Today's Message Index:
----------------------
1. 02:10 AM - Relay Diodes and OVM Modules (Andrew Butler)
2. 04:25 AM - Re: Re: Icom 200 (luigit@freemail.it)
3. 06:14 AM - Re: Re: Icom 200 (Daniel De Winter)
4. 07:17 AM - Re: Re: Calibrating fuel qty gauges (Hinde, Frank George (Corvallis))
5. 08:06 AM - Re: Re: Calibrating fuel qty gauges (BobsV35B@aol.com)
6. 08:48 AM - Re: Re: Calibrating fuel qty gauges (Hinde, Frank George (Corvallis))
7. 09:11 AM - Two fuses in series? (Sam Hoskins)
8. 09:25 AM - Re: Re: Calibrating fuel qty gauges (BobsV35B@aol.com)
9. 09:39 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
10. 10:06 AM - Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 (Speedy11@aol.com)
11. 10:26 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
12. 10:35 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
13. 10:52 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
14. 10:57 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
15. 11:05 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
16. 11:11 AM - Re: Calibrating fuel qty gauges (Speedy11@aol.com)
17. 11:23 AM - Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 (Speedy11@aol.com)
18. 11:32 AM - Re: Re: Calibrating fuel qty gauges (Bruce Gray)
19. 12:23 PM - Re: Re: Calibrating fuel qty gauges (Hinde, Frank George (Corvallis))
20. 12:42 PM - Re: Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 (Ernest Christley)
21. 12:51 PM - Re: Re: Calibrating fuel qty gauges (BobsV35B@aol.com)
22. 12:55 PM - Re: Re: Calibrating fuel qty gauges (BobsV35B@aol.com)
23. 01:46 PM - Re: Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 (Matt Prather)
24. 01:59 PM - Re: Why3 different alt disconnect relay wiring in Z schematics (messydeer)
25. 05:44 PM - Re: Re: Calibrating fuel qty gauges (Robert L. Nuckolls, III)
26. 06:10 PM - Re: Re: Why3 different alt disconnect relay wiring in Z schematics (Robert L. Nuckolls, III)
27. 07:23 PM - Re: Why3 different alt disconnect relay wiring in Z schematics (messydeer)
28. 07:24 PM - Re: Re: Calibrating fuel qty gauges (Robert L. Nuckolls, III)
29. 07:31 PM - Re: Two fuses in series? (Robert L. Nuckolls, III)
30. 07:35 PM - Re: Why3 different alt disconnect relay wiring in Z schematics (messydeer)
31. 07:48 PM - Re: Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 (Robert L. Nuckolls, III)
32. 07:53 PM - Re: Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 (Robert L. Nuckolls, III)
33. 08:19 PM - Re: Two fuses in series? (Sam Hoskins)
34. 09:21 PM - Re: Re: Calibrating fuel qty gauges (BobsV35B@aol.com)
35. 11:42 PM - Re: Two fuses in series? (Jay Hyde)
Message 1
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| Subject: | Relay Diodes and OVM Modules |
Hello,
Self excitation is built into Z13-8Q. There are two 1N5400 diodes attached to the
relay. One is in series with the coil. What is the purpose of having a diode
here instead of just a piece of wire? I have wired up mine with this diode in
place.
It appears to be linked to the presence of the Crowbar Overvoltage Module in parallel
with the relay coil, as the same set-up is depicted in other drawings where
it is employed (Z21A & Z31).
I have been queried as to why I have used a diode here (I basically followed the
drawings) and I am unable to answer. Can someone help me understand the physics
here so that I can come up with a meaningful answer.
Best regards,
Andrew Butler,
RV7 EI-EEO
Galway, Ireland.
Firewall Forward and wiring tidy up!
Message 2
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Message 3
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Luigi,=0A=0Ais this in your Esqual?=0A=0ADDW=0AEsqual=0A=0A=0A_____________
___________________=0AFrom: "luigit@freemail.it" <luigit@freemail.it>=0ATo:
aeroelectric-list@matronics.com; aeroelectric-list@matronics.com=0ASent: F
riday, 14 August, 2009 13:22:23=0ASubject: Re: AeroElectric-List: Re: Icom
=0AThank you Ralph.=0AI checked again the whole system with no results.=0AT
he connections on the molex are right.=0AIf you blow in the mike you can he
ar a weak answer in the earphone-but nothing else.=0AI tried to measure t
he resistance of the microphone while speaking but I don't see any change i
n value shown.=0AThe checks continue.=0AWhen I will obtain any result, -I
'll keep you informed.=0AGreetings from the-old world in a sunny day.=0AL
uigi=0ARome, Italy=0Ap.s.: the first check I made-was to install the radi
o on another plane. It works- in both ways.=0A- . =0A=0A=0A-------- =0A
Ralph - CH701 / 2200a =0A=0A=0A=0A=0ARead this topic online here: =0A=0Ahtt
p://forums.matronics.com/viewtopic.php?p=257443#257443 =0A=0A=0A=0A=0A=0A
=0A=0A=0A=0A=0A=0A=0A=0A--- Dada Music Movement, tutta la musica che vuoi!
========0A=0A=0A
Message 4
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| Subject: | Re: Calibrating fuel qty gauges |
Hmm..would seem I stand corrected here..and your right I have never flown behind
one.
OK I'll stand behind my fuel flow computer function in mt Dynon EMS then..that
is deadly accurate..as long as as I don't get a tank leak at least..:)
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of John Morgensen
Sent: Thursday, August 13, 2009 3:25 PM
Subject: Re: AeroElectric-List: Re: Calibrating fuel qty gauges
--> <john@morgensen.com>
Hinde, Frank George (Corvallis) wrote:
> --> (Corvallis)" <frank.hinde@hp.com>
>
> The only level guge I would rely on would be a sight tube, which cannot lie.
>
I am going to go out on a limb here and guess that you have never enjoyed flying
a Grumman Yankee with 11 gallons in each wing and an O-320. :-)
John Morgensen
RV4
Grumman AA1B-150 (For Sale)
RV9A (wiring)
Message 5
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| Subject: | Re: Calibrating fuel qty gauges |
Good Morning Frank,
Is the Dynon unit a fuel flow gauge or a fuel tank gauge?
The Dynon Fuel flow gauge in our grandaughter's homebuilt Legend Cub works
just as good as do the Shadin's we have in our certifed machines. The fuel
gauge in the Cub is a sight tube and is not worth much at all.
With only nineteen gallons of total fuel capacity, the fuel flow gauge and
totalizer is a very important tool when she flies her Cub from Palo Alto to
Oshkosh and back.
Happy Skies,
Old Bob
In a message dated 8/14/2009 9:19:15 A.M. Central Daylight Time,
frank.hinde@hp.com writes:
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)"
<frank.hinde@hp.com>
Hmm..would seem I stand corrected here..and your right I have never flown
behind one.
OK I'll stand behind my fuel flow computer function in mt Dynon EMS
then..that is deadly accurate..as long as as I don't get a tank leak at least..:)
Frank
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of John Morgensen
Sent: Thursday, August 13, 2009 3:25 PM
Subject: Re: AeroElectric-List: Re: Calibrating fuel qty gauges
--> <john@morgensen.com>
Hinde, Frank George (Corvallis) wrote:
> --> (Corvallis)" <frank.hinde@hp.com>
>
> The only level guge I would rely on would be a sight tube, which cannot
lie.
