line is that while adding capacitors to a
system with a lagging power factor will increase
the ohmic efficiency (let you get the same energy
out the other end of the wire at slightly less
current . . . and I DO mean slightly) it won't
have more than a similarly slight effect on your
light bill.
See:
http://tinyurl.com/yln6gwv
A few years back there was a big "gee whiz" promotion
on devices that would "save you a gazillion dollars"
that were inserted in a line between the
wall plug and appliance. I've not seen those critters
being hyped lately . . . I think they're out of
fashion.
Bob . . .
Message 18
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Subject: | Re: Lopresti HID claims |
Eric M. Jones wrote:
> Thanks,
> Photometric units contain plenty of traps for the unwary.
>
> BTW: "Cree Achieves 186 Lumens per Watt from a High-Power LED
> High-performance chip and R&D package combine for record-setting efficacy"
>
> Amazing.
Yes, I agree with your first comment.
The 2nd is likely at lower drive levels, they (LED's) "droop" typically at higher
drive levels.
We are watching the LED technology very closely. We work with Cree high powered
LED's in our flashlight offerings. LED can make a very good taxi light now, but
to collimate it for a landing light is still a big hurdle.
It still has a way to go to compete with HID for landing lights. Especially 50
watt or 75 watt HID as we now have, 5300 and 8300 Lumens output each respectively.
35 watt HID produces about 3200 lumens compared to ~1600 lumens from a 100
watt incandescent such as the well known GE4509, very common in light single
and twins. Also the 24/28 volt version of the same 100 watt lamp, the same 1600
lumens.
The 250 watt sealed beam incandescent aircraft lamps produce almost the same lumens
as a 35 watt HID.
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LED still has a long way to go to compete with HID as a landing light. This is
true in terms of total lumens and reach (distance).
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http://forums.matronics.com/viewtopic.php?p=276789#276789
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