>
I am going to go out on a limb here and guess that you have never enjoyed
flying a Grumman Yankee with 11 gallons in each wing and an O-320. :-)
John Morgensen
RV4
Grumman AA1B-150 (For Sale)
RV9A (wiring)
Message 6
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| Subject: | Re: Calibrating fuel qty gauges |
The Dynon is actually both. Its an integrated engine managemnt system..in o
ther words it takes numerous inputs (CHT, EGIT, RPM, MP, OAT etc) into a si
ngle 4" screen on the PX side that is swapable to the EFIS on my side..you
can also swap the EFIS to the EMS to let the PX have a full flight deck..pr
etty slick.
Anyway, the flowmeter uses one of those little turbine units as the flow se
nsor in the line feeding the engine. The Dynon then counts the pulses to te
ll you have much fuel you have burned. It works the same way as a lot of th
e experimental fuel flow transducers.
The Van's standard resistive float tank senders appear to be pretty accurat
e too and these are also read by the Dynon...I'd never trust them fully tho
ugh.
Palo Alto to OSH and back in a CUB?..Woah, she has more patience than I do.
.:)
The RV cruises at about 160kts on roughly 7 gallons an hour of autofuel (I
can get that down to about 6.6GPH at 12 to 14k) ...And with 42 gallons I ca
n almost make western Oregon to Fort collins Colorado in one tankful..but t
hats a bit tight for my comfort margins and the Wife won't stay in the airp
lane for 5.5 hours...:)
Frank
________________________________
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr
ic-list-server@matronics.com] On Behalf Of BobsV35B@aol.com
Sent: Friday, August 14, 2009 7:55 AM
Subject: Re: AeroElectric-List: Re: Calibrating fuel qty gauges
Good Morning Frank,
Is the Dynon unit a fuel flow gauge or a fuel tank gauge?
The Dynon Fuel flow gauge in our grandaughter's homebuilt Legend Cub works
just as good as do the Shadin's we have in our certifed machines. The fuel
gauge in the Cub is a sight tube and is not worth much at all.
With only nineteen gallons of total fuel capacity, the fuel flow gauge and
totalizer is a very important tool when she flies her Cub from Palo Alto to
Oshkosh and back.
Happy Skies,
Old Bob
Message 7
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| Subject: | Two fuses in series? |
Is it ever logical to put two fuses in series? I am attaching a PDF. In
the lower center area of the drawing, look at the switch labeled ECU PWR &
Injectors.
The idea is, if the SYS A ECU should blow, I wouldn't want a common fuse
taking out the SYS B ECU. Or is there another way to do this without adding
anymore switches? Maybe a fuse link, back at the main battery bus?
I now have 9 test flights in and I'm still fighting oil temp and highly
experimental induction issues.
Thanks.
Sam
www.samhoskins.blogspot.com
Message 8
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| Subject: | Re: Calibrating fuel qty gauges |
Good Morning Frank,
Sounds like you have a similar fuel flow setup to what our granddaughter
has. Works great!
She finished the Cub just in time to take it to Sun n' Fun 2008. I helped
by putting twenty-five of the required forty hours on it before she and her
father took it to Florida. That same year, she flew it solo to Oshkosh and
she repeated that trip this year. Her Cub was on display at Kid Venture.
She averages about eighty-five to ninety MPH. Sure is a good time builder,
but a larger fuel capacity would be nice. Legend Cub is now offering bigger
fuel tanks.
Happy Skies,
Old Bob
In a message dated 8/14/2009 10:49:59 A.M. Central Daylight Time,
frank.hinde@hp.com writes:
Palo Alto to OSH and back in a CUB?..Woah, she has more patience than I
do..:)
Message 9
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| Subject: | Re: Calibrating fuel qty gauges |
Hmmm ... I hadn't considered a ground problem. Since I was getting some
readings (and output checked with meter) I had assumed the wiring to be
suitable. Maybe it's not.
I'll check.
Stan Sutterfield
Do not archive
Any chance of a bad ground or some other noise working its way into the
system? It doesn't sound like sloshing error, and maybe not a sensor
problem - though I don't know enough to rule that out. It also doesn't
sound like a calibration problem. I would stop calibrating as I don't
think it will fix the problem (until you fix the real problem).
Message 10
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| Subject: | Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 |
I appreciate the piloting technique advice. I've been using similar
techniques since '73.
I always strive to know my fuel amount before takeoff and monitor
consumption during flight. I know how to do those things.
What I'm searching for is accurate fuel sensors rather than advice on
piloting.
I don't need measurement to 1/10 gallon, but measurement to within 1 gallon
should be obtainable.
Ernest, there is nothing wrong with going to FAA minimums. I do it
frequently during instrument approaches. The FAA fuel minimums are designed to
provide a necessary buffer for additional flight time. There is nothing
wrong with flying to FAA minimums. If your logic of never approaching the FAA
minimums were adhered to, many aircraft would not be able to land out of
an instrument approach. Flying to the FAA fuel minimums is quite acceptable
- providing a suitable backup plan is in effect. By the way, who wrote
the "rules" you quoted? If they are your rules, then they are opinion for
the rest of us - rules for you.
I will continue to pursue accuracy in fuel measurement - perhaps in
futility. As I study the Princeton sensors and the AF-3400, I cannot logically
see why they would not work as designed. So, maybe my installation is the
problem. I'll check wiring again.
Stan Sutterfield
Do not archive
My EI FL-2CA fuel gauges come with the ability to select the "rate of
update" which solves one of the problems, but isn't the REAL problem
that one shouldn't be playing down in the "low fuel minefield" any way?
Why worry about how to tell exactly when you're going to run out of
fuel? I'd rather have really accurate gauges down to a quarter tank,
and then who cares, it's time to fill up.
An accurate stick with marks on it, and confidence in fuel consumption
rates, IMHO, are much more important than measuring fuel quantities near
empty, unless you have no access at all to a physical measurement of
fuel levels.
Maybe that is one more thing Heinlein should have added to his list of
things a man should know how to do: tell how much fuel is in a tank by
how wildly the indicator is bouncing.
First rule: If you are so worried about the fuel remaining that you
need to know within a tenth of a gallon, you need to be punching the
"nearest" button on your GPS...not stretching your glide to the
destination.
Second rule: If the guage is bouncing all over the place, you either
have fuel or the guage is broken. One of the first things we learned in
my high-school chemistry class was how to interpret a bouncing arm on a
triple-beam scale. If it bounced equally to both side of the center
mark, then it was balanced. With the fuel level indicator, if it is
bouncing around the top, proceed. If it bounces around the bottom,
punch "nearest" of call the fuel truck before launching.
Third rule: The FAA minimums are minimums, not a GOAL.
Message 11
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| Subject: | Re: Calibrating fuel qty gauges |
Old Bob,
My thoughts exactly. I'm too timid to express them because of getting
flamed on the forum.
But, you expressed my thoughts precisely. The T-38 was always flown to 20
minutes fuel remaining. We did the same in the F-4, F-5 and F-16. Once I
was chasing a F-16 student on initial solo and he landed, blew a tire and
closed the only runway at MacDill. My 20 minute reserve was quite
sufficient. Accel to 450 on the deck, climb at .87 to FL400 and do an idle descent
to final at Patrick. Still landed with plenty of fuel. The key is to
have a suitable back up plan. In custom built aircraft, we don't need the
ability to zoom climb to the moon - we simply need a suitable backup plan
should something go wrong with the primary plan. If the back plan is good,
then flying to FAA fuel minimums is fine.
I like to know how much fuel is on board at any given time. Then I can
make decisions based on that information. The quantity information can be
obtained from a number of sources - gauges, optical sensors with warning
lights, preflight measurement, engine monitor calculations, and my own
calculations.
I desire accurate fuel gauges. If the accuracy of my fuel gauges is
questionable, then I must err on the conservative side which means I cannot
utilize my aircraft to its optimum.
I agree with Old Bob on this subject.
Stan Sutterfield
Good Afternoon 'Lectric Bob,
This may be just an exercise in semantics, but I do disagree with the
philosophy I think you are espousing.
There is nothing wrong with planning on arriving at a safe landing spot
with ten to fifteen minutes of fuel as long as you are confident you will
be
at that spot at the appointed time.
To say we should always have something beyond what is required is too
broad
for my liking. On those few occasions when I had the pleasure of flying a
T-38, we landed every time with "Bingo" fuel. In that airplane, Bingo
fuel
was a bit less than twenty minutes worth. Good enough for one full power
go
around and not much more.
We pay a LOT of money for every pound of payload we put in our flying
machines. I think it is very rational to reduce the amount of fuel down to
what
is required for the mission at hand. My cross country flyer has tip tanks
and it can fairly easily fly twelve hours with full tanks. My planning
for
that airplane often has me arriving with less than one hours worth of
fuel.
If I was able to be as certain of landing field availability as I was
when
flying the T-38 and as confident as I was of the accuracy of the fuel
gauges, I would not hesitate to fly my long ranger down to a Bingo fuel
of
twenty minutes.
Back when I was doing sling work with a helicopter, we added fuel for each
trip lifting air conditioners to a roof top. Carrying no more than about
five minutes of reserve fuel, we managed to get more air conditioners per
day
up on top of those roofs. The reserve fuel planned on should be based on
the accuracy of the fuel indicating system and the reliability of the
landing estimate
To do otherwise is as foolish as asking that every airplane be fitted with
four engines just in case one of them happens to quit. We have decided
that
a good single engine provides adequate safety for many of us. The same
thing goes for carrying extra fuel. Every ounce we carry that is not
needed
for the task at hand costs us money and $time$.
I prefer to know how much fuel is on board and how much I want when I
land.
Just my thoughts
Happy Skies,
Old Bob
Message 12
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| Subject: | Re: Calibrating fuel qty gauges |
VERY well said!
Now if I could only get accurate fuel gauges.
Stan Sutterfield
Do not archive
Good Afternoon Old Ian,
If you are saying you disagree with my philosophy, that is just fine.
I rarely plan to arrive with only ten minutes of reserve fuel, but there
are conditions where I would be happy to do so. The T-38 flights at
Edwards
were just such flights.
My personal planning at the average multi runway airport is forty-five
minutes. If there is only one runway, I want a close by alternate and fuel
to
get there
It All Depends!
That is more than what the FAA requires, but it is what I like to have.
However, I do NOT wish to arrive anywhere without knowing accurately how
much
fuel I do have on board. If I know that amount due to careful timing or by
the trust I have in my fuel gauges, I still want to know the amount, not
just that there is an indeterminate large amount of fuel on board.
You speak quite sarcastically about an airplane that was arriving at
"your"
destination and who was not listening to your pronouncements on the radio.
We all must remember that it is still legal for aircraft that have no
radio
to be using most airspace in this nation. You may not think that is
proper, but if you are flying in pilot controlled airspace, you should
always
be
aware that it is quite likely that a NORDO aircraft may be sharing "your"
airspace.
The most likely cause of a NORDO conflict is when you or the pilot of the
other aircraft have made the error of not tuning the correct frequency,
flipping the right audio switch, pressing the wrong mike button or other
similar pilot failures of omission or commission. I know I have made all
of those
errors at one time or another. While I try very hard to reduce my errors,
I know that I am human and all of us humans do make mistakes. Not only
that, but radios DO fail.
That is what planning is all about. We plan what we need and how to handle
what we don't expect. Such planning requires careful analysis of the
conditions that prevail and that includes a good idea as to how much fuel
we have
at any particular moment. I do not wish to carry somewhere between three
to five hours of fuel when I have no idea which amount of fuel is
actually
in my flying machine.
Whether I plan on landing with ten minutes fuel or four hours fuel, I want
to know how much there is and where it is located.
Happy Skies,
Old Bob
Didn't get that way by making Wild Guesses!
Message 13
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| Subject: | Re: Calibrating fuel qty gauges |
Bob,
The pilots on this forum are every bit as capable as professional pilots -
including optimizing the amount of fuel on board. One simply must plan the
flight including a back up plan (maybe two or three), crosscheck himself
along the way, and execute the most appropriate of the plans - with Plan A
being primary.
Regarding using accurate fuel information of make high risk "press-on"
decisions, the pilot must consider all information before making a decision -
whether to press on or to divert. WX, alternate airports, terrain,
aircraft familiarity, airport familiarity, fatigue, and fuel quantity are all
inputs to the decision process. A decision to press on is not necessarily
exponentially higher risk than a diversion plan. In fact, it may be less risk
if the destination airport is familiar with a suitable length runway
whereas the divert airport is unfamiliar with a minimum length runway. There
are
many variables - one reason flying is fun.
Now about getting those accurate fuel gauges with which to make my divert
decision.
Stan Sutterfield
But keep in mind my friend that we're not here to
offer advice and training to professional pilots.
Only a small percentage of our 1800 readers fly for
a living and many if not most are under 300 hour
pilots.
.........
One may argue that having accurate fuel data
can trigger an early termination of flight to
avoid the unhappy day . . . but it can also
be combined with other data to make a press-on
decision with an exponential rise in risk.
Message 14
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| Subject: | Re: Calibrating fuel qty gauges |
Terry,
How about a visit from another builder next time I'm in Seattle? I'd like
to see your project.
Stan Sutterfield
_www.rv-8a.net_ (http://www.rv-8a.net)
Do not archive
My RV-8A, if it every gets finished, has low fuel warning lights similar
to
what Bob N. has described that I bought as a kit a few years ago. It
already
has capacitive gauges and a fuel flow sender.
Terry
RV-8A
Seattle
Message 15
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| Subject: | Re: Calibrating fuel qty gauges |
Absolutely correct.
Stan
Do not archive
Knowing where the edge is may increase the comfort of going close to the
edge, but not knowing where the edge is attempting to make decisions
with no reliable data.
In short, would we rather make decisions from hard facts, or soft
ambiguity. I would rather have precise knowledge of fuel quantity, and
then rely on discipline to plan appropriately compared to never being
sure.
Chuck Jensen
Message 16
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| Subject: | Re: Calibrating fuel qty gauges |
Thank you, Paul!
Stan
Do not archive
The poor guy wants a reliable fuel quantity meter. He did not ask
about proper flight planning and all you guys philosophy on that wrong
subject.
If there is an instrument in the plane it should reflect what is
going on. Like oil pressure should read correctly in flight as well
as on the ground. same thing with the volt meter etc.
Level sensing fuel gauges do not give reasonable accuracy in flight
but usually give good data on the ground. A flow meter gauge reads
fuel remaining any time it is powered on.
I cite the example of the famous Cessna fuel cap o-ring. On a flight
from Denver to Cheyenne with full tanks. The poor pilot arrived in
Cheyenne with no reserve. To bad he did not have a reliable gauge
that told him the fuel remaining was drastically decreasing. Even if
he watched his gauge he probably did not believe it because it is so
erratic in flight. For sure this was not a flight planning issue.
So a functional gauge especially with a warning feature would be
desirable in case it is desired to monitor a fuel related failure mode.
Bottom line is we do not have to live with garbage gauges that have
been used for years or newfangled level sensing gauges that only are
good on the ground.
I guess I don't understand the resistance to functional gauges.
Please set me straight.
Paul
Message 17
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| Subject: | Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 |
Geek, Nerd, or Ernest,
I'm surprised you are willing to accept the poor excuse for fuel
measurement we've had for the past 60 years. With your skills, I would have
expected you to jump on this challenge and solve it.
There must be a solution.
Stan
Do not archive
No resistance, Paul. It is just that I don't think they can be had for
reasonable dollars and effort. You're trying to hit a moving target.
Literally, the fuel is jumping around all over the place. You can have
mechanics integrate over time to come up with an average level. You can
have electronics integrate for you, or you can do the integration on
your own.
Every design is a different moving target, and every gauge will have a
slightly different calibration. Install a simple gauge, then get to
know how it behaves and you will be better off.
Message 18
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| Subject: | Re: Calibrating fuel qty gauges |
I believe the answer is a calibrated capacitance fuel gage system.
Bruce
www.Glasair.org
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Speedy11@aol.com
Sent: Friday, August 14, 2009 2:10 PM
Subject: AeroElectric-List: Re: Calibrating fuel qty gauges
Thank you, Paul!
Stan
Do not archive
The poor guy wants a reliable fuel quantity meter. He did not ask
about proper flight planning and all you guys philosophy on that wrong
subject.
If there is an instrument in the plane it should reflect what is
going on. Like oil pressure should read correctly in flight as well
as on the ground. same thing with the volt meter etc.
Level sensing fuel gauges do not give reasonable accuracy in flight
but usually give good data on the ground. A flow meter gauge reads
fuel remaining any time it is powered on.
I cite the example of the famous Cessna fuel cap o-ring. On a flight
from Denver to Cheyenne with full tanks. The poor pilot arrived in
Cheyenne with no reserve. To bad he did not have a reliable gauge
that told him the fuel remaining was drastically decreasing. Even if
he watched his gauge he probably did not believe it because it is so
erratic in flight. For sure this was not a flight planning issue.
So a functional gauge especially with a warning feature would be
desirable in case it is desired to monitor a fuel related failure mode.
Bottom line is we do not have to live with garbage gauges that have
been used for years or newfangled level sensing gauges that only are
good on the ground.
I guess I don't understand the resistance to functional gauges.
Please set me straight.
Paul
_____
Message 19
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| Subject: | Re: Calibrating fuel qty gauges |
But the bigger question is..
Does does one become content with flying an RV 8 after an F16??..:)
Frank
Do not archive
________________________________
From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr
ic-list-server@matronics.com] On Behalf Of Speedy11@aol.com
Sent: Friday, August 14, 2009 10:23 AM
Subject: AeroElectric-List: Re: Calibrating fuel qty gauges
Old Bob,
My thoughts exactly. I'm too timid to express them because of getting flam
ed on the forum.
But, you expressed my thoughts precisely. The T-38 was always flown to 20
minutes fuel remaining. We did the same in the F-4, F-5 and F-16. Once I
was chasing a F-16 student on initial solo and he landed, blew a tire and c
losed the only runway at MacDill. My 20 minute reserve was quite sufficien
t. Accel to 450 on the deck, climb at .87 to FL400 and do an idle descent
to final at Patrick. Still landed with plenty of fuel. The key is to have
a suitable back up plan. In custom built aircraft, we don't need the abil
ity to zoom climb to the moon - we simply need a suitable backup plan shoul
d something go wrong with the primary plan. If the back plan is good, then
flying to FAA fuel minimums is fine.
Message 20
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| Subject: | Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 |
Speedy11@aol.com wrote:
> Geek, Nerd, or Ernest,
> I'm surprised you are willing to accept the poor excuse for fuel
> measurement we've had for the past 60 years. With your skills, I
> would have expected you to jump on this challenge and solve it.
> There must be a solution.
> Stan
But, I have solved it. I installed a capacitive fuel gauge which Jim
Weir designed and published in KitPlanes.
I have a sight gauge as backup. It has a 3/8 opening, so I don't have
to worry about foaming causing inaccuracies.
The final element of the solution is integrating the dial's reading with
my mind.
Before we can design a solution, be have to define the problem. The
problem here is that you have a tank partially full of fuel.
Measurement, by necessity is taken at a point source. That is, we
assume the amount of fuel in the tank from the level of fuel at one
specific place in the tank. When the plane is accelerated, the levels
at various points in the tank move, and the assumption is no longer valid.
You could, at the risk of complexity, compensate for this movement by
placing several gauges at several points in the tank and integrating
them.. The hard part is where to place the sensors, and how much
importance to place on each.
Another option is to note that the splashing is periodic, let the gauge
reflect that, and use the skills learned in high school chemistry class
to interpret the results.
I think the second option is more robust.
--
Ernest Christley, President
Ernest@TechnicalTakedown.com
TechnicalTakedown, LLC
www.TechnicalTakedown.com
101 Steep Bank Dr.
Cary, NC 27518
(919) 741-9397
Message 21
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| Subject: | Re: Calibrating fuel qty gauges |
Good Afternoon Stan,
Thanks for the comment!
Nice to have company.
Planning is Planning. What you do is dependent on the accuracy of the data
available. Doesn't change if we are flying a 747, DC-3, J-3 Cub, T-38, or
RV-3 (I have flown all of those except the RV-3. <G>)
Happy Skies,
Old Bob
In a message dated 8/14/2009 12:28:05 P.M. Central Daylight Time,
Speedy11@aol.com writes:
Old Bob,
My thoughts exactly. I'm too timid to express them because of getting
flamed on the forum.
But, you expressed my thoughts precisely. The T-38 was always flown to 20
minutes fuel remaining. We did the same in the F-4, F-5 and F-16. Once I
was chasing a F-16 student on initial solo and he landed, blew a tire and
closed the only runway at MacDill. My 20 minute reserve was quite
sufficient. Accel to 450 on the deck, climb at .87 to FL400 and do an idle descent
to final at Patrick. Still landed with plenty of fuel. The key is to
have a suitable back up plan. In custom built aircraft, we don't need the
ability to zoom climb to the moon - we simply need a suitable backup plan
should something go wrong with the primary plan. If the back plan is good,
then flying to FAA fuel minimums is fine.
I like to know how much fuel is on board at any given time. Then I can
make decisions based on that information. The quantity information can be
obtained from a number of sources - gauges, optical sensors with warning
lights, preflight measurement, engine monitor calculations, and my own
calculations.
I desire accurate fuel gauges. If the accuracy of my fuel gauges is
questionable, then I must err on the conservative side which means I cannot
utilize my aircraft to its optimum.
I agree with Old Bob on this subject.
Stan Sutterfield
Good Afternoon 'Lectric Bob,
This may be just an exercise in semantics, but I do disagree with the
philosophy I think you are espousing.
There is nothing wrong with planning on arriving at a safe landing spot
with ten to fifteen minutes of fuel as long as you are confident you will
be
at that spot at the appointed time.
To say we should always have something beyond what is required is too
broad
for my liking. On those few occasions when I had the pleasure of flying a
T-38, we landed every time with "Bingo" fuel. In that airplane, Bingo
fuel
was a bit less than twenty minutes worth. Good enough for one full power
go
around and not much more.
We pay a LOT of money for every pound of payload we put in our flying
machines. I think it is very rational to reduce the amount of fuel down to
what
is required for the mission at hand. My cross country flyer has tip tanks
and it can fairly easily fly twelve hours with full tanks. My planning
for
that airplane often has me arriving with less than one hours worth of
fuel.
If I was able to be as certain of landing field availability as I was
when
flying the T-38 and as confident as I was of the accuracy of the fuel
gauges, I would not hesitate to fly my long ranger down to a Bingo fuel
of
twenty minutes.
Back when I was doing sling work with a helicopter, we added fuel for each
trip lifting air conditioners to a roof top. Carrying no more than about
five minutes of reserve fuel, we managed to get more air conditioners per
day
up on top of those roofs. The reserve fuel planned on should be based on
the accuracy of the fuel indicating system and the reliability of the
landing estimate
To do otherwise is as foolish as asking that every airplane be fitted with
four engines just in case one of them happens to quit. We have decided
that
a good single engine provides adequate safety for many of us. The same
thing goes for carrying extra fuel. Every ounce we carry that is not
needed
for the task at hand costs us money and $time$.
I prefer to know how much fuel is on board and how much I want when I
land.
Just my thoughts
Happy Skies,
Old Bob
____________________________________
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
Message 22
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| Subject: | Re: Calibrating fuel qty gauges |
Good Afternoon Frank,
I certainly cannot speak for Stan, but I am very happy with the aircraft I
now have available. Not sure whether content is the word for my present
state, but it beats being grounded!
Happy Skies,
Old Bob
Do Not Archive
In a message dated 8/14/2009 2:24:37 P.M. Central Daylight Time,
frank.hinde@hp.com writes:
But the bigger question is..
Does does one become content with flying an RV 8 after an F16??..:)
Frank
Do not archive
____________________________________
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Speedy11@aol.com
Sent: Friday, August 14, 2009 10:23 AM
Subject: AeroElectric-List: Re: Calibrating fuel qty gauges
Old Bob,
My thoughts exactly. I'm too timid to express them because of getting
flamed on the forum.
But, you expressed my thoughts precisely. The T-38 was always flown to 20
minutes fuel remaining. We did the same in the F-4, F-5 and F-16. Once I
was chasing a F-16 student on initial solo and he landed, blew a tire and
closed the only runway at MacDill. My 20 minute reserve was quite
sufficient. Accel to 450 on the deck, climb at .87 to FL400 and do an idle descent
to final at Patrick. Still landed with plenty of fuel. The key is to
have a suitable back up plan. In custom built aircraft, we don't need the
ability to zoom climb to the moon - we simply need a suitable backup plan
should something go wrong with the primary plan. If the back plan is good,
then flying to FAA fuel minimums is fine.
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
Message 23
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| Subject: | Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 |
How about engrave graduated markings on a tab that extends to the bottom
of the tank, an LED light source, and a CMOS camera to view the tab, and
another LCD screen on which to view the actual fuel in the tank? Would
have to mount the camera on/in something not damaged by fuel.. Aim the
camera so that you can also see tank outlet so that you can tell if you
are sucking air. Seeing is believing. Tongue only slightly in-cheek.
Matt-
> <echristley@nc.rr.com>
>
> Speedy11@aol.com wrote:
>> Geek, Nerd, or Ernest,
>> I'm surprised you are willing to accept the poor excuse for fuel
>> measurement we've had for the past 60 years. With your skills, I
>> would have expected you to jump on this challenge and solve it.
>> There must be a solution.
>> Stan
> But, I have solved it. I installed a capacitive fuel gauge which Jim
> Weir designed and published in KitPlanes.
> I have a sight gauge as backup. It has a 3/8 opening, so I don't have
> to worry about foaming causing inaccuracies.
> The final element of the solution is integrating the dial's reading with
> my mind.
>
> Before we can design a solution, be have to define the problem. The
> problem here is that you have a tank partially full of fuel.
> Measurement, by necessity is taken at a point source. That is, we
> assume the amount of fuel in the tank from the level of fuel at one
> specific place in the tank. When the plane is accelerated, the levels
> at various points in the tank move, and the assumption is no longer valid.
>
> You could, at the risk of complexity, compensate for this movement by
> placing several gauges at several points in the tank and integrating
> them.. The hard part is where to place the sensors, and how much
> importance to place on each.
>
> Another option is to note that the splashing is periodic, let the gauge
> reflect that, and use the skills learned in high school chemistry class
> to interpret the results.
>
> I think the second option is more robust.
>
> --
> Ernest Christley, President
> Ernest@TechnicalTakedown.com
>
> TechnicalTakedown, LLC
> www.TechnicalTakedown.com
> 101 Steep Bank Dr.
> Cary, NC 27518
> (919) 741-9397
>
>
Message 24
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| Subject: | Re: Why3 different alt disconnect relay wiring in Z |
schematics
Thanks, Bob :-)
> The preferred methodology for PM alernator control...
I understand that you prefer this method, but I don't know why.
Are you saying it's better to place the alt disconnect AFTER the regulator (as
in Z-20 and Z-21) than BETWEEN the alternator and regulator (as in Z-16)? I had
heard disconnecting a PM regulator wired with the relay after the the regulator
could damage the regulator. You would want a failed regulator disconnected,
but what would happen if a good regulator were taken offline?
Also, if the regulator fails and is taken offline by a relay placed after the regulator,
could the failed regulator present a fire hazard by continuing to heat
up from the uninterrupted supply of power to it from the alternator? If so,
could a relay placed between the alternator and regulator, instead of after the
regulator, cut the power to the failed regulator and prevent this?
> ...assuming you're NOT depending on the AC output waveform to drive
> an engine tachometer
I don't know if I need the AC waveform for the tach or not. The Jabiru manual shows
a magnetic sensor plugged into a tach sensor tab on the engine. 2 leads go
from there to the tach gauge on the panel. I don't know if I have this sensor
or sendor.
If I don't have it or can't get it, then I suppose I would need to use one of the
alternator AC leads. Is one method preffered over the other?
And Z-20L shows a wire spliced into one of the alternator output leads going to
the tach. So if I do need an AC lead, why wouldn't this work in Z-20L?
> ... Z-21 . . . suggests a means by which alternator control
> relay power to energize can come from either the battery
> or the alternator.
I don't understand how this works and why this is an advantage.
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=257697#257697
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| Subject: | Re: Calibrating fuel qty gauges |
>I cite the example of the famous Cessna fuel cap o-ring. On a flight
>from Denver to Cheyenne with full tanks. The poor pilot arrived in
>Cheyenne with no reserve. To bad he did not have a reliable gauge
>that told him the fuel remaining was drastically decreasing. Even if
>he watched his gauge he probably did not believe it because it is so
>erratic in flight. For sure this was not a flight planning issue.
This is why the electronic dip-sticks at the
low fuel warning level is so important. Nothing
to calibrate. It's ON or OFF. It's independent
of the more complex gaging systems requiring
calibration.
>So a functional gauge especially with a warning feature would be
>desirable in case it is desired to monitor a fuel related failure mode.
How about independent gaging and warning systems?
One helps keep tabs on functionality of the other
by observing behaviors from one flight to the next.
>Bottom line is we do not have to live with garbage gauges that have
>been used for years or newfangled level sensing gauges that only are
>good on the ground.
>
>I guess I don't understand the resistance to functional gauges.
>Please set me straight.
No resistance whatsoever. Only a caution about
understanding their functionality, risks for failure
by mis-reporting real fuel level and loss of the
pilot's healthy skepticism. It's my client's
charter that I help produce a best-we-know-how-to-
do in fuel gaging to replace the best we knew how
to do 25 years ago. I intend to deliver on that
charter. At the same time, my studies of older
designs (and bad days in the cockpit that began with
reliance on those designs) reminds me of a very
wise axiom: "Trust but verify".
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 26
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| Subject: | Re: Why3 different alt disconnect relay wiring |
in Z schematics
At 03:58 PM 8/14/2009, you wrote:
>
>Thanks, Bob :-)
>
>
> > The preferred methodology for PM alernator control...
>
>
>I understand that you prefer this method, but I don't know why.
Because it totally removes the alternator's ability
to deliver power by breaking the AC output power
leads. Breaking the DC power output lead will not
allow you to disconnect the alternator from a shorted
rectifier regulator thus putting the alternator at-risk
for second-failure follwing a regulator failure.
>Are you saying it's better to place the alt disconnect AFTER the
>regulator (as in Z-20 and Z-21) than BETWEEN the alternator and
>regulator (as in Z-16)?
No, directly in the AC output lead . . . but if
your tachometer depends on the AC frequency
signature of the alternator for measuring
engine speed, then you can't put the disconnect
at the preferred point.
> I had heard disconnecting a PM regulator wired with the relay
> after the the regulator could damage the regulator.
Some regulators may indeed be at risk if the system
is operating unloaded . . . but I doubt it. It's
a voltage rating issue for the semiconductors inside
the regulator. It's not a big deal to craft a rectifier
regulator tolerant of unloaded, full speed operations.
The two designs for PM regulators that I participated
in were NOT at risk for no-load, hi-speed ops.
> You would want a failed regulator disconnected, but what would
> happen if a good regulator were taken offline?
If the regulator is designed to live in the world
to which it's sold, then it shouldn't be a problem.
It's easy to do, it's what we did, but I can't speak
for others. Disconnecting the AC input lead is, therefore,
the preferred, low-risk philosophy for ALL regulators.
>Also, if the regulator fails and is taken offline by a relay placed
>after the regulator, could the failed regulator present a fire
>hazard by continuing to heat up from the uninterrupted supply of
>power to it from the alternator? If so, could a relay placed between
>the alternator and regulator, instead of after the regulator, cut
>the power to the failed regulator and prevent this?
No fire risk. You might burn some alternator wires
but this isn't inherently hazardous beyond damage
to the alternator itself. If your tachometer doesn't
require a signal from the alternator, go with Z-16.
Bob . . .
Message 27
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| Subject: | Re: Why3 different alt disconnect relay wiring in Z |
schematics
> The preferred methodology for PM alernator control assuming
> you're NOT depending on the AC output waveform to drive
> an engine tachometer as shown in http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z20L.pdf where we see the AC windings permanently connected
> to the rectifier/regulator. Here, alternator control reverts
> to the older philosophy of opening the DC power output
> lead from the R/R.
>
> ....Thanks, Bob
> > The preferred methodology for PM alernator control...
> I understand that you prefer this method, but I don't know why.......
>
>
> ......Because it totally removes the alternator's ability
> to deliver power by breaking the AC output power leads.
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=257731#257731
Message 28
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| Subject: | Re: Calibrating fuel qty gauges |
At 12:50 PM 8/14/2009, you wrote:
>Bob,
>The pilots on this forum are every bit as capable as professional
>pilots - including optimizing the amount of fuel on board. One
>simply must plan the flight including a back up plan (maybe two or
>three), crosscheck himself along the way, and execute the most
>appropriate of the plans - with Plan A being primary.
>Regarding using accurate fuel information of make high risk
>"press-on" decisions, the pilot must consider all information before
>making a decision - whether to press on or to divert. WX, alternate
>airports, terrain, aircraft familiarity, airport familiarity,
>fatigue, and fuel quantity are all inputs to the decision
>process. A decision to press on is not necessarily exponentially
>higher risk than a diversion plan. In fact, it may be less risk if
>the destination airport is familiar with a suitable length runway
>whereas the divert airport is unfamiliar with a minimum length
>runway. There are many variables - one reason flying is fun.
>Now about getting those accurate fuel gauges with which to make my
>divert decision.
>Stan Sutterfield
Stan, you have missed the point. I was not suggesting
that ANY particular individual on this List was
incapable of operating an airplane in a prudent
manner. I WAS counseling caution with respect to
pushing the limits of endurance based on FAITH in
a fuel gaging system that was not personally calibrated
and verified by the owner/operator. Whether or not
that caution applies to you is something only
you can judge . . . it was not offered to you
or anyone in particular.
We've got builders wrestling with getting the
voltage regulators set right. Is it a good idea
to take bullet points from the 4-color brochure of any
OBAM aircraft gaging system and encourage our
fellow builders to take them as gospel?
We've read about the experiences and sentiments
of individuals who routinely and confidently
ran out the slosh many times in airplanes. But just
a few weeks ago we discussed the sad demise of a
builder who appeared to have lot of confidence from
source(s) unknown, yet his confidence proved fatal.
I'm working an accident now where a builder cherry
picked pieces of ideas from the 'Connection, from
a radio installation manual, and what appears to
have been advice from a friend. These were assembled
into a system designed to fail . . . and it did.
The thrust of my postings was two-fold . . . and
you've been around here long enough to understand
it as well as anyone. First, there is no substitute
for understanding the capabilities and limits of
any system upon which you plan to push the limits
of performance. Second, there is a well tested, legacy
process by which failure tolerant systems are designed
where an UNWILLINGNESS to push out to fuzzy limits
can be a useful component of raising confidence level
in the outcome of any flight. This is about risk
reduction.
It is technologically feasible to build, calibrate,
verify and maintain an accurate fuel gage that
would allow the willing pilot to taxi up to the
pumps with one gallon remaining . . . or fumes for
that matter. But I will never suggest that anyone
strive for that kind of performance as a design goal.
Further, I'm aware of no fuel gage presently offered
to the OBAM aircraft market capable of offering
that performance. Even if the gage existed and proved
capable, it would be wise for the supplier of that
product to discourage tugging the tail of the
fuel tiger.
I've spent many years working in a flight test environment
where pilots and program managers routinely got in
my face demanding assurances that the thing I just
bolted to their airplane wasn't going to cause a bad
day in the cockpit. I can also state that if any one
of those pilots taxied to the ramp with 10 minutes
remaining and then claimed that he could do it
routinely and at will would not be working where I
worked very long. Because we all know that fuel
gages on even our engineering flight test aircraft
are never calibrated and maintained to that degree of
accuracy.
You're encouraged to craft and operate your airplane
in any manner for which you have necessary skill and
acquired confidence. Please don't paint me with the
tar brush for suggesting that 1800 folks besides you
avoid landing with all the low fuel warning lights
flashing and the needles banging the stops.
I would be severely distressed to learn that the RV-10
went down because of some erroneous notions or shaky
ideas the pilot acquired on this List. Balance and
maneuvering skills necessary to ride a bike does not
make one good at walking the high wire.
Bob . . .
Message 29
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| Subject: | Re: Two fuses in series? |
At 11:01 AM 8/14/2009, you wrote:
>Is it ever logical to put two fuses in series? I am attaching a
>PDF. In the lower center area of the drawing, look at the switch
>labeled ECU PWR & Injectors.
>
>The idea is, if the SYS A ECU should blow, I wouldn't want a common
>fuse taking out the SYS B ECU. Or is there another way to do this
>without adding anymore switches? Maybe a fuse link, back at the
>main battery bus?
>
>I now have 9 test flights in and I'm still fighting oil temp and
>highly experimental induction issues.
Each ECU should enjoy its own fuse at the bus and
ideally be switched with it's own power switch.
Alternatively, consider going to a 3-pole switch
so that the two ECU's have no power path in common,
only the single switch.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 30
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| Subject: | Re: Why3 different alt disconnect relay wiring in Z |
schematics
> The preferred methodology for PM alernator control assuming
> you're NOT depending on the AC output waveform to drive
> an engine tachometer as shown in http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z20L.pdf where we see the AC windings permanently connected
> to the rectifier/regulator. Here, alternator control reverts
> to the older philosophy of opening the DC power output
> lead from the R/R.
>
> ....Thanks, Bob
> > The preferred methodology for PM alernator control...
> I understand that you prefer this method, but I don't know why.......
>
>
> ......Because it totally removes the alternator's ability
> to deliver power by breaking the AC output power leads.
Sorry about double posting. Meant to hit the preview button :-(
It seemed to me you were saying the Z-20 method of breaking the DC leads was best,
but now I see you mean breaking AC is best, like in Z-16.
So even if I ran the tachometer off the AC leads, I'd only have no tach when the
alternator is offline. I haven't seen the tachometer show up on anybody's Ebus
list, so going with the preferred AC disconnect might be better even in this
situation.
--------
Dan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=257733#257733
Message 31
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| Subject: | Re: AeroElectric-List Digest: 41 Msgs - |
08/13/09
At 03:43 PM 8/14/2009, you wrote:
>
>How about engrave graduated markings on a tab that extends to the bottom
>of the tank, an LED light source, and a CMOS camera to view the tab, and
>another LCD screen on which to view the actual fuel in the tank? Would
>have to mount the camera on/in something not damaged by fuel.. Aim the
>camera so that you can also see tank outlet so that you can tell if you
>are sucking air. Seeing is believing. Tongue only slightly in-cheek.
Actually, been there done that. I worked a Baron accident
about 30 years ago where there were allegations made
about behavior of fuel in partially filled tanks. We did
some testing that involved mounting a stack of 1/2" thick
optical sensors at the outlet of the tank. Each sensor
drove one light bulb in a vertical array on the panel.
Each light representing 1/2 of fuel depth at the outlet.
Had the privilege of meeting and flying with Al White
who was hired by Beech's law firm as a "disinterested
witness".
http://en.wikipedia.org/wiki/Alvin_S._White
We did a lot of maneuvers on the ground and in the air
with varying amounts of fuel in the tank to document
behavior. Bottom line was that we verified Beech's
admonition not to take off using main tanks and to
be careful about certain maneuvers after the tanks
were drawn below about 7 gal. Later, another group
stuck a camera and lights to record more details.
That stack of prisms at the outlet is not hard to build
if anyone wants to try it. I can recall seeing
that column of lights really "stroking" under pretty
ordinary conditions. It's pretty exciting in that
tank. Baffles and check valves are useful to
reduce violence of liquid motion.
Bob . . .
Message 32
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| Subject: | Re: AeroElectric-List Digest: 41 Msgs - 08/13/09 |
At 01:14 PM 8/14/2009, you wrote:
>Geek, Nerd, or Ernest,
>I'm surprised you are willing to accept the poor excuse for fuel
>measurement we've had for the past 60 years. With your skills, I
>would have expected you to jump on this challenge and solve it.
>There must be a solution.
Design goals for the system I'm working on now include
in-situ calibration at intervals equal to 5% of full
capacity. So an accuracy on the order of 2% of tank
capacity seems achievable. But even if it becomes
a product on either the TC or OBAM side of the house,
I'd still be reluctant to recommend that anyone plan
a flight that draws a tank down to less than 30 minutes
total fuel aboard.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 33
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| Subject: | Re: Two fuses in series? |
Yes, that is my preference, but I haven't figured out how to do that. The
limitation is the number of switches I already have installed, as seen at
the top of the drawing, and space limitation. I tried to install B&Cs
OFF-ON-ON switch, but it is fatter than the rest and does not fit.
I am dumfluxed. It is not an easy solution. If it was, I would have nailed
it down a year ago.
Sam
On Fri, Aug 14, 2009 at 9:30 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com>
>
>
> At 11:01 AM 8/14/2009, you wrote:
>
>> Is it ever logical to put two fuses in series? I am attaching a PDF. In
>> the lower center area of the drawing, look at the switch labeled ECU PWR &
>> Injectors.
>>
>> The idea is, if the SYS A ECU should blow, I wouldn't want a common fuse
>> taking out the SYS B ECU. Or is there another way to do this without adding
>> anymore switches? Maybe a fuse link, back at the main battery bus?
>>
>> I now have 9 test flights in and I'm still fighting oil temp and highly
>> experimental induction issues.
>>
>
> Each ECU should enjoy its own fuse at the bus and
> ideally be switched with it's own power switch.
> Alternatively, consider going to a 3-pole switch
> so that the two ECU's have no power path in common,
> only the single switch.
>
>
> Bob . . .
>
> ---------------------------------------
> ( . . . a long habit of not thinking )
> ( a thing wrong, gives it a superficial )
> ( appearance of being right . . . )
> ( )
> ( -Thomas Paine 1776- )
> ---------------------------------------
>
>
Message 34
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| Subject: | Re: Calibrating fuel qty gauges |
Good Evening 'Lectric Bob,
It appears to me that this discussion is getting way out of hand
I know I should leave it alone.
Nevertheless, I do not think you, Stan, or I are very far apart in what we
really want to see happen.
None of us want to see anyone run out of fuel.
I have mentioned occasions where I have found five to ten minutes of fuel
to be perfectly safe, but none of those were in conditions where the 30
minute FAA minimum was applicable. They were in operations where the conditions
and equipment warranted such operations and they were in complete
accordance with procedures approved by the ruling authority of that particular
operation.
I very rarely operate a trip where I plan on landing with as low a fuel
quantity as the FARs allow. That there are cases where such operations are at
least as safe as carrying five hours of extra fuel is not important.
What is important is that a rational decision has been made that is in
conformance with the regulations established for that particular operation.
My WAG is that it's much more likely that a person who has no idea how much
fuel is on board is more likely to run out of fuel than will a person who
knows exactly how much fuel is available.
Safety of flight is a function of acquiring data and making sensible
decisions based on that data. We are given guidance on those decisions by
various governing bodies. As long as we obey the rules and do the planning we
are
expected to do, all should be well. Or, at least, well within the level of
risk accepted for that operation.
It is obvious to me that we are looking at this problem from different
perspectives. It is too bad that we do not seem to be able to find a common
ground, but I think we can all agree that having accurate fuel flow equipment
is a good thing and having accurate knowledge of the fuel on board is a
good thing.
Any chance of agreement on those two points?
Happy Skies,
Old Bob
In a message dated 8/14/2009 9:25:38 P.M. Central Daylight Time,
nuckolls.bob@aeroelectric.com writes:
At 12:50 PM 8/14/2009, you wrote:
Bob,
The pilots on this forum are every bit as capable as professional pilots -
including optimizing the amount of fuel on board. One simply must plan
the flight including a back up plan (maybe two or three), crosscheck himself
along the way, and execute the most appropriate of the plans - with Plan A
being primary.
Regarding using accurate fuel information of make high risk "press-on"
decisions, the pilot must consider all information before making a decision -
whether to press on or to divert. WX, alternate airports, terrain,
aircraft familiarity, airport familiarity, fatigue, and fuel quantity are all
inputs to the decision process. A decision to press on is not necessarily
exponentially higher risk than a diversion plan. In fact, it may be less risk
if the destination airport is familiar with a suitable length runway
whereas the divert airport is unfamiliar with a minimum length runway. There
are many variables - one reason flying is fun.
Now about getting those accurate fuel gauges with which to make my divert
decision.
Stan Sutterfield
Stan, you have missed the point. I was not suggesting
that ANY particular individual on this List was
incapable of operating an airplane in a prudent
manner. I WAS counseling caution with respect to
pushing the limits of endurance based on FAITH in
a fuel gaging system that was not personally calibrated
and verified by the owner/operator. Whether or not
that caution applies to you is something only
you can judge . . . it was not offered to you
or anyone in particular.
We've got builders wrestling with getting the
voltage regulators set right. Is it a good idea
to take bullet points from the 4-color brochure of any
OBAM aircraft gaging system and encourage our
fellow builders to take them as gospel?
We've read about the experiences and sentiments
of individuals who routinely and confidently
ran out the slosh many times in airplanes. But just
a few weeks ago we discussed the sad demise of a
builder who appeared to have lot of confidence from
source(s) unknown, yet his confidence proved fatal.
I'm working an accident now where a builder cherry
picked pieces of ideas from the 'Connection, from
a radio installation manual, and what appears to
have been advice from a friend. These were assembled
into a system designed to fail . . . and it did.
The thrust of my postings was two-fold . . . and
you've been around here long enough to understand
it as well as anyone. First, there is no substitute
for understanding the capabilities and limits of
any system upon which you plan to push the limits
of performance. Second, there is a well tested, legacy
process by which failure tolerant systems are designed
where an UNWILLINGNESS to push out to fuzzy limits
can be a useful component of raising confidence level
in the outcome of any flight. This is about risk
reduction.
It is technologically feasible to build, calibrate,
verify and maintain an accurate fuel gage that
would allow the willing pilot to taxi up to the
pumps with one gallon remaining . . . or fumes for
that matter. But I will never suggest that anyone
strive for that kind of performance as a design goal.
Further, I'm aware of no fuel gage presently offered
to the OBAM aircraft market capable of offering
that performance. Even if the gage existed and proved
capable, it would be wise for the supplier of that
product to discourage tugging the tail of the
fuel tiger.
I've spent many years working in a flight test environment
where pilots and program managers routinely got in
my face demanding assurances that the thing I just
bolted to their airplane wasn't going to cause a bad
day in the cockpit. I can also state that if any one
of those pilots taxied to the ramp with 10 minutes
remaining and then claimed that he could do it
routinely and at will would not be working where I
worked very long. Because we all know that fuel
gages on even our engineering flight test aircraft
are never calibrated and maintained to that degree of
accuracy.
You're encouraged to craft and operate your airplane
in any manner for which you have necessary skill and
acquired confidence. Please don't paint me with the
tar brush for suggesting that 1800 folks besides you
avoid landing with all the low fuel warning lights
flashing and the needles banging the stops.
I would be severely distressed to learn that the RV-10
went down because of some erroneous notions or shaky
ideas the pilot acquired on this List. Balance and
maneuvering skills necessary to ride a bike does not
make one good at walking the high wire.
Bob . . .
(http://www.matronics.com/Navigator?AeroElectric-List)
(http://www.matronics.com/contribution)
Message 35
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| Subject: | Two fuses in series? |
Hello Sam,
The principle is not unusual in protection of power electrical systems;
isolation of part of a system rather than the whole system. I would be
concerned with the actual tripping characteristic of the fuse though.
Normally protective devices, such as a fuse, have an 'inverse time tripping'
characteristic- which means that the higher the current through them the
faster they trip/ blow. When one is coordinating the protection on a power
electrical system you need to make sure that these characteristics do not
overlap so that the 'upstream' fuse/device does not trip first. I think
that you would need to use what are called 'fast blow' fuses for the 5A fuse
and 'slow blow' for the 10A so that the 10A fuse gives the 5A a chance to
clear the fault.
How come you do not have a 5A fuse in the 'SYS B' ECU circuit?
Jay
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sam
Hoskins
Sent: 14 August 2009 06:02 PM
Subject: AeroElectric-List: Two fuses in series?
Is it ever logical to put two fuses in series? I am attaching a PDF. In
the lower center area of the drawing, look at the switch labeled ECU PWR &
Injectors.
The idea is, if the SYS A ECU should blow, I wouldn't want a common fuse
taking out the SYS B ECU. Or is there another way to do this without adding
anymore switches? Maybe a fuse link, back at the main battery bus?
I now have 9 test flights in and I'm still fighting oil temp and highly
experimental induction issues.
Thanks.
Sam
www.samhoskins.blogspot.com
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